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Home My WebLink About1992-05-12; City Council; 11679; MASTER DRAINAGE AND STORM WATER QUALITY MANAGEMENT PLANC I@ OF CARLSBAD - AGEW-A BILL 47. AB # 11, (i "77 TITLE: MASTER DRAINAGE AND STORM WATER QUALITV MANAGEMENT PIAN DEPT, I MTG, 5/12/92 CITY A I DEPT. ENG I I CITY M I I I 1 RECOMMENDED ACTION: That City Council accept the Master Drainage and etorrn Water Quality Managemen dated April 1992, authorize staff to solicit public and industry comments and schec public hearing for adoption of the final report and implementing ordinances. I ITEM EXPLANATION Q 0 9 !E 2 In February, 1988, City Council approved a contract with Fraser Engineering Inc Cooper Engineering Associates to update the 1980 Master Drainage Plan. Since tha the contract has undergone several delays and setbacks; however, the update i5 complete and staff offers for Council acceptance the proposed Master Drainage entitled Master Drainage and Storm Water Quality Management Plan (Master Plan) 1 April 1992. The full Master Plan report includes the Master Drainage and Storm Water C Management Plan document included with the agenda packet together with App documents "C" through "L" on file with the Engineering Department. The app documents provide greater detail on future facility sizing and cost estimates, Ft Emergency Management Agency reviews of the major drainage basins and dra calculations. The Council's attention is directed to Chapter 1 of the report "Executive Summary' brief overview of the goals and objectives, report background and synopsis of the recommendations. In addition, a detailed staff analysis of the report recommend' and their impacts on the development process is included in the memorandum datel 4, 1992 from the Assistant City Engineer to the Community Development Di recommended use of the Benefit Assessment Act of 1982 as a alternative me: financing ongoing maintenance and operation functions for the City's storm dri facilities. At this time, staff is recommending Council acceptance of the Master Plan documel authorization to solicit public and industry comment on the proposed Master Plan. Council authorization, it is staff's intention to present the plan for public inpu minimum of one community meeting attended by industry representatives as well : interested members of the public. The document will then be brought before ' Planning Commission as an information item for their review and comment. Onc public review process has been completed, the Master Plan and implementing ordin will be brought back to City Council for final approval and adoption. (attached Exhibit 2). This memorandum also provides additional information c I z 0 E i a z 3 0 0 FISCAL IMPACT The Master Plan update identifies 44.2 million dollars worth of future drainage improvements. Should the recommendations of this report be adopted, 39.5 million ( of this total would be raised through the exaction of facility fees on new and re building permits, The remaining 4.7 million dollars was previously allocated 6 construction of the downtown AT&SF railroad drainage facility (identified as facility the Master Plan). PAGE TWO OF AB NO. 1 I, 6 '7 9 0 0 Currently, there is approximately $1,780,000 available within the existing Planned L Drainage Area (PLDA) fee accounts. All funds collected to date are needed to cons facilities identified in both the 1980 Master Drainage plan and the proposed Master update. These funds will be transferred to the appropriate PLDA fee accounts I Council adoption of the updated Master Plan report and implementing ordinances. ENVIRONMENTAL REVIEW A Negative Declaration was issued by the Planning Director on April 30, 1992. EXHIBITS: 1. Master Drainage and Storm Water Quality Management Plan on file in the c of the City Engineer. 2. Memo from Assistant City Engineer to- Community Development Director d May 4, 1992. e 0 May 4, 1992 TO : Community Development Director FROM: Assistant City Engineer &@--- STAFF ANALYSIS OF DRAFT MASTER DRAINAGE AND STORM WATER QUALIT' MANAGEMENT PLAN The final draft of the Master Drainage and Storm Water Quality Management Plan (Mast€ Drainage Plan) is now complete and ready for City Council approval. The Master Drainag Plan was several years in the making and contains numerous recommendations tha deviate from the existing Master Drainage Plan program. This memo is intended t highlight the recommended changes and explain how the recommendations will effec City operations and the development process. The recommendations in the Master Drainage Plan document can be grouped into twc categories, those relating to the fee exaction program and those which relate to the Storn Water Quality Management Program. Storm Water Quality Manaaement Proclram In the midst of preparing the Master Drainage Plan document, the Regional Water Qualit! Control Board mandated City compliance with Federal storm water quality regulations a a co-permittee on a National Pollutant Discharge Elimination System (NPDES) permit. Thi: mandate forced a fundamental shift in the focus of the Master Drainage Plan from l program of purely flood control to a program of flood control and water qualit) enhancement. The primary effect of this shift in focus was the inclusion of a storm water qualit) management plan within the text of the report, the elimination of numerous concrete line( channels from the drainage plan and the inclusion of approximately one million dollars ir equipment and facility improvements to accomodate storm water testing and monitoring Chapter 5 of the Master Drainage Plan includes a complete discussion of the storm wate quality management program together with a recommended implementation program tc obtain compliance with the NPDES permit. The concrete lined channels were eliminate( along most of the major creek corridors in favor of naturalized or enhanced naturalizec channels. Unlined channels greatly contribute to the enhancement of storm water flows through soil filtration and natural biologic processes. In addition to water qualit) enhancement, the elimination of these concrete channels reduces negative environmenta impacts, adds to available open space, reduces facility costs and dovetails nicely with thc City's proposed Habitat Management Plan. 0 The primary thrust of Chapter 5 "Storm Water Quality Management Program" is thl creation of an implementation plan for the NPDES permit. In fact, the entire draft text o Chapter 5 was sent to the Regional Water Quality Control Board in satisfaction of th NPDES permit requirement for a draft implementation program. The major elements of th program, illicit connection and illegal discharge detection program and a program of Be: Management Practices (BMP). The concept of Best Management Practices is to essential1 do everything that is reasonable and economically feasible to reduce the inflow an transport of urban pollutants into and through the storm drainage system. Typically BMP' include the construction of pollutant control devices, sediment and siltation control, stree sweeping, storm water facility maintenance, public education, hazardous wast management, recycling and other source reduction controls and programs. Water Qualitv Financina Recommendations implementation program include the creation of a storm water monitoring and testin In preparing the Storm Water Quality Management Program, staff recognized thr implementation will be costly and, therefore, included recommendations on differer financing alternatives within the report. Presently, the City expends approximatel $31 0,000 of General Fund monies on programs that improve storm water quality. Thi includes $140,000 for drainage facility cleaning and maintenance and $1 70,000 fc street sweeping activities. In addition, the City is required to begin implementation of yearly testing and monitoring program with an estimated annual cost of $50,000 t $100,000. Future program requirements will likely include greater maintenance effort3 especially for sediment basins, increased enforcement against illegal dischargers and a ongoing public awareness campaign. The total cost of the storm water quality management program could easily reach a ha million dollars per year for the existing facilities and rise to a million dollars per year 2 facility buildout. Presently, such activities are funded out of the general fund. Give recent economic projections, it is unlikely that the required expansion of operations ca be accommodated through this funding source without cutting back on other program: The Master Drainage Plan report therefore recommends the investigation of tw alternative funding mechanisms. These include the creation of a drainage utility or drainage maintenance district. Both funding mechanisms require a majority vote of the voters included within the are of benefit. A drainage utility would function similar to a water or sewer utility. Month1 drainage fees would be assessed against properties in proportion to their size and Ian use. Collection would be accommodated through the existing water billing process i much the same manner as the collection of solid waste disposal fees. One potenti; problem with the formation of a drainage utility is that it is not entirely certain that ther is sufficient enabling state legislation to allow general law cities the ability to form ont It is reported that several cities in the state are currently in the process of forming suc a utility so more information on this form of revenue generation can be gained. 0 0 Alternatively, a drainage maintenance district can be formed under the Benefi Assessment Act of 1982 on all or any portion of the City in much the same manner a: the existing City Street Light and Landscape Assessment District. Fees would be chargec similar to a drainage utility except that collection would occur on in two installments 01 the property tax bill, One benefit of a drainage maintenance district is that it could b formed over a small area and expanded through an annexation process as propertie develop. Later on, existing development areas could be annexed upon majority vote of thr voters. An inherent problem with the partial district option is that new homeowners woulc be paying into the district while existing residents would not. It should be noted that thc district to maintain drainage facilities to be constructed in the Calavera Creek drainagi basin. The Master Drainage Plan recommendations do not require formation of a drainage utilitv or a maintenance district at this time. Rather, it recommends investigation of thesl alternatives as a way of reducing the potential financial burden to the General Fund Should Council approve the report with this recommendation intact, then the Utilities anc Maintenance Director and/or the City Engineer would in the future prepare a more detailel analysis and report for Council consideration. It can be expected that formation of eithel a utility or a district would necessitate considerable consultant expenses in preparing tht required assessment/fee spreads and districthtility reports. financing plan for Zone 7 currently calls for the formation of a drainage maintenancc Facilitv Fee Proaram The Master Drainage Plan report contains numerous facility fee recommendations whick differ significantly from the existing drainage facility fee program. This section of the staf, analysis is intended to explain the differences and to project the impacts on thc development process and the administration of the drainage facility program. The majo changes are enumerated as follows: 1) Use of AB 1600 as the basis of the drainage facility fee program. Currentl) drainage fees are collected under enabling legislation in the State Map Act. A3 such only subdivision developments are presently subject to drainage area fees Because approximately half of the City is developed or will not require z subdivision of land to develop, the existing fee program has a shortfall in funds 01 approximately 24 million dollars. AB 1600 allows for the collection of facility fees for all developments that have i need for or which impact a public facility. Since all properties have drainagc impacts and because drainage facilities have beneficial impacts to vehiculal movement, vector control and water quality enhancement, the proposed fee program can be applied to all development including redevelopment and remodeling activities. The use of AB 1600 as the basis of the fee program will result in the collection of an additional 20 million dollars in fee revenues. 0 0 2) Consolidation of the existing thirteen Planned Local Drainage Areas (PLDA together with the remainder of the City into four PLDA's. The four PLDA's wi correspond with the four major drainage basins within the City. This proposal wi fee accounts. It will also allow for the consolidation of funds from a larger base c properties such that adequate funds should be available to construct neede facilities in a more timely manner than can be presently accomodated. result in reduced administration time tracking and accounting for numerous PLDI 3) Exclusion of all growth management environmentally constrained lands from thc calculation of the available developable land base. The existing fee progran included all vacant land within the fee base. Since much of this land would not b8 developed it contributed further to the under collection of PLDA fees. The nev program accounts for this undevelopable land and provides a measure of relief t property owners whose land contains significant portions of constrained lands. I, other words, if it won't be developed it won't cause an impact and thus not b charged a fee. 4) Separation of the fees into two subcategories representing properties with hig runoff potential (commercial, industrial and high density residential zones) anc properties with low runoff potential (low and medium density residential tones1 This proposal places a higher fee burden on those developments that have thl greatest impact on the facilities. Generally, higher density developments are bette able to pay for facility impacts so this recommendation should not be to( detrimental to developers. 5) Require fee payment for all redevelopment projects and for all remodels whereii the building footprint is increased by 50% or greater. As discussed in item above, this recommendation recognizes the impacts caused by such developmen and allows for collection of fees in existing built out areas. The typical fee for ; residential remodel on a 7500 square foot lot would range from $300 to $701 dollars. 6) Eliminate the use of fee credits for onsite Master Plan facilities and make greate utilization of reimbursement agreements as the means of reimbursing developer: for constructed facilities. The current drainage fee ordinance allows developers tc receive fee credits for any Master Planned drainage facilities constructed with thc property development. The credit system essentially places control over facility planning to the developer inasmuch as facility fees are credited to the developer'$ immediate project. Other projects which may have a greater "City" priority and fo which the fees are also established can not be constructed because insufficien, funds are available for construction. * e The report recommendation is to eliminate fee credits altogether. Developers wi be required to secure construction of required Master Plan facilities prior to fin: map or issuance of building permits depending on the type of development. Th developer would then enter into a reimbursement agreement with the Cit) Reimbursements would be provided from the appropriate PLDA accounts dependin1 upon availability of funds and the needs of the Capital Improvement Program Because the fees are recommended to be paid at time of building permit issuanc and not the final map as currently practiced, the impact to the developer shoul be somewhat moderate. Reimbursements will be based on actual constructio costs. If the actual construction cost exceeds the facility cost as estimated in th report, a fee adjustment may be necessary to accommodate the increase il expenditure. DAVID HAUSER dah a r 0 %LA JwLm ATTORN EY AT LAW 1533 SOUTH HILL ST., SUITE D OCEANSIDE, CA 92054 MAY 12, 1992 Mayor and Councilmembers City of Carlsbad OFFICE: (61 9) 722-s RES.: (61 9) 722-: RE Carlsbad Master Drainage Plan and specifically drainage area DA and DAA fie+- @ 6 Mayor and Councilmembers; I represent Dale L. Schreiber, the owner of approximately five acres of property located at the intersection of Ponto Drive and Highway 101. The proposed master drainage plan for this area diverts the water from easterly of the AT&SF Railroad, forces it Westerly across my client's property and requires the need for another desiltation/retention basin in the wetlands at the mouth of the Batisquitas Lagoon. Attached is a photographic copy of the area. The following impacts are created by this diversion of water which could just as easily go easterly of the AT&SF Railroad into the existing desiltation/retention basin as previously approved in the SAMMIS DEVELOPMENT PLAN: 1. Creating a new large undercrossing of the AT&SF to accomodate a 78" pipe. 2. Relocation of the 16" high pressure gas line located westerly of the ATdSF Railroad. 3. Relocation of the main telephone trunk lines located westerly of the AT&SF Railroad. 4. Requirement to purchase easements for drainage where development will not be occurring. 5. Requiring a new at-grade intersection in the vicinity of Ponto Drive and 101. 6. Requiring filling of the land area at the existing Ponto Drive intersection. 7. Forcing a cost for construction that is not economically feasible to be borne by the affected land. 8. A loss of use of productive land because of a prior temporary drain system installed by the City of Carlsbad with no downstream improvements. I do not believe any independent work was done by the consultants in this study concerning the area under discussion. The westerly drainage system was the product of the drainage report accepted by the council in 1988 for zone 9. SqQm,7"p3 p9 C'7Y cnUdC/L I p,,c~ptJG &I= A-]/kj?k f42 * e Mr. Schreiber has expended in excess of $8,000 in the past year for help from engineers and professionals to understand the drainage problem. He has also had to sue his upland neighbor Mr. Chappee to force Mr. Chappee to retain the flood waters created by the City so that his business would not be washed downstream. Recently, the 16" gas line was undermined by storm waters coming into the area. This matter was referred to the gas company. I object to the negative declaration submitted by the planning department in that the Master Drainage Plan by itself will cause many environmental changes as well as impact the wetlands of the Batisquitas Lagoon because the document is the guide for a very specific solution to the storm water drainage in the area. This master plan needs to be resolved as quickly as possible in order to resolve the many issues which have been created by the City over the past seven years. Re pectf lly ubmitted l&u OUIS' TASCHNER Atorney for DALE L. SCHREIBER I I 'I I I I I I I I I I I I I I I I I I 1 I Table of Contents CHAPTER 1, EXECUTIVE SUMMARY ................................................................................ A. Goals and Objectives ....................................................................................................... B. Background ...................................................................................................................... C. Recommendations ............................................................................................................ CHAPTER 2, PLANNING AREA CHARACTERISTICS ..................................................... A, Planning Area BoundanestttttItt,ttttItt~~tt~tt~~~lt,,,t,t,t,l~~t~,~~~~~~t,,t,tltlt,lt,,,l,,,,,,,,,,,,,,,,,,,,,, ,,,..,,~ B. Physical Environment ...................................................................................................... C. Land Use .......................................................................................................................... D. Design Sensitivities .......................................................................................................... CHAPTER 3, METHODOLOGY ............................................................................................ A. Study Approach ............................................................................................................... B. Hydrologic Design Criteria .............................................................................................. D. Design Procedure ............................................................................................................. E. Computer Program ........................................................................................................... F. Sedimentation Basins .................................................................................................... .., C. Design Runoff Method ..................................................................................................... CHAPTER 4, FINANCING .: ..................................................................................................., A. General ............................................................................................................................ B. Source of Authority ......................................................................................................... C. History ............................................................................................................................. D. Present Financial Status ................................................................................................... E. Financing Method Alternatives ........................................................................................ G. Planned Local Drainage Areas (PLDA’s) ......................................................................... H. Fee Analysis .................................................................................................................... I. Fee Adjustments ................................................................................................................ J. Reimbursement for Constructed Facilities ......................................................................... CHAPTER 5, STORM WATER QUALITY MANAGEMENT PROGRAM ........................ A. Introduction .................................................................................................................... B. Brief History of Actions Leading to City’s NPDES Permit ............................................. C. ‘‘Early” NPDES Permi ..................................................................................................... D. Elements of Carlsbad’s Storm Water Quality Management Program ................................ E. Testing and Monitoring of Storm Water and Urban Runoff .............................................. F. Detection of Illicit Connections and Illegal Discharges ..................................................... G. Best Management Practices (BMP) .................................................................................. H. Program Costs and Funding ............................................................................................. F. Financing Recommendations ............................................................................................ 1992 Carlsbad Master Drainage and Table of Cc Storm Water Quality Management Plan CHAPTER 6, COST EmIMATES ............................................................................................. t A. General .............................................................................................................................. 4 B. Unit Costs .......................................................................................................................... I C. Additional costs .................................................................................................................. D. Estimated Construction bts .............................................................................................. CHAPTER 7, SUMMARY OF FIELD INVESTIGATIONS ..................................................... ( A. Introduction ........................................................................................................................ I B. Buena Vista Creek Basin .................................................................................................... C. Agua Hedionda Creek Basin ............................................................................................... D. Encinas Creek Basin ........................................................................................................... , E. San Marcos Creek Basin ...................................................................................................... F. Findings ............................................................................................................................... APPENDIX A, PROPOSED DRAINAGE FACILITIES ............................................................ A. Introduction ......................................................................................................................... B. Buena Vista Creek Basin ..................................................................................................... C. Agua Hedionda Creek Basin ................................................................................................ D. Encinas Creek Basin ............................................................................................................ E. San Marcos Creek Basin ...................................................................................................... F. Encinitas Creek Basin ......................................................................................................... : APPENDIX B, DRAINAGE IMPROVEMENT FACILITIES MAPS The following appendices are separately bound. APPENDIX C, COST ESI'IMATES, BY STORM DRAIN LINE ITEM APPENDIX D, COST ESTIMATES, FACILITY RECOMMENDATION TABLES APPENDIX I%, FEMA REVIEW, BUENA VISTA CREEK APPENDIX F, FEMA REVIEW, AGUA HEDIONDA CREEK 'APPENDIX G, FEMA REVIEW, SAN MARCOS CREEK APPENDIX H, CALCULATIONS, BUENA VISTA CREEK BASIN APPENDIX I, CALCULATIONS, AGUA HEDIONDA CREEK BASIN, VOLUMES I & I1 APPENDIX J, CALCULATIONS, ENCINAS CREEK BASIN APPENDIX K, CALCULATIONS, SAN MARCOS CREEK BASIN APPENDIX L, CALCULATIONS, ENCINITAS CREEK BASIN Table d Contents 1992 Carlsbad Master Drdnage a1 Page II Storm Water QudW Management PI1 I I I I I I 1 I B I I 1 I I I I 1 I. CHAPTER 1 EXECUTIVE SUMMARY A. Goals and Objectives This 1992 Master Drainage and Storm Water Quality Management Plan was commissioned bl Council in February of 1988. The purpose of the plan was to: 1. Reassess the storm drainage facility needs of the City and to update the 1980 Master Dra Plan. I 2. Incorporate the drainage facility needs of the southern part of the City which were fon included in the County’s Zone 1 Flood Control District. 3. Establish drainage facility costs, analyze viability of existing planned local drainage ( fee areas, recommend changes to existing PLD fee areas, establish new PLD fee areas for the SOL city area, allocate costs in accord with State Map Act and AB 1600 requirements and establish new area fees. 4. Provide new topographic mapping of the entire City at two foot contour intervals on p mylar sheets and in digital format compatible with our new Geographic Information System (G1 computer. 5. Field review existing facilities for conformity with file plans and make recommendatio facility maintenance needs. 6. Review the siltation and water quality requirements of the City and make recommend; for additional measures to protect our sensitive riparian waterways and lagoons. Over the course of preparing the Master Plan, the Federal Government implemented new reguli which mandated strict water quality control requirements. These new water quality reguli significantly altered the focus of the Master Drainage Plan. Whereas previous master drainagt studies focused on storm water flood control measures, the new regulations shifted the €0~ preservation and enhancement of storm water quality. This shift resulted in a significant re-evall of our previous Planned Local Drainage area fee concept. As a result, the numerous localized PL areas were combined into four large PLD fee areas which coincide with the four drainage basins v the City. This reflects the Federal Government emphasis on preserving and protecting the water ql of receiving waters and not just of a few localized basins. In light of this new focus the title of this I was changed from Master Drainage - Plan to Master Drainape and Storm Water Qualitv Manam - Plan. I 1992 Carlsbad Master Drainage and Storm Water Quality Management Plan Chc B. Background The Master DrainaBe and Storm Water Quality Management Plan, hereinafter called Master Pla includes all drainage areas within the incorporated boundary of the City of Carlsbad coven1 approximately 39 square miles. The Master Plan addresses only those facilities which provide tl backbone system to the City's storm water management infrastructure. Generally these consist of stor drainage pipes with a diameter of thirty inches or larger together with concrete and rock lined channel permanent sedimentation4mllutant control basins and other larger miscellaneous facilities. The existing and recommended future drainage facilities are shown on the 1" = 400' maps on file wi the City Engineer and the 1" = 1OOO' maps which accompany this document. Each proposed facility h a letter designation which begins with the letter A, B, C, or D corresponding with one of the four drainal basins in the City. The basin designations were assigned consecutively starting from the North a1 moving South as follows: 'A' for Buena Vista Lagoon drainage basin; 'B' for Agua Hedionda Lap drainage basin; 'C' for Encinas Creek drainage basin; and, 'D' for Batiquitos Lagoon drainage basi A total of 44.2 million dollars in recommended drainage improvements have been identified within th Master Plan report. These future facilities are anticipated to be fully funded through the Planned Loc Drainage Area (PLDA) fees recommended within this report with the exception of facility BB whic is funded through SANDAG Transnet funds. The PLDA fees recommended in the 1980 Master Drainage Plan were levied only upon developmer which proposed a subdivision of land. Those fees were collected at the time of the approval of the fin map. Pursuant to Section 66483 of the State Map Act fees may be levied upon development only insof as they are fairly apportioned within the fee area on the basis of benefits conferred or on the need for SUI facilities by the proposed subdivision and development of other property within such fee area. Sin( some of the recommended facilities Sewe previously developed areas, their cost could not be ful recouped through the 1980 Master Drainage Plan PLDA fees. This method of assessment placed the fi burden of funding needed facilities on the subdivider and allowed non subdivision developers to escal any obligation topay their fair share of needed drainage facilities. This method of fee collection has result( in a shortfall of funds required to build the recommended facilities and thereby delayed construction 1 necessitated use of alternate funding sources primarily from General Fund revenues. The Master Plan report recommends that PLDA fees be levied against all new developments within tl City. It further recommends that PLDA fees be levied against redevelopment projects and remod building permits. For building remodels the PLDA fee will be assessed whenever the building footpri is increased by 50% or greater. Such development projects can be found to derive benefit ftom tl construction of needed drainage facilities for the control of storm water flooding or the preservation ar enhancement of the quality of storm water entering the receiving waters of the City. Authority for tl levying of PLDA fees on non subdivided developments is contained within the provisions of AB 16( (Chapter 5 to Division 1 of Title 7 of the Government Code). All such fees would be paid at the time building permit issuance including PLDA fees for subdivisions. Construction of PLDA facilities wou continue to be secured prior to final map approval. .. ,- Chapter 1 Page 2 1992 Carlsbod Master Drainage 01 Storm Water Qudlty Management PI I I B 1 I I I 1 I I I I 1 I .. I 1 i I I As noted in the preceding section, this report recommends elimination of the existing PLD Area creation of four new PLD Areas coinciding with the four drainage basins which empty into the P Ocean. This recommendation is based upon several reasons as follows: 1. Master drainage facilities provide benefit to the City beyond the benefit provided to prc ownen in any one sub-basin. Most of the Master Plan facilities are needed to protect circulation elc roads used by all residents and emergency services. Also Master Plan facilities reduce the potenti the spread of water borne disease which improves the overall health of the community, 2. Improvingwater quality within the lagoons provides ageneral benefit to all Carlsbad resic New federal regulations require the City to improve water quality within the City's lagoons and tril: creeks. This must be accomplished by balancing the water quality levels of each of the subt throughout the overall lagoon basin. Therefore, advanced construction or increased facilities m needed in one basin to make up for deficiencies in another due to a lack of available land or environrr constraints. 3. Fewer basins are easier to administrate and will provide the City greater flexibili generating funds necessary to construct needed facilities in a timely manner. The Master Plan report also recommends a change in the manner in which fees are computed for va land use types. The existing PLDA fees are computed based upon property acreage regardless 01 use. Low density residentially zoned property is charged the same fee on an acreage basis as high rk residential, industrial or commercially zoned property. However, the storm water runoff rate for difl land uses are significantly different from one another. Therefore, this report recommends adopti a varied rate structure in line with average runoff coefficients widely accepted within the Enginel profession. This will result in higher fees for high density residential, commercial and industrial prc in recognition of the greater storm water contribution made by these type uses. Within the Ce Business 'District, this fee structure will help generate the funds required to construct badly ne facilities in the downtown area. An analysis ofthe Land Use maps of the City and the aerial photography prepared for this report indi approximately 11,800 acres of developable land remain in the City exclusive of General Plan desigr open space. Based upon a review of past records, this report projects 20% of the existing devel properties in the City will remodel or redevelop prior to build out, resultingin approximately 14,000 I of underdeveloped property in the City. Dividing the estimated facility costs by the sum ol undeveloped and under-developed acreage within each of the Planned Local Drainage (PLD) P yields the proposed fee as indicated below. C, Recommendations The following is a summary of the recommendations made in this Master Plan report: 1. Adopt this report titled 1992 Master Drainage and Storm Water Quality Management prepared in April of 1992 in replacement €or the previous Master Drainage Plan prepared in June of 1 1992 Carlsbad Master Ordnage and cha Storm Water Quallty Management Plan P 2. Consolidate the existing thirteen Planned Local Drainage fee areas together with the forme Zone 1 Flood Control District into four new Planned Local Drainage Fee Areas coincidingwith the fou major drainage basins in the City as shown on Figure 4-2 on page 32. 3, Make findings that there are no surplus funds in the existing Planned Local Drainage Are accounts and transfer the current fund account balances into the corresponding account for the ne7 Planned Local Drainage Fee Area. 4. Make. findings that the future drainage facilities identified in the Master Plan report ar required for the proper development of the City, that the facility costs included in the report are fair an accurate, and that the proposed fees have been fairly apportioned either on the basis of benefits conferre on property proposed for development or on the need for such 'facilities created by the propose development and the development of other property within the Planned Local Drainage Fee Area. 5. Adopt the following fees for the four proposed Planned Local Drainage Areas: Area - Low Runoff Areas High Runoff Areas A $4,014 $6,569 B $3,321 $5,435 C $1,924 $3,148 D $1,679 $2.747 1 6. Expand the Planned Locai Drainage Area Fee structure to require imposition of the fee to i non subdivision developments including commercial, industrial and residential remodels which increa the building footprint a minimum of 50% over the existing structure. Require payment of the new fees time of building permit issuance for those developments. 7. Revise Chapters 20.09 and 18.40 of the Carlsbad Municipal Code to effect the changes proposed in recommendations 1 to 6 listed above. 8. Adopt the sediment and water quality policies included within the report and continue wi the implementation of the water quality control program as required pursuant to the National Polluta Discharge Elimination System permit requirements. 9. Accept the recommendations of this Master Plan report on facility maintenance needs presented in Chapter 7. Chapter 1 1992 Carlsbad Masier Ordnage a Page 4 Storm Water Quality Management PI I I I I I I 1 I 1 I I I I I I 1 I I I CHAPTER 2 PLANNINGAREA CHARACTERISTICS A. Planning Area Boundaries In 1952 the City of Carlsbad incorporated with a population of 5,000 and an area of 4,781 acres, Citygrewslowlyatfirstatarateof490to850peryearuntill975. Since1975thegrowthratehasdol and the 1990 population is 63,126, according to 1990 U.S. Census data. The City of Carlsbad has annexed all properties with its sphere of influence covering approximate square miles. The City is bounded on the north by the City of Oceanside. On the east the City is bo^ by the Cities of Vista, San Marcos, and the County of San Diego. To the South the City borders Encinitas and a small portion of San Diego County. And finally, Carlsbad has the Pacific Ocean west. B. Physical Environment Physical GeoPraDhv and ToDoeraDhy Carlsbad is a very diverse city with steep hills to coastal areas. As a result, there are a wide varic drainage conditions. New orthophoto mapping was produced with contours extending approxin 200 feet beyond the sphere of influence. This study defined drainage basins up to and beyon( boundary. San Diego County 1"=200' mapping was used for supplemental topographic informs The four major waterways and their tributary canyons have carved valleys floored with alluvial ma1 Thus far, construction in the flood plains has not occurred to the extent that it is cause for concen major drainage basins with the exception of Encinas Canyon terminate in lagoons. GeomDhy and Soils Soil types range fiom alluvial in the lower flood plains to weathered granite on the peaks. predominant hydrologic soil type in this study was Group D except in the northwest where Grc predominates. Groups B & C are also represented.' Soil types are described in Chapter 4. * USDA, Soil Conservation Service, et.al., Soil Survey, San Dieao Area, California; 1973. 1992 Catlaad Master Dralnage and Ch Storm Water Quallty Management Plan Seismicitv Southern California is a seismically active area. An earthquake offshore of North County registered 5 Richter Magnitude in July 1986. Active faults in the area include the Elsinore Fault located 20 mill northeast of Carlsbad and the Rase Canyon Fault located 10 miles west of the City. Environmental Drainage basins were characterized by perennial and intermittent stream beds. These stream beds a the focal point of a sensitive network of riparian corridors. Within the lower portions of the basins, tl drainage channel spreads out to form somewhat narrow flood plains characterized by dense willow ar riparian plant growth and meandering stream channels. These areas generally act as natural siltatic control. At the end ofeach major drainage basin, with the exception of Encinas Canyon, is alagoon whi supports a delicate but rich variety of flora and fauna. It is a stated goal of the city to protect and enhan where possible all riparian and lagoon habitats. Hvdroloeic Features The City of Carlsbad is divided into four distinct watersheds, Listed below are those basins, starting ita the north. a. Buena Vista Creek - “Buena Vista Creek drains an areaof 19 square miles. The drainage area is lo1 and narrow with a distance of about 9 miles from the Pacific Ocean to its highest peak of 1,67 1 feet (MS in the San Marcos Mountains and a width of about 2 miles. Runoff fiom several tributaries quick combine into one main improved channel within the City of Vista. Flow is generally in a southwt direction through the City of Vista. As it leaves the City ofvista, flow becomes more westward and slop become more gentle, discharging into Buena Vista Lagoon about 3 miles downstream. Buena Vi! lagoon is a man made lake with a weir structure at the Ocean outlet controlling the discharge. Strea flow eventually enters the Pacific Ocean some 1.4 miles farther downstream after being temporari delayed by the considerable storage volume of the lagoon. The stream gradients range from 68 feet F mileintheupperreachesto32feetpetmileinthelowerreachesofthebasin. Theaveragegradientwith the reach studied is 39 feet per mile”? b. Agua Hedionda Creek - “Agua Hedionda Creek and a major tributary, Buena Creek, drain an a of 29 square miles. Agua Hedionda Creek originates in the hills south of the S’a Marcos Mountains a flows in a general southwest direction, confluencing with Buena Creek about 3 miles downstream. FK the confluence, it flows generally westward about 6 miles and enters Agua Hedionda Lagoon, From whi it discharges into the Pacific Ocean some 2 miles further downstream. The stream gmhents along Ag Hedionda Creek range from about 43 feet per mile in the upper reaches of the study area to about 35 fi per mile in the lower reaches approaching the lagoon. There is an extremely steep canyon reach betwe mile 5.2 and mile 6.0 along Agua Hedionda Creek which is called Los Monos Canyon. Stream gradie~ in this reach average 180 feet per mile. Buena Creek, with a drainage area of about 6 square mill originates in the San Marcos Mountains and flows about 5 miles in a southerly direction before confluences with Agua Hedionda Creek. The stream gradient of Buena Creek through the study rea 2 Army Corps of Engineers, LAX Angela District, Buena Vita Creek, July 1973. Chapter 2 Page b 1992 Carlsbod Master Drdnage c Storm Water Qudity Management P I I I I I I I I I I I I I I I I I I I is about 51 feet per mile”? c. Encinas Creek - Encinas Creek drains an area of 3.9 square miles. This basin originates 3,OO East of El Camino Real and drains westerly approximately22,OOO feet to the Pacific Ocean. The dra course generally parallels Palomar Airport Road along an alignment just south of this roadway, entire drainage area ranges in elevation from sea level to slightly over 440 feet. d. San Marcos Creek (Batiquitos Lagoon) - San Marcos Creek originates in the coastal rar mountains north and east of San Marcos and empties into the Batiquitos Lagoon about 2.6 miles E the Pacific Ocean. Encinitas Creek, a major tributary, originates in the mountains southwest c totals 46 square miles and ranges in elevation from sea level to slightly over 1700 feet in the Me Mountain range. “The stream gradient ranges from an average of 10 feet per mile near the mouth to about 600 fe mile in headwaters. San Marcos creek has a small and not well defined channel upstream from LaE Marcos. Below that point, the channel is well defined, steep, and rocky to the La Costa develol after which it becomes small and not well defined again to Batiquitos Lagoon. The flood plain is upstream hm Lake San Marcos. From Lake San Marcos Dam to the La Costa development, tl virtually no flood plain due to the steep, well defined channel. Through the La Costa developm the Batiquitos Lagoon, the flood plain is again broad. During large floods, flows exceed the ch capacity and inundate parts of the broad flood plain.” “Batiquitos Lagoon extends from the downstream limit of San Marcos Creek, namely the Pacific C as far as El Camino Real Road, some 2.6 miles upstream. It comprises about 600 acres of area and 1 provide considerable storage during large flds”4 Marcos and joins San Marcos Creek at the upstream end of Batiquitos Lagoon, The entire dminag C. LandUse 1. Existing Existing development in the City is located mainly in the northwest older portion and in the sou La Costa area. Existing highdensity residential development is located along the coast and at v; places in La Costa. Existing commercial development is centered in the older downtown area northwest quadrant, along Avenida Encinas, and along Palomar Airport Road. There are still agricultural areas located in the City. Finally, existing low and mediumdensity residential develo] comprise the majority of the land use in the City. 2, Futurq Proposed land use in the City of Carlsbad is varied. The choice of future drainage facilities is depe upon future land use designations as determined by the 1987 Citv of Carlsbad General Plan. Accc to the 1987 General Plan Map most of the undeveloped land is zoned for low to mediumd 3 Army Corps of Engineets, Los Angela District, APua Hedionda Creek, July 1973. 4 Army Corps of Engiqeets, Los Angela District, San Marcos Creek, April 1971. 1992 Carlsbad Master Drdnage and Cl- Storm Water Quality Management Plan residential land uses. These areas are located in the northeast and southwest portions of the City. Lar: planned industrial areas are located around Palomar Airport. Open space zoning is located along Agua Hedionda, Buena Vista, and Batiquitos Lagoons. There is a1 a strip of open space running north-south fiom La Costa Avenue to north of Faraday Avenue. The op space generally follows the tributary canyons. D. Design Sensitivities Drainage Facilities have been proposed in accordance with the land use constraints of the 1987 City Carlsbad General Plan. Underground storm drain lines or concrete channels have generally be undeveloped, enhanced natural channels consisting of drop structures are pro@& to decrease erosi drainage discharge velocities (considered to be above six feet per second): When erosive draina discharge velocities occur in open space zoned areas, the cost ofpotential remedial work was estimab proposed in areas slated for future development. When such lines empty into canyons expected to rema Chaptec 2 Page 8 1992 Carlsbad Mder Drainage c Storm Water Qucrlltv Management P I I I I I I I I I I I I I CHAPTER 3 METHODOLOGY A. Study Approach The approach of this project was to utilize previous hydrology studies for the major water count to analyze tributary areas where storm drain deficiencies occur. Storm drain facilities are recommc where existing facilities are inadequate or where projected development will require drainage facil B. Hydrologic Design Criteria The design criteria, as found in the County of San Diego Department of Public Works Flood Cc Division Hydrology Manual, specifies the design runoff conditions within the San Diego County 1 Control District will be based on the 100 year storm frequency as follows: 1. Design for areas over 1 square mile will be based on the 100 year frequency storm. 2. For areas under 1 square mile - a) The storm drain system shall be designed so that the combination of storm drain system capacil overflow both inside and outside the right of way will be able to carry the 100 year frequency 2 without damaging adjacent existing buildings or potential building sites. b) The storm drain system shall be designed so that the combination of storm drain system capacit allowable street overflow will be able to carry the 100 year frequency storm within the street rig1 way. c) Where a storm drain is requiredunder headings 1 or 2 above, then as a minimum, the storm drain be designed to carry the 10 year frequency storm. I 1 I I I 3. Sump areas are to be designed for a sump capacity or outfall of a 100 year frequency storm For this study, existing drainage systems were analyzed with respect to the above criteriz recommendations made accordingly. In undeveloped areas, where future street alignments and g are unknown, the recommended storm drain lines are sized for 100 year flow capacity, based o grades of existing flowlines. However, when these areas are developed the drainage system may act cany the 10 year storm underground, the 50 year storm to top of curb, and the 100 year storm 'H the street right-of-way. Drains at sumps should convey 100 year storm flows. The design flows were computed based on the following assumptions and data: 1. Ground cover was derived from the Soil Conservation Service 1969 survey maps updated I 1992 Carkbad Master Drainage and Storm Water Quality Management Plan CtU f ultimate development data corresponding to the 1000 scale city of Carlsbad General Plan Map dab April 1987 and fbture land use densities projected in the City’s Growth Management Program. 2. Hydrologic soil groups were determined from the 2000 scale soil group maps prepared by the Sc Conservation Service in 1969. Soil types were segregated into groups as a function of their probak infiltration capacity. The group designations include: Group A - Low Runoff Potential: Soils having high infiltration rates even when thoroughly wetted, consisting chiefly of deep, well excessively drained sand and/or gravel. These soils have a high rate of water transmission and wot result in a low runoff potential. Group B - Moderate Runoff Potential: Soils having moderate infiltration rates when thoroughly wetted, consisting chiefly of moderately de to deep, moderately well to well drained soils with moderately fine to moderately coarse textures. The soils have a moderate rate of water transmission. Group C - High Runoff Potential: Soils having slow infiltration rates when thoroughly wetted, consisting chiefly of (1) soils with a la) that impedes the downward movement of water, or (2) soils with moderately fine to fine texture ant slow infiltration rate. These soils have a slow rate of water transmission. Group D - Very High Runoff Potential: Soils having very slow infiltration rates when thoroughly wetted, consisting chiefly of (1) clay soils w a high swelling potential; (2) soils with a high permanent water table; (3) soils with clay pan or clay la] at or near the surface; and (4) shallow soils over nearly impervious materials. These soils have a vc slow rate of water transmission. Chapter 3 I 992 Camd Master Drolnage ( Page 10 Stom Water Qudltv Management P I I I 1 I I I I I I I I I I I I I I I 3. The following Manning roughness and rational method runoff coefficients were used: Manning Roughness "no Values PIPES " n " Cormgated Metal Pipe 0.024 Reinforced Concrete Pip 0.012 Cast in Place Concrete Pipe 0.015 U I ~ ~~ II Asbestos concrete Pipe I 0.011 v 1 ~ ~~ OPEN CHANNELS Wn" Revetment 0.040 . Concrete lined 0.015 Natural Grass 0.035 Reinforced Concrete Box Culverts 0.015 I - -. - 1 ~ I -. -. -. - - -. -. -. a Table 3-1 1992 Carlsbad Master Drainage and C Storm Water Qudlty Management Plan Table 3-2 4. The 100 year 6-hour and 24-hour precipitation values were taken fiom the County of San Dieg Department of Public Works Flood Control Division Hydrology Manual, Section II-A. 5. Rainfall intensities for the Rational Method hydrology computations were taken from the County ( San Diego Department of Public Works Flood Control Division Hydrology Manual, Appendix XI. 6. Watershedboundaries and grades for proposed storm drains were derived fiom 400 scale orthophol Incorporated, San Diego, California. 7. A number of major creeks have been identified in the City of Carlsbad. Previous ~vdrologic studic conducted by Federal, County and private institutions have established 100 year peak flows for the! major watercourses. Table 3-3 lists the studies available to the Master Drainage Plan Study as follow maps with 5 foot contours produced photographically horn maps prepared by Rick Engineerin: Chapter 3 1992 Carlsbad Master Drainage or Page 12 Storm Water Quality Management Pic I I I I I I I I I 1 I I I I I I I I 1 PREVIOUS SrUDIEs STREAM AUTHOR STUDY Watershed Sediment September 1985 Buem Vista Creek Control Plan June Applegate & Associates I. Hydrology Report December 1976 Flood Plain Information July 1973 Special Flood Plain Delineation Study Flood Insurance Study February 1978 Nolk & Associates Flood Plain Infomation August 1986 Special Flood Plain July 1973 Flood Plain Information December 1976 Hydrology Report February 1978 Nolte & Associates Delineation Study County of San Diego Corps of Engineers FEMA Agua Hedionda Creek Corps of Engineers Agua Hedionda Creek, Calavera Lake Inflow and outflow San Marax Creek County of San Diego April 1971 . Corps of Engineers ! Comprehensive Plan Zone 1 San Marcus Creek, San Diego County Flood Encinitas Creek Control District Kmbig, ’ Inc. July 1976 Watershed HECI Model Encinitas Creek Rick Engineering Analysis Hydrology Report August 1988 Master Drainage Plan September 1988 Hydraulic and Hydrologic September 1987 Northeastern Carlsbad Agua Hediondp Creek Hydrologic Study Dr. Howard H. Chang July 1989 East Branch of San Marcus San Marax Creek Creek Boyle Engineering July 1988 San Marcos Creek Flood Rick Engineering Encinas Creek Poutney & Associates, Inc. Study Control Imp. Rojed. Willdan Associatea August 1988 Drainage Study for May 1991 Enanitas Creek Dr. Howard H. (=hang Encinitas Cnek TABLE 3-3 1992 Carlsbad Master Drdnage and C hl Storm Water Quallty Management Plan P The 100 year peak flows previously established for major creeks in the City of Carlsbad have bet analyzed for usage in the Master Drainage Plan Study as follows: a) BUENA VISTA CREEK - The 100 year peak flows have been established in the Suecial Flood PI% Delineation Studv, February 1978 by Nolte and Associates. The flow ratesto be used in Master Drainai Plan are adopted from the 1978 Nolte study. b) AGUA HEDIONDA CREEK - The 100 year peak flows have been established in the Suecia1 Flq Plain Delineation Study by Nolte and Associates in February 1978. A Hvdroloeical Studv was conducted for Northeastern Carlsbd by Dr. Howard H. Chang in July 198 The flow rates used in the Master Drainage plan assumed the discharges listed in the Nolte 1978 stu< for the reach upstream of the confluence point east of Oak Lake and the results of the Chang 1989 stu< downstream of the above mentioned point. The flows in the two studies vary by approximately lo? c) SAN MARCOS CREEK - The 100 year peak flows have been established in the Flood Pla Information Studv, April, 1971 by the U.S. Amy Corps of Engineers, Los Angeles District. These flo rates have been adopted by FEMA for the Federal Insurance Study for San Marcos Creek within the Ci of San Marcos. Corps of Engineers peak flows and inundation limits for the 100 year flow have al: been used without modification for the determination of adequacy of existing structures in ti Comprehensive Plan for Flood Control and Drainage -Zone 1, San Diego County Flood Control Distri by Koebig, Incorporated in July 1976. A hydrologic analysis by Boyle Engineering Corporation in July 1988 on the east branch of San Marcc Creek generally confirmed the U.S. Army Corps of Engineers flow rates. Results of another hydrologic analysis by Willdan Associates in August 1988, for the San Marcos Crer Flood Control Improvement Project on the main branch of San Marcos Creek upstream of Lake Si Marcos, were within 10 to 15 percent of those values in the Corps of Engineers study. The actual desit; discharge values utilized for the flood control channel hydraulics, at the direction of the City of Si Marcos, were the values from the Corps of Engineers study. The 100 year flow rates to be used in the Master Drainage Plan for San Marcos will be adopted fio the Corps of Engineers study as follows: At mouth into Pacific Ocean 5,000 CFS Upstream from El Camino Real 12,000 Upstream from Rancho Santa Fe 13,000 d) ENCINlTAS CREEK - The 100 year peak flows were established by the U. S. Army Corps c Engineers, Los Angeles District in April 197 1. Koebig, Incorporated developed peak flow rates for tt Chapter 3 Page 14 1992 Carlsbad Master Dralnage a1 Storm Water Qudlty Management PIC I I I I I I I I 1, I I I I I Encinitas Creek basin in the July 1976 Comprehensive Plan for Flood Control and Drainage -Zc San Diego County Flood Control District. In 1980 the County of San Diego conducteda hydrology, of Encinitas Creek watershed, establishing peak flow rates for the 100 year flood. A more recent hydrologic study for Encinitas Creek was completed in August 1988 entitled # computer model by Rick Engineering as part of the Master Drainage Plan for the Encinitas ( Watershed. Rick Engineering’s study was accepted by the City of Carlsbad. The 100 ye& flow rates determined for Encinitas Creek as a result of the 1988 Rick Engineering are as follows: At entrance to Batiquitos Lagoon 4,560 CFS Downstream of confluence with tributary north of Olivenhein 4,210 Downstream of El Camino Real 3,430 Downstream of Rancho Santa Fe 1,300 The Rick Engineering Study identified deficiencies with the existing drainage structures cross1 Camino Real and La Costa Boulevard which result in over topping of these roads in storm e Mitigation alternatives for resolution of the deficiencies have been proposed in the recently corn: a Drainape Studv for Encinitas Creek prepared by Dr. Howard Chang dated May 1991. The pro mitigation involves the construction of a major flood water retention facility just west of Rancho Fe Road (South) and some berming along La Costa Avenue. The mitigation proposal is under environmental review as part of the Olivenhain Road widening project. e) ENCINAS CREEK - The 100 year peak flows were established by the Hvdmloev Studv f Determination of the ImDact From Runoff in Encinas Creek on the Promsed Immovements to Pa Aimort Rod by Poutney and Associates in September 1987. The 100 year flow rates to be used in the Master Drainage Plan for Encinas Creek are results of thc Poutney study as follows: I I Upstream from Interstate 5 1,750 CFS Downstream from Hidden Valley Road 1,560 Upstream from Laurel Tree Road 1,400 I I I 1992 Carlsbad Master Dralnage and CI Storm Water Quallty Management Plan C. Design Runoff Method The hydrologic analysis utilized for design of facilities.recommended in this report is the Ration Method for watersheds less than 0.5 square miles and the Modified Rational Method by routing su watersheds for watersheds greater than 0.5 square miles and less than 15 square miles. The Rational Formula is Q, = CIA where: Q, = The peak discharge in cubic feet/sec.* * 1 Acre in/hr. = 1.008 cubic feet/sec. C = Runoff Coefficient (Dimensionless) I = Rainfall intensity (incheshour) A = Tributary drainage area (Acres) If rainfall is applied at a uniform rate to an impervious area, the runoff attributed to this area wou eventually reach a rate equal to the rate of precipitation. The time required to reach this equilibrium termed the time of concentration. For small impervious areas one may assume that if precipitation persists at a uniform rate for at least long as the time of concentration the peak discharge will equal the precipitation rate. D. Design Procedure The following procedure was used in calculating quantity of storm flow at various locations along tl route of the proposed storm drains. Whenever the term “Manual” is used, it refers to the “County of Si Diego Department of Public Works Flood Control Division Hydrology Manual” dated January 198 The general procedure was developed by Los Angeles County Flood Control District and has bel modified herein for use in San Diego County. 1. On the drainage map, divide the runoff area into subareas of from 5 to 100 acres. These divisio~ should,ifpossible,bcbasedonthetopography,soiltype,andthelanddevelopment. Thesizeoftheiniti area should be chosen such that the length of travel for the water from the most remote point to the poi of concentration should not exceed 2,000 feet for natural watersheds and 1000 feet for urban areas a~ be of a generally uniform slope. 2. Determine the quantity of water for the initial area. a) Estimate the initial time of concentration. For natural watersheds this can be obtained from Append X-A of the “Manual”. Effective slope of natural watersheds may be estimated from Appendix X-B 1 the “Man~al”~ For urban areas overland time of flow can be obtained from Appendix X-C of tl “Manual”. Engineering judgement should be used for the validity of the computed initial times. minimum of 5 minutes should be used for all basins. Chapter 3 1992 Caflsbod Master Drdnage ai Page 16 Storm Water Qudlty Management PI’ I I I I 1 I I I I I, I I I I I I I I I b) Determine the type of soil fim “Hydrologic Soil Groups - RwoffPotentia]’’maps ofthe County interpretation study. c) Determine the ultimate land use from the Carlsbad General Plan. d) Obtain the runoff coefficient “C” fiom Table 3-2. e) Obtain thelocal 6-hour precipitation from Section 11-A“Precipitation Maps” ofthe “Manual”. 0 the local 24-hour precipitation from Section II- A “Precipitation Maps” of the “Manual”. ‘f) Obtain the intensity (I) from Appendix XI “Intensity - Duration Design Chart” of the “Manu g) Calculate the quantity of water (Q) from the “Rational Equation”, Q = CIA. 3. Determine the quantity of water for subsequent subareas as follows: a) Determine the water route from the point of concentration of the previous subarea to the PO concentration of the subarea in question. b) Calculate the time necessary for the quantity of water arriving at this subarea to pass through point of concentration by the above route. The physical properties of this route must be considere the velocities obtained from the following: 1) Iftravelingin a street the velocity can be figured from Appendix X-D, “Gutter and Roadway Disc1 - Velocity Chart” of the “Manual”. 2) If traveling in a ditch, pipe or other regular section calculate the velocity from the actual sec 3) If traveling in a natural watercourse the velocity can be derived from the approximation of the ch cross section. c) Measure the length of flow to the point of inflow of the next subarea downstream. From the ve: compute the time of flow and add this time to the time for the first area to determine a new ti1 concentration. When detenninmgthe time of concentration (Tc), the expected future drainage facility and route if to determine velocity and travel time (Tt). Wherever junctions occur, or there is a change in SIC drainage facility, it is necessary to calculate the velocity and travel time for the preceding reach, slope of the Hydraulic grade line is generally assumed to be parallel to the grade slope. d) Calculate Q for the second subarea, using the new time of concentration and continue downs in similar fashion until a junction with a lateral drain is reached. 1992 Cartsbad Master Drdnage and Chi Storm Water Qudity Management Plan P e) Start at the upper end of the lateral and cany its Q down to the junction with the main line. 4. Compute the peak Q at each junction. Let Q,, TI, I,, corresponding to the tributary area with the longc time of concentration. Let Qb, Tb, I,,, correspond to the tributary area with the shorter time ( concentration and Qp, Tp correspond to the peak Q and time of concentration when the peak flow occur a) If the tributary areas have the same time of concentration, the tributary Q’s are added to obtain th Peak Q. Qp = Q, + Q, b) If the tributary areas have different times of concentration, the smaller of the tributary Q’s must t corrected as follows: 1) The usual case is where the tributary area with the longer time of concentration has the larger Q. 1 this case, the smaller Q is corrected by a ratio of the intensities and added tc hy:e larger Q to obtain tt peak Q. The tabling is then continued downstream using the longer time or ~ ncentration. Q, = (Q, + Qb) I)$ Tp = T, 2) In some cases, the tributary area with the shorter time of concentration has the larger Q. In this cas the smaller Q is corrected by a ratio of the times of concentration and added to the larger Q to obtain tt peak Q. The tabling is then continued downstream using the shorter time of concentration. Q, = (Qb + QJ Tbn, Tp = Tb E. Computer Program In this project the Rational Method Hydrology Program version 1.2 by Advanced Engineering Sofbvsu has been used to compute and design the drainage systems for the different watersheds. The San Dieg County hydrologic design criteria has been incorporated in the software. The program develops anodc link model of the watershed and in the process estimates the conduit and channel sizes needed 1 accommodate the design storm peak flow rate. The designer then reviews the hydrologic results as 1 acceptability and options whether to proceed with the design or investigate an alternate hydrolog process in the subject subarea. With respect to the Urban Area Overland Time of Flow Chart in Appendix X-C of the “Manual” t€ computer program hasbeen designed to accurately compute initial flow times for urban areas with slopc of up to 2.5%. For slopes steeperthan 3% the estimated initial times start to deviate from the FAA curv T = l.g(l.1 -CMT.,)m [S( 1 OO)]’” In such cases the designer manually computes the initial time and run-off and inputs the values into t€ computer model. Chapter 3 Page 18 ~~~~ ~ ~~~~~ 1992 Carisbod Master Drdnage ar Storm Water Qudlty Management PIC I I 1 I I I I I I I I I I I I I I I I F. Sedimentation Basins Sedimentation basins have been proposed near where drainage discharges into the four major cha Their function is to decrease the amount of silt and other fine particulate matter deposited into the lagoons and major natural channels. If these sedimentation basins are not at full capacity at the tin design storm occurs, they will also function as storm water detention basins, attenuating discharg major channels, thus decreasing channel erosion. However, for Master Drainage Plan purposes existing and proposed sedimentation and detention basins are assumed to be at full capacity. An) proposed downstream have been sized accordingly. Sedimentation basin calculations are first approximations only. They are found in the back c hydrology calculation volumes for the basin or basin portion in which they occur. The method use based upon "The Erosion and Sediment Control Handbook"', The San Diego Hydrology Manua' the universal soil loss equation) with a five foot settling depth, exceeding the two foot mini recommended? Basin surface area was sized using the surface area formula in the following exm The settling velocity used was 0.00096 fps: In order to limit siltation of lagoons receiving runoff from the City of Carlsbad, the design partici used was 0.02- (medium silt)? Since basin surface area is inversely proportional to settling vell and settling velocity is directly proportional to particle size, a smaller design particle will res sedimentation basins requiring more land. However, the effective length of particle trajectory basin may be increased using baffles, decreasing the surface area required for particle sel Sedimentation basins in major channels (such as Buena Vista and Agua Hedionda Creeks) were using estimates of available land only. The calculation method requires assumptions of areas that will remain natural and areas that w subjectedto construction activity. These areas have been estimatedusing the 1987 Carlsbad Genera: and landuse projections (densities) assumed in the City's Growth Management Program. The mi\ soil Ioss equation alsorequiresthe estimation ofpercentages of sand, finesand, silt andclay. In this s these estimates were based upon SCS Soil Survey Documents.6 the City of Carlsbad Standards. Basin volume was sized to retain annual sediment load(calcu1ated 1 Erosion and Sediment Control Handbook Goldman et. al., McGraw Hill, 1986. ' Erosion and Sediment Control Handbook Section 8.2a, Goldman et. al, McGraw Hill, 1986. ' Erosion and Sediment Control Handbook Figure 8.12, Goldman et. al, McGraw Hill, 1986. . 5 Erosion and Sediment Control Handbook Section 82c, Goldman et. al., McGraw Hill, 1986. 6 Soil Survev, San Diego Area, California; USDA, SCS, et. al., 1973. 2 Erosion and Sediment Control Handbook Section 83, Goldman et. ai., McGraw Hill, 1986. 1992 Carlsbad Master Drainage and Chc Storm Water Qudlty Management Plan PC In the example which follows, variables and formulas used are the following. The Universal Soil Loss Equation: Sed.Vol.=RxKxLSxCxP where: R = rainfall erosion index in lOOft.tons/acre x in/hr. K = soil erodability factor in tons/acre per unit of R LS = slope length and steepness factor, dimensionless (see below) C = vegetative cover factor, dimensionless P = erosion control practice factor, dimensionless c and nc refer to developed and undeveloped areas respectively. LS = r(65.41 x sf’l+ 4.56 x s + 0.065](U72.5)m, where L = slope length in feet m = exponent dependant on slope steepness (s~+10,000) (s~+10,000)1’* s = slope steepness, dimensionless 0.2 for slopes < 1%, 0.3 for slopes 1% to 3%, 0.4 for slopes 3.5 % to 4.5%, 0.5 for slopes > 5% The Surface Area Formula: Sur. Area = 1.2 Q,o.,ve/V, in sf where: VI = settling velocity for the design particle, in fps d = design particle size, in mm Page references noted in the margins of the following calculation example refer topages in “The Erosi< pd Sediment Control Handbook . EXAMPLE: SEDIMENTATION BASIN AFB @ CONC. PT. 209.00 99 NODE - %rnV %SAND (-) % F.S. %SILT %ClAY 209.00 9.93 mm ?255 20.00 100.00 80.00 m.00 3635 5.00 50.00 45.00 2m.m 6657 10.00 45.00 20.00 25.00 201.00 21.66 80.00 20.00 20200 2931 100.00 200.10 260 100.00 mAL 238.97 AVERAGE 355 40.7s u.46 0.00 4225 Chapter 3 Page 20 1992 Carlsbad Master Drainage a Storm Water Qudlty Management PI I I I I Avg Den# P 8.15 d P 8.11 vs P 5.7 R P 5.14 K S L P 5.20 m 109.12 pcf 0.02 mm o.ooo96 fpa 50.00 0.10 5.93 46 5400.00 ft 050 I I 1 1 I I I I I I I I I I I P 5.20 Ls P 5.22 cc . P 5.24 PC P 5.6 Ac Area C P 5.22 cnc P 5.24 Pnc P 5.6 Aoc Area nc P 5.6 sed Vol C P6-10 110-ave P 8.16 Q10-a~ P 8.15 Sur Area Sur Area 4.86 0.50 0.90 10.94 todac-yr 167.28 ac 0.30 0.90 6.57 todac-yr 71.69 ac 156239 cy 0.S4 1.80 0.60 in/hr 38.63 ds 48285.04 sf 1.11 acrw p 8.19 Vol wata 8941.67 cy (Ydepth) Vol total 10504.06 cy Since ideal basin efficiency corresponds to the percentage of soil equal to or greater than the ( particle size7, an alternate method of basin size calculation could be to specify the required efficiency. (Fifty to seventy-five percent is recommended by Goldman et. al.) Given a dr determination of particle size frequency, the design particle necessary to achieve the specified efficiency maybe determined. This method is recommended for final design in areas where silt an particles constitute a high percentage of total soil particulates and basin size calculated using a t particle of 0.02mm results in unreasonably high areas of land required. Because the surface area required for sedimentation can vary greatly depending upon soil partic distribution, soil composition should be determined by field testing at the time of final design. A time more accurate information should be available, and sedimentation basins may be reliably sb sediment removal efficiency as dictated by City of Carlsbad design standards. ’ Erosion and Sediment Control Handbook Section 8.26, Goldman et. al., McGraw Hill, 1986. 1992 Carlsbad Master Dr&ge and ct Ston Water Quality Management Plan I Chapter 3 1992 Carisbad Master Drdnage a1 Page 22 Storm Water Qudity Management Pic I I I I I I I 1 1 I I I I I I I I I I. CHAPTER 4 FINANCING A. General The purpose of Planned Local Drainage Area (PLDA) fees is to design, construct and monitor s drainage and storm water quality enhancement facilities. The majority of the proposed storm l facilities examined by this study will be constructed with funds obtained from PLDA fees or w constructed when required as a condition of approval of land development. The guiding then apportioning the fees recommended by this study is fairness. Fee recommendations are based o concept that development creating the need for enlarging or adding drainage facilities should be: primary responsibility for providing the means to satisfy the need. The study also recognizes WOI storm drain facilities already in place and the value of the existing facilities to properties proposed developed. The study recommends a procedure to reimburse fee amounts to developers who build M Plan drainage facilities. This study anticipates a ‘%build-out” condition for the City per the pres adopted General Plan and land use projections in the City’s Growth Management Program. The I concludes that there are both specific and general benefits that have and will exist to all develor within the City as the result of well-functioning drainage facilities. The criteria used in determining the fees and requirements established in this report are: Does it make sense? 0 Is it fair? More specifically the following tests were used: Do the value of the benefits of the drainage facility exceed the cost of constructil Do the benefits from the drainage project accrue to those who are paying for it? These criteria must be affirmatively satisfied. The Carlsbad City Council must make the prec findings to satisfy the mandates of law in establishing the PLD area fees and requirements recommc by this study. The fees recommended by this study are summarized in Table 4-1. 1992 Carlsbad Master Dralnage and Ch Storm Water Quallty Management Plan F I HllAFec? PUlAFe@ hd" ForhofHighRunoff ForAreasofLowRumff h(HDA) (VAd WAC-) A $2747 $1,679 D $3,148 $1,W C $5,435 $3321 B $6359 I $4,014 r ~~ ~~~ TABLE 4=1 *See Table 4-3 for Land Use zones included within low and high runoff areas. B. Source of Authority The legislation providing authority for, and specifying the methodology of improvement exaction a] establishing fees are found in sections 65800 et seq., 66000 et seq. and 66410 et seq. of the Governme Code of the State of California. These sections impose numerous restrictions on the establishment ar use of facility fees. Generally, fees must be reasonable and fairly apportioned within the fee benefit area based upon bene€ conferred to the developingproperty oron the needs created by the development. Funds collected throui such facility fees must be kept in separate fee area accounts and expended solely for the construction reimbursement of specified facilities within the appropriate fee area. In addition, facility fee hnds mi be expended or committed within five years of their payment, otherwise, they are subject to refund. F this reason, the study recommends that the City include within its annual budgetary process a mechanisr to budget and/or appropriate the fees collected during the prior year to the various facilities for whir: the fees were collected. C. History The City of Carlsbad commissioned and approved two previous master drainage plans. The fin completed in April of 1971 had no provision for drainage fees and recommended that facilities t constructed by developers, the City, the County or by funds from the Federal Government, The 1971 pli failed to anticipate the taxpayer revolt that resultedin the passage of Proposition 13 and that has continue to make the passage of general obligation bonds unlikely, The second plan, completed in June of 198( recognized the difficulty of passing bonds and increasing property taxes and established a fee prograr that had the levy of Planned Local Drainage Area (PLDA) fees triggered when land was subdivided Chapter 4 Page 24 1992 Catlsbad Master Drdnage an Stom Water Qudlty Management PIC I I I I i I I I 1 I I I I I '* D I I 1 1. The fee system established in 1980 was based upon the cost of needed facilities divided by the nul of acres within the Planned Local Drainage Area. The resulting fee was charged against subdi\ property on an acreage basis regardless of type of development proposed. The fee program had w weaknesses which have been addressed in this proposed Master Plan. The following list identifies the weaknesses of the existing fee structure together with a discussic how the weakness is addressed within the proposed fee program : 1. The 1980 Planned Local Drainage Areas (PLDA) distributed the cost of drainage faci over properties that were already developed or that were used for schools, parks, streets, freeways, L right-of-way, open space and other uses that had no new development potential and would 1 contribute PLDA fees. This had the effect of inflating the potential developable area thereby red1 the fee collection for the Planned Local Drainage Areas. The Growth Management Program deve: numerous land use and constraints maps which have been incorporated into the preparation of a refined analysis of developable areas within this study. 2. The 1980 PLDA fees were only assessed against property being subdivided under aut1 ability of the City to collect adequate fees within drainage areas that were relatively built out or had previously subdivided. Under the 1980 Master Drainage Plan three Planned Local Drainage Area a zero dollar fee rate. Several other areas were seriously constrained in their ability to generate ade fees to pay for needed facilities. New state law under AB 1600 (Government Code Section 66000 et seq.) provides the City with : authority to establish facility fees which may be imposed upon all development and not just subdivi This study recommends the use of AB 1600 to increase the base of development responsible for pro' of needed drainage facilities to include all new development, including subdivisions, and all redel ment, remodels and building alterations which contribute to the increase of drainage runoff. With additions, the City will be able to collect fees in an amount approaching one hundred percent of th of the drainage facilities proposed in this Master Plan. of the Subdivision Map Act (Section 66410 et seq. of the Government Code). This greatly limit( 3. Until recently, most drainage master plans, including the City's 1980 Master Plan, pri~ focused on the quantitative nature of storm water flows and not the qualitative nature. However, si 40%) of the Water Quality Act of 1987 alters this fundamental perception by mandating an incl emphasis on the qualitative nature of storm water runoff. It is no longer considered acceptable to ( drainage facilities solely to transport water from one place to another. It is now required to ir measures assuring that water quality is maintained or enhanced in some environmentally sound u during its transport. This shift in emphasis now requires local agencies to review and consider storm drainage facilitil much broader context. Whereas the previous Master Plan mainly addressed the issue of flood con1 a facility by facility basis, this study further considers the overall nature and protection of the watt as a whole. The importance of this new emphasis is reflected in the title change of this report st Carlsbad Master Drainage and Storm Water Oualitv Manapement Plan. 1992 Carlsbad Master Drainage and ct Storm Water Qudlty Management Plan I 4. The 1980 PLDA fee program included a provision to grant up to one hundred percent fee ere( for the construction of Master Plan facilities by the developer. This feature effectively removed contr of the budgetary process &om the City by allowing developers to direct needed funds to their particul facility. The proposed fee structure eliminates fee credits for this purpose by requiring full payment all PLDA fees at time of building permit issuance. Reimbursement will then be made to develope subject to the availability of surplus funds on a schedule which allows the City to retain sufficient fun, to construct priority drainage projects. D. Present Financial Status The Planned Local Drainage Area (PLDA) fee accounts presently contain approximately $700,000.00 unencumbered funds and $1,120,000 in encumbered funds. The account balances correspond to ten the thirteen PLDA’s established in the 1980 Master Drainage Plan. Three of the PLDA’s had no fee a1 thus an account balance of $0.00. It should be noted that there are no outstanding developer reimburseme obligations within any of the fee areas. There is one outstanding obligation within PLDA No. 7 to rep, monies to the City General Fund in the amount of $300,000 for monies advanced to construct the Jam Drive storm drain. Table 4-2shows the current balances for the PLDAaccounts togetherwith a tabulatic of account expenditures for the previous 10 years. All funds collected to date are needed to constru facilities identified in both the 1980 Master Drainage Plan and this report. There are no surplus fun available. The estimated construction cost for the new storm drain facilities proposed in this Master Plan approximately 44.2 million dollars. Of this amount, approximately one half is expected to be fund’ under the fee schedule established with the recommendations of the 1980 Master Storm Drain stud Another 4.7 million dollars was recently allocated from SANDAG Transnet funds io construct Mas1 Plan facility BB in order to protect the downtown road system from flooding during storm events. TI leaves apotential unhnded balance of approximately 17.4 million dollars. With adoption ofthe prop fee structure there will be no unfunded facility costs. Chapter 4 Page 26 1992 Corlsbad Mcaster Drdnoge a Storm Water Qudlty Management PI I i I 1 I I I I I I I I I I I i I I I 1 EXISlWG PLDA FEE ACCOUNTS AS OF SEPTEMBER 9,1991 ACCOUNT ToTALFUNDS FUNDBALA FUNDS WBEmITURES (ACCRUED FEES FEE REMAIM) CURRENT UNDESIGNP ALLOCATED TOTAL FUND PLDA NUMBER AND INTEREST) (SI-) 1 NIA NIA NIA $0 $0 NIA 2 N(4 N(4 N/A $0 SO N/A 3 $52,47t $0 $10,643 $63,119 $2,658 350-810-18-72-8740 5 $30,86s $0 $968 $31,837 $1,686 350-810-18-71-8740 4 $26,698 $0 $968 $27,666 $3,808 350-810-18-70-8740 6 $18,00( $0 $968 $18,974 $200 350-810-18-71-8740 7 ($215,12 $0 $468,773 $253,645 $2,273 350-8 10-18-74-8740 8 N/A NIA N/A $0 $0 NIA Table 4-2 E. Financing Method Alternatives Several sources of hnds were considered to finance the drainage facilities proposed by this plan categories reviewed were: Development Exactions Assessment District Proceedings General Fund Contributions Federal and State Funding Special Benefit District Fees Development exactions are requirements to construct and/or to pay for facilities. They are app developments at the time that various types of permits or approvals are sought. This type of requir is equitable to the Developer since the construction or fee is required when the need for the fac triggered by the development being proposed. The 1980 Master Storm Drain incorporated this app With careful attention to the drainage impacts, project specific and cumulative, at the discret approval stage development exactions work well. 1992 Carlsbad Master Drainage and Storm Water Quality Management Plan c1 I Assessment District proceedings allow facilities to be constructed with €un& obtained by the sale bonds. They are typically used by land Owners who wish to construct large public works facilities. 1 City of Carlsbad has determined that assessment district proceedings should be used only for la projects that provide facilities which benefit the general population of the City. General Fund monies are general fund contributions withdrawn from the operating funds of the C Since the adoption ofthe 1980 Master Storm Drain Study, General Fund monies have typically beenu; for storm drain projects only when reimbursement was expected to ofkt their use within a short til Federal and State appropriations, grants and loans are available at limited times with vary requirements of application procedures, qualification criteria, matching funds, use restrictions 2 accounting regulations. The lack of reliability in obtaining grants and loans effectively removes thl from consideration in any long-term planning. The City should remain poised to take advantage opportunities to obtain federal and state funds. It is recommended that any federal and state hnds be U: in areas of the City that have low development potential, are more densely developed and that have sto drain facility needs that are significant. An example of this approach is the City Council approval of 3 million dollars from SANDAG Transnet Local Funds to improve drainage of streets in PLDA “A”. Special Benefit Districts are established under Section 54700 et seq. of the Government Code, titled Benefit Assessment Act of 1982. The Districts may be formed to provide for the maintenance 2 operation costs of drainage, flood control or street lighting. The districts may also impose aSSeSSme to finance the cost of installation and improvement of drainage and flood control facilities. The act alla fees for flood control purposes to be determined on the basis of the proportionate storm water runoff fn each parcel. A special benefit district would be initiated by the City Council and approved by I landowners within the proposed district in a simple majority vote. The City presently has one spec benefit district for drainage purposes, the Buena Vista Channel Maintenance District. E Financing Recommendations This report recommends development exaction as the primary source of funding for new storm draina facilities. Development exactions would take the form of both payment of fees and construction facilities. This method is consistent with past practice and the City.’s Growth Management Progra Historically, the financing of storm drainage facilities has been considered the responsibility of thc wishing to develop their property. This is because the need for new or upgraded facilities can be direc linked to land development practices. The City’s Growth Management Program recognizes this fact inclusion of a facility standard which requires that “Drainage faciiities must be provided as required ’ the City concurrent with development”. In general, developers are fully responsible for the construction of both onsite and offkite draina facilities which are necessary to mitigate their project impacts and/or to provide for the ordel development of their property. In some caw, it is necessary or desirable to construct facilities whil are in excess of the need of a single developer and provide a benefit to the community as a whole. : handle these cases, the City established, and this report recommends the continued use of, Planned Loc ~~~~___ ~___ ~~~___ ~~___ Chapter 4 Page 28 ~~~ ~ ~ ~ ~~~ 1992 corlsbad Mostel Drainage a Storm Water Quollty Management PI I I I I 1 I I 1 I I I 1 I I I I I I Drainage Area (PLDA) fees. The funds generated by the collection of PLDA fees can then be used t City to either construct needed facilities or to reimburse developers for the construction of facilit The existing drainage fee program requires payment of PLDA fees only upon the subdivision of This practice was the result of State legislation which only provided authorization for the levy 01 fees on subdivisiotrs. Recent State legislation in the form of AB 1600 (Government Code Section ( et seq.) now provides the City with the authority to levy such facility fees on all developments that il the need for such public facilities. The ability to charge a PLDA fee to all developers eliminal inherent inequity with the old fee structure and allows the City the opportunity to collect nearl: hundred percent of the future cost of the Master Plan drainage facilities. The notable exception 1 the funding of facility BB which is to be funded by SANDAG Transnet Funds. This report recommends that any person who constructs or causes to be constructed any building si pay a PLDA fee as listed in Table 4-1. This requirement would apply to new construction as well remodeling, enlargement or alteration to any building where additional impermeable surface a added. For residential remodels, enlargement or alterations it is suggested that the fee be requirec where the building footprint is expanded by 50% or greater over the existing condition. This anangt will help prevent the fee from exceeding the value of the potential benefit to such projects. PLDA fees should be levied for all lands subdivided prior to October 16,1980, the effective date fc 1980 PLDA fees, and for any project which has not previously paid or received credit for paym PLDA fees. Fees would not be charged for projects constructed upon property which have pa received credit for PLDA fees prior to the effective date of this fee program and which property : subject to an agreement to pay increased PLDA fees pursuant to a condition of project approval. P fees should be paid by all who increase the drainage burden. The sum of all PLDA fees levied ai any one property should not exceed the total of the fees recommended in this report. Fees should be computed on the basis of each acre or fraction thereof of the lot or parcel of land on r the construction is located plus the area equal to one-half the width of public and private street frc the lot or parcel. Projects located adjacent to arterial streets would compute their fee on the basis area exclusive of the arterial street plus an area equal to a thirty foot strip of the arterial frontage The following types of land uses or ownerships should be exempted from inclusion in the area fc computation : 1. Any portion of an arterial street in excess of thirty foot half width. 2. Zoned open space under public ownership. 3. Lands owned by governmental agencies that are used for public purposes. 4. Railroad right of way. 5. Public utility right-of-way when owned by the utility in fee title. 6. Property which paid PLDA fees prior to the effective date of the new fee program and u is not subject to an agreement to pay for increased drainage area fees pursuant to a condition of appr I 1992 Carlsbad Master Drdnage and Storm Water QuaHty Management Plan Chc PC G. Planned Local Drainage Areas (PLDA’s) The 1980 Drainage Master Plan divided the City into thirteen independent PLDA’s for the purpose ( fee collection as shown on Figure 4-1. A large portion of the southern part of the City was not include in a PLDA because at the time it was included within Zone 1 of the San Diego County Flood Contn District. The Zone 1 Flood Control District was dissolved in July of 1985 and the responsibility for floc control was turned over to each of the respective jurisdictional agencies. This study recommends consolidation of the existing thirteen PLD Areas and the City portion of the 01 Zone 1 Flood Control District into four new PLD Areas. The PLD Areas would correspond to each ( the four major drainage basins within the City as shown on Figure 4-2. The few small areas which dra~ to sumps or directly into the Ocean would be included into the basin which surrounds them. The fol basins are labeled “A” through “D” in ascending order from north to south as follows : 0 Buena Vista, PLDA “A’which includes all areas within the City whch drain in the Pacif Ocean via Buena Vista Lagoon. 0 Agua Hedionda, PLDA “B” which includes all areas within the City which drain into tl Pacific Ocean via Agua Hedionda Lagoon. 0 Encinas Creek, PLDA “C which includes all areas within the City which drain into tl Pacific Ocean via Encinas Creek. 0 San Marcos Creek, PLDA “D” which includes all areas within the City which drain in the Pacific Ocean via Batiquitos Lagoon. There are several reasons for consolidation of the existing fee areas and incorporation of the previous undesignated drainage areas into four Planned Local Drainage Areas. The reasons are as follows: 1. Master drainage facilities provide benefit to the City beyond the benefit provided to proper owners in any one sub-basin. Most of the Master Plan facilities are needed to protect circulation eleme roads used by all residents and emergency services. Also Master Plan facilities reduce the potential f the spread of water borne disease which improves the overall health of the community. 2. Improvingwater quality within the lagoons provides a general benefit to all Carlsbad residenl New federal regulations included within Section 402(p) of the 1987 amendment to the Water Quali Act require fhe City to improve water quality within the City’s lagoons and tributary creeks. This mi be accomplished by balancing the water quality levels of each of the subbasim throughout the overr lagoon basin. Therefore, advanced construction or increased facilities may be needed in one basin make up for deficiencies in another due to a lack of available land or environmental constraints. 3. Fewer basins are easier to administer and will provide the City greater flexibility in generati] funds necessary to construct needed facilities in a timely manner. Chapter 4 1992 Carlsbad Moster Drdnage a Page 30 Storm Water Qudity Management PI I I i I I 1 1 I I I I I I I I I 1 I I PLANNED LOCAL DRAINAGE FEE AREAS FlcueE 41 1992 Carlsbad Master Drdnage and CI storm Water QUdlty Management Plan Chapter 4 Page 32 1992 Cadsbad Master Drainage c Storm Water Qudlty Management P I I I I I I 1 I I I I I 1 I .’ I I I H. Fee Analysis In determining fet amounts the primary consideration is to effectively and fairly apportion fees in re1 to the development’s demand on required drainage facilities. In the 1980 Master Plan this accomplished by simply dividing the total cost of needed drainage facilities by the total number of, of remaining developable land. Though easy to understand and to calculate, the inherent problem this method is that it assumes the drainage burden is uniform for all land use types which is certainl the case. Drainage runoff is directly related to the permeability or absorption characteristics of the upon which the rainfall occurs. Permeability is measured by a value known as the “runoff coeffic and can be statistically related to land use. The values of various runoff coefficients for different soil and land uses is shown on Table 3-2. They range from a low of .30 for Open Space and rural are high of .95 for industrial lots. To simplify the fee structure, this study grouped land uses into three general categories. These in land with high runoff potential, land with low runoff potential and land that is non developable or \ is governmentally owned. The non-developable/governmentally owned category was excluded fro fee analysis. Table 4-3 shows the breakdown of the three groups by City land use designation. An av runoff coefficient factor of .55 was assumed for land uses with low runoff potential and .90 for lanc high runoff potential. These figures represent a weighted average of the various land uses and soils and take into account the various land constraints identified in the growth management ordinanl The next step in computing the fee was to determine the total amount of land within each of th facilities. Two categories of development were considered - new development and redevelop remodeling. For the first category all undeveloped parcels of land were identified and included F the fee analysis. To determine the potential acreage which could be redeveloped it was necess; review past redevelopmenthemodel rates and to set a time in the future at which point all funds \ need to be collected to construct the Master Planned facilities. A time period of thirty years correspo to time for City buildout was selected. Given a review of past records on redevelopment and re1 rates, it w-as assumed that within this time frame approximately twenty percent of the ex developments will remodel and or redevelop. Tables 4-4 through 4-7 list the total amount of develc and redevelopable acreage for each of the four PLD Areas by runoff potential category. * Indicates that actual use will determine PLD Fee Category proposed PLD Areas which would ultimately contribute to the construction of the Master Plr I 1992 Carlsbad Master Drdnage and ct storm Water Qudlty Management Plan I I h PLDA FEE CATEGORY GENERAL PLAN NON LAND USE GOVERNMENTA POTENTIAL POTENTIONAL DESIGNATION DEVELOPABLE, HIGH RUNOFF LOW RUNOFF NO-FEE AREA E + -7 PI + 0 + P 4 HC + H + J + G os + U 4 + NRR * * * TC + RS + - RRE + RRI + C + N 4 TS + RC + SBD + RL + RLM + + RM RMH + 4 RH + TABLE43 ~~ ~~ Chapter 4 Page 34 ~ ~~ 1992 Carisbad Master Drdnage a Storm Water Qudlty Management PI I I I I I I I I I B 1 I I I I I I I I PLDA FEE CATEGORY DEVELOPED UNDEVELOPED EXCLUDED GENERAL PLAN LAND USE LAND (Acres) (Acres) (Acres) Runoff Low Rumff AREA LAND DESIGNATION Runoff Low Runoff High Area Area Area High Area (Acres) Area (Acres) E 18.6 J 40.1 H 16.5 TOTAL 1441.8 4 = 785.5 + 0.20 X 545.5 = 894.6 4 = 178.3 + 0.20 X 262.6 = 230.8 TABLE44 LAND USE ACREAGE TOTALS FOR PLD AREA "A" 1992 Carlsbad Master Drdnage and C Storm Water Qudlty Management Plan . PLDA FEE CATEGORY DEVELOPED EXCLUDED UNDEVELOPED GENERAL PLAN LAND USE LAND LAND AREA DESIGNATION Runoff Low Rud High (Acres) (Acres) Area Area Runoff Low Rumff High (Acres) Area (Acres) Area Area (Acres) E H 24.0 J 45.4 RH 4632.8 1540.2 2416.5 720.3 1012.1 TOTAL 61.6 63.8 59.4 4. = 2416.5 + 0.20 X 1012.1 = 2618.9 L+,= 1540.2 + 0.20 X 720.3 = 1684.3 TABLE 4-5 LAND USE ACREAGE TOTALS FOR PLD AREA " B" Chapter 4 1992 Carlsbod Master Drdnage a Page 36 Storm Water QudlW Management PI I I I I I I I I I I 1 I I I I I I ! I L PLDA FEE CATEGORY DEVELOPED AREA LAND LAND EXCLUDED UNDEVELOPED GENERAL PLAN LAND USE DESIGNATION High Low Runoff Runoff High Low Runoff Area Area Area Runoff Area (Acres) (Acres) (Acres) (Acres) Area (Acres) E 1\43 J 12.4 RH 1024.3 357.0 I 814.3 271.0 193.6 TOTAL 0.0 I 0.0 0.0 ~ ~~~ AH = 357.0 + 0.20 X 196.6 = 395.8 4 = 814.3 + 0.20 X 271.0 = 868.5 TABLE44 LAND USE ACREAGE TOTALS FOR PLD AREA "C" 1992 Carlabad Master Drdnage and Cr Storm Water Qudlty Management Plan 1 I I PLDA FEE CATEGORY I : .- 2 ." I DEVELOPED UNDEVELOPED EXCLUDED GENERAL PLAN LAND USE LAND AREA LAND DESIGNATION Runoff LOW RUDO~T High Area Area Area High Low Runof' (Acres) (Acres) (Acres) Runoff Area (Acres) Area (Acres) E 87.2 J 35.0 H HC 88.0 0.0 % = 3965.2 + 0.20 X 1785.1 = 4322.2 4 = 838.7 + 0.20 X 551.6 = 949.0 TABLE 4-7 LAND USE ACREAGE TOTALS FOR PLD AREA "D" Chapter 4 Page 38 1992 Carlsbod Master Drainage c Storm Water Quality Management P I I I I I I I I I I I I I I I 1 I I I Consideringtheprecedingcategories,theareawithineachPLDAthatislikelytodevelopandtheunfu cost of storm water facilities the following formulas were developed: 0 Fee Per acre for Low Runoff areas ( '?'H) ( c::J 4-3 ( 4:-) +( c:J4%) (4-9(X$) Fee per acre €or High Runoff areas ( c::J ( 4:J ( C::J ( :.) + ( C?J (%:. i" Where CL =OS, a weighted runoff coefficient for areas with low runoff potential. CH =0.90, a weighted runoff coefficient €or areas with high runoff potential. 4 =The area in acres, of land within the basin that has runoff coefficient CLy that development potential and that are not exempt from PLDA fees. 41 =The area, in acres, of land within the basin that has runoff .Coefficient Cw thal development potential and that are not exempt from PLDA fees 2$= The unfunded cost of storm drainage facilities within the basin. Thevaluesofvariables~,A,aad~$foreachofthefourPLDAreastogetherwiththefeesrecomm to be levied on an acreage basis are contained in Table 4-8. In order to maintain the relevance of tl to the cost of the storm drain facilities recommended by this study the fees should be adjusted on an : basis. This study recommends that the December ENR (formerly Engineering News-Record) Col tion Cost Index (CCI) for Los Angeles be used to provide the basis for PLDA fees adjustment. 'I adjustment should be made in conjunction with the City Budget approval. The ENR CCI was estat in 1921 and has a base year of 1913. The ENR index is widely accepted in the constructic engineering professions. 1992 Carisbod Master Ordnage and CI Storm Water Qudlty Management Plan <aura TABLE 4-8 Chapter 4 1992 Carlsixxl Master Drdnage anc Page 40 Stom Water QuoHty Management Plar I I I I I I I I I I I I 1 I I I I 1 I I. Fee Adjustments This study recommends that an administrative variance procedure be established to allow waiv payment of PLDA fees. Requests for relief would be limited to the following circumstances: 1. When portions of the project have slopes greater than 40 percent as defined in Chapter 2 Carlsbad Municipal Code (CMC) the fee for those portions may be waived. The criteria for w should be that the slope is undisturbed and has a flourishing cover of native vegetation, that the o irrevocably convents with the City or another public agency to maintain the slope as open space an4 theslopedareahasnotbeenusedtocomputeanyportionoftheprojectareausedtoestablishthemaxi development density of the project. The waiver of PLD fees for this item should be limited to the equal to the 40 percent or greater slopes that meet all of the preceding requirements. 2. When portions of the project have slopes greater than 25 percent and less than 40 perc defined in Chapter 21.95 CMC one-half the fee for those portions may be waived. The criteria foru should be that the slope is undisturbed and has a flourishing cover of native vegetation, that the ( irrevocably convents with the City or another public agency to maintain the slope as open space an the sloped area has not been used to compute more than one-half of an area equal to the sloped are: to establish the maximum development density of the project. 3. The increment of a project that is replacing a building destroyed by accidental fire or n disaster may be considered to be deducted from the valuation of the project PLDA fee. 4. Structures that will not be in place from November 16 through April 14 of any ye considered temporary for the purposes of this report. Temporary buildings may have the pay= PLDA fees reimbursed when they have been removed and when the areas under and appurtenant tc are restored to their natural hydrologic condition. Appurtenant areas include parking areas, 1 activity areas and other areas accessory to the use of the building. Structures and appurtenant are have not been or are not removed between any November 16 through April 14 period duriq existence are not eligible for reimbursement of any portion of the PLDA fee. An application for waiver or refund of PLDA fees should be submitted in writing by the owner land involved. The request should be accompanied by: 1. Written statement citing the reason(s) why the refund is justified. 2. Proof of ownership of the land should be provided when fees have been previously p preliminary title report, dated within 30 days of the request for refund, that names the requato' are being waived prior to their payment. title owner of the land will be satisfactory proof. Proof of ownership should not be required wh 3.The current fee for an administrative variance. 1992 Carisbad Master Drdnage and C Storm Water Qudlty Management Plan J. Reimbursement for Constructed Facilities A developer who constructs all or a portion of one or more of the drainage facilities identified in t; Master Plan study is eligible for reimbursement from hnds accumulated through collection of PLI fees. The maximum reimbursement is limited to the actual cost of installing the facilities. The form a manner in which reimbursements are given will be determined at the time the developer enters intl reimbursement agreement with the City. All reimbursement agreements are approved by City Count Whenever the actual cost of installation of a drainage facility exceeds the cost estimate in this rep adjusted €or inflation, a revised fee schedule should be adopted to ensure that adequate funds are collect to cover $he reimbursement payments. Chapter 4 Page 42 1992 Carlsbad Master Drdnage ar Storm Water Qudity Management PIC I I I I I I I I I I I I I 1 I I I I I CHAPTER 5 STORM WAmR QUALITY MANAGEMENT PROGRAR A. Introduction At this time, pollutants in storm water discharges are largely uncontrolled not only in the City of Carl: but in most cities in the United States. The U.S. Environmental Protection Agency determinec pollutants in runoff from urban areas and from construction sites are a leading cause of water q\ impairment. In recognition of this problem, recent Federal Legislation was enacted which now req that the City of Carlsbad establish a Storm Water Quality Management Program. The majority of storm water runoff from urban areas and construction sites contain pollutants whic’ their way into the surface waters of the United States and are therefore subject to the provisions ( Clean Water Act (CWA). Studies have shown that many storm drains receive illicit discharges I include a wide variety ofwastes from sources such as illegal sewage connections and waste dump; industrial and automotive by-products. In addition there are numerous “non point” sources of pol11 which find their way into the storm drainage system such as fertilizers, pesticides, grease, automotive and power plant soot, trash, human and animal excrement, etc. Storm water discharges industrial facilities may also contain toxins and other noxious pollutants. In urbanizing areas SL Carlsbad and the surrounding communities, soil erosion and sedimentation caused by constn activities together with increased runoff from developed property contribute significantly t degradation of surface water quality. Removal of these wastes and sediment materials from storm discharges presents an opportunity €or dramatic improvements in the quality of water found in OUI creeks and lagoons. The Environmental Protection Agency (EPA) tried a variety of approaches since 1972 to address water based pollutants under the National Pollutant Discharge Elimination System (NPDES). The effort met with little success; therefore, when the Clean Water Act was reauthorized pursuant to the’ Quality Act of 1987, Section 402(p) to the Clean Water Act was amended to require EPA issua~ regulations establishing permit application requirements for: 1) storm water discharges associated with large municipal jurisdictions being served by se storm drain systems; and, 2) storm water discharges from any jurisdiction whose storm water discharged into rec waters found to be in violation of established water quality objectives. Within Carlsbad all three lagoons have been found to be in violation of established water ‘ objectives. The. task of administering the Water Quality Act in California was delegated by the EPA to the Rt Water Quality Control Boards. In the past, the Regional Boards pursued regulation ofnon stonr discharges from discrete “point” sources, such as an industrial or sewer outfall pipes, through is 1992 Carlsbad Master Drainage and C Storm Water Quollty Management Plan and enforcement of National Pollutant Discharge Elimination System (NPDES) permits. These “poim source NPDES permits required technology based or water quality based effluent limitations an controls for the reduction and/or elimination of pollutants in discharges to surface waters. Today, tt majority of “point” source discharges have been curtailed or are effectively regulated to protect tt beneficial uses of surface waters. During the past decade, a great deal of information was learned about “non point” storm water dischargt and urban runoff through the National Urban Runoff Program (NURP). By monitoring runoff ar receiving waters,’ NURP and other studies indicate that 40 to 80 percent of pollutants currently foun in our lakes, streams, rivers, and other surface waters are a result of runoff from urban areas. Urban are: are normally covered with structures and asphalt upon which a variety of pollutants settle or are spillec These impermeable surface areas prevent absorption of both water and pollutants into the ground thl allowingmorepol1utantsandstormwaterrunofftofindtheirwayintothereceivingwaters.Theincrease storm water runoff subsequently results in increased potential for downstream erosion. Pollutants found in the greatest frequency and concentration are metals (cadmium, copper, lead, zinc sediments, oil and grease, and polyaromatic k :drocarbOns (combustion products of petroleum). In t€ San Diego area, nutrients such as nitrogen and phosphorus from fertilizer are also significant pollutan in estuaries, lagoons, and ephemeral streams. Nutrients are responsible for increased algal blooms wil their subsequent decreases in dissolved oxygen. Most fish kills in the region are probably due to dissolve oxygen depletion as a consequense of nutrient loading. Organic priority pollutants, such as pesticidc and herbicides, are found at lesser frequencies dependent upon the type of land use found in the basi and application techniques used by the land owners. In an effort to control the discharge of these “non point”sources of pollutants, the Regional Water Qualii Control Board for the San Diego Region, issued a single NPDES permit to the City of Carlsbad, the Counl of San Diego, the S.D. Port District and all other Cities in San Diego County pursuant to Order No. 9( 42 dated July 16,1990. A single permit was issued to all municipalities, the County and the Port Distril County fail to meet minimum water quality control objectives. Because water quality management mu be effective throughout the basin and since established jurisdictional boundaries do not coincide wii drainage basin boundaries, the Regional Board opted to include all agencies within the County under 01 permit as co-permittees. Through issuance of the NPDES permit, the Regional Water Quality Contn Board is requiring Carlsbad and other San Diego jurisdictions to develop and implement Storm Watr Quality Management Programs to eliminate and/or reduce storm water pollutants from reaching t€ streams, lakes, lagoons, bays, ocean and other surface waters within the County. because it was found by the Regional Board that essentially all surface and Ocean waters in San Diet B. Brief History of Actions Leading to City’s NPDES Permit 1. Clean Water Act of 1972 amended the Federal Pollution Control Act to prohibit “point”sourc discharges without a National Pollutant Discharge Elimination System (NPDES) permit. 2. Water Quality Act of 1987 amended the Clean Water Act by addition of Section 402(p) whic established NPDES permit requirements for ‘fnon point” source discharges from municipally owne storm drainage systems. Chapter 5 1992 Cadsbad Master Drdnage ar Page M Storm Water Quality Management PIC I I I I I I I 1 I 1 I I I I I I I I I 3. On December 7, 1988, EPA published draft regulations governing permit applic; requirements. Due to litigation with environmental groups, the regulations were not finalized. 4. Carlsbad City Council on July 10,1990, adopted Resolution No. 90-235 noticing City’s i~ to apply for a NPDES permit pursuant to Order No. 90-42 of the San Diego Regional Water Qu Control Board. 6. The Regional Water Quality Control Board for the San Diego Region issued Order Nc 42 on July 16,1990, naming the City of Carlsbad as a co-permittee on a National Pollutant Disc1 Elimination System (NPDES) permit. 7. The final regulations for NPDES permit requirements promulgated by the Environm Protection Agency were published in the Federal Register on November 16, 1990. 8. Carlsbad City Council on July 16,1991, adopts Resolution No. 91228 authorizing Ma] sign Implementation Agreement with other co-permittees listed under the NPDES permit. C. “Early” NPDES Permits As written, the proposed federal regulations governing storm water discharges are complex, bu some, costly, and require tight time schedules for compliance. Seeing the complexity and potential associated with the federal regulations, a number of municipalities in the State, including Carl requestedtheir local Regional Water Quality Control Board to issue “ear1y”permits (astormwater p issued prior to promulgation of the final federal regulations). “Early” permits are exempt from so, the stricter requirements of the EPA for a period of five years. The intent of issuing “early” permit to: 1. Establish reasonable permit conditions and requirements specific to the local a; and its hydrological characteristics; 2. Allow flexibility and a working relationship between local governments and the 1 writer (Regional Board staff); 3. Establish reasonable time schedules for compliance; 4. Establish area-specific monitoring programs; 6. Allow for prioritizing programs for impacted waters; and 7. Avoid costly and burdensome federal regulations. Within San Diego County it was determined by the Regional Water Quality Control Board (Re; Board) that all municipalities including Carlsbad together with the County of San Diego and tk Diego Port District were subject to NPDES permitting requirements. In July of 1990 the Regional 1992 Carlsbad Master Drainage and ct Storm Water Qudlty Management Plan I issued Order Number 90-42, titled Waste Discharge Reauirements for Storm Water and Urban Runc from the Countv of San Dieno. - the Incorporated Cities of San DiePo Countv. and The San DiePo Unific Port District, which mandated Carlsbad’s participation as a co-permittee on an “early” NPDES perm D. Elements of Carlsbad’s Storm Water Quality Management Program The basic elements required to complete the proposed Storm Water Quality Management Program f Carlsbad are outlined within the text of Order No. 90-42 of the Regional Board. The following is a bri synopsis of the required elements together with the implementation or submittal dates contained in Ord No. 90-42. Much of the inventory work needed to complete the elements was completed by virtue oft completion of this Master Drainage Plan. The basic elements of the proposed Storm Water Quali Management Plan for Carlsbad are as follows: 1. Enter into a cooperative “implementation” agreement with the co-permittees on the NPDl permit defining the roles and fiscal responsibilities of each party to the agreement by July 31, 1991 2. Inventory existing storm water pollution control programs, illicit discharge detectil programs, monitoring programs and data, storm water conveyance system maps, land use maps, a1 existing laws, ordinances, and codes which provide the City authority to implement and enforce stol water pollution control measures and submit the information to the Regional Board by July 31, 199 3. Develop and implement a storm water, urban runoff and receiving water monitoring progra to evaluate the type and characteristics of pollutant loading in order to target priority pollutants ar evaluate the efficiency of pollutant control programs. Submit proposed program by July 31, 1991. 4. Develop and implement an illicit connection/illegal discharge detection program to identi and eliminate non storm water discharges to storm water conveyance systems. Submit proposed progra by January 31, 1992. 5. Develop a fiscal analysis of the capital and operating expenditures necessary to accompli; the activities of the proposed Storm Water Quality Management Program. Submit to Regional Wat Quality Control Board (Regional Board) by January 31 of each year. 6. Develop and implement best management practices (BMPs) to control discharges of pollutar to and from storm water conveyance systems to the maximum extent practicable (MEP). The BMP’s shr address structural and ma-structural techniques for the control of pollutants in urban runoff and stor water discharges from industrial, commercial and residential areas. Where necessary codes, ordinanc January 31, 1992. and standards shall be enacted to ensure implementation of the program. Submit proposed program 1 7. Inventory and compile data regarding existing programs and data. Prepare report on adequac of data relevant to the EPA promulgated requirements and recommend actions necessary to correct a program deficiencies. Submit report to Regional Board by July 31, 1992. Chapter 5 1992 Carlsbad Master Drdnage a1 Page 46 Storm Water Qudity Management PI I I I I I I I I I I I I I I I I I I I 8. Conduct an annual analysis of the effectiveness of the overall storm water pollution co management program in Carlsbad. If the water quality objectives of the receiving waters are vi0 as a result of storm waterhrban runoff discharges, then identify proposed programs which will res1 the attainment of the water quality objectives, and a time schedule to implement the new prog! Submit report to Regional Board January 31,1993, and each January 31 thereafter. E. Testing and Monitoring of Storm Water and Urban Runoff A major task necessary to establish the Storm Water Quality Management Program is implement of a program for the testing and monitoring of storm water flows. Testing and monitoring is nece to determine the type, quantity and characteristic of the pollutants within the various conveyance syz and within the receiving waters in the City. Testing should be conducted on dry weather flows to c illegal dumping or connection of non storm water into the conveyance system, and during storm e to determine the residual pollutant loads from all non point sources within the drainage basin. The testing and monitoring program should be coordinated with other cities and agencies h jurisdiction over the portion of the drainage basins which extend beyond Carlsbad’s city limits. TI- that basins cross jurisdictional boundaries was a primary motivation for including all Cities, the C and the Port District as co-permittees under one NPDES permit. It has been suggested by Regional : staff that the North County cities and the County of San Diego join together viasome form of coop agreement to establish a coordinated testing and monitoring program for the North County drz basins. Such cooperation would produce greater consistency in the test data and result in lower u each of the individual cities and the County. As of this report date, the staffs from Carlsbad, other County Cities and the County have generally agreed to work together to formulate such a coope arrangement. In the development of the testing program and the later evaluation of test data it will be necess consider the physical characteristic, ecology and beneficial uses of the receiving waters. As previously in the report, Carlsbad contains four separate and distinct drainage basins. Each of these ’ extend in a general eastward direction through the City and contain perennial or intermittent fl~ streams. Of the four basins only one, Encinas Creek, which parallels Palomar Airport Roa discharges directly into the Pacific Ocean, is located entirely within the Carlsbad city limits. Tht three basins originate outside of Carlsbad and terminate at “lagoo11s”within Carlsbad prior to dish into the Pacific Ocean. In addition to the three “lagoons”, there is a fresh water reservoir, knc Calavera Lake, located along the north fork of Agua Hedionda Creek. The term lagoon is used parenthetically above because in reality only Agua Hedionda Lagoon is ! to tidal influences. Buena Vista Lagoon is a fresh water reservoir created by the installation of structure near the discharge point at the ocean. Batiquitos Lagoon is a brackish water estuary est closed to tidal inff uences except during major storm events, at which time the sand and cobble dl which block the outlet are washed away. Each ofthe lagoons, their tributary streams, Calavera La the Pacific Ocean has different capabilities to absorb and handle storm water pollutants. In additio of these bodies of water has different beneficial uses as defined in the various water quality contrc and reports produced by the Regional Board. A listing of the beneficial uses is presented in Ta 1 and 5-2. 1992 Carlsbad Master Drdnage and C Storm Water Qudlty Management Plan The testing an mitoring program would be conducted on dry weather flows and during storm even1 The dry weather resting is used primarily to detect illicit connections and will be discussed in more del; in Section F of this Chapter. The methodology for storm water testing should be worked out cooperation with the other North County co-permittees and must be approved by the Regional Boar The Regional Board has indicated a willingness to consider a graduated testing program which begi at the receiving water and progresses up stream until there are no further water quality violations. Givl the limited amount of rainfall in the North County the co-permittees may wish to select initial upstrea test sites to more quickly define the extent and nature of the pollutant loading. The following is a recommended strategy for completing the storm water testing program: 1. Meet with other North County NPDES co-permittees to develop a strategy €or storm watl testing, stream flow and rainfall measurement, consultant selection and hiring, cost sharing ar cooperative agreement if neqary. 2. Submit the strategy €or storm water testing and monitoring to the Regional Board for approvi 3. Finalize a cooperative agreement with other North County co-permittees and submit E Council approval. 4. Prepare request €or proposals from consulting firms specializing in water quality testing ax monitoring. 5. Form a committee of co-permittees to review proposals and make recommendation c consultant selection. 6. Negotiate a contract with the selected consultant for the required testing and monitorir: program. Verify hnding sources and prepare an agenda bill €or Council approval, Scope of work shou; at a minimum include: A) Research and review of available records regarding previous water quality testin done within the basins, existing seream gauging stations, rainfall stations, topographic mapping of th basins, land use mapping, and hydrologic studies. B) Prepare comprehensive topographk maps delineating each of the basin boundarie which clearly identify the major hydrologic features such as streams, lined and unlined channels, majc dams and retention structures, lakes and lagoons. Prepare land use overlay maps at the same scale. Th City of Carlsbad has the mapping data recommended by this item. C) Analyze the existing data and make recommendations on location of proposed ne? stream gauges, rainfall measurement stations, and storm water test sites. D) Upon City approval, obtain and install the necessary automatic flow samplers, flov meters, rain gauges and other testing equipment. Chapter 5 1992 Carlsbad Moster Drdnage an1 Page 48 Storm Water Quallty Management Pla I I I I I 1 1 I 1 I I I I I ', I I I I .. I E) Provide all technical support necessacy to actuate and maintain the automatic sam and other test equipment during runoff producing rain storms. F) Accomplish the required testing and analysis within laboratories and utilizinl methods approved by the Regional Board. G) Reduce and collate the data into report form acceptable to the Regional Board. D the type ,magnitude (concentration and mass load) and sources of pollutants in the storm water sy Provide pollutographs or other suitable graphic representations of the data. H) Maintain full written records of all sampling and testing in accordance with Rei Board requirements, Provide City with copies of all reports, test data and field notes. I) Develop and/or utilize a suitable pollutant monitoring program on a P.C. computer system for delivery to the City. J) Evaluate the effectiveness of pollution control measures and compliance with quality objectives as established by the Regional Board. Make recommendations on the need €or f testing and proposed mitigation programs 7. Council approval of consultant contract. ' 8. Consultant implementation of testing program. 1992 Carlsbad Master Drdnage and C Storm Water Qudlty Management Plan -tion of race ad eoLo tion of rare ad eoLn SAN MARCOS CREM Y Wd& brbirrt CALAVERASIAKE Cold treshwata bbiat PtuJuvltionotrrrerrri~ngaedspacics wildlife brbitat .) TABLE 5-1 Chapter 5 1992 Carlsbad Mater Drdnage anc Page 56 Stom Water Gauallty Management Pial I I I I I I I I I I I I I I I I 1 I I TABLE 5-2 F. Detection of Illicit Connections and Illegal Discharges A major focus of the Regional Water Quality Control Board (Regional Board) and the Envirom Protection Agency (EPA) has been placed on the detection of illicit connections and illegal discl of non storm water waste into storm water conveyance systems. EPA sponsored studies have shov severe and widespread contamination problems have resulted from these two waste discharge sc It is not expected that illicit connections will be a major factor within Carlsbad because ofthe arid c and lack of significant natural water flows which can be used to disguise illicit waste streams. Ho the illegal discharge of wastes into storm conveyance systems does occur with considerable €?a in Carlsbad. Sources of illegal discharges are numerous and vaned. Significant waste contributions originat gas stations and other automotive businesses that lack recycling systems, grease and oil separato proper sewer discharge systems. At many of these facilities, surfaces are washed down with deg agents and discharged directly into storm drainage conveyance systems. Another source of illega discharge results from improperly stored or disposed wastes at commercial and industrial facilities are exposed to rainfall or storm water flows. Not all illegal discharges originate €?om commercial or industrial uses. Individual residents fie( drain motor home holding tanks, radiator coolants, crankcase and other engine fluids into storm 1992 Carlsbad Master Drainage and C . Storm Water Quality Management Plan or upon hard surfaces which ultimately wash into storm drains. In addition residents wash out containe or directly pour unW portions of pesticides, household cleaners, detergents, paints, solvents and othl harmful wastes intostorm drains or onto surfaceswhich drain into storm drains. Arecent study conductt in San Diego indicated that 90% of the residents believed that storm drains flowed directly to the sew' plant. Carlsbad is required under the NPDES permit to develop and implement a program to detect ax eliminate illicit connections to storm drains and illegal discharges of non storm water wastes into stor water conveyance systems. A primary component of the program is field screening and testing of d weather flows at storm drain discharge points for priority pollutants (commonly found pollutants whit indicate illegal discharge may have occurred). Should any priority pollutants be found, a more detailc investigation would be conducted upstream of the test point to determine the source of the discharg It is proposed that initial testing be accomplished by an outside consulting firm. Continued testing future years would be conducted by City staff who would receive training from the consultant. The d and wet weather testing programs may be combined into one contract and conducted by the san consultant; however, this may not be practicable due to timing constraints and the need to coordinate tl wet weather testing with other agencies. The following is a proposed strategy for a separate program for the detection and elimination of illic connections and illegal discharges: 1. Prepare request for proposal from qualified consultants. 2. Review submittals and select consultant. 3. Negotiate a contract for the required testing and detection program. Obtain funding sour and prepare an agenda bill for Council approval. Scope of work should at a minimum include; A) Review of City Master Drainage and Storm Water Quality Management Pian and La Use maps to determine appropriate test sites. B) Field review pipe discharge points and perform appropriate tests in accordance w Regional Board requirements. Tests should generally be conducted at all discharge points for pipes inches in diameter or greater where dry weather flows exist. C) After initial field screening and testing is complete, plot test results on a City mi Prepare a strategy to conduct further testing or site visits to determine the source of pollution. Condr the necessary secondary testing and field review to determine the source of the pollutant discharge D) Prepare a report which includes maps, field notes, test results and written opinion the possible sources of pollutant discharges discovered through the.testing and field inspections. E) Provide City with appropriate test kits together with field test manuals and train h or more City staff members in appropriate test methods and reporting requirements. Chapter 5 1492 Carlsbad Mcmter Drdnage c Page 52 Storm Water Qudlty Management P I I I I I 1 I I 1 I I I I I I I I I I 4. Once an illicit connection or illegal discharge has been dimered, City should beg abatement process with the owner of the property in violation. Abatement should begin by WI notification to the owner of the property uponwhich the violation exists identifying the violation tog with a request to cease and desist the discharge activity and to begin clean up measures if approp For violators with minimally toxic discharges a phased program of abatement may be considered. responsive violators should be referred to City Council for initiation of abatement proceeding possible legal action. 5. Develop a program of public education on the nature of storm drains and the har environmental effects which can result from the improper use and disposal of common household, and automotive products. Possible suggested elements of the program are as follows: A) Prepare a public information pamphlet explaining the problem, why it is impc to Carlsbad and suggesting ways individuals can contribute to the solution. The pamphlets cou mailed to residents or made available at public information counters throughout the City. B) Create a public service video on storm water quality issues for showing on local 1 T.V. C) Develop a student awareness program within the local schools. D) Create public awareness in storm drains by stenciling water birds, fish, turtle frogs on storm drain manhole covers. Such a program was used successfully in a Washington 1 community to raise the publics’s level of understanding regarding the consequence of discha] harmful materials into the storm drain. Stenciling may be accomplished by students as part of the st^ awareness program suggested above. G. Best Management Practices (BMP) The Water Quality Act requires municipalities to control discharges containing storm water pollu to the maximum extent practicable (MEP). Generally it has been held by the Environmental Protec Agency that MEP means the use of Best Management Practices (BMP) for the control of pollutants, approach was chosen in lieu of a more stringent program based on quantitative effluent limital because there are no generally accepted effluent limits. As noted earlier, the City is required to su a proposed program of BMP to the Regional Board by January 31,1992. Best Management Practices include implementation of structural and non-structural controls. Struc controls are physical improvements made to the storm water conveyance system which remove or re stom water pollutant levels. Non-structural controls are programs and practices which tend to elim or reduce pollutants at their source before they enter the storm water conveyance system. Table 5-3 potential structural and non-structural controls which could be utilized in Carlsbad. Although many of the elements of BMP have been in use in Carlsbad and other communities for n years, the concept of an integrated program implementing BMP is new. To prevent propagatic numerous community standards regarding BMP, the State has budgeted hnds for the preparation statewide guidelines manual for Best Management Practices. When this manual becomes available City will need to review the contents and incorporate all or portions of it into the City’s proposed 1992 Carlsbad Master Drdnage and Cha Storm Water Quality Management Plan Pa Management Practices program. The following is a brief discussion of some of the more importa~ elements of BMP which will need to be addressed in the proposed BMP manual. Land Use Restrictions Land Use restrictions and regulations can play a crucial role in the control of storm water pollutants. has generally been found that preservation of natural streams and drainage courses enhance water qualii by providing a natural filtering mechanism to remove urban pollutants. Collecting and combining urba runoff in concrete lined conveyance systems for direct discharge into receiving waters provides litt: opportunity for the reduction or control of storm water based pollutants. Land Use policies which preserve natural water courses or provide naturalized drainage channels are ' ' be encouraged within the City. Additionally, Open Space policies should be reviewed to coordinate tl needs of storm water pollution management with habitat preservation, aesthetics and other Open Spac needs. Naturalized channels and pollution management basins should be landscaped with native pla species which balance the needs of fire suppression, habitat values, maintenance, aesthetics and pollutic absorption. Appropriate buffer zones should be maintained between lot lines and major storm wat management features to enhance their pollution control value and to reduce potential negative impac on adjacent development. Other Land Use regulations which affect storm water quality and should be considered when preparil the BMP manual are : zone code enforcement to eliminate unauthorized uses which may contribute pollutant loading; rezoning of property which is incompatible with the preservation ofwater quality; an density reductions. Maintenance and Owration Good maintenance and operation ofthe storm water conveyance system is an essential component of B Management Practices. This includes the sweeping of streets and parking lots, removal of accumulai silt and debris from inlets, pipes, channels and filtration/desiltation basins, cleaning of grease and oil tra and, other maintenance functions which generally remove or reduce pollutant loads before they can discharged to the receiving waters. Carlsbad's municipally owned storm drainage system is maintain by the Streets Division of the Utilities and Maintenance Department. Street sweeping activities i accomplished through private contract with the Oceanside Disposal Company. Maintenance functiotls need to be reviewed to assure maximum effectiveness for pollutant remov Street sweeping schedules should be accelerated prior to predicted storm events which occur after lo dry periods. Sincc oil and pase bind to fine particulate materials, new street sweeping equipment whi captures these fine particles are to be investigated and utilized when practicable. Desiltation basins 2 other urban pollutant facilities should be designed to accommodate necessary maintenance activitia both dry and wet weather. Maintenance of privately owned storm drainage and pollutant control facilities is also important for overall control and reduction of storm water pollutants. Adequate provisions should be included wit1 the various homeowners associations to properly maintain private facilities and to assure that adequ funds are available for maintenance. Chapter 5 1992 Cotlsbod Mmter Drdnage t Poge 54 Storm Water Qudlty Management f I I I I I I I I I I I I I I I I I I I Private Development Restrictions and Conditions State laws regarding the conditioning of subdivisions and other land development projects cun provide the City with sufficient latitude to restrict and/or condition developments to comply wit to require pollutant mitigation measures together with monitoring programs designed to evalual effectiveness of the installed mitigation. All new development projects within Carlsbad shou conditioned to comply with currently established BMP as well as any new BMP established pr issuance of the respective building permits. Construction Sites BMP Program. In addition, the California Environmental Quality Act (CEQA) provides added aut1 Construction activities generate numerous types of pollutants detrimental to water quality such as el and diesel oils, hydraulic fluids, paints and solvents, herbicides and, fertilizers; however, the significant pollutant originating from construction sites is soil. In small quantities soil does not il water quality or degrade riparian habitat. In fact soil deposition is a natural process vital to the long survival of marine and riparian habitats. However, soil loss at construction sites can significantly e: natural levels and overwhelm both habitats and drainage facilities located downstream. Exa sedimentation can clog vital storm drains, disturb natural stream flows, suffocate bottom dwelling 1 and animals and, create impediments to boating in the lagoon areas. In the long term, exa sedimentation can prematurely impair the vitality of water based habitats as exemplified b Batiquitos Lagoon. Carlsbad has exhibited a strong commitment to reduce construction site sedimentation in orc preserve its lagoons and riparian habitats. The 1980 Drainage Master Plan included a model erc control ordinance which formed the basis of the subsequent erosion control program within the During the past eleven years, substantial advancements in erosion control methods and practices occurred and been incorporated into the City’s Engineering Standards and Inspection Manuals. 1 erosion control methods and practices should be reviewed and consolidated into the pro1 comprehensive manual of BMP for the City. Waste Minimization. Collection and Recvcling A key feature of Best Management Practices is to eliminate the source of environmental pollutants their introduction into the drainage system. To this end, the City ahd other agencies are being encou by the Regional Board to establish effective programs for the reduction of waste, collection of con household hazardous wastes and recycling of motor oils.The City has implemented many aspects of programs and is in the process of expanding their role in this regard. Several times a year the City no residents and establishes local collection points for household hazardous wastes. Numerous handou the subject ofwaste collection, reduction and recycling are available at public offices throughout the In the future, the City will need to expand the circulation of the handouts and to establish convenienl round hazardous waste collection centers within the City. Compliance and Enforcement Presently the only effective enforcement carried out on a regular basis within the City is conductc the Engineering Inspection Division with regard to land development and construction activities 1992 Carlsbad Master Drdnage and Chc Storm Water Qudlty Management Plan PC the Fire Department with regard to hazardous waste storage, disposal and cleanup. Enforcement Zoning violations and homeowner association maintenance requirements are carried out on a compla basis only. The City does not presently have an effective program to reduce or prevent the illegal dumpi and discharge of prohibited materials from sources such as automotive wrecking and repair faciliti gas stations, industrial facilities, recreational vehicle holding tanks or home mechanics. No policy, condition, facility or standard will properly control storm water pollution without effect compliance and enforcement. A key component of Best Management Practices is to obtain I cooperation of individuals, companies, homeowners associations, developers, departments and 0th in complying with Best Management Practices. In addition, appropriate City staff must be assigned a properly trained to enforce those elements of Best Management Practices required by Municipal col City Standards and conditions of approval. The City will need to carefully review the enforcement requirements and staffing levels necessaq comply with the proposed Best Management Practices program to be submitted to the Regional Bo, as part of the NPDES permit. Chapter 5 Page 56 1992 Camad Master Drdnage Storm Water Quality Management I I 1 I I I I I I 1 1 I I I I I I I I ~ sravcnrrw,~NI)NflRvcFvRAbcOrcTRo~ H struduralcomls FbtionBasiae Desiitation Basins wetponds Grassy Swales/Bu&r Strips hmus Pavement Fbmus channel Iinings Grease/oil Water Sepalatoft 11” II J Silt Fences, Hay Bales, Sad Bags, Jute Matting HydtDseeding and other lhsion control Measu~es Chad Planting ad Naturalization No~coatrds Public Education - About use and disposal of housebold, automotive and yard products - About stom dmins discharping to stmms and lagoom Spill prevention and Cleanup Resporrie Pmgnns HolrseholdHa;QIldouswastecollection clankcase oil Recycling Staed and Parking Lot Cleaning U H pesticide and Fertilizer Application Reduction Rogranrr Waste Minimization ad Redrwtion Programs Stom Dain W and Conveyance System Maintenam and Operation Improved hazamhm Waste Stocdge, Transpoa ad D$posal pllograms LaaduseIkst&hs - zoae code EnfO~xmXlt -DensityRed&n - Chlpatibie ZOthg - Buffer Axeas TABLE53 1 m cansbad ~oster Drdnage and Chc Storm Water Qudlty Management Plan PC H. Program Cats and Funding The full cost to implement the Storm Water Quality Management Program is not known at this time however, the major capital mts of the program have been estimated and are included in the propose drainage fee structure. This includes costs €or the proposed sedimentation basins and the monitorin equipment required to sample dry and wet weather drainage flows. These costs were included in the fe structure because they represent capital costs to the City and as such may be factored into the Planne Local Drainage Area fee calculation. Total capital cost figure for the sedimentation basins is $ 9.2 million dollars and for the test equipment $900,000.00. A more complete breakdown of these co; estimates is included within Appendix C of this report. Funding for non-capital elements of the Storm Water Quality Management Program will come fro sources other than Planned Local Drainage Area fees. The proposed Fiscal Year 91-92 budget for tl City includes $3O,OOO in General Fund monies for program implementation to be used primarily to fu~ consultant contracts to perform testing and monitoring functions. This figure may increase significant in future years depending upon the testing requirements imposed by the Regional Board. In addition to testing and monitoring, General Fund monies will be expended €or staff time spent ( mentation of erosion control measures and construction of localized filtration and sedimentation basi: will be funded directly by developers. Ifneeded, low interest loans and grant monies are available fro the State Water Resources Control Board for non point source pollution control facilities. A significant program cost which has received Iittle attention in the past but will increase in importanl as a result of this program is the maintenance and operation of storm drainage facilities. This is especial true €or inlet structures, filtration basins and sedimentation basins. Without proper maintenanc accumulated silts and debris can reduce the effectiveness of pollutant control facilities or be washed do\ the drainage system and degrade surface and/or receiving waters. Presently, drainage maintenan functions within the City are almost completely funded from General Fund monies. A small portion the drainage maintenance budget is derived through a special Drainage Maintenance District formed cooperation with adjacent property owners for the maintenance of the Buena Vista Creek Cham between El Camino Real and Jefferson Street. program development, enforcement activities and administration. Other program costs such as imp1 The City may wish to investigate alternatives to General Fund financing of the drainage maintenan operations. Alternative financing mechanisms wouId free General Fund monies for other City uses a provide a stable source of hnds for continued mai I- lance operations. Two alternative sources of fun which deserve careful consideration are: 1) To form a Drainage Utility and establish a monthly sewice charge similar to the charges p for water and sewer service; and, 2) To establish a citywide drainage maintenance district and.assess maintenance fees similal the City'<, St: .et Light and Lank :: Maintenance District. Both alternatives place the financial burden for drainage facility maintenance directly upon the users . ,the system. Each alternative requires that a rate structure be established which equitably distributes ca based upon the demand created by the use of the property. Generally the rate structure would be ba Chapter 5 1992 Carlsbod Master Drdnage ( Page 58 Stonn Water Qudlty Management F I I 1 I I I I I I D I I I 1 D I I I ’. 1 upon current land use, acreage and amount of impermeable surfacing (usually reflected as an av for the property’s zoning designation). In each case a mechanism to review individual charges property owner appeal would need to be established. The following is a brief discussion of each ( two alternatives. Drainage Maintenance District The City may form a drainage maintenance district pursuant to the Benefit Assessment Act of (Government Code Sections 54701 to 54715). A maintenance district formed under this act may in a few parcels, as in the case of the City’s existing Buena Vista Channel Maintenance District, or i include all parcels within the City. A maintenance district formed under this Act requires a s majority vote of the voters included within the proposed district. Assessments would be collected I property owners tax bill in the same manner as the existing Street Light and Landscape Mainte District. This method avoids the need to establish a new billing mechanism or to include additional on existing water bills. Drainage maintenance districts may impose a benefit assessment to finance maintenance and ope of the drainage conveyance system, including storm water monitoring, as well as the cost for instal and improvement of facilities. Given that the proposed Planned Local Drainage Area Fees will 6 the construction of new and upgraded facilities the City would need only to finance the maintenanc operation costs for the foreseeable future. In later years, replacement costs for aging facilities n factored into the assessment. Drainage - Utility Alternative funding for drainage maintenance and storm water monitoring may be provided throu formation of a Drainage Utility. A Drainage Utility would hnction in a similar manner to a water or utility. A majority vote of the voters within the City would be required to implement a Drainage I Once formed fees may be imposed to pay for drainage maintenance and operation functions as Y installation of new facilities, upgrades or replacement facilities. A disadvantage of this method the City would be required to establish a new billing system or include the fee within the existing billing system. Inclusion of the fee on the existing water bills would be impractical given that th Water District does not cover the entire City. For areas within the City that are outside the City District boundaries a separak billing system would still be required. 1992 Carlsbad Master Drdnage and C Storm Water Quality Management Plan Chapter 5 1992 Camad Master Drainage or Page c1) Stom Water Qucllty Management PI( rn I I I I I I I 1 I I 1 I I I I 1 1 1 CHAPTER 6 COST ESTIMATES A. General In this section, the basis of the unit prices used for the construction cost estimates are developel presented. These unit prices provide a means of budgeting for propcxed improvement pro comparing alternative projects and for developing drainage assessment fees for proposed Planned 1 Drainage (PLD) Areas. Except in the case of sedimentation basins, land costs are not included il estimates, since all right of way containing Master Drainage Plan facilities shall be dedicated to the B. Unit Costs The unit costs used in this study are presented in the following tables. Sources of information fc development of these costs include local contractors, material suppliers, data from professional jou and local municipatity bonding estimate costs. C. Additional Costs To accommodate the additional costs of field construction contingencies, engineering fees, legal fee contract administration costs, an allowance of 38% was added to all calculated construction costs. 38% represents an estimate of the sum of these variables and is included in the costs shown in Ti 6-1 through 6-4 thereby obtaining the drainage facility totals given in this report. Construction Contingencies An allowance for construction contingencies is macle for unavoidable uncertainties in the project de Items such as conflicts with existing underground utilities and variations in depths of pipelines increase construction costs and should be planned for. A contingency allowance of 15% was assu for this report. Engineering Fees Some of the costs included in the engineering of construction projects are special site investigations, surveys, preparation of construction plans and specifications, special site investigations, and matt testing. For this report, engineering fees were assumed to be 10% of the construction costs. 1992 Carlsbad Master Drainage and Cha Storm Water Quallty Management Plan Pa D. Estimated Construction Costs The following tables presents the estimated construction costs of the proposed storm drain facilities fo each of the major drainage basins identified in this study. Future construction costs are expected to change with the fluctuations in the economy. A means to inde the costs to a baseline is required. The most widely referenced construction cost reference is th Engineering News Record Construction Cost Index (ENR-CCI) which is computed from prices c construction materials and labor. The ENR-CCI is basedon avalue of 100 in 1913. The index hassteadil increased since 1913, with a current value of 5930.24 for Los Angela in March, 1991. Storm Drain Piping Included in the prices for drainage pipe are excavation, shoring, bedding, pipe installation, backfii compaction and site clean-up. The costs for pipe diameters 30" through 48" assume a mean installc depth of 8 feet. The costs for pipe diameters 60" through 96" assume a mean installed depth of 13 fee All pipe is assumed as jointed R.C.P. Enhanced Natural Channels Based upon typical channel sections, the number of two foot high drop structures necessary to achiey a slope giving a design flow rate less than 6 feet per second was estimated. Using Manning's equatic for channel flow velocity in typical sections, it was noted that for Q > 150 cfk, a slope of less than 0.0: fpf was necessary to achieve velocities of 5 fps. Therefore the number of drop structures in any givc channel was determined by the following formula. no. of drop structures = US-.Ol) 2 where: L = length of the channel .in feet S = slope of the channel in feet/€oot The length of each drop structure was based upon typical channel sections and associated Q,, valuc This relationship is shown in Table 6-3. A unit cost of $44.00 per lineal foot was based on a two foot high masonry wall with a two foot cutc wall and rip rap extending five feet out from the base of the wall. An additional twenty percent w included in the estimate to covet difficult working conditions and access problems. Potential Remedial Work An estimate of the cost of erosion damage to natural channels in areas zoned open space was made. 'I costing procedure for enhanced natural channels was used. Chapter 6 1992 Carlsbad Master Drdnage ( Page 62 Storm Water Qudlty Management 1 I I 1 I I I I I I I I I I I I I I I I @a Chwk Concrete or earthen channel cost estimates were based on earthwork excavation and export costs of, per cubic yard. In the construction of a channel in an area classified as “rural” the excavation qu, was reduced by 20% to account for the existing natural channel condition. For channels in rive: or stream beds, calculated excavation quantity was reduced by 50%. In “undeveloped” areas wi appreciable existing watercourse, 90% of the calculated excavation quantity was used. The cost of earthen channels with rip rap along one side was based on a rip rap thickness of 3 feet at per square foot. The rip rap runs from the top of the channel to 2 feet below the channel bottom For both concrete and earthen channels, chain link fence (on both sides of the channel) was esti~ at $25 per lineal foot. For all channels a 12 foot wide decomposed granite access road was esti~ at $9.50 per lineal foot of channel. Concrete channel costs include a four inch concrete lining c $225 per cubic yard. Box Culverts Box culvert estimated costs are based on earthwork and structural concrete volumes. Eartl excavation and subsequent backfill costs were assumed at $7.00 per cubic yard. Excavation and t costs were assumed at $5.50 per cubic yard. Excavation quantities were based on vertical trench for the lower 5 feet and 1:l side slope to daylight points. The bottom of the trench was assumed 2 feet wider than exterior box dimensions. A 15% allowance was added for miscellaneous ap: nances. Structural concrete costs included bedding, formwork, steelwork and site clean up and estimated at $525 per cubic yard. Repaving cost was based on a repaving width equal to the excay width plus 4 feet. New pavement section was 4 inches of A.C. over 12 inches of aggregate bas Catch Basins Unit prices of $7,040.00 for catch basins assume a 14 foot curb inlet opening and includes an 1; given line was based upon the hydrologic €low rate (Q) of the area through which the proposed drain line passes. If more than one line passes through a basin, the Q of that basin is apportioned tc line proportionally by length. A flow rate into each of 0.5 c& per lineal foot of curb inlet opex assumed. Cleanouts Unit prices for cleanouts assume type ‘B’. Spacing for cleanouts for pipe up to 48“ diameter will be 300 feet. For pipes greater than 48“ diameter, spacing will be every 500 feet. by 30 foot long R.C.P. lateral and a concrete lug-in at the main line. The number of catch basins fi Junction Structures Unit prices for junction structures are based on a modified type D-9 cleanout, $3,750.00 is used fa junction structure.. 1992 Carlsbad Master Drdnage and ct Storm Water Qudlty Management Plan I Sedimentation Basins A unit price for each sedimentation basin was calculated as a lump sum based on typical design featun shown in Figure 8.1 of “The Erosion and Sediment Control Handbook”’. The channel (if any) into and out of the basin was assumed to be lined with 4” thick concrete at $520.C per cubic yard (the City of Carlsbad unit cost for drainage channel concrete). Major creek channels (SUC as Buena Vista Creek and Agua Hedionda Creek) were assumed to be 40 feet wide by 20 feet high wil one to one side slopes. At the entrance, 50 lineal feet of lining was used and 75 lineal feet at the outle Smaller channel entrances were assumed to be 20 feet wide by 8 feet high and 30 feet long with one I one side slopes. Basin shape was estimated to be eight times as long as wide. As recommended by ,Goldman et. al., 01 baffle was estimated for each basin not in a major channel. The baffle was estimatedto be equal in leng to one half of the basin width. Its height is that of the outlet riser crest. Eight baffles of the same size we estimated for major channels inorder to increase the effective basin area in these locations where availab land is the factor limiting sediment removal efficiency. The Carlsbad unit price of$550 per cubic yard E a cast in place wall 8 inches thick (12 inches thick for major channels) was used for these baffles. The City of Carlsbad grading unit price ($3.50 per cubic yard of embankment or excavation) was us to calculate the earthwork cost for each basin. This volume was estimated to be approximately thn quarters sedimentation basin total volume plus the height of the weir. Grading Quantity = 3/4 [basin volume + (weir height x basin surface area)] Eight (8) inch perforated PVC pipe surrounded by 6 inches of gravel in a 20 inch wide trench runnil the length of the basin for each outlet was estimated at $20.00 per lineal foot. Where outlet RCP sin 48 inches and greater was required, 12 inch perforated PVC pipe in a trench surrounded by 8 inches gravel at $35.00 per lineal foot was used. Weighted standpipe drainage structures were estimated $l,OOO.00 each for tributary basins and $3,500.00 each for outlet pipe sizes 48 inches or greater diameter. Reinforced concrete pipe draining these structures was sized to pass the 100 year stor excepting those in major channels which were sized to pass the ten year storm. A fifty foot minimu length for each pipe was used. Two antiseep collars were estimated at $4,000.00 for each RCP out1 less than 48 inches in diameter. For RCP outlets 48 inches or greater in diameter, each pair was estimatc at $5,000.00. Emergency weir spillway cost was estimated by using the unit mt for 4 inch drainage channel coI1crt for a weir 20 feet wide (30 feet wide in major channels) and a length such that the design flow is at to flow over a 2.5 foot high weir (5 foot high in major channels and basins with a design Q greater th 2000 cfs). Rip rap was used for the first 20 lineal feet of tributary outlet channel. For major cham 50 lineal feet of rip rap was used. Six foot high chain link fence surrounding the basin was estimated at $13.00 per lineal foot. Land acquisition costs are estimated at $1 per square foot for sedimentation basin bottom land. Chapter 6 I 992 Cadbod Mater Dfdnage a Page 64 Storm Water Quality Management PI I I I I I I I I I I I 1 I I I I I I I It should be recognized that sedimentation basin sizes are first approximations only. At the time of design, soil composition should be determined by field testing. It will then be possible to reliably dc basins with sediment removal efficiencies in accordance with City of Carlsbad Design Stand However, only those items included in sedimentation basin cost estimates which are dependant on 1 fencing, perforated drain pipe with gravel and land costs. surface area would be expected to fluctuate greatly with soil composition. These items are perir TABLE 6-1 *For pipe diameters 30" through 48", a mean depth of pipe = 8' was assumed. *For pipe diameters 60" through %", a mean depth of pipe = 13' was assumed. TABLE602 1 rn Carkbad Master Drdnage and C Storm Water Quality Management Plan TABLE 6-3 I Udl C.rt - M-d NM cL.~clr ritL Dro) SWctua c 500 18 12 44 1936.00 550 20 14 48 2112.00 2000 78 42 164 7216.00 2500 98 52 204 8976.00 3000 118 62 244 10736.00 3 500 138 72 284 12496.00 TABLE 6-4 Chapter 6 1992 Carlsbad Master Drolnage a1 Page 66 Storm Water Qucjlty Management PI I I I I I I I I I B I I I I I I I I I B = Bomm wid& in feet Z = Side slope ntion D = Dcptb in feet CYN = Existing anyoa FLT = Existing condition u 0.1 CHN = Existing earthen chrnrl No a- mad or few TABLE 6-5 B=Baamrvidtbinfett Z = Si& slop rltio D=D+ethhfwt UND = Uo&vdopcd RUR i RIlnl ESB = &dag Sheam Bed TABLE 6-6 1992 Carlsbad Mater Drdnage and Storm Water Qudity Management Plan - Cr 1 Pipe - 39" mm/a Pipe - 42" 25oom/ea _I * Erosion and Sediment Control Handbook Goldman et. al., McGraw Hill, 1986. Chapter 6 1992 Carlsbad Master Drainage 1 Page 66 stonn Water Qudlty Management I I I I I I I I I I I I I I I I I I I I CHAPTER 7 SUMMARY OF FIELD INVESTIGATIONS A. Introduction Before making recommendations for drainage improvements a field investigation was conducted. goal ofthis investigation was to document conditions and problems associated with existing stom structures. Plans of existing storm drain structures were obtained from the City of Carlsbad, adjc city and Caltrans records. Drainage facilities were plotted on worksheets in order to determir location of major drainage lines. These existing drainage facilities and surrounding conditions investigated during the months of October, November and December of 1988. Caltrans and adjc city plans were transmitted to the City of Carlsbad for their records. The entire City of Carlsbad was inspected to check for general conformance to the record drawing detailed measurements were taken to verify slope, invert elevations and outlet elevations. Instead I - Cooper verified the location of the storm drain facility as shown on record improvement plar examined their condition. The limits of the investigation were those portions of Buena Vista Creek Basin, Agua Hedionda Basin, Encinas Creek Basin and San Marcos Creek Basin within the City of Carlsbad sphere of infll The investigation was conducted by driving near the locations of possible interest and walking to not visible from the road. Photographs were taken of significant conditions, noting the time o direction and location of the photograph. Photographs were mounted in two albums and delive the City of Carlsbad in December of 1988. Facilities were found to be in generally good condition. Some, however, were poody maintained effectiveness hindered by vegetation overgrowth, siltation and/or ponding. Some structures are in c due to erosion. B. Buena Vista Creek Basin Drainage structures in the Buena Vista Creek Basin showing evidence ofvegetation overgrowth, si or ponding are seen in photograph numbers 8,9, 10, 11, 18,26,27,28,30,31,32,34,35,39,1 41 of the Buena Vista creek section of Album 1. Damage or potential damage from erosion can b in photographs number 1,14 and 25. Some storm drain lines such as line AC are incomplete and need improvements discussed in other sc of this report. The current conditions of line AC are shown in pictures 12,13 and 14 of the Buen; Creek section of Album 1. Vandalism can influence the effectiveness of storm drain lines as can t in picture number 42. 1992 Carlsbad Master Drainage and Storm Water Quality Management Plan CI C. Agua Hedionda Creek Basin Drainage structures in the Agua Hedionda Creek basin showing evidence of vegetation overgrow siltation or ponding are seen in picture numbers 8,10, 11,12,15, 16,19,20,27,28,29,30,31,34, : 36,37, 38,39,40,41,43,47,50,51,52,53,54,55,56,57,58,59, 60,61,64,65,66, 67,68, 69, ' 71,72,73,74, 76,80,81,82,82,, 84,85,89,95,96,97,98,99 and 100 of the Agua Hedionda Cre Basin section of Album 1. Damage or potential damage from erosion can be seen in pictures 6 and Obstruction due to littering can be seen in photographs 13,33 and 70. D. Encinas Creek Basin Drainage structures in the Encinas Creek Basin showing evidence of vegetation overgrowth, siltation ponding are seen in photograph numbers 4,13,22,23,27,31,33,39,44,46,47,50,54 and 55 of ~ Encinas Creek section of Album 2. Incomplete construction can be seen in photographs 1 and 5. Dam2 or potential damage from erosion can be seen in photographs 2, 3,11 and 16. E. San Marcos Creek Basin Drainage Structures in the San Marcos Creek Basin showing evidence ofvegetationovergrowth, siltati or ponding are seen in photograph numbers 2,5,8,9,11,14,15,18,19,, 20,21,22,24,25,27,29, : 34,35,36,37,38,39,47 and 48 of the San Marcos Creek portion of Album 2. Damage or poten1 damage from erosion can be seen in photographs 12,17 and 23. Obstruction due to littering can be st in photographs 3 and 30. F. Findings In summary, the-field investigation located many areas of vegetation overgrowth, siltation and pondi~ These areas can be seen in the photographs accompanying this document. Areas of erosion damage well as areas of severe littering or vandalism were also noted and photographed. General conformance to record improvement plans was found. Storm drain facilities which WI damaged, covered by vegetation and filled with silt were documented by the photographs submitted the City of Carlsbad in December of 1988. It is recommended that the City of Carlsbad clean silted pip trim brush and repair damaged storm drain facilities. Chapter 7 19%~ carisbad Moster Drainage c Page 70 Storm Water Qudlty Management P m 1 I I I I I I I I I I I I I I I I I APPENDIXA PROPOSED DRAINAGE FACILITIES A. Introduction In the descriptions which follow, it will be noted that several existing facilities, some of which constructed relatively recently, are considered undersized. This is primarily because the 1985 re Intensity-Duration Design (I-D-D) Chart was used for this study. The original I-D-F (Intel Duration-Frequency) curves (developed in about 1965) were based on extremely limited data fro] San Diego National Weather Service (NWS) and the Mount Laguna rain gauges. The new I-D-D 1 is based on up-to-date precipitation data and statistical analysis which makes the results much reliable and consistent with Federal and State studies and reports. The I-D-D Chart is applicable to duration hydrology procedures such as the rational method. Since the City of Carlsbad desires that natural channels in canyon areas remain as natural as po8 “enhanced natural channels” are proposed in these areas when drop structures are necessary to I the flow velocity to less than 6 feet per second. However, if channel areas having a design flow ve of greater than 6 feet per second are located in areas zoned open space, the cost of potential remedial was estimated, since the construction of drop structures may not conform to land use requireme Recommendations are limited to proposed pipe sizes of 30“ (inches) or greater in diameter. RCP to reinforced concrete pipe. The following general procedures were used to determine the adequ, existing lines and to recommend improvements if necessary. 1. If computations indicate a new replacement pipe line size is not more than 6 inches in diameter than the existing facility no improvements are deemed necessary. 2. If computations indicate a new replacement pipeline size is more than 6 inches in diameter largt the existing facility and the additional capacity 9 be conveyed in the street, no improvemer deemed necessary. 3. If computations indicate a new replacement pipeline size is more than 6 inches in diameter larg the existing facility and the additional capacity cannot be conveyed in the street, the re improvements are shown on the maps as the new size required. Cost estimates generally refl construction of new facilities to replace the existing undersized facilities. However, in some loc a parallel pipe to the existing pipe line may be provided. In these cases cost estimates refl construction of these parallel lines. Generally, where existingpipeline diameters are 48 inches and new parallel pipelines are considered to be most likely and hence are shown on the maps. For s existing pipelines, replacement with larger diameter is considered more feasible. In ail cases, u shown as replacing existing with larger sizes or providing parallel pipelines to secure the adc capacity, the final determination as to the most cost effective method should be left to a detailed a during final design. 1992 Carisbad Master Drdnage and APP storm Water Quality Management Plan P 4. Other alternatives to reducing peak flows and hence reducing size of new facilities include on-si storm detention facilities. These! should be evaluated on a case by case basis during detailed desigr B. Buena Vista Creek Basin Facility A Sedimentation Basins A1 and A2 are proposed at points along Buena Vista Creek recommended by ti Buena Vista Lagoon Sediment Control Plan prepared by June Applegate and Associates in Septemb of 1985 and adopted by the City of Carlsbad. Preliminary estimates of sedimentation basin size are bas on approximations of available land only. Facility A4 This is an extension eastward along Carlsbad Village Drive from the end of the existing Central Busine storm drain system. This 30" RCP line will connect to an existing 24" RCP line which ends at Jeffersc Street. This system receives drainage originatingeast ofhterstate 5 andconnects tothe Central Busine District storm drain line becoming 36" RCP for the last 200 feet. The sizes used for this line are fro City approved plans. Facility AAA Drainage facilities are needed for the residential areas north of Laguna Drive west of Interstate 5 whic drain into the down line end of the Central Business District storm drain system. New 33" RCP is needc along Jefferson Street and existing 24" and 30" RCP along Laguna Drive should be upgraded to 45" RC as indicated on plans. Facility AAAA This 24" RCP line is smaller than the standard 30" minimum otherwise used as the lower limit of faciliti in this study. It is needed to carry drainage north to Laguna Drive along Monroe Street correcting loc ponding conditions, Facility AAB A 36" RCP line is needed along Grand Avenue to carry drainage immediately west of Interstate 5 to tl Central Business District storm drain system. Facility AB One 975' segment of the Caltrans line in Interstate 5 is undersized. This line drains residential areas ea to Highland Drive. The City should construct a parallel 33" line of approximately the same length alor Pi0 Pic0 Drive, connecting to the next segment of the Caltrans line which at 36" has adequate capacit 1 Appendlx A 1992 Carlsbad Master Drainage a1 Page 72 Storm Water Qudlty Management PIC I I I I I I I I I D I B 1 I I I I I 1 Facility AC Along the northemmost section of Highland Drive in a residential area, 36" RCP is required to drainage to an existing AC channel in an area zoned open space. Facility ADA One section of 36" RCP is needed in a residential area along Carlsbad Village Drive from Valley to Monroe Street to connect existing lines. Facility AD Two portions of existing storm drain lines in Monroe and Canyon Street residential areas shol upgraded to conform to current standards, since streets are unable to carry the remainder of the dr; flow. These portions are shown in the plans. The currently disconnected sedimentation basin southwest corner of the intersection of Monroe Street and Marron Road should be reconnec calculations show it is of adequate size to use as a detention basin. Facility AE One improvement is needed in the storm drain system draining the primarily residential are: Chestnut Avenue northward along El Camino Real. A short (100') segment of 24" RCP sho replaced by 36" RCP to conform to existing standards. Facility AFA An enhanced natural channel is proposed to route drainage from the existing residential area dr system ending east of Avenida de Louisa to Buena Vista Creek through an area designated for resic development. Facility AFB A natural channel carries drainage through an area designated as open space to a proposed sedimel basin facility. From this facility northwest to Buena Vista Creek, potential remedial work ha estimated where natural channel velocities exceed 6 feet per second. C. Agua Hedionda Creek Basin Facility B This is a sedimentation basin proposed in Agua Hedionda Creek upstream of the Carlsbad Mobile Park in the approximate location recommended in the Hvdroloeical Studv for Northeastern C; prepared by Howard H. Chang in July of 1989. A preliminary estimate of basin size is based u approximation of available land only. 1992 Carlsbad Master Drdnage and APC Storm Water Qudlty Management Plan F Facility BA In the commercially zoned area north of Palomar Airport Road adjacent to Interstate 5, one 27" RCP lir should be upsized to 45". New facilities begin with a double 66" RCP culvert (or box equivalen conveying drainage under the AT & SF Railroad tracks to Cannon Lake. The existing 30" DIP inadequate, and the area is currently poorly drained. The line continues north of Cannon Lake with 51" RCP parallel to an existing undersized 66"RCP. Facility BB This facility begins at the intersection of Pine Avenue and Harding Street and receives drainage fro! residential areas east of Interstate 5. New 30" RCP is proposed north along Harding Street, then 42" RC west along OakStreet to Roosevelt Street. New 51" RCP is required from this point west along Oakstre' to discharge into what is currently an earthen channel parallel to the AT & SF Railroad. This earth< channel which has only 0.1% slope is unable to carry drainage flow and shc d be replaced t underground drainage facilities. A reinforced concrete box of increasing size is shou n on the plans. Tt existing 63" RCP at the southern (downstream) end of the eastern channel is undersized. A parallel 7; is required to carry drainage as shown. Alternatively, the 63" RCP as well as downline 72" RCP could be removed. The discharge point of th line could be lower. A replacement line would then have significantly greater slope and could be asmallc size. This alternative should be examined for the entire line at the time of detailed design. Facility BBA This 30" RCP along Chinquapin Avenue in a residential area is needed to carry drainage west of Intersta 5 to the improvements of line BB. Facility BBB This line through a residential neighborhood currently consists of 24", 27" and 30" RCP which shoul be upgraded to 33" and 45" RCP to conform to current standards, since Chestnut Avenue is marginall unable to carry the portion of the drainage flow which existing pipes will not carry. This line current1 discharges into existing earthen channel BB. Facility BBC This 30" RCP in a residential neighborhd is needed to carry drainage originating east of Interstate ! west and north along Palm and Madison Streets to line BBB at Chestnut Avenue. Along Madison Stree this line replaces an existing 18" RCP line. Facility BC This facility extends from Chestnut Street west then south behind the high school, along James Driv and eventually to Park Drive before discharging to Agua Hedionda Lagoon. From just north ofTamarac Avenue to Agua Hedionda Lagoon, there is an existing storm drain. Except for a few short sections c this existing facility, the storm drain will not convey adequate storm water to meet current city criteri; Appendlx A Page 74 1992 Carlsbad Master Drdnage an Storm Water Quality Management PIC I I I I I I 1 1 U D I I I I I 1 I I I At Tamarack Avenue an existing 48'' RCP culvert should be parallelled with a second 48" RCP CI as shown to provide the needed capacity. On James Drive, from south of Tamarack Avenue to the end of the James Drive the excess storm can be carried in the street. If pipe flow contains sufficient head, drainage water will flow out of the J over this approximately 520 foot length of the facility. From the end of James Drive to within approximately SO0 feet of the end of the facility, a parallc RCP section is proposed to connect to an existing 60" RCPon Park Drive. Within the segment from 1 Drive to Park Drive, there is a 140 foot segment where the existing capacity is marginal. During design the final decision on whether or not to install this 140 foot segment should be made. Facility BCA This 24" RCP line collects drainage from the residential areas surrounding Park Drive and Tam Avenue directing flow to James Drive where this line connects to facility BC. This facility is neu to correct local ponding conditions. Facility BD Currently, positive drainage does not exist from the end of the existing line. The existing con includes siltation and cattail overgrowth and can be Seen in photograph 26 of Album 1. Sedimen basin BD is proposed to decrease the deposition of silt into Agua Hedionda Lagoon. Facility BE Storm drain facility BE receives drainage from facilities BED and BEC. Approximately 1850 1 BE is installed as 84" RCP and discharges from a manmade pond to a natural canyon. Storm attenuation is required upstream of the recently installed 84" RCP line in order to meet current t standards. Downstream from the existing pond discharge, this master plan shows a proposed future 84' extension of BE approximately 1500 feet to the west discharging to a proposed sedimentation I A sedimentation basin is proposed at the point where drainage leaves the area zoned for industriz development and enters an area designated open space. From this point to Agua Hedionda L; potential remedial work was estimated where channel velocities exceed 6 feet per second. Facility BEA Natural channel velocities exceed 6 feet per second in this open space zoned area near Agua Ha Lagoon. The cost of potential remedial work has been estimated. Drive curb inlet south of Tamarack Avenue, Accordingly, no additional facility upgrade is nece 1992 Carlsbad Master Drainage and APP~ Storm Water Qudltv Management Plan P' Facility BEB This 39" RCP line &reds water from an area designated for industrial park development into line B immediately prior to proposed sedimentation basin BE. Facility BEC This storm drainage system in Faraday Avenue is relatively new in the Palomar Industrial Par immediately north of Mcaennan Airport. One 500 length of 54" RCP is undersized by current standarc and should be 66 inches in diameter. Storm water attenuation is required to bring this facility in conformance with current design standards. Improvement is necessary, since Faraday Avenue designated as a secondary arterial street in the transportation element of the City's General Plan. Facility BED An existing storm drain system along Rutherford Road is also new in the Palomar Industrial Park nor ofthe airport. Several portions of this line are significantly undersized. Storm water attenuation is aga required to bring this facility into conformance with current design standards. Facility BF North of Tamarack Avenue immediately east of Sierra Morena Avenue, where channel velocities excec 6 feet per second, an enhanced natural channel has been proposed. Drainage from existing residenti development storm drains north of Tamarack Avenue and east of El Camiw, Real currently discharg into an open field south of Tamarack Avenue and west of El Camino Real. New 75" RCP is proposc to carry drainage water south to proposed sedimentation basin BF immediately north of El Camino Re; The size of this basin was estimated omitting the amount of suspended soil material calculated to 1 draining into the existing sedimentation basin at Pontiac Drive and Tamarack Avenue. Drainage thc flows in a proposed double 8'x 4' RCB under El Camino Real. Southwest of El Camino Real, a pr maintained earthen channel (connecting with an existing concrete channel) is proposed to be upgradc to concrete . At the end of this existing concrete channel a second sedimentation basin is proposed. Fro it water drains into the final portion of Aqua Hedionda Creek which is actually contiguous with tl Lagoon. Facility BFA This 42" RCP line south of El Camino Real is proposed to carry drainage from an area designated f residential development north and west to the concrete channel of facility BF south of sedimentatic basin BF1. Facility BFB North of Tamarack Avenue immediately east of El Camino Real, where channel velocities exceed 6 fe per second, an enhanced natural channel has been proposed. Drainage east and west of El Camino Re from Chestnut to Tamarack currently drains into an earthen channel and undeveloped lot at the southel comer of El Camino Real and Tamarack Avenue. A 48" RCP pipe is proposed to route this water to li, BF north of sedimentation basin BFl. Appendix A 19% Carlsbad Master Dralnage a Page 76 Storm Water Qudity Management PI 1 I I I 1 I I I 1 1 I I I 1 I 1 I I I Facility BG This is asmall (4'x4') concrete channel carrying drainage from an undeveloped residential area soutl of and parallel to El Camiw Real at future Cannon Road to Aqua Hedionda Creek. Faciiity BH These 36"' 57" and 72" RCP lines are proposed to carry drainage from an area designated for resid1 development south and west of Elm Avenue and future College Boulevard south to Aqua Hedionda ( just north El Camino Real and future Cannon Road. Facility BJ This line travels along future Cannon Road through an area zoned for residential development. It b at the City of Carlsbad boundary and des water from existing lines in the City of Oceanside's LC Village south and west to Aqua Hedionda Creek just west of Rancho Carlsbad Mobile Home Pa begins as large (63" and 66") RCP and becomes an enhanced natural channel as it is joined by vi branch lines. A sedimentation basin is proposed immediately upstream of Rancho Carlsbad Mobile From this point, an 80 foot wide earthen channel is proposed to carry drainage to Agua Hedionda C The City of Carlsbad does not choose to construct a narrower concrete channel in this area. It is pa that detailed design studies using other methods could determine a narrower section for this e2 channel. Facility BJA This is a 33" RCP line carrying drainage through an area designated for residential development enhanced natural channel of line BJ. Facility B JB An enhanced natural channel carries drainage through a portion of an area designated for resid development to a proposed sedimentation basin northeast of future Cannon Road and College Blvd proposed sedimentation basin drains into an earthen channel of line BJ. Facilities BJBA, BJBB and BJBC Potential remedial work has beenestimated in these open space zoned areas south of Calavera Lakey natural channel flow velocities exceed 6 feet per second. Facility BJC These 33" and 42" RCP lines carry drainage through an area designated for residential developm the enhanced natural channel of line BJ. 1992 Corkbod Master Drainage and APPS Storm Water Quality Management Plan PC Facility BJD This 48" RCP line carries drainage originating in the City of Oceanside west through an area designar for residential development to the upstream end of the enhanced natural channel of line BJ. Facility BL This line carries drainage from south and east of El Camino Real and College Boulevard north acn El Camino Real and through areas designated for commercial and residential development to Ac Hedionda Creek. This is a new storm drain line except that one segment of existing 54" RCP should paralleled by new 57" RCP, and the existing 60" RCP under El Camiw Real should be replaced by : RCP or a parallel pipe to conform to current standards. Facility BLA Existing 33"RCP storm drain lines along College Blvd carrying drainage north to El Camino Real undersized. Storm water attenuation is required to bring these lines into conformity with current desj standards. Facility BM An enhanced natural channel is proposed to carry drainage through an area designated for residen; development to Aqua Hedionda Creek. Within this channel, there currently exists a lake which i expected will remain for scenic or recreational purposes. Facility BN This is an enhanced natural channel required to direct drainage from an existing industrial park to AI Hedionda Creek without erosive velocities which would otherwise occur. Facility BO This is another enhanced natural channel directing drainage from an existing industrial park to AI Hedionda Creek. Channel enhancement is required to prevent erosion. Facility BP This is a long (7330') natural channel carrying City of Oceanside drainage from the city boundary ah future Cannon Road and receiving additional drainage from areas designated for or currently buill industrial park developments. Since most of the area containing this channel is zoned open space, cost of potential remedial work is estimated where design storm velocities exceed 6 feet per second, sedimentation basin is proposed upstream of Agua Hedionda Creek in an area zoned for industrial p development. Appendix A 1992 Carisbad Master Drolnage Page 70 Storm Water Qudlty Management I I I I I I I I I I I I I I 1 I I I I Facility BPA This enhanced natural channel connects existing industrial park drainage facilities to natural channe Storm water attenuation is required to bring the upstream 18" RCP into conformity with current dc standards. Facility BPB These proposed 36" and 45" RCP lines run through an area designated for industrial park develoF and empty into natural channel BP. Facility BPC Storm water attenuation is required to bringexisting 36"RCP lines into conformity with current d standards. a proposed brow ditch, directs the discharge of this industrial park line into natural ch BP. Facility BPD Storm water attenuation is required to bring existing 24" and 30" RCP industrial park storm draia conformity with current design standards. An enhanced natural lined channel is also proposed to cc outflow from an existing sedimentation basin to natural channel BP. Facility BPDA Storm water attenuation is required to bring an existing 42" RCP industrial park storm drai, conformity with current design standards. Facility BPDB Storm water attenuation is required to bring an existing 48" RCP line in an industrial park into confc with current design standards. Facility BQ Potential remedial work was estimated in this area zoned open space where channel velocities f 6 feet per second. -1 ?. . D. Encinas Creek Basin Facility C This proposed facility will complete the major drainage system in the Encinas Basin. The prc channel and enhanced natural channel connects the existing 12' x 8' RCB west of Palomar Oaks 7 .. the Encinas Creek natural channel downstream of Facility CC 2200' West of College Blvd. Al confluence of Facility CC the natural channel of the creek will carry runoff though a designata 1992 Carlsbad Master Drdnage and APP Storm Water Qudlty Management Plan P space. The existing facility between the confluence of proposed facility CI and CH south of Palom Airport Road was found inadequate with the current standards and should be replaced by this proposc facility to handle the projected discharges. The existing facilities across the Paseo Del Norte and Carlsb; Blvd. are also found inadequate with the current standards and additional 1O'x 4' RCB and 12'x 5' RC should be constructed along with those existing facilities, respectively, to handle the projectr discharges. Facility CA The proposed facility CA is a concrete trapezoidal channel which will complete a drainage system I connecting to an existing concrete channel just east of the AT & SF Railroad. The upstream area undeveloped and high density future development will aggravate the drainage deficiency unless tf facility is built. This facility will also mitigate the erosion problem along the railroad. Facility CB Facility CB is comprised of 39" and 60 RCP's which will carry runoff from a mostly undeveloped ar north of Palomar Airport Road and drain into Encinas Creek after crossing Palomar Airport Road. T upstream area is mostly undeveloped and higher density future development will require the construdic of this facility. Facility CC Facility CC is a storm drain proposed to be constructed and will carry runoff from an undeveloped ar northofPalomarAirportRoadwithanoutfalltotheproposedchanneloffacilityCthrougha72"diamet pipe under Palomar Airport Road. Construction of this facility will be required along with t development of the undeveloped upstream areas. Facility CD Facility CD is a storm drain proposed to be constructed will carry runoff from an undeveloped area nor of Palomar Airport Road with an outfall to proposed facility C through a double 48" diameter pipe und Palomar Airport Road. The upstream area is undeveloped and higher density future development w require the construction of this facility. Facility CDA Facility CDA is a 36" RCP proposed to pickup the canyon northerly ofPalomar Airport Road and easter of proposed line CD. Appendlx A Page 80 1992 Carisbad Master Drainage a Storm Water Qudlty Management PI I I I I I 1 I I I B I I I 1 B B I 1 I Facility CH Facility CH is comprised of 30", 36" and 42" RCP's, connecting an existing 36" RCP with the proF channel o€ facility C just south of Palomar Airport Road through an existing 6'x 3' RCB. This 6'x 3' under Palomar Airport Road was found adequate with the current standards. The area is m undeveloped and higher density development will require the construction of the facility. Facility CI Facility CI is an existing facility across Palomar Airport Road draining to the proposed facility C. facility was found inadequate at the downstream portion where it crosses Palomar Airport Roac additional 30 RCP is required to upgrade to the current standards. Facility CJ Facility CI will extend an existing 36" RCP upstream. This improvement will alleviate nuisance pa density future development will aggravate the drainage problems unless this facility is built. and reduce the potential for mosquito breeding. The upstream area is mostly undeveloped and 1 Facility CK Facility CK will improve the existing drainage facility along Carnino Vida Robles, north of Las F Drive. The downstream 550' of the existing 24" RCP in this system was found inadequate by the c standards and should be upgraded by the addition of a retention basin. Facility CM Facility CM is proposed to be constructed to carry runoff along Palomar Airport Road and El C Real northwest of the intersection of the two roads. With as outfall to the natural swale through tl course just south of Patomar Airport Road. The streets provide the only conveyance for draina are of inadequate capacity by current standards. The upstream area is partially undeveloped an density future development will aggravate the drainage deficiencies unless this facility is built. Facility CMA This proposed 51" RCP will join proposed Facility CM and it will carry runoff across Palomar, Road. The upstream area is partially undeveloped and high density future development will ag the drainage deficiencies unless this facility is built. 0 1992 Carlsbod Moster Drdnage and APF Storm Water Quality Management Plan i Facility CO Facility CO is proposed to be constructed to connect existing27" RCP along College Blvd. to the existi] 48" RCP across Palomar Airport Road, and the existing 48" RCP to the proposed facility C, th completing a drainage system draining into Encinas Creek. The proposed facility will alleviate floodil future development will aggravate the drainage deficiencies unless this facility is constructed. between the facility C and Palomar Airport Road. The upstream is undeveloped and the higher densi E. San Marcos Creek Basin Facility DA Facility DA is comprised of 48", 54", 60,72", and81", RCP's that will cany runoff from both develop and undeveloped areas with an outfall to Batiquitas Lagoon. Most of the upstream portion of this facili runs parallel to the AT & SF Railroad and the most downstream portion along Carlsbad Blvd.. TI existing 24" RCP from Poinsettia Lane to the confluence of proposed line DAA was found inadequa with the current standards and needs to be replaced to carry the projected discharges. The upstream arc is mostly undeveloped and higher density future development will aggravate the drainage deficienc unless this facility is constructed. One debris basin is also proposed at the downstream of this facilil to mitigate the impact of siltation on Batiquitos Lagoon due to grading of new development in the futur Facility DAA Facility DM, proposed to be constructed, will be required to upgrade or replace the existing 24" RC by a proposed 39" RCP since the existing facility is inadequate with the present standards. This facili! will drain into the facility DA. The upstream area is undeveloped and future development will aggrava the drainage deficiency unless this facility is built. Facility DBA Facility DBA is a storm drain line proposed to be constructed and will complete a drainage system b connecting upstream and downstream existing facilities. The upstream area is mostly undeveloped an future development will require construction of this facility. Facility DBB This proposed 30 RCP to be constructed to connect existing 30 RCP across Interstate 5 to the existin 60" RCP across Avenida Encinas. The System has found to be deficient for future development. Facility DG Facility DG is a storm drain line proposed to be constructed and will complete a drainage system b; connecting upstream and downstream existing facilities thus completing a major drainage systen Appendlx A 1992 Carfsbad Moster Drdnage an1 Page 82 Storm Water Crudity Management PI01 I I draining into San Mar- Creek. The upstream area is mostly undeveloped and future developmen require construction of this facility. 1 Facility DH I I Facility DH comprises an enhanced natural channel to prevent erosion along the natural channel d high velocity. The enhanced natural channel will consist of drop structures at points along the ch to reduce the slope of the stream flow. I Facility DI and DL4 I I Both of these facilities are comprised of a 42" RCP connecting with the existing 42" RCP at upst just west of Ave. Del Para and Unicornio St. with an outfall to the existing swale passing through : course. The area at the downstream portion of the two basins is undeveloped and future develop in this area will require the construction of both facilities. I Facility DIB Facility DIB is a debris basin at the downstream northerly of Alga Road. It is proposed to be constn I I 1 to mitigate the impact of siltation as part of the future development in the area. Facility DM & DMA Facility DM and DMA comprises of an enhanced natural channel to prevent erosion along the nz channel due to highvelocity. The enhanced natural channel will consist of drop structures at points : the channelto reduce the slope of the stream flow. I El Encinitas Creek Basin I Facility DQ I 1 Facility DQ is a storm drain proposed to be constructed and is comprised of 33", 36" and 45" R carrying runoff from and through undeveloped area east of Rancho Santa Fe Road draining intc natural swale at the downstream end. The upstream area is undeveloped and high density fi development will require the installation of the facility. 1 I Facility DQA This proposed storm drain will join proposed facility DQ at its most downstream end. It will carry n: through an undeveloped area and should be constructed as part of the future development. I 1992 Corlsbad Master Drainage and Siorm Waier Qudtiy Management Plan APPen Pa€ Facility DR This is a proposed debris basin at the down stream to mitigate the impact of siltation on Encinitas Cre as part of the future development in the area, Facility DSB Facility DSB is a storm drain proposed to be constructed along Camino Alvaro and Rancho Santa Fe Ra replacing the existing 36" RCP. The system has found to be deficient between the existing 2'x 4' R( across Rancho Santa Fe Road and the existing 30' ACP on Alvaro.. Facility DT-1 Improve the existing triple %foot RCB under La Costa Avenue. We recommend adding an additio triple &foot by 12-foot RCB and adding a berm along LA Costa Avenue and El Camino Real to incre; the available headwater at the culvert. The top ofberm is proposed to elevation 20.2(the top of the bric above the culverts is at elevation 20.8) to provide 1.3 foot of freeboard to meet County of San Dit Criteria. Facility DT-2 The El Camino Real roadway should be raised above the 100-year water surface. It should be rai! to approximately elevation 84.0 AMSL and quadruple 4-foot by 12-foot RCB culverts be construc under the road to match the existing creek invert. Additonal studies are required to determine the following: existing elevation of El Camino Real, In1 elevation along Encinitas Creek and final design requirements for roads am structures. Facility DT-3 This proposed facility is a 15'x 4' RCB across Rancho Santa Fe Road along the course of Encinitas Cre The existing 2-1O'x 4' RCB was found inadequate with the current standards and the proposed faci should be added to the existing to handle properly the projected discharges. This will eliminate flood on both sides of the creek upstream of Rancho Santa Fe Road. Facility DU Line DU has already been constructed. A debris basin at the downstream end of the existing facili! proposed to be constructed to mitigate the impact of siltation on Batiquitos Lagoon due to gradingof n development. Appendix A 1992 Carisbad Master Drainage Page 04 Storm Water Qudlty Management I I I I I 1 I I I I I I I I I I I I I I Facility DV Facility DV is a 60” RCP proposed to be constructed across the El Camino Real to replace the exi 60 CMP draining into Encinitas Creek. Facility DX Facility DX is a 30” RCP proposed to be constructed across Olivenhain Road and replaces the exi 24” RCP since the existing facility is not adequate to handle to projected discharges. 1992 Carlsbad Master Drdnage and APP storm Water Quality Management Plan P . Appendix A Page 86 1992 Carlsbod Master Drdnage a Stom Water Qudlty Management PI ”_ -. - E 6, 245. 000 E E. 259.cc.n - I 1 I I i - 1 2