HomeMy WebLinkAbout1997-11-18; City Council; 14440; AWARD OF THE CONTRACT FOR THE CONSTRUCTION OF THE NORTH BATIQUITOS SEWAGE FORCE MAIN REPLACEMENT, CMWD PROJECT NO. 85-401, CONTRACT NO. 34521|34522.
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CITY OF CARLSBAD - AGENDA BILL d
\ AB# w TITLE: AWARD OF THE CONTRACT FOR THE DEPT. HD.
CITY ATTY MTG. 1 1 I1 8/97
CITY MGR DEPT. CMWD
CONSTRUCTION OF THE NORTH BATIQUITOS
SEWAGE FORCE MAIN REPLACEMENT,
CMWD PROJECT NO. 85401,
CONTRACT NO. 34521134522
RECOMMENDED ACTION:
Adopt Resolution No. q?-6q0 for award of contract for the construction of tt-
Batiquitos Sewage Force Main Replacement, CMWD Project No. 85-401, Cont
34521/34522.
ITEM EXPLANATION:
On August 26, 1997, the City Council authorized the advertisement of bids
replacement of the North Batiquitos Sewage Force Main, CMWD Project No. 85-4(
project involves the replacement of two deteriorated pipelines. The first pipeline is a
force main extending from the Batiquitos Pump Station to a gravity sewer located ad
Interstate 5. The second pipeline is a water pipeline located in parallel with the sewa
main near Interstate 5. Both pipelines are within a 40-foot wide easement grantei
property owner as shown on the attached location map. The sewer portion of the F
being presented to the City Council for review and approval. The water portion of thc
is being presented to the District Board of Directors for review and approvr
construction contract will be a three party contract between the Contractor, City of (
and Carlsbad Municipal Water District. The specifications state that the lowest res
bidder is based on the overall combined bid of the Sewage Force Main and 12-inc
Main. The bid opening was held on October 29, 1997, and five (5) sealed bids were r
as follows:
Company Sewage Force Main 12-inch Water Main 1
El Cajon Grading $402,954 $47,960 $45
4 Point Pipeline $243,925 $46,980 $25
Orion Construction $240,021 $59,594 $2$ C.E. Wilson $265,585 $61,660 $32 CDM Construction $278,439 $44,2 1 7 $32
The contract will involve separate bid schedules for sewer and water, and the fiscr
will be separated accordingly.
The Carlsbad Municipal Water District has prepared plans and specifications to cons
sewer pipeline which are on file in the office of the District Engineer and are incorpo
reference.
was published September 19, 1997. The Project Manager and the Purchasing stE
reviewed the complete bid documents from all parties in detail and concluded the
overall, responsive bidder is 4 Point Pipeline, Inc., for a contract amount of $290,90!
contract will be awarded to 4 Point Pipeline, Inc. subject to the Board of Director’s a
In accordance with Section 3.28.120 of the Municipal Code, an lnvitatia
c Q 0 Page 2 of Agenda BII No. /4, q Y 0
ENVIRONMENTAL IMPACT:
The Planning Director has reviewed the documentation and concluded that the pro
prior compliance with a Mitigated Negative Declaration issued on November 19 ,I 9
mitigation measures include staking of all coastal sage scrub habitat adjacen
construction corridor, mitigation of any disturbed coastal sage scrub habitat as requ
qualified project biologist, minimization of the release of construction related pol11
accordance with the City Grading Standards, and re-vegetation of the construction
consistent with the approved Brocatto Project (CT 89-19) Habitat Enhancement La
Plan. The Planning Commission approved the Coastal Permit and adopted the I
Negative Declaration and Mitigation and Monitoring program issued on August 20, 1 S
FISCAL IMPACT:
The estimated costs for construction of the sewer force main portion of this projec
follows:
To date, there are approximately $417,960 available in the sewer line replacement
Therefore, there are sufficient funds available for this project.
EXHIBITS
1. Location Map
2. Resolution No. 97-690 for award of the contract for the construction of tt-
Batiquitos Sewage Force Main Replacement, CMWD Project No, 85-401, (
No. 34521/34522.
i NORTH EATIQUITOS SEWAGE Project
i +.r%ACEMENT PROJECT 85-401
c -- FORCE MAIN No.
Exhibit
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RESOLUTION NO. 97-690
A RESOLUTION OF THE CITY COUNCIL OF CARLSBAD,
CALIFORNIA, FOR AWARD OF CONTRACT FOR THE
CONSTRUCTION OF THE NORTH BATIQUITOS SEWAGE
FORCE MAIN REPLACEMENT, CMWD PROJECT NO. 85-
401, CONTRACT NO. 34521134522
WHEREAS, the City Council of Carlsbad, California, has previously auth!
the advertisement for bids for the North Batiquitos Sewage Force Main Replace
CMWD Project No. 85-401, Contract No. 34521134522; and
WHEREAS, five (5) sealed bids were received October 29, 1997, fo
project; and
WHEREAS, all bid documents received from all bidders have been revie!
detail and the Board of Directors does hereby find that the lowest respc
responsible bid received for the construction of said project was submitted by 4
Pipeline in the amount of $290,905 of which the sewage force main replac
portion of the project is $243,925; and
WHEREAS, funds in the amount $287,925, to include $243,925 for the SI
force main, $24,000 for construction contingencies, $4,000 for surveyinglsoils .
and $16,000 for inspection services, have been appropriated in the water replac
budget and are available.
NOW, THEREFORE, BE IT RESOLVED, as follows:
I. That the above recitations are true and correct.
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2. That the bid amount in the amount of $243,925 submitted by 4 Point Pi
is hereby accepted, and the Mayor is hereby authorized and directed to execu
agreement, therefore, a copy of which is on file in the Offke of the City Clerk.
PASSED, APPROVED AND ADOPTED at a regular meeting of the City C
of Carlsbad, California, held on the 18th day of November , 1s
by the following vote to wit:
AYES: Council Members Lewis, Finnila, Nygaard, Kulchin, and Hall
NOES: None
ABSENT: None
ATTEST:
<
ALETHA L. RAdTENKRANZ, City clerk
(SEAL)
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1 1 Table of Contents
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st D. Design Sensitivities ..................................................................................
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C-R 1, EXECTII‘LVE SUMMARY ...............................................................
A. Gods aad Objectives ................................................................................. B. Report Summary c. Recommendations ...................................................................................... .......................................................................................
CHApI1ER 2, PLANNING AREA C€€A.RA~RIsTIcs ......................................
A. Pkmning Area Boundaxies a * * * a a @ a * @ a * a a * * * a * a a * * * * *. . * e a a a * a * t * a n a a e * a a * a a a e n a . a a a a a a a * a * a a e e a * a a a
B. Physical &vironment
C. hd Use ................................................................................................... ...............................................................................
CHAPTER 3, METHODOLOGY .........................................................................
A. Study Approach ..........................................................................................
C. Design Runoff Method ...............................................................................
D. Design Procedure ..................................................................................... E. computer Program
F. Sedimentation Basins .................................................................................
B. Hydrologic Design Crikria ........................................................................
.....................................................................................
C-R 4, FINANCING ....................................................................................
A* ked * *****e * * * * * * * * * * * * * * ******a a * 9 * * t t t * 9 ***a * * * * * * * * * * * * b * * * * * a ****a ** * 4 a at * * a *
B. Source OfAuthority .................................................................................... c. €€istory
F. Fjicing Recommendations ..................................................................... G. bed Ipcal Drainage Areas (PLDA’s) ..................................................
........................................................................................................
D. Present Ficia.l Stakus ............................................................................ E. Ficing Method Akernatives ..................................................................
H. Fee Analysis
I. Fee ad^ .............................................................................................
J. Fee Credits and Reimbursement for Constsuded Facilities .....................
CHApI*ER 5, STO’RM WAmR QU&m MANAGEMENT PROGRAM .............
A. Introduction ...............................................................................................
B. BriefHistory ofActions Leading to City’s “DES Permit
C. “Esucly” “DES Permits ............................................................................ D. Elements of Carlsbad’s Storm Water Quality h-mt Prog- E. Testing and Monitoring of Storm Water and Urban Runoff ...................... F. Detedion of Illicit Connections and Illegal Discharges ............................
G. Best Management Pradices 03MP)
H. Program Costs and Funding .......................................................................
............................................................................................... 8
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Master Drainage and Storm Water Quality Management Plan
Carisbad, California, March 1994
Table of C
CHAPTER 6, COS" EmmS ........................................................................... a
C. Additional Costs ............................................................................................ 6E
D. Constxuction Itern Cost &timakes .................................................. .: ........... &
CHAPTER 7, SlJMMARY OF FIELD I"IMn0NS ...................................... 7:
A. GeneraJ. .......................................................................................................... 6f
B. Unit Costs ...................................................................................................... 6f
E. Facility Construction Cost Estimates ........................................................... 72
A. Introduction .................................................................................................. 7:
B. Buena Vista, Creek .................................................................................... 7f
C. Agua Hedionda Creek .............................................................................. 7t
D. &c- Creek Basin ..................................................................................... 74 E. SLUL &cos Creek €kin ............................................................................... 7r F. Findings ......................................................................................................... 3
APPENDIX 4 PROPOSED DRAINAGE FACILmS ........................................... 7:
A. Introduction .................................................................................................. 72
D. Encinas Creek Basin ..................................................................................... 84
B. Buena, Vista, Creek .................................................................................... 7t
C. Agua Hedionda Creek .............................................................................. 7%
E. San Marcos Creek Basin ............................................................................... % F. 'IE;ncinitas Creek Basin ................................................................................... 8t
APENDIX B, DRAINAGE IMPROVEMEN" FACILlTlES MAPS
The following apdices are sepa;ratelybound.
APPENDIX C, COST ESTIMATES, BY STORM DRAIN LINE
APPENDIX D, DEUETED
APPENDIXE, FEMAREWEW, BUl%NAVISTACRIEEK
APPENDIX F, FEMA REVIEW, AGUA HEDIONDA CREEK
APPENDIX G, FEMA REVIEW, SAN MARCOS CREEK BASIN
APPENDIX I, CALCULATIONS, AGUA EIEDIONDA CREEK BASIN, VOLUMES I &II
APPZNDIX J, CALCU~ONS, ZNCW CR@ZK BASIN
APPENDIX K, CALCUmONS, SAN MARCOS CREEK BASIN
APPENDIX L, CALCULATIONS, ENCmAS CREEK BASIN
Table of Contents
Page ii Master Drainage and Storm Water Quality Management Plat
Carlsbad, California, March 199d
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CHAPL'ER 1
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U A. Goals and Objectives
1 This Master Drainage and Storm Water Quality Management Plan was commissioned by City Cot
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 Dr I Plan.
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2. Incorporate the drainage facility needs of the southern part of the City which were fo
included in the County's Zone 1 Flood Control District.
3. Establish drainage facility costs, analyze viability of existing planned local drainage (PI
areas, recommend changes to existing PLD fee areas, establish new PLD fee ateas for the SO
city area, allocate costsin accord with StateMap Act and AB 1600 requirements and establii I PLD area fees.
4. Provide new topographic mapping of the entire City at two foot contour intervals on 1
mylar sheets and in digital format compatible with our new Geographic Information System
on computer.
5. Field review existing facilities for codormity with file plans and make recommendatic
facility maintenance needs.
6. Review the siltation and water quality requirements ofthe City and make recommendatic
additional measures to protect our sensitive riparian waterways and lagoons.
Over the course of preparing the Master Plan, the Federal Government implemented new re@
which mandated strict water quality control requirements. These new water quality regulations s
cantly altered the focus of the Master Drainage Plan. Whereas previous master drainage plan s
focused on storm water flood control measures, the new regulations shifted the focus to preservatic
enhancement of storm water quality. This shift resulted in a simcant re-evaluation of our pri
Planned Local Drainage area fee concept. As a result, the numerous localized PLD fee area
combined into four large PLD fee areas which coincide with the four drainage basins within the Ciq
reflects the Federal Government emphasis on preserving and protecting the water quality of rec
waters and not just of a few localized basins. In light of this new focus the title of this report was ch
fkom Master Drainage Plan to Master Drainage and Storm Water Ouality Management Plan.
Master Drainage and Storm Water Quality Management Plan ct
Carlsbad. California. March 1994 m
€3. Reportsummary
The Master Drainage and Storm Water Quality Management Plan, hereinafter called Master Plan, include
all drainage areas within the incorporated boundary of the City of Carlsbad covering approximately 3
square miles. The Master Plan addresses only those facilities which provide the backbone system to th
City's storm water management Mastructure. Generally these consist of storm drainage pipes with
diameter of thirty inches or larger together with concrete and rock lined channels, permanent sedimen
tatiodpollutant control basins and other larger miscellaneous facilities.
The existing and recommended future drainage facilities are shown on the 1 n = 400' maps on file with th
City Engineer and the 1 I( = 1000' maps which accompany this document. Each proposed facility has alette
designation which begins with the letter A, B, C, or D corresponding with one ofthe four drainage basin
as follows: 'A' for Buena Vista Lagoon drainage basin, 'B' for Agua Hedionda Lagoon drainage bash
'C' for Encinas Creek drainage basin, and, 'D' for Batiquitos Lagoon drainage basin.
A total of 42.9 million dollars in recommended future drainage facilities are identified within the Maste
Drainage Plan report. Of this amount, approximately 34.3 million dollars in facility costs are direct1
attributable to the needs created by new development. The remaining 8.6 million dollars are attributabl
to facility deficiencies created by existing development (Reference Table 6-7).
in the City. The basin designations were assigned consecutively starting fiom the North and moving Sout
The financing plan presented in this report recommendsthat 100% ofthe drainage fkcility costs attributabl
to new development be financed by developers through payment of'Planned Local Drainage Area (PLDA
fees or by direct construction of drainage facilities. Ofthe 34.3 million dollars in facility costs attributabl
to new development, 18.8 million dollars will be collected in new PLDA fee revenues, 13.7 million dollar
will occur fiom direct developer construction of drainage facilities and 1.8 million dollars will be appliel
fiom previously collected PLDA fee revenues. The 13.7 million dollars in direct developer constructio
of facilities occurs in proposed PLDA "D" for reasons discussed below.
The 8.6 million dollars attributable to existing facility deficiencies will be hded through a combinatio
of sources as follows: 1.3 million dollars are available fiom previously collected PLDA fees; 1.6 millio
dollars will be generated fiom PLDA fees charged against existing developments that redevelop o
remodel; 4.3 million dollars in SANDAG Transnet funds and 0.5 million dollars in redevelopment ta
increment bond funds are budgeted in the current Capital Improvement Program; and, 0.2 million dollar
has been contributed by the County of San Diego for drainage improvements adjacent to McClella
Palomar Airport. The remaining 0.7 million dollars is presently u&nded and will require funding &or
other non-fee sources such as the general find, federal and state grants, general obligation bonds, an
assessment districts.
It should be noted that the 1.3 million dollars in existing PLDA funds, allocated to mitigate existin;
deficient facilities, will in fact be used to mitigate impacts created by the developments which paid th
PLDA fees, Due to knding shortfalls, many of these impacted facilities were deferred until adequat
funding was available. Since the development was allowed to proceed once the fees were paid, these sam
facilities are now categorized as wholly or partly deficient under this plan.
The report recommends establishment of four new Planned Local Drainage Areas (PLDA' s) correspond
ing to the four drainage basins described above. The existing thirteen PLDA's are to be abolished and m
Master Drainage and Storm Water Quality Management Pla
Carlsbad, California, March 199 Chapter 1
Page 2
remaining fbnds will be transferred into the respective new PLDA. With the exception of the PLI
basin ‘WY the fees recommended for each of the PLDA’s are based upon recovery of 100% of tht
attributable to new development and 20% of the costs attributable to existing development. Th(
figure was used because it represents the percentage of the existing development base which is esti
to redevelop or remodel over the life of fee program.
For basin ‘D’y it is recommended that the primary method of financing be direct developer constr
as a condition of development approval. The reasons for using this method of financing over a fee
program are as follows: 1) Only a small percentage ofthe drainage facility needs in basin ‘D’ are attrib
to existing deficiencies; 2) The facilities are located on undeveloped lands which require their insta
in order to make the underlying property suitable for development; 3) Amajority ofthe facilities are 1(
within large master plan developments that have the financial capability to knd such facilities w
benefit of a fee program; and, 4) The facilities in the southern portion ca fbasin ‘D’ are to be financed tb
a proposed Community Facilities District currently under formation.
The report does recommend that a small fee be levied on development within basin ‘D’ in or
reimbursethe City for capital expenses associatedwiththe Storm Water Testing andMonitoring prc
In addition, it may be necessary to establish additional local benefit assessment districts such as tl
proposed in the southern part of basin ‘D’ to reimburse developers on a facility by ficility basis.
The PLDA fees recommended in the 1980 Master Drainage Plan were levied only upon develop
which proposed a subdivision of land. Those fees were collected at the time of the approval of thl
map. Pursuant to Section 66483 of the Subdivision Map Act fees may be levied upon developmen
insofar as they are fairly apportioned within the fee area on the basis ofbenefits conferred or on the
for such facilities by the proposed subdivision and development of other property within such fee
Since some of the recommended facilities serve previously developed areas, their cost could not bi
recouped through the 1980 Master Drainage Plan PLDA fees. This method of assessment placed t
burden of finding needed facilities on the subdivider and allowed non subdivision developers to e
any obligationto paytheir fair share ofneeded drainage facilities. This method offee collection has re
in a shod& of itnds required to build the recommended lkcilities and thereby delayed construm
necessitated use of alternate ftnding sources primarily fiom General Fund Revenues.
The Master Plan report recommends that PLDA fees be levied against all new developments with
City. It further recommends that PLDAfees be levied against redevelopment projects and remodel bu
permits. For building remodels the PLDA fee will be assessed whenever the building footprint is incr
by 50% or greater. Such development projects can be found to derive benefit fiom the constructi
needed drainage facilities for the control of storm water flooding or the preservation and enhancem
the quality of storm water entering the receiving waters of the City. Authority for the levying of E
fees on non subdivided developments is containedwithin the provisions ofAJ3 1600 (Chapter 5 to Dii
1 of Title 7 of the Government Code). All drainage area fees are to be paid at the time of building F
issuance or prior to Einal map approval, whichever comes first. Construction of PLDA facilitie
administration of fee credits will continue to be secured prior to final map approval.
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 oflam
Low density residentially zoned property is charged the same fee on an acreage basis as high dt
residential, industrial or coqunercially zoned property. However, the storm water runoff rate for difl
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Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994 Chi
land uses are sigdicantly different fiom one another. Therefore, this report recommends adoption of varied rate structure in line with average runoff coefficients widely accepted within the Engineerhi
profession. This will result in higher fees for high density residential, commercial and industrial project
in recognition ofthe greater storm water contribution made by these type uses. Within the Central Bushes
District, this fee structure will help generate the finds required to construct badly needed facilities in th
downtown area.
An analysis ofthe Land Use maps ofthe City and the aerial photography prepared for this report indicate
approximately 9,2 15 acres of developable land remain in the City exclusive of General Plan designate1
open space and constrained lands. Based upon a review of past records, this report projects 20% of th
existing developed properties in the City will remodel or redevelop prior to build out, resulting in a
additional 1,386 acres of property within the City which will be subject to PLDA fees.
The fees proposed in this report were prepared fiom the best available records concerning existing an
future land uses and were determined using a formula which takes into consideration drainage runoj
factors, the various land use types and, existing and future development needs. The proposed fee prograr
excludes all governmental and public school lands, major transportation corridors, and all constrained lan
as defined in Chapter 21.53.230 of the Carlsbad Municipal Code. The proposed fee program provides fa
direct fee credits to offset the cost of developer constructed Master Drainage Plan improvements and alsi
provides for reimbursement should the fee credit exceed the developers fee obligation. Under the propose
fee program, new development will pay only for impacts created by such new development. The cost ti
mitigate existing deficient facilities will be paid through a combination of drainage area fees charged ti
redevelopment and remodel projects, previously collected drainage fee revenues and other City findin
sources. Considering the above, the overall program should easily meet or exceed thevarious requirement
established by State Law for implementation of a facility fee program.
c. Rf3commennda~cms
The following is a summary of the recommendations made in this Master Plan report:
1. Adopt this report titled Master Drainage and Storm Water Quality Management Plan prepare
in March of 1994 in replacement for the previous Master Drainage Plan prepared in June of 198(
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 coinciding wit
the four major drainage basins in the City as shown on Figure 4-2 on page 32.
3. Make findings that there are no surplus fbnds in the existing Planned Local Drainage Are
accounts and transfer the current fhd account balances into the corresponding account for th
new Planned Local Drainage Fee Area.
4. Make findings that the fbture drainage facilities identified in theMaster Plan report are require
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 benefii
Master Drainage and Storm Water Quality Management Ple
Carisbed. California. March 199 Chapter 1
Page 4
coderred on property proposed for development or on the need for such facilities created
proposed development and the development of other property within the Planned Local Di
Fee Area.
5. Adopt the following fees for the four proposed Planned Local Drainage Areas:
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6. Expand the Planned Local Drainage Area Fee structure to require imposition of the fel
non subdivision developments including commercial, industrial and residential remodels
increase the building footprint a minimum of 50% over the existing structure. Require pa
of the new fees at time of building permit issuance for those developments.
7. Exclude constrained lands from inclusion in the fee program.
8. Maintain the existing fee credit and reimbursement provisions of the existing fee prog
9. Revise existing City Codes and adopt appropriate resolutions to establish a revised drl
facility fee in accordance with recommendations 1 through 8 listed above.
10. Adopt the sediient and water quality policies included within the report and continu
the implementation of the water quality control program as required pursuant to the Ni
Pollutant Discharge Elimination System permit requirements.
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Master Drainage and Storm Water Quality Management Plan ct
Carisbad, California, March 1994
Master Drainage and Storm Water Quelity Management Pla
Carisbad, California, March 199 Chapter 1
Page 6
CHApfER2
PUNMNGAREACHARACIERX~CS
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A PhmingAreaBcnmMes
In 1952 the City of Carlsbad incorporated witha population of 5,000 and an area of4,78 1 acres. T
grew slowly at first at a rate of 490 to 850 per year until 1975. Since 1975 the growth rate has d
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 approxima
quare miles. The City is bounded on the north by the City of Oceanside. On the east the City is bc
by the Cities of Vista, San Marcos, and the County of San Diego. To the South the City borde
Encinitas and a small portion of San Diego County. And finally, Carlsbad has the Pacific Oca
west.
B. PhpSicalEmimnmat
Physical Geographv and ToDogJaphy
Carlsbad is a very diverse city with steep hills to coastal areas. As a result, there are a wide va
drainage conditions. New orthophoto mapping was produced withcontours extending approximatt
feet beyond the sphere of influence. This study defined drainage basins up to and beyond this bou
San Diego County 1"=200' mapping was used for supplemental topographic information. E
The four major waterways and their tributary canyons have carved valleys floored with alluvial mi
Thus far, construction in the flood plains has not occurred to the extent that it is cause for concei
major drainage basins with the exception of Encinas Canyon terminate in lagoons.
Georrrauhy and Soils
Sod types range&om alluvial in the lower flood plains to weathered granite on the peaks. The predoi
hydrologic soil type in this study was Group D except in the northwest where Group A predom
Groups B & C are also represented.' Soil types are described in Chapter 4. I
* USDA, Soil Conservation Service, et.al., Soil Survey, San Diego Area California; 1973.
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
CI
Seismicity
Southern California is a seismically active area. An earthquake offshore ofNorth County registered 5.:
Richter Magnitude in July 1986. Active faults in the area include the Elsinore Fault located 20 milei
northeast of Carlsbad and the Rose Canyon Fault located 10 miles west of the City.
Environmental
Drainage basins were characterized by perennial and intermittent stream beds. These stream beds are thc
focal point of a sensitive network of riparian corridors. Within the lower portions of the basins, thc
drainage channel spreads out to form somewhat narrow flood plains characterized by dense willow an(
riparian plant growth and meandering stream channels. These areas generally act as natural sitatioi
control. At the end ofeachmajor drainage basin, with the exception ofEncinas Canyon, is a lagoon whicl
supports a delicate but rich variety of flora and fauna. It is a stated goal ofthe city to protect and enhancc
where possible all riparian and lagoon habitats.
Hvdrologic Features
The City ofcarlsbad is divided into four distinct watersheds. Listed below are those basins, starting eon
the north.
a. Buena Vista Creek - “Buena Vista Creek drains an area of 19 square miles. The drainage areais long
and narrow with a distance ofabout 9 miles from the Pacific Ocean to its highest peak of 1,671 feet (MSL
inthe SanMarcos Mountains and awidth ofabout 2 miles. Runoff &om several tributaries qukkly combinc
into one main improved channel within the City oWista. Flow is generally ina southwest direction througl
the City of Vista. As it leaves the City of Vista, flow becomes more westward and slopes become mort
gentle, discharging into BuenaXstaLagoonabout 3 miles downstream. BuenaVistalagoonis amanmadc
lake with a weir structure at the ocean outlet controlling the discharge. Stream flow eventually enters thc
Pacific Ocean some 1.4 miles farther downstream after being temporarily delayed by the considerablc
storage volume of the lagoon. The stream gradients range from 68 feet per mile in the upper reaches tc
32 feet per mile in the lower reaches of the basin. The average gradient within the reach studied is 39 fee
per mile7’.2
b. Agua Hedionda Creek - “Agua Hedionda Creek and a major tributary, Buena Creek, drain an area
of 29 square miles. Agua Hedionda Creek originates in the hills south of the San Marcos Mountains an(
flows in a general southwest direction, confluencing with Buena Creek about 3 miles downstream. Fron
the confluence, it flows generally westward about 6 miles and enters Agua Hedionda Lagoon, fiom whicl
it discharges into the Pacific Ocean some 2 miles firther downstream. The stream gradients along Agui
Hedionda Creek range fiom about 43 feet per mile in the upper reaches of the study area to about 3 5 fee
per mile in the lower reaches approaching the lagoon. There is an extremely steep canyon reach betweex
mile 5.2 and mile 6.0 along Agua Hedionda Creek which is called Los Monos Canyon. Stream gradient:
in this reach average 180 feet per mile. Buena Creek, with a drainage area of about 6 square miles
originates in the San Marcos Mountains and flows about 5 miles in a southerly direction before i
confluences with Agua Hedionda Creek. The stream gradient of Buena Creek through the study read
is about 5 1 feet per mile77.3
* Army Corps of Engineers, Los Angeles District, Buena Vista Creek, July 1973.
3 Army Corps of Engineers, Los Angeles District, Am Hedionda Creek, July 1973.
Chapter 2
Page 8
Master Drainage and Storm Water Quality Management Plai
Carlsbad, California, March 199d
c. Encinas Creek - Encinas Creek drains an area of 3.9 square miles. This basin originates 3,0(
East of El Camino Real and drains westerly approximately 22,000 feet to the Pacific Ocean. The dr
course generally parallels Palomar Airport Road along an alignment just south ofthis roadway. The
drainage area ranges in elevation fiom sea level to slightly over 440 feet.
d. Batiquitos Lagoon Watershed - The BatiquitosLagoon watershed is divided into two major dr
basins known as the San Marcos Creek watershed and the Encinitas Creek watershed. San Marcos
originates in the coastal range of mountains north and atst of San Marcos and empties into the Bati
Lagoon about 2.6 miles east of the Pacific Ocean. Encinitas Creek, a major tributary, originates
mountains southwest of San Marcos and joins San Marcos Creek at the upstream end of Bati
Lagoon. The entire drainage area totals 46 square miles and ranges in elevation Erom sea level to s
over 1700 feet in the Merriam Mountain range.
“The stream gradient ranges f?om an average of 10 feet per mile near the mouth to about 600 feet PC
in headwaters. San Marcos creek has a small and not well defined channel upstream fiom Lal
Marcos. Below that pointy the channel is well defined, steep, and rocky to the La Costa developmen which it becomes small and not well defined again toBatiquitosLagaon. The flood pl&h broad ups
fiom Lake San Marcos. From Lake San Marcos Dam to the La Costa development, there is virtu:
flood plain due to the steep, well defhed channel. Through the La Costa development to the Bati
Lagoon, the flood plainis againbroad. During large floods, flows exceed the channel capacity and ini
parts of the broad flood plain.”
“BatiquitosLagoon extends fiom the downstream limit of San M~~COS Creek, namely the Pacific 0
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 flood^".^
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I C. Landuse
1. Existing
Existing development in the City is located mainly in the northwest older portion and in the southe;
Costa area. Existing high-density residential development is located along the coast and at various 1
in La Costa. Existing commercial development is centered in the older downtown area in the nortl
quadrant, along Avenida Encinas, and along Palomar Airport Road. There are still large agricultural
located in the City. Finally, existing low and medium-density residential development compris
majority of the land use in the City.
2. Future
Proposed land use in the City of Carlsbad is varied. The choice of fbture drainage facilities is depe
upon future land use designations as determined by the 1987 City of Carlsbad General Plan. Acca
to the 1987 General PlanMap most ofthe undeveloped land is zoned for low to medium-density residc
land uses. These areas are located in the northeast and southwest portions of the City. Large pla
industrial areas are located around Palomar Airport.
4 Army Corps of Engineers, Los Angela District, San Marcos Creek, April 1971.
Master Drainage and Storm Water Quality Management Plan Chr
Carlsbed, California, March 1994 I
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Open space zoning is located along Agua Hedionda, Buena Vista, and Batiquitos Lagoons. There is alsc
a strip of open space running north-south fiom La Costa Avenue to north of Faraday Avenue. The ope1
space generally follows the tributary canyons.
D. Design hithities
Drainage Facilities have been proposed in accordance with the land use constraints of the 1987 City o
Carlsbad General Plan. Underground storm drain lines or concrete channels have generally been proposec
in areas slated for future development. When such fines empty into canyons expected to remai
undeveloped, enhanced natural channels consisting of drop structures are proposed to decrease erosivl
drainage discharge velocities (considered to be above six feet per second). When erosive drainag
discharge velocities occur in open space zoned areas, the cost of potential remedial work was estimated
Chapter 2
Page 10 Master Drainage and Storm Water Quality Management PI Carlsbad, California, March 19!
CHApfER 3
METHODOLOGY
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A. stu~Approach
The approach of this project was to utilize previous hydrology studies for the major water cours
to analyze tributary areas where storm drain deficiencies occur. Storm drain facilities are recom where existig facilities are inadequate or where projected development will require drainage fac
1 B. Hydrologic Design Criteria
The design criteria, as found in the County of San Diego Department of Public Works Flood C
Division Hydrology Manual, specifies the design runoff conditions within the San Diego County
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 fi-equency storm.
2. For areas under 1 square mile -
a) The storm drain system shall be designed so that the combination of storm drain system capaci
overflow both inside and outside the right ofway will be able to carry the 100 year fiequency storm w
damaging adjacent existing buildings or potential building sites.
b) The storm drain system shall be designed so that the combination of storm drain system capaci
allowable street overflow will be able to carry the 50 year fi-equency storm within the street right-o
c) Where a storm drain is required under headings 1 or 2 above, then as a minimum, the storm drai
be designed to carry the 10 year fiequency storm.
3. Sump areas are to be designed for a sump capacity or outfall of a 100 year fiequency storm.
For this study, existing drainage systems were analyzed with respect to the above criteri
recommendations made accordingly. In undeveloped areas, where fbture street alignments and g
are unknown, the recommended storm drainlines are sized for 100 year flow capacity, based on the g
of existing flowlines. However, when these areas are developed the drainage system may actually
the 10 year stormunderground, the 50 year storm to top of curb, and the 100 year storm within the
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 fiom the Soil Conservation Service 1969 survey maps updated withult
development data corresponding to the 1000 scale city of Carlsbad General Plan Map dated April
and fbture land use densities projected in the City’s Growth Management Program.
Master Drainage and Storm Water Quality Management Plan Ch
Carlsbad, California, March 1994 P
2. Hydrologic soil groups were determined fiom the 2000 scale soil group maps prepared by the Soi
Conservation Service in 1969. Soil types were segregated into groups as a knction of their probabb
infiltration capacity. The group designations include:
Group A - Low Runoff Potential:
Soils having high atration rates even when thoroughly wetted, consisting chiefly of deep, well tc
excessively drained sand andor gravel. These soils have ahigh rate ofwater transmission and would resul
in a low runoff potential.
Group B - Moderate Runoff Potential:
Soils having moderate idtration rates when thoroughly wetted, consisting chiefly of moderately deel
to deep, moderately well to well drained soils with moderately fine to moderately coarse textures. Thes
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 layer tha
impedes the downward movement of water, or (2) soils with moderately fine to fine texture and a slot
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 wit1
a high swelling potential; (2) soils with a high permanent water table; (3) soils with clay pan or clay laye
at or near the surface; and (4) shallow soils over nearly impervious materials. These soils have a very slot
rate of water transmission.
Chapter 3
Page 12
Master Drainage and Storm Water Quality Management Pla
Carlsbad, California, March 199
3. The following Manning roughness and rational method runoff coefficients were used:
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Concrete lined
TABLE 3-1
Master Drainage and Storm Water Quality Management Plan CI
Carlsbad, California, March 1994 I
Coefficient C
Mobile Homes
TABLE 3-2
4. The 100 year 6-hour and 24-hour precipitation values were taken fiom the County of San Diegc
Department of Public Works Flood Control Division Hydrology Manual, Section II-A.
5. Rainfall intensities for the Rational Method hydrology computations were taken fiom the County o
San Diego Department of Public Works Flood Control Division Hydrology Manual, Appendix XI.
6. Watershed boundaries and grades for proposed storm drains were derived fiom 400 scale orthophotc
maps with 5 foot contours produced photographically fiom maps prepared by Rick Engineering
Incorporated, San Diego, California.
7. A number of major creeks have been identified in the City of Carlsbad. Previous hydrologic studiei
conducted by Federal, County and private institutions have established 100 year peak flows for these majoi
watercourses. Table 3-3 lists the studies available to the Master Drainage Plan Study as follows:
Chapter 3
Page 14 Master Drainage and Storm Water Quality Management Plat
Carlsbad, California, March 1994
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1 Buena Vista Creek
Delineation Study Noite & Associates
Encinitas Creek
Watershed HEC-I Model
Encinitas Creek Analysis Hydrology Rick Engineering
Agua Hedionda Creek Dr. Howard H. Chang
Project August 1988
Drainage Study for
May 1991
TABLE 3-3
Encinitas Creek Encinitas Creek Dr. Howard H. Chang
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Master Drainage and Storm Water Quality Management Plan Ch
Cadsbad, California, March 1994 F
The 100yearpeakflowspreviouslyestablishedformajorcreeksinthe CityofCarlsbadhave beenanalyzed
for usage in the Master Drainage Plan Study as follows:
a) BUENA VISTA CREEK - The 100 year peak flows have been established in the S~eCial Flood Plain
Delineation Studu, February 1978 by Nolte and Associates. The flow rates to beused inMaster Drainage
Plan are adopted fiom the 1978 Nolte study.
b) AGUA HEDIONDA CREEK - The 100 year peak flows have been established in the SDecial Flood
Plain Delineation Study by Nolte and Associates in February 1978.
A Hvdroloaical Study was conducted for N-4 arl by Dr, Howard H. Chang in July 1989.
The flow rates used in the Master Drainage plan assumed the discharges listed in the Nolte 1978 study
for the reach upstream of the confluence point east of Oak Lake and the results of the Chang 1989 study
downstream of the above mentioned point. The flows in the two studies vary by approximately 10%.
c) SANMARCOS CREEK- The 100yearpeakflowshave beenestablishedintheFloodPlainInformation studv. April, 1971 by the U.S. Army Corps of Engineers, Los Angeles District. These flow rates have
been adopted by FEMA for the Federal Insurance Study for San Marcos Creek within the City of San
Marcos. Corps of Engineers peak Bows and inundation limits for the 100 year flow have also been used
without modification for the determination of adequacy of existing structures in the comprehensive Plan
for Flood Control and Drainage - Zone 1, San Diego County Flood Control District by Koebig,
Incorporated in July 1976.
A hydrologic analysis by Boyle Engineering Corporation in July 1988 on the east branch of San Marcos
Creek generally con6rmed the U.S. Army Corps of Engineers flow rates.
Results of another hydrologic analysis by Wddan Associates in August 1988, for the San Marcos Creek
Flood Control Improvement Project on the main branch of San Marcos Creek upstream of Lake San
Marcos, were within 10 to 15 percent ofthose values in the Corps ofEngineers study. The actual design
dischargevaluesutilized forthe floodcontrol channelhydraulics, atthedirectionofthecity ofSanMarcos,
were the values fiom the Corps of Engineers study.
The 100 year flow rates to be used in the Master Drainage Plan for San Marcos will be adopted fiom the
Corps of Engineers study as follows:
At mouth into Pacific Ocean 5,000 CFS
12,000 Upstream from El Camino Real
Upstream from Rancho Santa Fe
d) ENCINITAS CREEK - The 100 year peak flows were established by the U. S. Army Corps of
Engineers, Los Angeles District in April 1971. Koebig, Incorporated developed peak flow rates for the
Encinitas Creek basin in the July 1976 Comprehensive Plan for Flood Control and Drainage -Zone 1, San
13,000
Chapter 3
Page 16
Master Drsinage and Storm Water Quality Management Plan
Cadibad. California. March 1994
Diego County Flood Control District. In 1980 the County of San Diego conducted a hydrology st
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 i
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 year flow rates determined for EnCinitas Creek as a result of the 1988 Rick Engineering
are as follows:
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I north of Olivenhein 4,210
3,430
1,300
Downstream of confluence with tributary
Downstream of El Camino Real
Downstream of Rancho Santa Fe
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The Rick Engineering Study identified deficiencies with the existing drainage structures cross
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
Drainage Studv for Encinitas Creek prepared by Dr. Howard Chang dated May 1991. The prc
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 undeI
environmental review as part of the Olivenhain Road widening project.
e) ENCNAS CREEK - The 100 year peak flows were established by the Hvdrolow Studv f
Determination of the ImPact From Runoff in Encinas Creek on the Proposed Improvements to Pa
Airport Road 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 the
Poutney study as follows: I Upstream from Interstate 5 1,750 CFS
Downstream from Hidden Valley Road
Upstream fiom Laurel Tree Road
1,560
1,400
Master Drainage and Storm Water Quality Management Plan Cb
Carisbed, California, March 1994 F
- C. DesignRunoffMethod
The hydrologic analysis utilized for design of facilities recommended in this report is the Rational Methoc
for watersheds less than 0.5 square miles and the Modified Rational Method by routing sub-watershed for watersheds greater than 0.5 square miles and less than 15 square miles.
The Rational Formula is Qp = CIA where:
Qp = The peak discharge in cubic feet/sec.*
* 1 Acre in/hr. = 1.008 cubic feet/sec.
C = Runoff Coefficient (Dimensionless)
I = Ra;lfall intensity (ichedhour)
A = Tributary drainage area (Acres)
If rainfall is applied at a dorm rate to an impervious area, the runoff attributed to this area woulc
eventually reach a rate equal to the rate of precipitation. The time required to reach this equilibrium i,
termed the time of concentration.
For small impervious areas one may assume that if precipitation persists at a uniform rate for at least a
long as the time of concentration the peak discharge will equal the precipitation rate.
D. DesignProcedme
The following procedure wasused in calculating quantity ofstorm flow at variouslocations along the routc
ofthe proposed storm drains. Whenever the term"Manual" isused, it refers to the "County of SanDiego
Department of Public Works Flood Control Division Hydrology Manual" dated January 1985. The
general procedure was developed by Los Angeles County Flood Control District and has been modfiet
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 divisions should
ifpossible, be based on the topography, soil type, and the land development. The size of the initial arei
should be chosen such that the length of travel for the water from the most remote point to the point o
concentration should not exceed 2,000 feet for natural watersheds and 1000 feet for urban areas and bc
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 Appendir
X-A of the "Manual". Effective slope of natural watersheds may be estimated from Appendix X-B of
"Manual". Engineering judgement should be used for the validity of the computed initial times. A
minimum of 5 minutes should be used for all basins.
the "Manual". For urban areas overland tie of flow can be obtained fiom Appendix X-C of the
Chapter 3
Page 18
Master Drainage and Storm Water Quality Management Plar
Carlsbad, California, March 1994
b) Determine the type of soilfiom“Hydro1ogic Soil Groups -Runof€Potential” maps ofthe Count4
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inlerprelation study,
c) Determine the ultimate land use from the Carlsbad General Plan.
d) Obtain the runoff coefficient “C” from Table 3-2.
e) Obtain the local 6-hour precipitation&om SectionII-A“Precip~tat~onMaps” ofthe “Manual”. 0
the local 24-hour precipitation from Section II- A “Precipitation Maps” of the “Manual”.
t) Obtain the intensity (I) fiom Appendix XI “Intensity - Duration Design Chad7 of the ‘‘Manu;
g) Calculate the quantity of water (Q) fiom the “Rational Equation”, Q = CIA
3. Determine the quantity of water for subsequent subareas as follows:
a) Determine the water route fiom the point of concentration of the previous subarea to the p
concentration of the subarea in question.
b) Calculate the time necessary for the quantity ofwater arriving at this subarea to pass through to il
of concentration by the above route. The physical properties of this route must be considered i
velocities obtained fiom the following:
1) Iftraveling in a street the velocity can be figured fiom Appendix X-D, “Gutter and Roadway Disc - Velocity Chart” of the “Manual”.
2) Iftraveling in a ditch, pipe or other regular section calculate the velocity fiom the actual sec
3) Iftraveling in a natural watercourse the velocity can be derived from the approximation of the c
cross section.
c) Measure the length of flow to the point of innow of the next subarea downstream. From the v
compute the time of flow and add this time to the time for the first area to determine a new I
concentration.
When determining the time of concentration (Tc), the expected kture drainage facility and route
drainage facility, it is necessary to calculate the velocity and travel time for the preceding reach. Th
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 downsti
similar fashion until a junction with a lateral drain is reached.
e) Start at the upper end of the lateral and carry its Q down to the junction with the main line.
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to determine velocity and travel tie (Tt). Wherever junctions occur, or there is a change in SI 1
Master Drainage and Storm Water Quality Management Plan C Carlsbad, California, March 1994
4. Compute the peak Q at each junction. Let Q, T, Ia, corresponding to the tributary area with the longe
time ofconcentration. Let Qb, T,,, I, correspond to the tributary areawith the shorter time ofconcentratio and Qpl T correspond to the peak Q and time of concentration when the peak flow occurs. P
a) Ifthe tributary areas have the same time of concentration, the tributary Q's are added to obtain the Pea
Q. QP=Qa+Qb
b) If the tributary areas have different times of concentration, the smaller of the tributary Q's must b
cotreded as follows:
1) The usual case is where the tributary area with the longer time of concentration has the larger Q. I
this case, the smaller Q is corrected by a ratio of the intensities and added to the larger Q to obtain the pea
Q. The tabling is then continued downstream using the longer time of concentration.
Q, = (Q, + QJ Ia& Tp = T,
2) In some cases, the tributary area with the shorter time of concentration has the larger Q. In this cast
the smaller Q is corrected by a ratio of the times of concentration and added to the larger Q to obtain th
peak Q. The tabling is then continued downstream using the shorter time of concentration.
Q, = (Qb + QJ Tb/T, T, = Tb
E. ComputerProgmm
In this project the Rational Method Hydrology Program version 1.2 by Advanced Engineering Softwar
has been used to compute and design the drainage systems for the different watersheds. The San Diegc
County hydrologic design criteria has been incorporated in the software. The program develops a node
link model of the watershed and in the process estimates the conduit and channel sizes needed tc
accommodate the design storm peak flow rate. The designer then reviews the hydrologic results as tc
acceptability and options whether to proceed with the design or investigate an alternate hydrologic proces
in the subject subarea.
With respect to the Urban Area Overland Time of Flow Chart in Appendix X-C of the "Manual" the
computer program has been designed to accurately compute initial flow times for urban areas with slope
ofup to 2.5%. For slopes steeper than 3% the estimated initial times start to deviate &om the FAA curve
Tc= l.g(l.1 -C)(Lp
[S(lOO)]'"
In such cases the designer manually computes the initial time and run-off and inputs the values into thi
computer model.
Chapter 3
Page 20 Master Drainage and Storm Water Quality Management Ha
Cerlsbed, California, March 199<
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E SedimentatirmBasim
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 tht
lagoons and major natural channels. Ifthese sedimentation basins are not at full capacity at the ti
design storm occurs, they will also hction as storm water detention basins, attenuating dischars
major channels, thus decreasing channel erosion. However, for Master Drainage Plan purposes
existing and proposed sedimentation and detention basins are assumed to be at kll capacity. An
proposed downstream have been sized accordingly.
Sedimentation basin dmlations are first approKimations only, They are found in tt\e back
hydrology calculation volumes for the basin or basin portion in which they OCCUT. The method us(
based upon “The Erosion and Sediment Control Handbook”’, The San Diego Hydrology Manua
the City of Carlsbad Standards. Basin volume was sized to retain annual sediment load (calculate(
the universal soil loss equation) with a five foot settling depth, exceeding the two foot mii
The settling velocity used was 0.00096 Qs.4
In order to limit siltation of lagoons receiving runoff ftom the City of Carlsbad, the design partic
used was 0.02mm (medium silt).5 Since basin surface area is inversely proportional to settling ve
and settling velocity is directly proportional to particle size, a smaller design particle will re
sedimentation basins requiring more land. However, the effective length of particle trajectory in thc
may be increased using bafnes, decreasing the surface area required for particle settling. Sedimer
basins in major channels (such as Buena Vista and Agua Hedionda Creeks) were sized using estimi
available land only.
The calculation method requires assumptions of areas that will remain natural and areas that i
subjected to construction activity. These areas have been estimated using the 1987 Carlsbad Gener
and land use projections (densities) assumed in the City’s Growth Management Program. The un
soil loss equation also requires the estimation of percentages of sand, fine sand, silt and clay. In this
these estimates were based upon SCS Sod Survey Documents6
recommended? Basin surface area was sued usig the surface area formula in the following exa
Special Note: Basin design for the purpose of drainage fee estimation was purposefully calculate
conservative design criteria. This was done because basin costs may flucuate significantly due tr
values and environmental mitigation requirements. For most basins a particle size approaching fini
or 0.074 mmwill be acceptable provided the design allows for adequate storagevolume and has prot
against resuspension of settled particles in a 10 year storm.
I Erosion and Sediment Control Handbook: Goldman et. al., McGraw Hill, 1986.
2 Erosion and Sediment Control Handbook: Section 8.2i, 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. ’ Erosion and Sediment Control Handbook Section 8.2c, Goldman et. al., McGraw Hill, 1986.
6 Soil Sww, San Dieero Area. California; USDA, SCS, et. al., 1973.
Master Drainage and Storm Water Quality Management Plan CI
I Carlsbad, California, March 1994
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 100ft.tondacre x in/hr.
K = soil erodability factor in tondacre 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 s2) + 4.56 x s
L = slope length in feet
s = slope steepness, dimensionless
m = exponent dependant on slope steepness
0.2 for slopes x 1%,
0.3 for slopes 1% to 3%,
0.4 for slopes 3.5 % to 4.5%,
0.5 for slopes > 5%
+ 0.065](V72.5)m, where
(s2t- 10,000) (s?+ 10yOOO)'~
The Surface Area Formula:
Sur. Area = 1.2 Q,,,-/Vs in sf
where:
V, = settling velocity for the design particle, in @s
d = design particle size, in mm
Page references noted in the margins of the following calculation example refer to pages in "The Erosioi
and Sediment Control Handbook".
EXAMPLE: SEDIMENTATION BASIN AFB @ CONC. PT. 209.00
AREA %GRAV %SAND % F.S. %SILT %CLAY
209.00 9.93 100.00
209.00 72.55 20.00 80.00
205.00 36-35 5.00 50.00 45.00
203.00 66.57 10.00 45.00 20.00 25.00
201 .00 2 1.66 80.00 20.00
202.00 29.31 100.00
200.1 0 2.60 100.00
TOTAL 238.97
NODE (acres)
AVERAGE 3.55 40.75 13.46 0.00 42.25
Chapter 3 Master Drainage and Storm Water Quality Management Pla
Page 22 Carlsbad, California, March 199
Avg Dens 109.12 pcf
P8.46 d 6-82 mrn
P 8.11 VS 0.00096 fps
P 6.7 R 60.00
P 6.14 K 0.10
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8 6.93 %
L 6400.00 ft
P 6.20 rn 0.60
P 6.20 LS 4.86
P 6.22 Cc 0.60
P 6.24 PC 6-90
P 5.6 AC 10.94 tonhc-yr
Area c 167.28 ac
P 6.22 Cnc 0.30
P6.24 Pnc 0.90
P 6.6 Anc 6.67 tonlac-yr
Area nc 71.69 ac
P 6.6 Sed Vol 1662.39 cy
C 0.64
P6-10 1.80
I1 Cbave 0.60 inltnr
P 8.16 01 0-ave 38.63 cfs
P 8.16 Sur Area 48286.04 sf
Sur Area loll acw
p 8.19 Vol water 8941.67 cy (6’ depth)
Vol total 10604.06 cy
Since ideal basin efficiency corresponds to the percentage ofsoil equal to or greater than the design p;
size’, an alternate method of basin size calculation could be to speclfj7 the required basin efficiency.
to seventy-five percent is recommended by Goldman et. al.) Given a detailed determination of p;
size frequency, the design particle necessary to achieve the specified basin efficiency may be deterr
This method is recommended for final design in areas where silt and clay particles constitute i
percentage of total soil particulates and basin size calculated using a design particle of 0.02mm res
unreasonably high areas of land required.
Because the surface area required for sedimentation can vary greatly depending upon soil particl distribution, soil composition should be determined by field testing at the time of final design. At tha
more accurate information should be available, and sedimentation basins may be reliably sized for sed
removal efficiency as dictated by City of Carlsbad design standards.
7 Erosion and Sediment Control Handbook Section 8.26, Goldman et. al., McGraw Hill, 1986.
Master Drainage and Storm Water Quality Management Plan Ch
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Chapter 3
Page 24
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CmR4
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k General
The purpose of Planned Local Drainage Area (PLDA) fees is to design and construct storm draina
storm water quality enhancement facilities. The guiding theme of apportioning the fees recommen
this study is fairness. Fee recommendations are based on the concept that development creating tE
for enlarging or adding drainage facilities should bear the primary responsibility for providing the
to satis@ the need. The study also recognizes worth of storm drain hcilities already in place and th
of the existing facilities to properties proposed to be developed. The study recommends a procec
reimburse fee amounts to developers who build Master Plan drainage facilities which mc
requirements for the use of drainage area fees. This study anticipates a “build-out” condition for thl
per the presently adopted General Plan and land use projections in the City’s Growth Manag
Program. The study concludes that there are both specific and general benefits that have and will e I all development within the City as the result of well-fbnctioning drainage facilities.
The criteria used in determining the fees and requirements established in this report are:
0 Does it make sense?
0 Is it fhk?
8 More specifically the following tests were used:
0 Do the value of the benefits of the drainage facility exceed the cost of constructi
Do the benefits fiom the drainage project acme to those who are paying for it?
These criteriamust be afhnatively satisfied. The Carlsbad City Council must make the preceding fu
to satisfy the mandates of law in establishing the PLD area fees and requirements recommended 1
study. The fees recommended by this study are summarized in Table 4-1.
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Master Drainage and Storm Water Quality Management Plan
Carisbad. California, March 1994
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Area (PLDA)
A
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D
PLDA Fee* PLDA Fee*
Runoff Runoff
($/Acre) ($/Acre)
$1,564 $2,560
93,362 $5,502
$2,514 $4,114
$34 $56
For Areas of Low For Areas of High
The fee system established in 1980 was based upon the cost of needed facilities divided by the nun
acres within the Planned Local Drainage Area. The resulting fee was charged against subdivided prc
on an acreage basis regardless oftype of development proposed. The fee program had several weak
which have been addressed in this proposed Master Plan.
The following list identifies the weaknesses ofthe existing fee structure togetherwith a discussion c
the weakness is addressed within the proposed fee program :
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1. The 1980 Planned Local Drainage Areas (PLDA) distributed the cost of drainage facilitit
properties that were already developed orthat wereused for schools, parks, streets, freeways, utili0
of-way, open space and other uses that had no new development potential and would never con
collection for the Planned LocalDrainage Areas. The GrowthManagement Program developed nun
land use and constraints maps which have been incorporated into the preparation of a more refined a
of developable areas within this study.
PLDA fees. This had the effect of inflating the potential developable area thereby reducing 1
2. The 1980 PLDA fees were only assessed against property being subdivided under authc
the SubdivisionMap Act (Section 66410 et seq. ofthe Government Code). This greatly limited the
of the City to collect adequate fees within drainage areas that were relatively built out or hac
previously subdivided. Under the 1980 Master Drainage Plan three Planned Local Drainage Area
zero dollar fee rate. Several other areas were seriously constrained in their ability to generate ad
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 subdil
This study recommends the use of AB 1600 to increase the base of development responsible for prc
of needed drahge facllXes to include all new development, includmg subd;&ons, and all red4
ment, remodels and building alterations which contribute to the increase of drainage runoff. Wit1
additions, the City will be able to collect fees in an amount approaching eighty five percent of the
the drainage facilities proposed in this Master Plan.
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3. Until recently, most drainage master plans, including the City’s 1980 Master Plan, pr
focused on the quantitative nature of storm water flows and not the qualitative nature. However, z
402(p) of the Water Quality Act of 1987 alters this fbndamental perception by mandating an inc
emphasis on the qualitative nature of storm water runoff. It is no longer considered acceptable to
drainage fhcilities solely to transport water from one place to another. It is now required to i
measures assuring that water quality is maintained or enhanced in some environmentally sound I
during its transport.
This shift in emphasis now requires local agencies to review and consider storm drainage facilities in broader context. Whereas the PreviousMaster Plan mainly addressed the issue offlood control ona
by facility basis, this study fbrther considers the overall nature and protection of the watershed as a
The importance ofthis new emphasis is reflected in the title change ofthis report study to Carlsbad
Drainage and Storm Water Ouality Management Plan. I
Master Drainage and Storm Water Quality Management Plan C
Carlsbad, California, March 1994
EXISTING PLDA FEE ACCOUNTS AS OF FEBRUARY
(ACCRUED ToTAL FUNDS FEES D<PmD,.,.URES ToTAL FUND ACCOUNT FEE
(s1Acre) AND INTERESn NUMBER PLDA
1 NIA $0 $0 NIA
2 NIA $0 $0 NIA
3 350-810-18-70-874 $3,808 $33,128 $968
4 350-810-18-71-874 $1,686 $35,786 $968
5 350-810-18-72-874 $2,658 $72,350 $10,643
6 350-81 0-1 8-73-874 $200 $21,273 $968
7 350-81 0-1 8-74-874 $2,273 $282,913 $468,773
8 NIA $0 $0 NIA
9 350-81 0-1 8-75-874 $2,878 $2.1 12,727 $59,057
10 350-810-18-76-874 $1,196 $337,960 $1,935
11 350-810-18-77-874 $1,630 $534,177 $1 4,513
12 350-810-1 8-78-874 $4,445 $34,384 $968
13 350-810-18-79-874 $2,858 $0 $0
$3,464,698 $558,793
17,1994
CURRENT REMAINING
ALLOCATED UNDESIGNATED
FUNDS FUND BALANCE
NIA NM
NIA NIA
$0 $32,160
$0 $34,818
$0 $61,707
$0 $20,305
$0 so4
NIA NIA
$1,219,959 $833,7 1 1
$0 $336,025
$0 $51 9,664
$0 $33.41 6
$0 $0
$1,219,959 $1,871,806
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construction of Master Drainage Plan facilities from the following knding sources - 4.3 million t
in SANDAG Transnet funds, 0.5 million dollars in Redevelopment Tax Increment bond money a
million dollars fiom the County of San Diego, This leaves the City with an unfunded obfigat
approximately 18 million dollars. This remaining 18 million dollars in unfhded improvements
presumably be constructed as a condition of development approval or require additional contributi
the City. As wiU be seen the revised fee program substantially addresses the existing funding defic
e
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E. Finandng Method Alternatkes
Several sources of funds were considered to hance the drainage facilities proposed by this plar
categories reviewed were:
Development Exactions
Assessment District Proceedings
General Fund Contributions
Federal and State Fundmg
Special Benefit District Fees
Development exactions are requirements to construct mdor to pay for faciities. They are app developments at the time that various types of permits or approvals are sought. This type of requh
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 Drainage Plan incorporat
approach. With careful attention to the drainage impacts, project specific and cumulative,
discretionary approval stage development exactions work well.
Assessment District proceedings allow facilities to be constructed with finds obtained by the sale of
They are typically used by land owners who wish to construct large public works facilities. The f
Carlsbad has determined that assessment district proceedings should be used only for large projer
provide facilities which benefit the general population of the City.
General Fund monies are general hnd contributions withdrawn from the operating fbnds ofthe City
the adoption of the 1980 Master Storm Drain Study, General Fund monies have typically been UI
storm drain projects only when reimbursement was expected to offset their use within a short time.
present financial climate, this type ofuse. for General Funds will be increasingly difficult to accomm
Federal and State appropriations, grants and loans are available at limited times withvarying require
of application procedures, qualification criteria, matching funds, use restrictions and accounting r
tions. The lack of reliability in obtaining grants and loans effectively removes them fiom considt
in any long-term planning. The City should remain poised to take advantage of opportunities to
federal and state funds. It is recommended that any federal and state funds be used in areas of tf.
that have low development potential, are more densely developed and that have storm drain facili9
that are significant. An example of this approach is the City Council approval of 4.3 million dollar
SANDAG Transnet Local Funds to improve drainage of streets in PLDA “A”.
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Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
C
Specid Benefit Districts are established under Section 54700 et seq. of the Government Code, titled ti
Benefit Assessment Act of 1982. The Districts may be formed to provide for the maintenance an
operation costs of drainage, flood control or street lighting. The districts may also impose assessmenl
to finance the cost of installation and improvement of drainage and flood control facilities. The act allow
fees for flood control purposes to be determined onthe basis ofthe proportionate storm water runoff fi-01
each parcel. A special benefit district would be initiated by the City Council and approved by tk
landowners within the proposed district in a siple majority vote. The City presently has one speci
benefit district for drainage purposes, the Buena Vista Channel Maintenance District.
E Financing Recommet2datbns
This report recommends development exaction as the primary source of funding for new storm drainag
facilities. Development exactions would take the form of both payment of fees and construction c
facilities. This method is consistent with past practice and the City’s Growth Management Progran
Historically, the financing of storm drainage facilities has been considered the responsibility of thos
wishing to develop their property. This is because the need for new or upgraded facilities can be directl
linked to land development practices. The City’s Growth Management Program recognizes this fact b
inclusion of a facility standard which requires that “Drainage facilities must be provided as required b:
the City concurrent with development”.
In general, developers are hlly responsible for the construction ofboth onsite and offsite drainage facilitie
which are necessary to mitigate their project impacts andor to provide for the orderly development ofthei
property. In some cases, it is necessary or desirable to construct facilities which are in excess of the neec
of a single developer and provide a benefit to the community as a whole. To handle these cases, the Ci?
established, and this report recommends the continued use oc Planned Local Drainage Area (PLDA) fees
The funds generated by the collection ofPLDAfees can thenbe used by the City to either construct needec
facilities or to reimburse developers for the construction of facilities.
A total of 42.9 million dollars in recommended hture drainage facilities are identified within the Maste
Drainage Plan report. Of this amount, approximately 34.3 million dollars in facility costs are directl:
attributable to the needs created by new development. The remaining 8.6 million dollars are attributablc
to facility deficiencies created by existing development.
Thefinancingplanpresentedinthisreportrecommendsthat lOO%ofthedrainagefacilitycosts attributablc
to new development be financed by developers through payment of Planned Local Drainage Area fees o
by direct construction of drainage facilities. Ofthe 34.3 million dollars in facility costs attributable to nev.
development, 18.8 million dollars will be collected in new PLDA fees, 13.7 million dollars will occur &on
direct developer construction of drainage facilities and 1.8 million dollars will be applied fiom previouslj
collected PLDA fee revenues. The 13.7 million dollars in direct developer construction of facilities occur2
in proposed PLDA ‘ID” for reasons discussed below.
The 8.6 million dollars attributable to existing facility deficiencies will be fbnded through a combinatior
of sources as follows: 1.3 million dollars are available fiom previously collected PLDA fees; 1.6 millior;
dollars will be generated fiom PLDA fees charged against existing developments that redevelop 01
Chapter 4
Peg9 30
Master Drainage and Storm Water Quality Management mer
Carlsbad, California. March 1994
remodel; 4.3 million dollars in SWAG Transnet hnds and 0.5 million dollars in redevelopme
increment bond finds are budgeted in the current Capital Improvement Program; and, 0.2 million c
has been contributed by the County of San Diego for drainage improvements adjacent to Mc(
Palomar Airport. The remaining 0.7 million dollars is presently unfbnded and will require fundin]
other non fee sources such as the general hnd, federal and state grants, general obligation bonc
assessment districts.
It should be noted that the 1.3 million dollars in existimg PLDA hnds, allocated to mitigate e
deficient facilities, will in fact be used to mitigate impacts created by the developments which pi
PLDA fees. Due to funding shortfalls, many of these impacted facilities were deferred until ad
knding was available. Since the development was allowed to proceed once the fees were paid, thes
facilities are now categorized as wholly or partly deficient under this plan.
The report recommends establishment of four new Planned Local Drainage Areas (PLDA’ s) correi
ing to the four drainage basins described above. The existing thirteen PLDA’s are to be abolished a
remaining finds will be transferred into the respective new PLDA. With the exception of the PLI
basin ‘D’, the fees recommended for each of the PLDA’s are based upon recovery of 100% of thl
attributable to new development and 20% of the costs attributable to existing development. Th
figure was used because it represents the percentage of the existing development base which is est
to redevelop or remodel over the life of fee program.
For basin ‘D’, it is recommended that the primary method of financing be direct developer consb
as a condition of development approval. The reasons for using this method of financing over a fee
program are as follows: 1) Only a small percentage ofthe drainage facility needs in basin ‘D’ are attd
to existing deficiencies; 2) The facilities are located on undeveloped lands which require their in&
in order to make theunderlying property suitable for development; 3) Amajority ofthe facilities are I
within large master plan developments that have the financial capability to hnd such facilities v
benefit ofafee program; and, 4) The facilitiesin the southern portion ofbasin ‘D’ are to be financed tl
a proposed Community Facilities District currently under formation.
The report does recommend that a small fee be levied on development within basin ‘D’ in 01
reimburse the City for capital expenses associated with the Storm Water Testing and Monitoring prc
In addition, it may be necessary to establish additional local benefit assessment districts such as 1
proposed in the southern part of basin ‘D’ to reimburse developers on a facility by facility basis.
The existing drainage fee program requires payment off LDA fees only upon the subdivision of lan
subdivisions. Recent State legislation in the form of AI3 1600 (Government Code Section 66000 (
now provides the City with the authority to levy such facility fees on all developments that impact ti
for such public facilities. The ability to charge a PLDA fee to all developers eliminates an inherent i~
with the old fee structure and allows the City the opportunity to collect a greater percentage ofthc
cost of the Master Plan drainage &&ties.
This report recommends that any person who constructs or causes to be constructed any building c
a subdivision map should pay a PLDA fee as listed in Table 4- 1. This requirement would apply
construction as well as all remodeling, enlargement or alteration to any building where adc
impermeable surface area is added. For residential remodels, enlargement or alterations it is suggesi
Master Drainage and Storm Water Quality Management Plan
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C
Carisbad, California, March 1994
the fee be required only where the building footprint is expanded by 50% or greater over the existin
condition. This arrangement will help prevent the fee fiom exceeding the value of the potential benefit 1
such projects.
PLDA fees should be levied for all lands subdivided prior to October 16,1980, the effective date for ti
1980 PLDA fees, and for any project which has not previously paid or received credit for payment ofPLD.
fees. Fees would not be charged for projects constructed upon property which have paid or received cred
for PLDA fees prior to the effective date of this fee program and which property is not subject to a
agreement to pay increased PLDA fees pursuant to a condition of project approval. PLDA fees shoul
be paid by all who increase the drainage burden. The sum of all PLDA fees levied against any one propert
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 whic
the construction is located plus the area equal to one-halfthe width of public and private street frontin
the lot or parcel. Projects located adjacent to arterial streets would compute their fee on the basis of IC
area exclusive of the arterial street plus an area equal to a hty foot strip of the arterial fiontage.
The following types of land uses or ownerships should be exempted from inclusion in the area for fe
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 whicl
is not subject to an agreement to pay for increased drainage area fees pursuant to a condition o
approval.
7. Constrained lands as they are defined in Chapter 21.53.230 of the Carfsbad Municipal Code
G.
The 1980 Drainage Master Plan divided the City into thirteen independent PLDA’s for the purpose of fee
collection as shown on Figure 4-1. A large portion of the southern part of the City was not included in
aPLDA because at the time it was included within Zone 1 ofthe San Diego County Flood Control District.
The Zone 1 Flood Control District was dissolved in July of 1985 and the responsibility for flood 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 old
Zone 1 Flood Control District into four new PLD Areas, The PLD Areas would correspond to each of
the four major drainage basins within the City as shown on Figure 4-2. The few small areas which drain
to sumps or directly into the ocean would be included into the basin which surrounds them. The four basins
are labeled “A” through “D” in ascending order from north to south as follows :
Planned ]Local Drainage Areas (PLDA’s)
Chapter 4
Page 32 Master Drainage and Storm Water Quality Management Plan
Carlsbed, California, March 1994
8 Buena Vista, PLDA“A” which includes all areas within the City which drain in the P
1
1 Ocean via Buena Vista Lagoon.
Agua Hedionda, PLDA “B which includes all areas within the City which drain in1 I
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Pacific Ocean via Agua Hedionda Lagoon.
0 Encinas Creek, PLDA “C” which includes all areas within the City which drain in!
San Marcos Creek, PLDA “D which includes all areas within the City which drai
There are several reasons for consolidation of the existing fee areas and incorporation of the pre.
Pacific Ocean via Encinas Creek.
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the Pacific Ocean via Batiquitos Lagoon.
undesignated drainage areas into four Planned Local Drainage Areas. The reasons are as follow!
1. Master drainage facilities provide benefit to the City beyond the benefit provided to pr
owners in any one sub-basin. Most of the Master Plan facilities are needed to protect &CI
element roads used by all residents and emergency services. Also Master Plan facilities redl
potential for the spread ofwater borne disease which improves the overall health ofthe corn
2. Improving water quality within the lagoons provides a general benefit to all Carlsbad res
New federal regulations included within Section 402(p) of the 1987 amendment to the
Quality Act require the City to improve water quality within the City’s lagoons and tri
creeks. This must be accomplished by balancing the water quality levels of each of the sub
throughout the overall lagoon basin. Therefore, advanced construction or increased facilitil
environmental constraints.
3. Fewer basins are easier to administer and will provide the City greater flexibility in gent
fhds necessary to construct needed facilities in a timely manner.
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be needed in one basin to make up for deficiencies in another due to a lack of available 1
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Upon City Council action establishing the four new PLDA’s, it will be necessary to transfer fund
the existing PLDA accounts to new PLDA accounts. To assure that the collected hnds are used
same purpose for which they were collected, the existing fbnds should be transferred to the res1
account for the new PLDA which encompasses the old existing PLDA as follows:
Existing PLDA Proposed PLDA
2,7,8,9,10,12,13 B
11 C
None D
Master Drainage and Storm Water Quality Management Plan C
Cadsbad, California, March 1994
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EXISTING
PLANNEDLOCAI,
DRAINAGE FEE AREAS
FlaJRE 4-1
Chapter 4
Page 34 Master Drainage and Storm Water Quality Menagement Plai
Carlsbad. California, March 1994
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PROPOSED
PLANNEDLOCAI, 1 DRAINAGE FEE AREAS
ROwE 4-2
Master Drainage and Storm Water Quality Management Plan c
Carlsbad, California, March 1994
H. FeeAncilysis
In determining fee amounts the primary consideration is to effectively and fairly apportion fees in relatio
to the development’s demand on required drainage facilities. In the 1980 Master Plan this wa
accomplished by simply dividing the total cost of needed drainage facilities by the total number of acre
ofremaining developable land. Though easy to understand and to calculate, the inherent problem with thi
method is that it assumes the drainage burden is uniform for all land use types which is certainly not th
case. Drainage runoff is duectly related to the permeability or absorption characteristics of the land up0
which the rainfall occurs. Permeabiity is measured by a value known as the “runoff coefficient” and can
be statistically related to land use. The values ofvarious runoff coefficients for dserent soil types and lane
uses is shown on Table 3-2. They range from a low of .30 for Open Space and rural areas to high of .92
for industrial lots.
To simpw the fee structure, this study grouped landusesinto three general categories. These include lanc
with high runoff potential, land with low runoff potential and land that is non developable or which i!
governmentally owned. The non-developabldgovernmentally owned category was excluded from the fec
analysis. Table 4-3 shows the breakdown of the three groups by City land use designation. An averagc
runoff coefficient factor of .55 was assumed for land uses with low runoff potential and -90 for land wit1
high runoff potential. These figures represent a weighted average of the various land uses and soils type:
and take into account the various land constraints identied in the growth management ordinance.
The next step in computing the fee was to determine the total amount of land within each of the four
proposed PLD Areas which would ultimately contribute to the construction of the Master Planned
facilities. Two categories of development were considered - new development and redevelopmentl
remodeling. For the first category all undeveloped parcels of land were identified and included within the
fee analysis. To determine the potential acreage which could be redeveloped it was necessary to review
past redevelopmenthemodel rates and to set a time in the future at which point all fbds would need ta
be collected to construct the Master Planned facilities. A time period of thirty years corresponding to time
for City buildout was selected. Given a review of past records on redevelopment and remodel rates, it was
assumed that within this time frame approximately twenty percent of the existing developments will
remodel and or redevelop. Tables 4-4 through 4-7 list the total amount of developable and redevelopable
acreage for each of the four PLD Areas by runoff potential category.
In determining the amount of low and high runoff areas the formula at the bottom of Tables 4-4 through
4-7 was used. The formula computes the low and high runoff areas by adding the respective undeveloped
area with 20% of the developed area. The resultant sum is then multiplied by 0.85 to account for the area
excluded due to the presence of constrained lands. The 85% figure was obtained by averaging the amount
of unconstrained lands reported in the various approved zone plans throughout the City.
Chapter 4
Page 36
Master Drainage and Storm Water Quality Management Plan
Carisbad, California, March 1994
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PLDA FEE CATEGORY
GENERAL PLAN NON
LAND USE LOW RUNOFF HIGH RUNOFF DEVELOPABL
DESIGNATION POTENTIONAL POTENTIAL GOVERNMEN1
NO-FEE ARE
E +
J +
H +
GENERAL PLAN
DESIGNATION
4 = (618.9 + 0.2 X 576.2) X 0.85 = 624.0 4 = (198.3 + 0.2 X 401.8) X 0.85 = 236.9
TABLE 4-4
LAND USE ACREAGE TOTALS FOR PLD AREA "A"
Chapter 4
Page 38
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
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PLDA FEE CATEGORY
DEVELOPED UNDEVELOPED EXCLUDED
GENERAL PLAN LAND LAND AREA LAND USE
DESIGNATION Low High Low High
Area Area
Runoff Runoff Runoff Runoff Area
(Acres) (Acres) (Acres) (Acres)
Area Area (Acres)
E 40.3
J 30.4
RH
TOTAL
186.2 22.7
1297.8 1233.7 2791.9 11 62.8 2431.5
PLDA FEE CATEGORY
DEVELOPED UNDEVELOPED EXCLUDED
LAND LAND AREA GENERAL PLAN
LAND USE
DESIGNATION Low High Low High
Runoff Runoff Runoff Runoff Area
Area Area Area Area (Acres)
(Acres) (Acres) (Acres) (Acres)
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LAND USE
DESIGNATION
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PLDA FEE CATEGORY
DEVELOPED UNDEVELOPED EXCLUDED
AREA LAND LAND
Low High Low High
Runoff Runoff Runoff Runoff Area
Area Area Area Area
(Acres) (Acres) (Acres) (Acres)
(Acres)
74.5
29.6
In establishing the appropriate formula for the determination of the per acre fee for each planned loc
drainage area, two basic criteria were utilized. First the ratio of the per acre fee for low and high run0
areas must equal the ratio ofthe weighted runoff coefficients for the low end high runoff areas as follow
FL CL
FH CH
- _--
where FL = per acre fee for low runoff areas
FH = per acre fee for high runoff areas
CL = 0.55 = weighted average runoff coefficient for areas with low runoff potential
CH = 0.90 = weighted average runoEcoefficient for areas with high runoff potential
Secondly, the product of the per acre fee for low runoffareas multiplied by the total number ofundevelope
acres with low runoff potential plus the product of the per acre fee for high runoff areas multiplied by tb
total number of undeveloped acres with high runoff potential must equal the total recoverable cost c
drainage facilities within each respective planned local drainage area as follows:
ptFL+qFH = C$
where 4. = number of undeveloped acres with low runoff potential
4 = number of undeveloped acres with high runoff potential
C$ = total recoverable cost of unfbnded drainage facilities subject to the fee program
By solving for these two equations a fee formula for low and high runoff areas was established as follows
CL Z$
CLAL + CH4.i
e, E$
CL4 + CHAH
FL =
FH =
The values of variables 4, 4 and C$ for each of the four PLD Areas together with the fees recommendea
to be levied on an acreage basis are contained in Table 4-8. For PLD Areas "A", "B'l and "C" the value
of X$ is the total recoverable cost of the facilities as determined in Table 6-7. The value of E$ for PLDA
"D" represents the recoverable costs for facilities necessary to implement the Storm Water Testing and
construction of the facilities.
Monitoring Program. The remaining facility costs in PLDA 'ID" will be fbnded through direct develope1
Chapter 4
Page 42
Master Drainage and Storm Water Quality Management PIar
Carlsbad, California, March 1994
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The value of the variable Z$ used in the fee computation formula is an estimate of the percentage c
facility costs that is permissibly recoverable through the proposed facility impact fee program. Esse]
the figure represents the cost required to mitigate 20% of the existing facility deficiencies and 1C
the costs required to mitigate impacts caused by future development less the existing PLDA fee b
attributable to new development. (See Table 4-8). The 20% figure corresponds with the antic
percentage of the existing development base that will be subject to fee payment as redevelopme
remodels occur over the life ofthe fee program. Amore detailed explanation and analysis ofthe recor
facility costs is presented in Chapter 6 of this report.
State law precludes establishment of a facility fee unless it can be shown to be reasonably related
impacts created by the development. The proposed program meets the intent of this law by rec
existing development to pay their prorata share to mitigate existing deficiencies while new develc
is required to pay the kll costs to mitigate their impacts. The remaining 80% ofthe cost needed to IT
existing deficiencies will be hded through previous drainage fee contributions and other City 6
sources
In order to maintain the relevance of the fees to the cost of the storm drain facilities recommended
study the fees should be adjusted on an annual basis. This study recommends that the ENR (fo
Engineering News-Record) Construction Cost Index (CCI) for Los Angeles be used to provide th
for PLDA fees adjustment. The fee adjustment should be made in conjunction with the City 1
approval. Since the Los Angeles CCI is published on a quarterly bask in the ENR, it is recommend
the March value of the CCI be used as a basis for determining fee increases. The January 1994 EN
for Los Angeles was 549.13 based on the 1967 average = 100. The ENR index is widely acceptec
construction and engineering professions.
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z 0
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w w LL a w
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TABLE^-^
c
I. Fee AdJustmab
his study recommends that an administrative variawe procedur6 be established to dm Wa!
payment of PLDA fees. Requests for relief would be limited to the following circumstances:
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1. When portions of the project have slopes greater than 25 percent and less than 40 per1
defined in Chapter 21.95 CMC one-halfthe fee for those portions may be waived. The criteria for 7
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 su
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.
2. The increment of a project that is replacing a buildmg destroyed by accidental fire or I
disaster may be considered to be deducted fiom the valuation of the project PLDA fee.
3. Structures that will not be in place fiom November 14 through April 14 of any ye
considered temporary for the purposes of this report. Temporary buildings may have the pap
PLDA fees reimbursed without interest when they have been removed and when the areas undc
appurtenant to them are restored to their natural hydrologic condition. Appurtenant areas include pi
areas, walks, activity areas and other areas accessory to the use of the building, Structures and appur
areas that have not been or are not removed between any November 16 through April 14 period a
their 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 of tk
involved. The request should be accompanied by:
I
1. Written statement citing the reason(s) why the rehnd is justified.
2. Proof of ownership of the land should be provided when fees have been previously pa
preliminary title report, dated within 30 days ofthe request for refund, that names the requestor as fi
owner of the land will be satisfactory proof Proof of ownership should not be required when fees are
waived prior to their payment.
3. The current fee for an administrative variance (may be waived subject to City Eni
determination). e
Master Drainage and Storm Water Quality Management Plan Chi
Carlsbad, California, March 1994 P
J.
A developer who constructs all or a portion of one or more ofthe drainage facilities identified in this Maste
Plan study may be eligible for reimbursement from funds accumulated through collection of PLDA fee
insofar as the facility cost was included within the fee computation formula. No fee credits o
reimbursements are allowed for facility costs not included in the fee program. The maximum reimburse
ment is limited to the actual cost of installing the facilities. The form and manner in which reimbursement
are given will be determined at the time the developer enters into areimbursement agreement with the City
All reimbursement agreements are approved by City Council. Whenever the actual cost of installation o
a drainage facility exceeds the cost estimate in this report adjusted for inflation, a revised fee schedulc
should be adopted to ensure that adequate fbds are collected to cover the reimbursement payments.
Any request for reimbursement should be made as early as possible (preferably during the planninl
approval stage) to ensure adequate lead time for the allocation of available funds for reimbursement.
Fee credits will be given for all developments which construct onsite master planned drainage facilitie
up to the maximum amount ofPLDA fee paid by the development. Fee credits will be determined at thc
time PLDA fees are due and will in all cases be based upon the value of the facility as it is estimated in thi
report adjusted for inflation unless a revised fee schedule is approved in advance of the fee payment.
Fee Credits and Rehbursement for Constsucted Facilities
Chapter 4
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Carlsbad, California, March 199~
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STORMI WAmRQUALY 1 WAGEMEN” PROGRAM
k TntrddOn I At this time, pollutants in storm water discharges are largely uncontrolled not only in the City of Car
but in most cities in the United States. The U.S. Environmental Protection Agency determine
pollutants in runoEfiom urban areas and fiom construction sites are a leading cause of water c
impairment. In recognition of this problem, recent Federal Legislation was enacted which now re
that the City of Carlsbad establish a Storm Water Quality Management Program.
The majority of storm water runoff ftom 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
include a wide variety of wastes fiom sources such as illegal sewage connections and waste dump
industrial and automotive by-products. In addition there are numerous “non point” sources of pollu
which find their way into the storm drainage system such as fertilizers, pesticides, grease, oils, auton
and power plant soot, trash, human and animal excrement, etc. Storm water discharges fiom indi
facilities may also contain toxins and other noxious pollutants. In urbanizing areas such as Carlsbs
the surrounding communities, soil erosion and sedimentation caused by construction activities to1
with increased runoff from developed property contribute significantly to the degradation of sudace
quality. Removal of these wastes and sediment materials fiom storm water discharges presei
opportunity for dramatic improvements in the quality of water found in our local creeks and lagc
The Environmental Protection Agency (EPA) tried a variety of approaches siice 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@) to the Clean Water Act was amended to require EPA issuiu
regulations establishing permit application requirements for:
B
1) storm water discharges associated with large municipal jurisdictions being served by sel
storm drain systems; and,
2) storm water discharges fiom any jurisdiction whose storm water discharged into recc
waters found to be in violation of established water quality objectives.
Within Carlsbad all three lagoons have been found to be inviolation of established water quality objec
The task of administering the Water Quality Act in California was delegated by the EPA to the Rei
Water Quality Control Boards. In the past, the Regional Boards pursued regulation of non storm
discharges fiom discrete “point” sources, such as an industrial or sewer outfall pipes, through issu
and enforcement ofNational Pollutant Discharge Elimination System (NPDES) permits. These “p
Master Drainage and Storm Water Quality Management Plan Ch
Carisbad, California, March 1994 F
sourceNPDES permits required technology based or water quality based effluent limitations and control
for the reduction and/or elimination of pollutants in discharges to surface waters. Today, the majority a
“point” source discharges have been curtailed or are effectively regulated to protect the beneficial uses
of surface waters.
During the past decade, agreat deal ofinformation was learned about “non point” storm water discharges
and urban runoff through the National Urban Runoff Program (”RP). By monitoring runoff an(
receiving waters, NURP and other studies indicate that 40 to 80 percent of pollutants currently found i
our lakes, streams, rivers, and other surface waters are a result of runoff fkom urban areas. Urban area
are normally covered with structures and asphalt upon which a variety of pollutants settle or are spilled
These impermeable surface areas prevent absorption of both water and pollutants into the ground thu
allowing more pollutants and storm water runoff to find their way into the receiving waters. The increase
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 hydrocarbons (combustion products of petroleum). In th
San Diego area, nutrients such as nitrogen and phosphorus fkom fertilizer are also si&cant pollutant
in estuaries, lagoons, and ephemeral streams. Nutrients are responsible for increased algal blooms wit]
their subsequent decreases in dissolved oxygen. Most fish kills in the region are probably due to dissolver
oxygen depletion as a consequense ofnutrient loading. Organic priority pollutants, such as pesticides an,
herbicides, are found at lesser fkequencies dependent upon the type of land use found in the basin anc
application techniques used by the land owners.
In aneffort to control the discharge ofthese“non point” sources ofpollutants, theRegional Water Quality
ControlBoard forthe SanDiego Region, issued asingleNPDES permit to the City ofcarlsbad, the Count
of San Diego, the S.D. Port District and all other Cities in San Diego County pursuant to Order No. 90
42 dated July 16,1990. A single permit was issued to all municipalities, the County and the Port Distric
because it was found by the Regional Board that essentially all surface and ocean waters in San Diegc
County fail to meet minimum water quality control objectives. Because water quality management mus
be effective throughout the basin and since established jurisdictional boundaries do not coincide wit1
drainage basin boundaries, the Regional Board opted to include all agencies within the County under on1
permit as co-permittees. Through issuance of the NPDES permit, the Regional Water Quality Contrc
Board is requiring Carlsbad and other San Diego jurisdictions to develop and implement Storm Wate
Quality Management Programs to eliminate and/or reduce storm water pollutants fiom reaching thl
streams, lakes, lagoons, bays, ocean and other surface waters within the County.
B. Brief History of Actions Lea- to City’s “DES Permit
1. Clean Water Act of 1972 amended the Federal Pollution Control Act to prohibit “point” source
discharges without a National Pollutant Discharge Elition System (NPDES) permit.
2. Water Quality Act of 1987 amended the Clean Water Act by addition of Section 402(p) whicl
established NPDES permit requirements for “non point” source discharges fiom municipally
owned storm drainage systems.
Chapter 5
Page 48 Master Drainage and Storm Water Quality Management Pla~
Carisbed, California, March 199t
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3. On December 7, 1988, EPA published draft regulations governing permit appli
requirements. Due to litigation with environmental groups, the regulations were not final
4. Carlsbad City Council an July 10,1990, adoptedResolutionNo. 90-235 notiimg Ciky’s
to apply for a NPDES permit pursuant to Order No. 90-42 of the San Diego Regional
Quality Control Board.
5. The Regional Water Quality Control Board for the San Diego Region issued Order N
42 on July 16,1990, naming the City of Carlsbad as a co-permittee on a National Po
Discharge Elimination System (NPDES) permit.
6. The final regulations for WDES permit requirements promulgated by the Environr
Protection Agency were published in the Federal Register on November 16, 1990.
7. Carlsbad City Council on July 16,1991, adopts Resolution No. 91228 authorizing Ma
sign Implementation Agreement with other co-permittees listed under the ”DES permii
.
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I C. “Early” NPDES Permits
As written, the proposed federal regulations governing storm water discharges are complex, burden
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 Car
requested their local Regional Water Quality Control Board to issue“ear1y” permits (a storm water p
issued prior to promulgation of the hal federal regulations). “Early” permits are exempt fi-om sor
the stricter requirements of the EPA for a period of five years. The intent of issuing “early” permits
to:
1. Establish reasonable permit conditions and requirements specific to the local agency a I hydrological characteristics;
I (Regional Board staff);
2. Mow flexibility and a working relationship between local governments and the permit -
3. Establish reasonable time schedules for compliance;
4. Establish area-specific monitoring programs;
5. Allow for prioritizing programs for impacted waters; and
6. Avoid costly and burdensome federal regulations.
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Within San Diego County it was determined by the Regional Water Quality Control Board (Rei
Board) that all municipalities including Carlsbad togetherwiththe County of SanDiego and the Sanl
Port District were subject to NPDES permitting requirements. In July of 1990 the Regional Board i
Master Drainage and Storm Water Quality Management Pian Ch
Carlsbad, California, March 1994 P
Order Number 90-42, titled Waste Discharge Reauirements for Storm Water and Urban Runoff from th
Countv of San Dieno. the Incorporated Cities of San Diego County. and The San Diego Unified POI District. which mandated Carlsbad’s participation as a co-permittee on an “early” NPDES permit.
D. w Elements of Carlsbad’s Storm Water opdiiy Management Pro-
The basic elements required to complete the proposed Storm Water Quality Management Program fc
Carlsbad are outlined within the text of Order No. 90-42 of the Regional Board. The following is a brit
synopsis ofthe required elements together with the implementation or submittal dates contained in Orde
No. 90-42. Much of the inventory work needed to complete the elements was completed by virtue of th
completion of this Master Drainage Plan. The basic elements of the proposed Storm Water Qualit
Management Plan for Carlsbad are as follows:
1. Enter into a cooperative “implementation” agreement with the co-permittees on the NPDES
permit dehg the roles and fiscal responsibilities of each party to the agreement.
2. Inventory existing stormwater pollution control programs, illicit discharge detection programz
monitoring programs and data, storm water conveyance system maps, land use maps, and existin
laws, ordinances, and codes which provide the City authority to implement and enforce storr
water pollution control measures.
3. Develop and implement a storm water, urban runoff and receiving water monitoring prograr
to evaluate the type and characteristics of pollutant loading in order to target priority pollutant
and evaluate the efficiency of pollutant control programs.
4. Develop and implement an illicit connectiodillegal discharge detection program to identi@ an(
eliminate non storm water discharges to storm water conveyance systems.
5. Develop a fiscal analysis ofthe capital and operating expenditures necessary to accomplish th
activities of the proposed Storm Water Quality Management Program.
6. Develop and implement best management practices (BMPs) to control discharges ofpollutant
to and from storm water conveyance systems to the maximum extent practicable (MEP). Th
BMP’s shall address structural and non-structural techniques for the control ofpollutants in urba
runoff and storm water discharges from industrial, commercial and residential areas. Wher
necessary codes, ordinances and standards shall be enacted to ensure implementation of thl
program.
7. Inventory and compile data regarding existing programs and data. Prepare report on adequaq
of data relevant to the EPA promulgated requirements and recommend actions necessary tc
correct any program deficiencies.
8. Conduct an annual analysis of the effectiveness of the overall storm water pollution contra
management program in Carlsbad. If the water quality objectives of the receiving waters arc
Chapter 5
Page 50
Master Drainage and Storm Water Quality Management Pla
Carlsbad. California, March 199a
violated as a result of storm water/urban runoff discharges, then identify proposed programs
will result in the attainment of the water quality objectives, and a time schedule to impleme
new programs.
Testing and Mcmitoring of Storm Water and Urban Runoff
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A major task necessary to establish the Storm Water Quality Management Program is implemental
a program for the testing and monitoring of storm water flows. Testing and monitoring is necess
determine the type, quantity and characteristic of the pollutants within the various conveyance q
and within the receiving waters in the City. Testing should be conducted on dry weather flows to
illegal dumping or connection of non storm water into the conveyance system, and during storm
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 1
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 i
stathat theNorth County cities and the County of SanDiego join together via some form of coope
agreement to establish a coordinated testing and monitoring program for the North County dri
each of the individual cities and the County. As of this report date, the staffs fiom 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. Ofthe four basins only one, Encinas Creek, which parallels Palomar Airport Road and disc1
directly into the Pacific Ocean, is located entirely within the Carlsbad city liits. The other three
originate outside of Carlsbad and terminate at “lagoons” within Carlsbad prior to discharging in1
Pacific Ocean. In addition to the three “lagoons”, there is a fiesh water reservoir, knownasCalavera1
located along the north fork of Agua Hedionda Creek.
The term lagoon is used parenthetically above because in reality only Agua Hedionda Lagoon is SI
to tidal influences. Buena Vista Lagoon is a fiesh water reservoir Greated by the installation of i
structure near the discharge point at the ocean. Batiquitos Lagoon is a brackish water estuary esse]
closed to tidal influences except during major storm events, at which time the sand and cobble de
which block the outlet are washed away. Each of the lagoons, their tributary streams, Calavera Ld
the Pacific Ocean has different capabilities to absorb and handle storm water pollutants. In addition
of these bodies ofwater has different beneficial uses as defined in the various water quality control
and reports produced by the Regional Board. A listing ofthe beneficial uses is presented in Tables 5
basins. Such cooperation would produce greater consistency in the test data and result in lower c(
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5-2.
The testing and monitoring program would be conducted on dry weather flows and during storm e
The dry weather testing is used primarily to detect illicit connections and will be discussed in more
in SectionF ofthis Chapter. Themethodology for stormwater testing should beworked out in coope
Master Drainage and Storm Water Quality Management Plan ct
Carlsbed. California, March 1994 I
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with the other North County co-permittees and must be approved by the Regional Board. The Regioni
Board has indicated a willingness to consider a graduated testing program which begins at the receivh
water and progressesup streamuntil there are no hrther water quality violations. Given the limited amour
of rainfall in the North County the co-permittees may wish to select initial upstream test sites to mor
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 "DES co-permittees to develop a strategy for storm wate
testing, stream flow and raidall measurement, consultant selection and hiring, cost sharing anc
cooperative agreement if necessary.
2. Submit the strategy for storm water testing and monitoring to theRegionalBoard for approval
3. Finalize a cooperative agreement with other North County eo-permittees and submit fo
Council approval.
4. Prepare request for proposals from consulting fkms specializing in water quality testing an(
monitoring.
5. Form a committee of co-permittees to review proposals and make recommendation or
consultant selection.
6. Negotiate a contract with the selected consultant for the required testing and monitoring
program. Ver@ hnding sources and prepare an agenda bill for Council approval. Scope of work
should at a minimum include:
A) Research and review ofavailable records regarding previous water quality testing done
within the basins, existing stream gauging stations, rainfall stations, topographic mapping
of the basins, land use mapping, and hydrologic studies.
B) Prepare comprehensive topographic maps delineating each of the basin boundaries
which clearly identifl the major hydrologic features such as streams, lined and unlined
channels, major dams and retention structures, lakes and lagoons. Prepare land use overlay
maps at the same scale. The City of Carlsbad has the mapping data recommended by this
item.
C) Analyze the existing data and make recommendations on location of proposed new
stream gauges, rainfall measurement stations, and storm water test sites.
D) Upon City approval, obtain and install the necessary automatic flow samplers, flow
meters, rain gauges and other testing equipment.
E) Provide all technical support necessary to actuate and maintain the automatic samplers
and other test equipment during runoff producing rain storms.
Chapter 5
Page 52
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
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F) Accomplish the required testing and analysis with laboratories and uti II methods approved by the Regional Board.
G) Reduce and collate the data into report form acceptable to the Regional Board. 1
the type ,magnitude (concentration and mass load) and sources of pollutants in the
water system. Provide pollutographs or other suitable graphic representations of th
€3) Maintain full written records of all sampling and testing in accordance with Re
Board requirements. Provide City with copies of all reports, test data and field nc
I) Develop andor 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
need for hrther testing and proposed mitigation programs 1
7. Council approval of consultant contract.
8. Consultant implementation of testing program.
Master Drainage and Storm Water Quality Management Plan CI
Carlsbad, California, March 1994
Noneontact water recreation - fishin
Wildlife Habitat
Wildlife habitat
Preservation of rare and endangered species
Wildlife habitat
CALAVERASLAKE
Cold fresh water habitat
Preservation of rare and endangered species
Wildlife habitat
TABLE 5-1
Chapter 5
Page 54
Master Drainage and Storm Water Quality Management Plai
Carlsbad, California, March 1996
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II E Detection of Illicit coltmectians and Illegal Discharges
A major focus of the Regional Water Quality Control Board (Regional Board) and the EnviroIzl
Protection Agency @PA) has been placed on the detection of illicit connections and illegal discha
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. Ho1
the illegal discharge of wastes into storm conveyance systems does occur with considerable frequc
Carlsbad.
Sources of illegal discharges are numerous and varied. Significant waste contributions originate fic
stations and other automotive businesses that lack recycling systems, grease and oil separators, and
and discharged directly into storm drainage conveyance systems. Another source of illegal waste disl
results from improperly stored or disposed wastes at commercial and industrial facilities which are e?
to rainfall or storm water flows.
Not all illegal discharges originate from commercial or industrial uses. Individual residents frequent1
motor home holding tanks, radiator coolants, crankcase and other engine fluids into storm drains o
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sewer discharge systems. At many of these facilities, surfaces are washed down with degreasing
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994 C
hard surfaces whichultimately washinto stormdrains. In addition residents washout containers or direct
pour unused portions of pesticides, household cleaners, detergents, paints, solvents and other harmfi wastes into storm drains or onto surfaces which drain into storm drains. A recent study conducted in Sa
Diego indicated that 90% of the residents believed that storm drains flowed directly to the sewer plan
Carlsbad is required under the WDES permit to develop and implement a program to detect and elimina
illicit connections to storm drains and illegal discharges of non storm water wastes into storm watc
conveyance systems. A primary component of the program is field screening and testing of dry weathc
flows at storm drain discharge points for priority pollutants (commonly found pollutants which indica
illegal discharge may have occurred). Should any priority pollutants be found, a more detailed investigatio
would be conducted upstream of the test point to determine the source of the discharge.
It is proposed that initial testing be accomplished by an outside consulfig firm. Continued testing inhtur
years would be conducted by City staffwho would receive training ftom the consultant. The dry and wt
weather testing programs may be combined into one contract and conducted by the same consultan
however, this may not be practicable due to timing constraints and the need to coordinate the wet weathc
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 €tom qualified consultants.
2. Review submittals and select consultant.
3. Negotiate a contract for the required testing and detection program. Obtain fbnding source ani
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 Plan and Lanc
Use maps to determine appropriate test sites.
B) Field review pipe discharge points and perform appropriate tests in accordance Wit€
Regional Board requirements. Tests should generally be conducted at all discharge point!
for pipes 36 inches in diameter or greater where dry weather flows exist.
C) Mer initial field screening and testing is complete, plot test results on a City map
Prepare a strategy to conduct hrther testing or site visits to determine the source 01
pollution. Conduct the necessary secondary testing and field review to determine thc
source of the pollutant discharge.
D) Prepare a report which includes maps, field notes, test results and written opinion or,
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 two
or more City staffmembers in appropriate test methods and reporting requirements.
Chapter 5
Page 56
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
4. Once an illicit connection or illegal discharge has been discovered, City should beg
abatement process with the owner of the property in violation. Abatement should begin by M
notification to the owner of the property upon which the violation exists ident@ring the vi0
together with a request to cease and desist the discharge activity and to begin clean up mes
if appropriate. For violators with minimally toxic discharges a phased program of abatemen
be considered. Non responsive violators should be referred to City Council for initiati
abatement proceedings and possible legal action.
5. Develop a program of public education on the nature of storm drains and the hi
environmental effects which can result &om the improper use and disposal of common housc
yard and automotive products. Possible suggested elements of the program are as follow
A) Prepare a public information pamphlet explaining the problem, why it is import
Carlsbad and suggesting ways individuals can contribute to the solution. The pam
could be mailed to residents or made available at public information counters throu
the City.
B) Create a public service video on storm water quality issues for showing on local
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C) Develop a student awareness program within the local schools.
D) Create public awareness in storm drains by stenciling water birds, fish, turtles anc
on storm drain manhole covers. Such a program was used successfidly in a Washi
State community to raise the publics’s level of understanding regarding the conseq
of discharging hdl materials into the storm drain. Stenciling may be accomplis1
students as part of the student awareness program suggested above.
n
G. Best Management Practices (BMP)
The Water Quality Act requires municipalities to control discharges containing storm water polluti
the maximum extent practicable (MEP). Generally it has been held by the Environmental Prot
Agency that MEP means the use of Best Management Practices (BMP) for the control of pollutant:
approach was chosenin lieu ofamore stringent programbased on quantitative effluent limitations bc
there are no generally accepted effluent limits.
Best Management Practices include implementation of structural and non-structural controls. Stn
controls are physical improvements made to the storm water conveyance system which remove or I
storm water pollutant levels. Non-structural controls are programs and practices which tend to eh
or reduce pollutants at their source before they enter the storm water conveyance system. Table 5.
potential structural and non-structural controls which could be utilized in Carlsbad.
Althoughmany ofthe elements ofBMP have beeninuse in Carlsbad and other communities for many
the concept of an integrated program implementing BMP is new. To prevent propagation of nun
community standards regarding BMP, the State has budgeted hnds for the preparation of a stai
guidelines manual for Best Management Practices. When this manual becomes available, the City wi
to review the contents and incorporate all or portions of it into the City7s proposed Best Manag
Master Drainage and Storm Water Quality Management Plan CI
Carlsbad, California, March 1994
Practices program. The following is a brief discussion of some of the more important elements of BM
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. 1
has generally been found that preservation of natural streams and drainage courses enhance water qualit
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 littl
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 t,
be encouraged within the City. Additionally, Open Space policies should be reviewed to coordinate thc
needs of storm water pollution management with habitat preservation, aesthetics and other Open Spacc
needs. Naturalized channels and pollution management basins should be landscaped with native plan
species which balance the needs of fire suppression, habitat values, maintenance, aesthetics and pollutioi
absorption. Appropriate buffer zones should be maintained between lot lines and major storm wate
management features to enhance their pollution control value and to reduce potential negative impact
on adjacent development.
Other Land Use regulations which affect storm water quality and should be considered when preparini
pollutant loading; rezoning of property which is incompatible with the preservation ofwater quality; and
density reductions.
Maintenance and Operation
Good maintenance and operation ofthe storm water conveyance system is an essential component ofBesi
Management Practices. This includes the sweeping of streets and parking lots, removal of accumulatec
silt and debris &om inlets, pipes, channels and filtratioddesiltation basins, cleaning of grease and oil traps
and, other maintenance functions which generally remove or reduce pollutant loads before they can bc
discharged to the receiving waters. Carlsbad’s municipally owned storm drainage system is maintainea
by the Streets Division of the Utilities and Maintenance Department. Street sweeping activities arc
accomplished through private contract with the Oceanside Disposal Company.
Maintenance fbnctions need to be reviewed to assure maximum effectiveness for pollutant removal. Streei
sweeping schedules should be accelerated prior to predicted storm events which occur after long dq
periods. Since oil and grease bind to fine particulate materials, new street sweeping equipment whick
captures these fine particles are to be investigated and utilized when practicable. Desiltation basins and
other urban pollutant facilities should be designed to accommodate necessary maintenance activities in
both dry and wet weather.
Maintenance of privately owned storm drainage and pollutant control facilities is also important for the
overall control and reduction of storm water pollutants. Adequate provisions should be included within
the various homeowners associations to properly maintain private facilities and to assure that adequate
funds are available for maintenance.
the BMP manual are : zone code enforcement to elirmnate unauthorized uses which may contribute tc
Chapter 5
Page 58
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Carlsbad. California. March 1994
Private Development Restrictions and Conditions
State laws regarding the conditioning of subdivisions and other land development projects CUI
provide the City with sufficient latitude to restrict andor condition developments to comply with thc
Program. In addition, the Catiforria Environmentd Quality Act (CEQA) provides added autho
require pollutant mitigation measures together with monitoring programs designed to evalua
effectiveness of the installed mitigation. AU new development projects within Carlsbad shoi
conditioned to comply with currently established BMP as well as any new BMP established p
issuance of the respective building permits.
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I Construction Sites
Construction activities generate numerous types of pollutants detrimental to water quality such as
and diesel oils, hydraulic fluids, paints and solvents, herbicides and, fertilizers; however, tht
si@cant pollutant originating fiomconstruction sites is soil. In small quantities soil does not impai~
quality or degrade riparian habitat. In fact soil deposition is anatural process vital to the long term si
of marine and riparian habitats. However, soil loss at construction sites can signrficantly exceed I
levels and overwhelm both habitats and drainage facilities located downstream. Excessive sedimei
can clog vital storm drains, disturb natural streamflows, suffocate bottom dwelling plants and anima
create impediments to boating in the lagoon areas. In the long term, excessive sedimentatk
prematurely impair the vitality of water based habitats as exemplified by the Batiquitos Lagoon.
Carlsbad has exhibited a strong commitment to reduce construction site sedimentationin order to PI
its lagoons and riparian habitats. The 1980 Drainage Master Plan included a model erosion c
ordinance which formed the basis of the subsequent erosion control program within the City. Dur
past eleven years, substantial advancements in erosion control methods and practices have occurr
been incorporated into the City’s Engineering Standards and Inspection Manuals. These erosion c
methods and practices should be reviewed and consolidated into the proposed comprehensive ma
BMP for the City.
Waste Minimization Collection and Recvclinq
A key feature of Best Management Practices is to eliminate the source of environmental pollutanl
their introduction into the drainage system. To this end, the City and other agencies are being encoi
by the Regional Board to establish effective programs for the reduction of waste, collection of cc
household hazardous wastes and recycling ofmotor oils. The City has implemented many aspects c
programs and is in the process of expanding their role in this regard. Several times a year the City I
the subject ofwaste collection, reduction and recycling are available at public offices throughout tE
In the fiture, the City will need to expand the circulation of the handouts and to establish convenie
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 conductec
Engineering InspectionDivision with regard to land development and construction activities and, t
Department with regard to hazardous waste storage, disposal and cleanup. Enforcement of:
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
residents and establishes local collection points for household hazardous wastes. Numerous hand(
C
violations and homeowner associationmaintenance requirements are carried out ona complaint basis onl~
The City does not presently have an effective program to reduce or prevent the illegal dumping an
discharge of prohibited materials from sources such as automotive wrecking and repair facilities, ga
stations, industrial facilities, recreational vehicle holdmg tanks or home mechanics.
No policy, condition, facility or standard will properly control storm water pollution without effectiv
complianceand enforcement. A key component ofBest Management Practicesis to obtainthe cooperatio
of individuals, companies, homeowners associations, developers, departments and others in complyin
withBest Management Practices. In addition, appropriate'city stafFmust be assigned and properly traine to enforce those elements ofBest Management Practices required by Municipal Code, City Standards an
conditions of approval.
The City will need to carefully review the enforcement requirements and stafEng levels necessary tc
comply with the proposed Best Management Practices program to be submitted to the Regional Boarc
as part of the "DES permit.
Chapter 5 Page 60
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
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Land Use Restrictions - Zone Code Enforcement - Density Reduction - Compatible Zoning - Buffer Areas
H. Program Costs and Ftmding
The full cost to implement the Storm Water Quality Management Program is not known at this tic
however, the major capital costs of the program have been estimated and are included in the propose
drainage fee structure. This includes costs for 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 1 millio
dollars and for the test equipment $900,000.00. A more complete breakdown of these cost estimates
included within Appendix C of this report.
Funding for non-capital elements of the Storm Water Quality Management Program will come fro1
sources other than Planned Local Drainage Area fees. The proposed Fiscal Year 9 1-92 budget for the Cil
includes $30,000 in General Fund monies for program implementation to be used primarily to fun
consultant contracts to perform testing and monitoring functions. This figure may increase significant1
in fiture years depending upon the testing requirements imposed by the Regional Board.
In addition to testing and monitoring, General Fund monies will be expended for staff time spent 01
program development, enforcement activities and administration. Other program costs such as implemen
tation of erosion control measures and construction of localized filtration and sedimentation basins wil
be funded directly by developers. Ifneeded, low interest loans and grant monies are available from the Stat1
Water Resources Control Board for non point source pollution control facilities.
A significant program cost which has received little attention in the past but will increase in importanc~
as a result of this program is the maintenance and operation of storm drainage facilities. This is especie
true for inlet structures, filtration basins and sedimentation basins. Without proper maintenance
accumulated silts and debris can reduce the effectiveness ofpollutant control hcilities or be washed dow
the drainage system and degrade surface and/or receiving waters. Presently, drainage maintenancl
hctions within the City are almost completely finded fiom General Fund monies. A small portion of thl
drainage maintenance budget is derived through a special Drainage Maintenance District formed i~
cooperation with adjacent property owners for the maintenance of the Buena Vista Creek Channe
between El Camino Real and Jefferson Street.
The City may wish to investigate alternatives to General Fund financing of the drainage maintenanct
operations. Alternative financing mechanisms would fiee General Fund monies for other City uses anc
provide a stable source of funds for continued maintenance operations. Two alternative sources of &nd$
which deserve careful consideration are:
1) To form a Drainage Utility and establish a monthly service charge similar to the charges paic
for water and sewer service; and,
2) To establish a citywide drainage maintenance district and assess maintenance fees similar tc
the City’s Street Light and Landscape Maintenance District.
Both alternatives place the financial burden for drainage facility maintenance directly upon the users oi
the system. Each alternative requires that a rate structure be established which equitably distributes costs
based upon the demand created by the use of the property. Generally the rate structure would be based
Chapter 5
Page 62 Master Drainage and Storm Water Quality Management Plar
Carlsbad, California, March 1994
upon current land use, acreage and amount of impermeable surfacing (usually reflected as an avers<
the property’s zoning designation). In each case a mechanism to review individual charges upbn prc
owner appeal would need to be established. The following is a brief discussion of each of th(
alternatives.
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Drainage Maintenance District
The City may form a drainage maintenance district pursuant to the Benefit Assessment Act of
(Government Code Sections 54703 - 54719). A maintenance district formed under this act may ir
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 simple ml
vote of the voters included within the proposed district. Assessments would be collected on the prc
owners tax bill in the same manner as the existing Street Light and Landscape Maintenance Distrid
method avoids the need to establisha new billing mechanism or to include additional costs on existing
bills.
Drainage maintenance districts may impose a benefit assessment to finance maintenance and opera1
the drainage conveyance system, including storm water monitoring, as well as the cost for installatic
improvement of facilities. Given that the proposed Planned Local Drainage Area Fees will han
construction of new and upgraded facilities the City would need only to finance the maintenant
operation costs for the foreseeable future. In later years, replacement costs for aging facilities n I factored into the assessment.
Drainage Utility
Alternative fbnding for drainage maintenance and storm water monitoring may be provided throu
formation of a Drainage Utility. ADrainage Utility would finction 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 fbnctions as F
installation of new facilities, upgrades or replacement facilities. A disadvantage of this method is tl
City would be required to establish a new billing system or include the fee within the existing water
system. Inclusion of the fee on the existing water bills would be impractical given that the City
District does not cover the entire City. For areas within the City that are outside the City Water C
boundaries a separate billing system would still be required.
Master Drainage and Storm Water Quality Management Plan . CI
Carlabad, California, March 1994 I
Chapter 5
Page 64
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
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C-R 6
COST-m
A General
In this section, the basis of the unit prices used for the construction cost estimates are developc
presented. Theseunit prices provide ameans ofbudgeting for proposed improvement projects, com alternative projects and for developing drainage assessment fees for proposed Planned Local Dr
(PLD) ARM. Except in the cue Of dhientation basins, land costs are not included in cost escu
since all right of way containing Master Drainage Plan facilities shall be dedicated to the City.
B. UdtC0st.s
The unit costs used in this study are presented in the following tables. Sources of information f
development of these costs include local contractors, material suppliers, data fiom professional jo
and local municipality bonding estimate costs.
c. Additidcosts
To accommodate the additional costs of field construction contingencies, engineering fees, legal fec
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 Tat
1 through 6-4 thereby obtaining the drainage facility totals given in this report.
Construction Contingencies
An allowance for construction contingencies is made for unavoidable uncertainties in the project d
Items suchas conflictswithexistingunderground utilities and variationsin depthsofpipelines may inc
construction costs and should be planned for. A contingency allowance of 15% was assumed fc
report.
Engineering Fees
Some ofthe costs included in the engineering of construction projects are special site investigations
surveys, preparation of construction plans and specifications, special site investigations, and mat
testing. For this report, engineering fees were assumed to be 10% of the construction costs.
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Master Drainage and Storm Water Quality Management Ran Ch
Carlsbad. California, March 1994 P
D. ConsMcm Item Cost Estimates
The following section presents the construction item cost estimates utilized in the preparation of th
construction costs for the facilities 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 based on a value of 100 in 19 13. The index has steadil
increased since 1913, with a current value of 6348.44 for Los Angeles in January, 1993.
S tom Drain Piping
Included in the prices for drainage pipe are excavation, shoring, bedding, pipe installation, backfil
compaction and site clean-up. The costs for pipe diameters 30" through48" assume a mean installed dept
of 8 feet. The costs for pipe diameters 60" through 96" assume a mean installed depth of 13 feet. AU pip
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 achiev
a slope giving a design flow rate less than 6 feet per second was estimated. Using Manning's equatio
for channel flow velocity in typical sections, it was noted that for Q > 150 Cfs, a slope of less than 0.01
fpf was necessary to achieve velocities of 5 as. Therefore the number of drop structures in any give
channel was determined by the following formula.
no, of drop structures = L[S-.Ol]
2
where:
L = length of the channel in feet
S = slope of the channel in feedfoot
The length ofeach drop structure was based upon typical channel sections and associated Q,, values. Thi
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 cutoj
wall and rip rap extending five feet out from the base of the wall. An additional twenty percent was include
in the estimate to cover 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. Th
costing procedure for enhanced natural channels was used.
Chapter 6
Page 66
Master Drainage and Storm Water Quality Management PIS
Carisbad, California, March 199
Open Channels
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 qua
was reduced by 20% to account for the existing natural channel condition. For channels in river bi
stream beds, calculated excavation quantity was reduced by 50%. In “undeveloped” areas wil
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
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per square foot. The rip rap runs Born the top of the Ghannel to 2 feet below the ~hmd bottom
For both concrete and earthen channels, chain link fence (on both sides of the channel) was esth
$25 per lineal foot. For all channels a 12 foot wide decomposed granite access road was estimated at
per lineal foot ofchannel. Concrete channel costs include a four inch concrete lining cost of $225 pel
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 q
costs were assumed at $5.50 per cubic yard. Excavation quantities were based on vertical trend
for the lower 5 feet and 1: 1 side slope to daylight points. The bottom of the trench was assumec
2 feet wider than exterior box dimensions. A 15% allowance was added for miscellaneous appurten
Structural concrete costs included bedding, formwork, steelwork and site clean up and were esti
at $525 per cubic yard. Repaving cost was based on a repaving width equal to the excavation wid1
4 feet. New pavement section was 4 inches of A.C. over 12 inches of aggregate base. 1 Catch Basins
Unit prices of $7,040.00 for catch basins assume a 14 foot curb inlet opening and includes an 18 i
30 foot long R.C.P. lateral and a concrete lug-in at the main line. The number of catch basins for anj
line was based upon the hydrologic flow rate (Q) of the area through which the proposed storm dri passes. If more than one line passes through a basin, the Q of that basin is apportioned to ear
proportionally by length. A flow rate into each of 0.5 cfs per lineal foot of curb inlet opening is ass I Cleanouts
1 Unit pricesfor 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.
Junction Structures
Unit prices for junction structures are based on a modified type D-9 cleanout, $3,750.00 is used fi
junction structure.
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8 Master Drainage and Storm Water Quality Management Wan
Carlsbad, California, March 1994
C
Sedimentation Basins
A unit price for each sedimentation basin was calculated as a lump sum based on typical design feature
shown in Figure 8.1 of “The Erosion and Sediment Control Handbook”1.
The channel (ifany) into and out of the basin was assumed to be lined with 4“ thick concrete at $520.0
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 wit
one to one side slopes. At the entrance, 50 lineal feet of lining was used and 75 lineal feet at the outlei
Smaller channel entrances were assumed to be 20 feet wide by 8 feet high and 30 feet long with one tl
one side slopes.
Basin shape was estimated to be eight times as long as wide. As recommended by Goldman et. al., onc
baf€le was estimated for each basin not in a major channel. The baffle was estimated to be equal in lengtl
to one halfofthe basin width. Its height is that ofthe outlet riser crest. Eight baffles ofthe same size werc
estimated for major channels in order to increase the ef€ective basin area in these locations where availabk
land is the factor limiting sediment removal efficiency. The Carlsbad unit price of $550 per cubic yard fo
a cast in place wall 8 inches thick (12 inches thick for major channels) was used for these baflles.
The City of Carlsbad gradmg unit price ($3.50 per cubic yard of embankment or excavation) was usec
to calculate the earthwork cost for each basin. This volume was estimated to be approximately threi
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 running the
length of the basin for each outlet was estimated at $20.00 per lineal foot. Where outlet RCP sized 48
inches and greater was required, 12 inch perforated PVC pipe in a trench surrounded by 8 inches of gravel
at $35.00 per lineal foot was used. Weighted standpipe drainage structures were estimated at $l,OOO.OC
each for tributary basins and $3,500.00 each for outlet pipe sizes 48 inches or greater in diameter
Reinforced concrete pipe draining these structures was sized to pass the 100 year storm excepting those
in major channels which were sized to pass the ten year storm. A fifty foot minimum length for each pipe
was used. Two antiseep collars were estimated at $4,000.00 for each RCP outlet less than 48 inches in
diameter. For RCP outlets 48 inches or greater in diameter, each pair was estimated at $5,000.00.
Emergency weir spillway cost was estimated by using the unit cost for 4 inch drainage channel concretc
for a weir 20 feet wide (30 feet wide in major channels) and a length such that the design flow is able tc
flow over a 2.5 foot high weir (5 foot high in major channels and basins with a design Q greater than 200C
cfs). Rip rap was used for the first 20 lineal feet of tributary outlet channel. For major channels 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.
It should be recognized that sedimentation basin sizes are first approximations only. At the time of final
Chapter 8
page t3a Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
design, soil composition should be determined by field testing. It will then be possible to reliably (
basins with sediment removal efficiencies in accordance with City of Carlsbad Design Stanr
However, only those items included in sedimentation basin cost estimates which are dependant on
surface area would be expected to fluctuate greatly with soil composition. These items are peri
fencing, perforated drain pipe with gravel and land costs.
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.Fa pipe di- 30" throueh 48", a mcm depth of pipe = fJ was SllRllllCd
.For pipe di.mctcn 60" through W", a nuan dcpth ofpipc = 13'- d
TABLE 6-1
Master Drainage and Storm Water Quality Management Plan C Carlsbad, California, March 1994
4 12x4 4898 165.00
1 12x5 5-84 52.00
3 12x8 44799 250.00
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2.5
ulllt cost - cooae.te Lii Cba0ne-b
2 D Existing
Condition Cort/L.F.
1 3 CHN” 52.70 I 2.5 2.5 1 I 1 1 I 3 3 I CYN* FLT l I 54.60 55.90
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3 I 2 I 3 I FL?# I 92.00
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4 1 .s I 4 I CHN 1 108.50
4 1.5 4 CYN 112.40
4 1.5 4 FLT 115.70
6 1 .s 5 CHN 123.60
I 6 6 I 1 1.5 .s I 5 5 I CYN FLT 1 130.56 137.20
8’ 1.5 6 CHN 140.40
8 1 .s 8 CYN 148.60
I 8 I 1.5 ,I 6 ! FLT 1 156.70
B = Bottom width in feet. cm= m unyoa
.z * si slop ntion FLT = Exihg~condition i flat
D=Dqtthiatwt tXN=JlXihgouthcacbmrsl
l NO - mad a faoce
TABLE 6-4
B
2.5
2.5
2.5
udt ,cat - cmaete Ihal ChMneb
2 D Existing C0stlL.P. Condition
1 3 CHN l 62.70
1 3 CYN * 54.60
1 3 FLT* 55.90
2 1, I FLT* I 92.00 II.
I 4 I 1.5 I 4 I CHN I 106.60 11
B = Bottan width in feat’ CYN = Bxirtineeanyon
z = si rlopc ratio0 FLT = Fhistbg conditioa is sat
D-Dq&infat CWN= EtxidogawtlKaclMOnOl
TABLE 6-5
Meatsr Drainage and Storm Water Quality Management Plan Chapter 6 Cadsbad, California. March 1994 Page 71
Pipe p9” 2000.00/ea
Pipe -X2” 2 500 .OO/ea
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Costs Attributable to Potential
costs* PLDA Facility Exisb;ng Recoverable Facil Costs Attributable to
NewDevelopment 14evelopment
Total
Cost
A $3,022,945 $1,383,893 $1,639,053 $1,711,704
B $21,256,416 $1 5,480,973 $5,775,443 $1 6,636,061
C $3,989,850 $3,580,514 $409,336 $3,662,381
D $14,603,823 $13,801,948 $801,875 $1 3,962,321
Totals $42,873,034 $34,247,328 $8,625,707 $35,972,46$
Chapter 6
Page 74
Master Drainage and Storm Water Quality Management Plan
Carlsbed. California, March 1994
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SuMIs.IARY OF FIELD I"IGATI0NS
A. htrodwtion
Before making recommendations for drainage improvements a field investigation was conducted
goal of this investigation was to document conditions and problems associated with existing storm
structures. Plans of existing storm drain structures were obtained firom the City of Carlsbad, adjl
city and Caltrans records. Drainage facilities were plotted on worksheets in order to determine the lo
of major drainage lines. These existing drainage facilities and SUKOWI~~~ conditions were invest
during the months of October, November and December of 1988. Caltrans and adjoining city plan
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 ver@ slope, invert elevations and outlet elevations. Instead 1 - Cooper vedied the location of the storm drain facility as shown on record improvement piax
examined their condition.
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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 inill
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 delivered
City of Carlsbad in December of 1988.
Facilities were found to be in generally good condition. Some, however, were poorly maintained
effectiveness hindered by vegetation overgrowth, siltation andor pondmg. Some structures are in d
due to erosion.
B. Buena Vista Creek Basin
Drainage structures in the Buena Vista CreekBasin showing evidence ofvegetation overgrowth, si1
or pondmg are seen in photograph numbers 8,9,10,11,18,26,27,28,30,3 1,32,34,35,39,40 a
of the Buena Vista creek section of Album 1. Damage or potential damage from erosion can be SI
photographs number 1, 14 and 25.
Some storm drain lines such as line AC are incomplete and need improvements discussed in other sei
of this report. The current conditions ofline AC are shown in pictures 12,13 and 14 of the Buena
Creek section of Album 1. Vandalism can influence the effectiveness of storm drain lines as can bc
in picture number 42.
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Master Drainage and Storm Water Quality Management Plan Ch
Carlsbad, California, March 1994 P
C. Agua Hedionda Creek Bash
Drainage structures in the Agua Hedionda Creek basin showing evidence of vegetation overgrowtl
siltation or ponding are seen in picture numbers 8, 10, 11, 12, 15, 16, 19,20,27,28,29,30, 3 1,34,3!
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, 69,7(
71, 72,73, 74,76, 80, 81, 82, 82,, 84, 85, 89, 95, 96, 97, 98,99 and 100 of the Agua Hedionda Cree
Basin section of Album 1. Damage or potential damage fiom erosion can be seen in pictures 6 and 11
Obstruction due to littering can be seen in photographs 13,33 and 70.
D. Enchas CreekBasin
Drainage structures in the Encinas Creek Basin showing evidence of vegetation overgrowth, siltation c
ponding are seen in photograph numbers 4, 13,22,23,27,3 1,33,39,44,46,47,50,54 and 55 of th Encinas Creek section ofAlbum 2. Incomplete construction can be seen in photographs 1 and 5. Damag
or potential damage fiom erosion can be seen in photographs 2,3, 11 and 16.
E. San Marc- Creek Basin
Drainage Structures in the San Marcos CreekBasin showing evidence ofvegetation overgrowth, siltatio
or ponding are seen in photograph numbers 2,5,8,9, 11, 14, 15, 18, 19,, 20,21,22,24,25,27,29,3~
34,35,36,37,38,39,47and48oftheSanMarcosCreekportionofAlbum2, Damageorpotentialdamag
fiom erosion can be seen in photographs 12, 17 and 23. Obstruction due to littering can be seen i
photographs 3 and 30.
E Findings
In summary, the field investigation located many areas of vegetation overgrowth, siltation and pondmg
These areas can be seen in the photographs accompanying this document. Areas of erosion damage a
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 wer
damaged, covered by vegetation and filled with silt were documented by the photographs submitted ti
the City of Carlsbad in December of 1988. It is recommended that the City of Carlsbad clean silted pipe5
trim brush and repair damaged storm drain facilities.
Chapter 7
Page 76 Master Drainage and Storm Water Quality Management Pla
Carlsbad, California, March 199
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APPENDlXA
PROPOSED DWAGE 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 ri
Intensity-Duration Design (I-D-D) Chart was used for this study. The original I-D-F (Intensity-Dur
Frequency) curves (developed in about 1965) were based on extremely limited data fiom the San
National Weather Service (NWS) and the Mount Laguna rain gauges. The new I-D-D Chart is ba
up-to-date precipitation data and statistical analysis which makes the results much more reliab
consistent with Federal and State studies and reports. The I-D-D Chart is applicable to short du
hydrology procedures such as the rational method.
Since the City of Carlsbad desires that natural channels in canyon areas remain as natural as PO
the flow velocity to less than 6 feet per second. However, ifchannel areas having a design flow v(
of greater than 6 feet per second are located in areas zoned open space, the cost of potential remedia
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.
“enhanced natural channels” are proposed in these areas when drop structures are necessary to r(
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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. Ifcomputations indicate a new replacement pipeline size is more than 6 inches in diameter largc
the existing facility& the additional capacity can be conveyed in the street, no improvements are d
necessary.
3. If computations indicate a new replacement pipeline size is more than 6 inches in diameter largc
the existing facility and the additional capacity cannot be conveyed in the street, the required improw
are shown on the maps as the new size required. Cost estimates generally reflect the construction (
facilities to replace the existing undersized facilities. However, in some locations, a parallel pipe
existing pipe lie may be provided. In these cases cost estimates reflect the construction of these 1
lines. Generally, where existing pipeline diameters are 48 inches and larger, new parallel pipeh
considered to be most likely and hence are shown on the maps. For smaller existing pipelines, replac
with larger diameter is considered more feasible. In all cases, whether shown as replacing existin
larger sizes or providing parallel pipelines to secure the additional capacity, the final determinatio
the most cost effective method should be left to a detailed analysis during final design.
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994 API
4. Other alternatives to reducing peak flows and hence reducing size ofnew facilities include on-site ston
detention facilities. These should be evaluated on a case by case basis during detailed design,
B. Buena Vista Creek Basin
PacfLityA
Sedimentation Basin A1 is proposed along Buena Vista Creek in the vicinity of the South Coast Aspha
Plant as recommended by the Buena Vista Lagoon Sediment Control Plan prepared by June Applegat
and Associates in September of 1985 and adopted by the City of Carlsbad. Preliminary estimates c
sedimentation basin size are based on approximations of available land only. The second basi
recommended within the Buena Vista Creek just east of Jefferson Street was excluded due to limitatioi
in available land and environmental considerations.
FadlicyAA
This is an extension eastward along Carlsbad Village Drive fiom the end of the existing Central Busines
storm drain system. This 30" RCP line will connect to an existing 24" RCP line which ends at Jefferso
Street. This system receives drainage originating east ofhterstate 5 and connects to the Central Busines,
District stom drain line becoming 36" RCP for the last 200 feet. The sizes used for this line are &-om Cie
approved plans.
FadlityAAA
Drainage facilities are needed for the residential areas north of Laguna Drive west of Interstate 5 whid
drain into the down line end of the Central Business District storm drain system. New 33 It RCP is needec
along Jefferson Street and existing 24" and 30" RCP along Laguna Drive should be upgraded to 45" RCI
as indicated on plans.
FadlltyAAAA
This 24" RCP line is smaller than the standard 30" minimum otherwise used as the lower limit of facilities
in this study. It is needed to carry drainage north to Laguna Drive along Monroe Street correcting local
ponding conditions.
FadlityAC
Along the northernmost section of Highland Drive in a residential area, 36" RCP is required to route
drainage to an existing AC channel in an area zoned open space.
Appendix A
Page 78
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
FdQAD
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Two portions of existing storm drain lines in Monroe and Canyon Street residential areas shoi
upgraded to conform to current standards, Smce streets are unable to carry the remainder of the dr;
flow. These portions are shown in the plans. The currently disconnected sedimentation basin
southwest comer 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.
FadlityAFA
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.
FadlityAFB
A natural channel carries drainage through an area designated as open space to a proposed sedimen
basin facility. From this facility northwest to Buena Vista Creek, potential remedial work ha!
estimated where natural channel velocities exceed 6 feet per second.
FadlityAG
This facility will carry drainage under the future College Boulevard from proposed developm
Calavera Hills. The drainage facility will extend approximately 600 feet into Oceanside and conne
an existing storm drain which discharges into Buena Vista Creek.
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C, Agua Hedicmda Creek Basin I: FadlityBA
I In the commercially zoned area north ofpalomar Airport Road adjacent to Interstate 5, one 27" RC
should be upsized to 45".
FadlityBAA
New facilities begin with a double 66" RCP culvert (or box equivalent) conveying drainage under t!
& SF Railroad tracks to Cannon Lake. The existing 30" DIP is inadequate, and the area is currently p
drained. The line continues north of Cannon Lake with a 51" RCP parallel to an existing undei
66"RCP.
FadlityBB
This facility begins at the intersection of Pine Avenue and Hardmg Street and receives drainage
residential areas east ofhterstate 5. New 30" RCP is proposed north along Harding Street, then42'
west along Oak Street to Roosevelt Street. New 5 1" RCP is required from this point west along Oak!
to discharge into what is currently an earthen channel parallel to the AT & SF Railroad. This a
Master Drainage and Storm Water Quality Management Plan APPt Carlsbad, California, March 1994 P
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channel which has only 0.1% slope is unable to carry drainage flow and should be replaced by undergrounl
drainage facilities. A reinforced concrete box of increasing size is shown on the plans. The existing 63
RCP at the southern (downstream) end of the eastern channel is undersized. A parallel 72" is require(
to carry drainage as shown.
Alternatively, the 63" RCP as well as downline 72" RCP could be removed. The discharge point of thi
line could be lower. A replacement line would then have signtficantly greater slope and could be a smalle
size. This alternative should be examined for the entire line at the time of detailed design.
FadUtyBBA
This 30" RCP along Chinquapin Avenue in a residential area is needed to carry drainage west ofhterstat
5 to the improvements of line BB.
FadUty BBB
This line through a residential neighborhood currently consists of 24", 27" and 30" RCP which shoulc
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.
FadUtyBBC
This 30" RCP in a residential neighborhood is needed to carry drainage originating east of Interstate 5
west and north along Palm and Madison Streets to line BBB at Chestnut Avenue. Along Madison Stred
this line replaces an existing 18" RCP line.
FadlityBC
This facility extends fiom Sandalwood Lane south to Park Drive before discharging to Agua Hediond,
Lagoon. The facility was constructed in FY 89-90. Due to a shortfall in drainage area fee fbnds the ciq
borrowed $300,000 fiom the General Fund to be repaid fiom drainage area fees. This amount is includec
in the cost estimate for reimbursement of the General Fund.
FadlityBCA
This 24" RCP line collects drainage from the residential areas surrounding Park Drive and Tamaracl
Avenue directing flow to James Drive where this line connects to facility BC. This facility is necessq
to correct local pondmg and flooding conditions.
FadUty BCB
This facility extends fiom the James Drive storm drain east along Magnolia Avenue to Valley Street. Thc
facility will be extended by adjacent land development to drain low areas ofvalley Street north OfMagnOlii
Street.
Appendix A
Page 80
Master Drainage and Storm Water Quality Management Plai
Carisbad, California, March 199r
Facility BCC
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This facility extends &urn the James Drive storm drain east along Chestnut Avenue to Valley Stree
facility is needed to accommodate drainage flows which presently flood portions of Chestnut A I during storm events.
FadlityBD
Currently, positive drainage does not exist fiom the end ofthe existing line. The existing condition in siltation and cattail overgrowth and can be seen in photograph 26 of Album 1. Sedimentation ba!
is proposed to decrease the deposition of silt into Agua Hedionda Lagoon.
FadlityBE
The improvements contemplated in this area ofMarcario Canyon consist ofremedial work to enhm
natural channel by provision of drop structures and other features to reduce erosive drainage fla
FadlityBEA
Natural channel velocities exceed 6 feet per second in this open space zoned area near Agua Hec
Lagoon. The cost of potential remedial work has been estimated.
FacilityBF
North of Tamarack Avenue immediately east of Sierra Morena Avenue, where channel velocities e
6 feet per second, an enhanced natural channel has been proposed. Drainage from existing resic
development storm drains north of Tamarack Avenue and east of El Camino Real currently disc1
into an open field south of Tamarack Avenue and west of El Camho Real. New 75" RCP is pro
to cany drainage water south to proposed sedimentation basin BF immediately north of El Camino
The size of this basin was estimated omitting the amount of suspended soil material calculated
draining into the existing sedimentation basin at PontiacDrive and Tamarack Avenue. Drainage then
in a proposed double 8' x 4' RCB under El Camino Real.
Special Note: The proposed 75" RCP east ofEl Camino Real may be replaced with an enhanced n
channel to mitigate riparian loss and to accommodate Habitat Management Plan goals. This deci,
to be made at time of development application.
Facility BFA
This 42" RCP line south of El Camino Real is proposed to carry drainage from an area designatr
residential development north and west to the concrete channel of facility BF south of sedimentation
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Master Drainage and Storm Water Quality Management Plan APP4
Carlsbad, California, March 1994 P
Facility BFB
North of Tamarack Avenue immediately east of El Camino Real, where channel velocities exceed 6 fet
per second, an enhanced natural channel has been proposed. Drainage east and west of El Camino Re: fiom Chestnut to Tamarack currently drains into an earthen channel and undeveloped lot at the southern
corner of El Camino Real and Tamarack Avenue. A 48" RCP pipe is proposed to route this water to lin
BF north of sedimentation basin BF1.
FadIiVBG
This proposed faciity will carry drainage fiom fbture development areas located along the west side t
El Camino Real opposite the Rancho Carlsbad Mobile Home Park.
FadIiWBH
These 36", 57" and 72" RCP lines are proposed to carry drainage fiom an area designated for residenti;
development south and west of Carlsbad Wage Drive and future College Boulevard south to Agu
Hedionda Creek just north El Camino Real and future Cannon Road. The .facilities include a 10,600 cubi
yard sedimentation basin just prior to discharge into Agua Hedionda Creek.
FacilityBJ
This line travels along fbture Cannon Road through an area zoned for residential development. It begin
at the City of Carlsbad boundary and carries water fiom existing lines in the City of Oceanside's Leisur
Village south and west to Agua Hedionda Creek just west of Rancho Carlsbad Mobile Home Park. I
begins as large (63 'I and 66'9 RCP and becomes an enhanced natural channel as it is joined by various branc
lines. A sedimentation basin is proposed immediately upstream of Rancho Carlsbad Mobile Park. Fro1
this point, an 80 foot wide earthen channel is proposed to carry drainage to Agua Hedionda Creek. Th
City of Carlsbad does not choose to construct a narrower concrete channel in this area. It is possible thz
detailed design studies using other methods could determine a narrower section for this earthen channe
FacilityBJA
This is a 33" RCP line carrying drainage along the kture College Boulevard to the enhanced naturs
channel of line BJ.
FacilityBJB
An enhanced natural channel carries drainage through a portion of an area designated for residentiz
development to a proposed sedimentation basin northeast of hture CannonRoad and College Boulevard
This proposed sedimentation basin drains into an earthen channel of line BJ.
Facilities BJBA, aTBB &BJBC
Potential remedial work has been estimated in these open space zoned areas south of CalaveraLake wher
natural channel flow velocities exceed 6 feet per second.
Appendix A
Page 82
Master Drainage and Storm Water Quality Management Pla
Carlsbad, California, March 199
FacilityBJC
These 33 '' and 42" RCP lines carry drainage through an area designated for residential developrr
the enhanced natural channel of line BJ.
FadlltyBJD
This enhanced natural channel canies drainage originating in the City of Oceanside west through 2
designated for residential development to the upstream end of the enhanGed naturd Ghannel of li!
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This line carries drainage fiom south and east of El Camino Real and College Boulevard north acr
Camino Real and through areas designated for commercial and residential development to Agua Ha
Creek. This is a new storm drain line except that one segment of existing 54" RCP should be par,
by new 57" RCP, and the existing 60" RCP under El Camino Real should be replaced by 78" RC
parallel pipe to codorm to current standards. The 60" RCP through the Carlsbad Research Center (
is currently guaranteed for construction as a condition of the CRC project. Credits and fees for tl
were accounted for at time of Final Map approval for CRC Unit 5. The cost estimate for this 1
kcludes provision for a potential bridge structure on College Boulevard across Agua Hedionda (
The need for a bridge structure versus a box culvert will be determined at the time of development app
FacilityBM
An enhanced natural channel is proposed to carry drainage through an area designated for resic
development to Agua Hedionda Creek. Within this channel, there currently exists a lake whic
expected will remain for scenic or recreational purposes.
FadlityBP
This is a long (7330') natural channel carrying City of Oceanside drainage from the city boundary
fbture Cannon Road and receiving additional drainage f?om areas designated for or currently bi
industrial park developments. Since most ofthe area containing this channel is zoned open space, th
of potential remedial work is estimated where design storm velocities exceed 6 feet per secon
sedimentation basin is proposed upstream of Agua Hedionda Creek in an area zoned for industria
development. The cost estimate for this facility includes provision for a potential bridge strum
Faraday Road across Agua Hedionda Creek. The need for a bridge will be determined at ti
development approval.
Facility BPA
This enhanced natural channel connects existing industrial park drainage facilities to natural channt
m
I Facility BPB
These proposed 36" and 45" RCP lines run through an area designated for industrial park develof
and empty into natural channel BP.
Master Drainage and Storm Water Quality Management Plan Aiw
Carlsbad, California, March 1994 P
FacilityBPC
Storm water attenuation is required to bring existing 36" RCP lines into conformity with current desig
standards. A proposed brow ditch, directs the discharge of this industrial park line into natural cham
BP.
Fadlity BPD
Storm water attenuation is required to bring existing 24" and 30" RCP industrial park storm drains inti
conformity with current design standards. An enhanced natural lined channel is also proposed to connec
outflow fiom an existing sedimentation basin to natural channel BP.
Facility BPDA
Storm water attenuation is required to bring an existing 42'' RCP industrial park storm drain int
conformity with current design standards.
Fadlity BPDB
Storm water attenuation is required to bring an existing 48" RCP line in an industrial park into conformit
with current design standards.
Fadltty BQ
Potential remedial work was estimated in this area zoned open space where channel velocities exceed
feet per second.
D. Encinas CreekBasin
FacilityC
This proposed facilitywill complete the major drainage system in the Encinas Basin. The proposed channr
and enhanced natural channel connects the existing 12' x 8' RCB west ofPalomar Oaks Way to the Encina
Creek natural channel downstream ofFacility CC 2200' West of College Boulevard. After the confluenc
of Facility CC the natural channel of the creek will carry runoff though a designated open space. Th
existing facility between the confluence of proposed facility CI and CH south of Palomar Airport Roa
was found inadequate with the current standards and should be replaced by this proposed facility to hand1
the projected discharges. The existing facilities across Paseo Del Norte and Carlsbad Boulevard are als
found inadequate with the current standards and additional 10' x 4' RCB and 12' x 5' RCB should b
constructed along with those existing facilities, respectively, to handle the projected discharges.
Appendix A
Page 84
Master Drainage and Storm Water Quality Management pls
Carlsbad, California, March 199
FadlityCA
The proposed facility CA is a concrete trapezoidal channel which will complete a drainage syst
connecting to an existing concrete channel just east of the AT & SF Railroad. The upstream i
undeveloped and high density%ture development will aggravate the drainage deficiency unless this f
is built. This facility will also mitigate the erosion problem along the railroad.
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1 FadlityCB
Facility CB is comprised of 39" and 60" RCP's which will carry runoff &om a mostly undevelope
north of Palomar mort Road and drain into Encinas Creek after crossing Palomar Airport Roac
upstream area is mostly undeveloped and higher density future development will require the constn
of this facility.
FadlityCC
Facility CC is a storm drain proposed to be constructed and will carry runoff fiom an undevelope
north off alomar Airport Road with an outfall to the proposed channel of facility C through a 72" dk
pipeunder Palomar AirportRoad. Constructionofthisfacilitywill berequiredalongwiththe develo
of the undeveloped upstream areas. I FadlityCE
This facility will drain fbture residential areas along the proposed Hidden Valley Road to Encinas 1
FadlltyCF I This facility will convey drainage along the future Alga Road and empty into basin CFA.
Faciliw CFA
Drop structures and other enhancements will be made to the existing natural drainage course to r
erosion potential. Additionally, a desiitation basin will be installed just upstream of the pro
Cobblestone Wage access road. An enhanced natural channel will then convey drainage.on do
Encinas Creek.
FacilityCJ
Facility CJ will extend an existing 36" RCP upstream. This improvement will alleviate nuisance PO
and reduce the potential for mosquito breeding. The upstream area is mostly undeveloped and 1
density kture development will aggravate the drainage problems unless this facility is built.
F&f&IT
Facility CK will improve the existing drainage facility along Camino Vida Robles, north of Las P
Drive. The downstream 550' of the existing 24" RCP in this system was found inadequate by the a
standards and should be upgraded by the addition of a retention basin.
Master Drainage and Storm Water Quality Management Plan APPl Carlsbad, California, March 1994 F
FadlityCM
Facility CMis proposed to be constructed to carryrunoffalongPalomar Airport Road andEl CaminoRei
northwest ofthe intersection ofthe two roads. It will outfall to the natural swale through the golfcours
just south of Palomar Airport Road. The streets provide the only conveyance for drainage and are c
inadequate capacity by current standards. The upstream area is partially undeveloped and high densit
fbture development will aggravate the drainage deficiencies unless this facility is built.
FdtyCMA
This proposed 5 1" RCP will join proposed Facility CM and it will carry runoff across Palomar Airpoi
Road. Theupstream area is partially undeveloped and high density fbture development will aggravate th
drainage deficiencies unless this facility is built.
E. San Marcos Creek Basin
FadlityDA
Facility DA is comprised of 48"' 54", 60"' 72"' and 8 1 " RCP's that will carry runoff fiom both developec
and undeveloped areas with an outfall to Batiquitos Lagoon. Most of the upstream portion of this faciliq
runs parallel to the AT & SF Railroad and the most downstream portion along Carlsbad Boulevard.. Thc
existing 24" RCP fiom Poinsettia Lane to the confluence of proposed line DAA was found inadequate wit1
the current standards and needs to be replaced to carry the projected discharges. The upstream area i,
mostly undeveloped and higher density fbture development will aggravate the drainage deficiency unlesr
this facility is constructed. One debris basin is also proposed at the downstream of this facility to mitigatc
the impact of siltation and storm water pollutants on Batiquitos Lagoon due to grading and nev
development in the fkture. An alternate proposal may be to route the storm drain fiom its point of crossin1
at the AT & SF Railroad line southeast along the Avenida Encinas right of way to the existing siltatioi
basin adjacent to the Rosalina subdivision. The existing basin would require relocation and enlargemen
to accomodate the new flows. This alternative should be throughly reviewed prior to new developmen
within zone 9.
FadlityDAA
Facility DAA, proposed to be constructed, will be required to upgrade or replace the existing 24" RCP
by a proposed 39" RCP since the existing facility is inadequate with the present standards. This facilio
will drain into the facility DA. The upstream area is undeveloped and fbture development will aggravate
the drainage deficiency unless this facility is built.
FadlityDBA
Facility DBA is a storm drain line proposed to be constructed and will complete a drainage system by connecting upstream and downstream existing facilities. The upstream area is mostly undeveloped and
future development will require construction of this facility.
Appendix A
Page 86
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
Facility DBB
This proposed 30" RCP to be constructed to connect existing 30" RCP across Interstate 5 to the ex
60" RCP across Avenida Encinas. The System has found to be deficient for fbture development.
FadlityDF
This facility colle& drainage Born the Aviara development and discharges into the Batiquitos La
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The facility was constructed as an offsite requirement for the Aviara project and may potentially be si
to reimbursement as part of the drainage fee program.
Fadlily DFA
This permanent sedimentation basin is located at the lower end of Facility DF and discharges direc
the Batiquitos Lagoon. When installed, the temporary basin located upstream in the Aviara projec
be removed. Ifthis basin is eliminated and the Aviara basin is made permanent the Aviara develop
be eligible for reimbursement for this facility. 1 Facility DH
Facility DH comprises an enhanced natural channel to prevent erosion along the natural channel (
high velocity. The enhanced natural channel will consist of drop structures at points along the cl
to reduce the slope of the stream flow. 4 FaciliqDI
This facility is comprised of a 42" RCP connecting with the existing 42" RCP at upstream just P
Avenida Del Para and Unicomio Street with an outfill to the existing swale passing through a golfc
The area at the downstream portion of the two basins is undeveloped and future development in th
will require the construction of both facilities.
Fa,dlityDIB
Facility DIB is a debris basin at the downstream northerly of Alga Road. It is proposed to be const
to mitigate the impact of siltation as part of the fbture development in the area.
FadlityDM
Facility DM comprises of an enhanced natural channel to prevent erosion along the natural cham
to reduce the slope of the stream flow.
to high velocity. The enhanced natural channel will consist of drop structures at points along the c
Master Drainage and Storm Water Quality Management Pian APl Carlsbed. California, March 1994
Facility DMA, DMB, DMD &DME
These future facilities are located within undeveloped areas of zones 10 and 17. As such, there are n
definite or proposed plans for the development of the included drainage basins except for the fbtw
extension of Carrillo Way. The estimates for these facilities were based upon channel construction an
enhancement as well as culvert crossings under the fiture Carrillo Way.
FadlityDMF
This facility will handle drainage along the extension of El Fuerte Street to enhanced natural channel DM
E Encinitas CreekBasin
Fadlity DQ
Facility DQ is a storm drain proposed to be constructed and is comprised of 33", 36" and 45" RCP'
carrying runofffiom and through undeveloped area east ofRancho SantaFe Road draining into the naturs
swale at the downstream end. The upstream area is undeveloped and high density fbture development wi
require the installation of the facility.
FacilityDW
This proposed storm drain will join proposed facility DQ at its most downstream end. It will carry runof
through an undeveloped area and should be constructed as part of the future development.
FadlityDQB &Dw
These two facilities are needed to drain runoff from the proposed realignment of Rancho Santa Fe Roac
through fbture development and empty into the northeast fork of Encinitas Creek.
FadlityDR, DRA, DRB &DRC
These comprise the Master Plan facilities for the proposed Arroyo La Costa project. They include
enhancement of the natural channel, installation of a sedimenthetention basin, and extension of existing
concrete culverts to handle the existing and proposed drainage.
FadlityDS
Facility DS is a storm drain proposed to be constructed along Camino Alvaro and Rancho Santa Fe Road
replacing the existing 36" RCP. The system has found to be deficient between the existing 2'x 4' RCB
across Rancho Santa Fe Road and the existing 30" ACP on Alvaro.
Appendix A
Page 88 Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
FadlityDTA
The Encinitas Creek study prepared by Howard Chang indicates that the existing triple box culvert
La Costa Avenue is inadequate to handle the 100 year flood flows. By installing retention basin DT
addition of a berm along La Costa Avenue, the flooding and overtopping of La Costa Avenue I
prevented.
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This retentiodsedimentation basin is needed to retain drainage in order to mitigate floodin
overtopping of El Camino Real and La Costa Avenue located downstream of the proposed facili
FadlityMC
This proposed facility is a 15'x 4' RCB across Rancho Santa Fe Road along the course ofEncinitas (
The'existing 2-1O'x 4' RCB was found inadequate with the current standards and the proposed j
should be added to the existing to handle properly the projected discharges. This will eliminate flc
on both sides of the creek upstream of Rancho Santa Fe Road.
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FadlltyMD
This fhcility includes two culvert crossings of Encinitas Creek beneath the fbture Calle Acervo an(
remedial work to enhance the natural drainage courses. li FadlityDU
This sedimentation basin will work in combination with the existing basin at the southwest coi
Batiquitos Lane and Poinsettia Lane to reduce erosion potential for existing and proposed develol
in the respective basin.
FacilityDV
Facility DV is a 60" RCP proposed to be constructed across the El Camino Real to replace the e
60" CMP draining into Encinitas Creek.
I FadlityDW
I 24"CMP's.
I FadlityDZ
FacilityDWisa33"RCPproposed tobe constructedacrossOlivenhainRoadandreplacesthetwo e
This facility will carry drainage along Rancho Santa Fe Road fiom new development within Carlsb
fiom existing development in Encinitas. I
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1 Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994 API
Appendix A
Page 90
Master Drainage and Storm Water Quality Management Plan
Carlsbad, California, March 1994
E 8.225.000
,
BUENA VISTA LAGOON
E 6,2%000 I
- ---
~ = ~
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~ - - ~~ -~
E e.235.m
~ -- -- - -~ ~
PAClRC OCEAN
~~ ~~
DEBRIS BASIN
BATIWITOS LAGOOW