Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
CDP 98-01A; La Costa Glen Skilled Nursing Center Expansion; La Costa Glen Skilled Nursing Center Expansion; 2008-04-11
PRELIMINARY STORM WATER MANAGEMENT PLAN For LA COSTA GLEN SKILLED NURSING CENTER EXPANSION S.D.P. 98-01(B) C.U.P. 98-01(B) C.D.P. 98-01(B) V 08-_ Revised: April 11,2008 January 28, 2008 JN: 021039-5 Prepared by: RECEIVED O'DAY CONSULTANTS, INC. 2710 Loker Avenue West, Suite 100 AP-0 2 9 2CQ8 Carlsbad, California 92010-6609 _.^ Tel: (760)931-7700 CITY OF CARLSBAD Fax:(760)931-8680 PLANNING DEPT RECEIVED CITY OF CARLSBAD PLANNING DEPT George O'Day RCE 32014 Date Exp. 12/31/08 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION TABLE OF CONTENTS ITEM r PAGE COVER SHEET .................................................................... „. ................ i TABLE OF CONTENTS ............................................................................ ii 1.0 INTRODUCTION ..................................... . .................................... 1 1.1 PURPOSE ......................................................................... 1 1.2 LOCATION ....................................................................... 1 2.0 PROJECT REVIEW & PERMITTING PROCESS .................................... 1 2. 1 DETERMINE APPLICABLE STORM WATER BMP REQUIREMENTS ............................................................... 2 2.2 PRIORITY PROJECT PERMANENT STORM WATER BMP REQUIREMENTS ............................................................... 2 2.3 STANDARD PERMANENT STORM WATER BMPS REQUIREMENTS ............................................................... 2 2.4 CONSTRUCTION CRITERIA ................................................ 3 2.5 CONSTRUCTION SITE PRIORITY ......................................... 3 2.6 STORM WATER STANDARDS TABLE 1 ................................. 3 3.0 PREPARE AND SUBMIT APPROPRIATE PLANS ................................. 3 3.1 REQUIRED BMP ELEMENTS ............ .................................... 3 3.2 OPTIONAL BMP ELEMENTS ................................................ 3 3.3 TREATMENT CONTROL BMPS ............................................ 4 4.0 PERMANENT BEST MANAGEMENT PRACTICES SELECTION ............. 4 4. 1 IDENTIFY POLLUTANTS FORM THE PROJECT AREA ............ 4 4.1.1 ANTICIPATED POLLUTANTS OF CONCERN ............... 4 4.1.2 POTENTIAL POLLUTANTS OF CONCERN ................... 4 4.2 IDENTIFY POLLUTANTS OF CONCERN IN RECEIVING WATERS .......................................................................... 4 4.2. 1 IDENTIFY THE HYDROLOGIC UNIT CONTRIBUTION. . . 4 4.2.2 IDENTIFY 303(d) IMPAIRMENTS IN THE RECEIVING WATERS ............................................................... 5 4.3 BENEFICIAL USES OF RECEIVING WATERS .......................... 5 4.3.1 BIOL - PRESERVATION OF BIOLOGICAL HABITATS OF SPECIAL SIGNIFICANCE ..................................... 5 4.3.2 REC1 - CONTACT RECREATION ............................... 5 4.3.3 REC2- NON-CONTACT RECREATION ........................ 5 4.3.4 EST-ESTUARINE HABITAT .................................... 5 4.3.5 MAR -MARINE HABITAT ....................................... 6 4.3.6 WILD - WILDLIFE HABITAT .................................... 6 4.3.7 RARE - RARE, THREATENED, OR ENDANGERED SPECIES ............................................................... 6 4.3.8 MIGR - MIGRATION OF AQUATIC ORGANISMS .......... 6 January 28, 2008 - ii - 021039-5 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION TABLE OF CONTENTS (CONTINUED) ITEM PAGE 4.4 IDENTIFY CONDITIONS OF CONCERN 6 5.0 ESTABLISH PERMANENT STORM WATER BEST MANAGEMENT PRACTICES ". 6 5.1 SITE DESIGN BMPS 7 5.1.1 MAINTAIN PRE-DEVELOPMENT RAINFALL RUNOFF CHARACTERISTICS 7 5.1.2 MINIMIZE IMPERVIOUS FOOTPRINT 7 5.1.3 CONSERVE NATURAL AREAS 7 5.1.4 MINIMIZE DIRECTLY CONNECTED IMPERVIOUS AREAS 8 5.1.5 MAXIMIZE CANOPY INTERCEPTION AND WATER CONSERVATION CONSISTENT WITH THE CARLSBAD LANDSCAPE MANUAL 8 5.1.6 CONVEY RUNOFF SAFELY FROM TOPS OF SLOPES 8 5.1.7 VEGETATE SLOPES WITH NATURAL OR DROUGHT TOLERANT VEGETATION 8 5.1.8 STABILIZE PERMANENT CHANNEL CROSSINGS 8 5.1.9 INSTALL ENERGY DISSIPATERS 8 5.2 SOURCE CONTROL BMPS 9 5.2.1 DESIGN OUTDOOR MATERIAL STORAGE AREAS TO REDUCE POLLUTION INTRODUCTION 9 5.2.2 DESIGN TRASH STORAGE ARES TO REDUCE POLLUTION INTRODUCTION 9 5.2.3 USE EFFICIENT IRRIGATION SYSTEMS AND LANDSCAPE DESIGN 10 5.2.4 PROVIDE STORM WATER CONVEYANCE SYSTEM STENCILING AND SIGNAGE 10 5.3 INDIVIDUAL PRIORITY PROJECT CATEGORIES 10 5.4 TREATMENT CONTROL BMPS 10 5.4.1 TREATMENT CONTROL BMP DESIGN STANDARDS 11 5.4.2 TREATMENT CONTROL BMP SELECTION 11 5.4.3 POLLUTANTS OF CONCERN 11 5.4.4 STRUCTURAL TREATMENT CONTROL BMP SELECTION 12 5.4.5 TREATMENT CONTROL BMP INFORMATION 13 5.4.6 STRUCTURAL TREATMENT LIMITED EXCLUSIONS.... 13 5.5 PERMANENT BMPS APPLICABLE TO THE PROJECT SITE 13 6.0 CONSTRUCTION STORM WATER BMPS 14 January 28, 2008 - Hi - 021039-5 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION TABLE OF CONTENTS (CONTINUED) ITEM PAGE 7.0 CONSTRUCTION BMPS 14 7.1.1 EROSION CONTROL BMPS.- 14 7.1.2 TEMPORARY SEDIMENT CONTROL BMPS 14 7.1.3 WIND EROSION BMPS 15 7.1.4 TEMPORARY TRACKING CONTROL BMPS 15 7.1.5 NON-STORMWATER MANAGEMENT BMPS 15 7.1.6 WASTE MANAGEMENT & MATERIALS POLLUTION CONTROL BMPS 15 7.2 CONSTRUCTION BMP CONCLUSION 16 8.0 IMPLEMENTATION & MAINTENANCE REQUIREMENTS 16 8.1 OPERATION AND MAINTENANCE PLAN.. 16 8.2 ACCESS EASEMENT/AGREEMENT 16 9.0 APPENDICES 17 APPENDIX A: VICINITY MAP APPENDIX B: STORM WATER REQUIREMENTS APPLICABILITY CHECKLIST January 28, 2008 - iv - 021039-5 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION TABLE OF CONTENTS (CONTINUED) ITEM APPENDIX C: CITY OF CARLSBAD STANDARDS EXCERPTS • TABLE 1: STANDARD DEVELOPMENT PROJECT & PRIORITY PROJECT STORM WATER BMP REQUIREMENTS MATRIX (PAGE 8) • TABLE 2: ANTICIPATED AND POTENTIAL POLLUTANTS GENERATED BY LAND USE TYPE (PAGE 12) • TABLE 3: NUMERIC SIZING TREATMENT STANDARDS (PAGE 20) • TABLE 4: STRUCTURAL TREATMENT CONTROL BMP SELECTION MATRIX (PAGE 21) • APPENDIX B: DRAFT ENVIRONMENTALLY SENSITIVE AREAS WITHIN THE CITY OF CARLSBAD MAP (PAGE 34) APPENDIX D: PRELIMINARY HYDROLOGY STUDY • 'PRELIMINARY DRAINAGE STUDY FOR LA COSTA GLEN SKILLED NURSING CENTER EXPANSION' PREPARED BY O'DAY CONSULTANTS, INC DATED JANUARY 28, 2008 APPENDIX E: BENEFICIAL USES OF RECEIVING WATERS APPENDK F: 2002 CWA SECTION 303(d) LIST OF WATER QUALITY LIMITED SEGMENTS APPENDIX G: SOURCE CONTROL BMP FACT SHEETS • CITY OF CARLSBAD GS-16: REFUSE BIN ENCLOSURES • CASQA SD-10: SITE DESIGN AND LANDSCAPE PLANNING • CASQA SD-11: ROOF RUNOFF CONTROLS • CASQA SD-12: EFFICIENT IRRIGATION • CASQA SD-13: STROM DRAIN STENCILING • CASQA SD-32: TRASH ENCLOSURES APPENDIX H: TREATMENT CONTROL BMP FACT SHEETS • CASQA MP-52: DRAIN INSERTS • CASQA TC-40: MEDIA FILTERS • CASQA TC-60: MULTIPLE SYSTEM FACT SHEET • SECTION 6: LONG-TERM MAINTENANCE OF BMPS APPENDIX I: APPLICABLE MANUFACTURER'S BMP INFORMATION January 28, 2008 - v - 021039-5 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION TABLE OF CONTENTS (CONTINUED) ITEM APPENDIX J: MAP EXHIBITS • LA COSTA GLEN SKILLED NURSING CENTER EXPANSION PRELIMINARY STORM WATER MANAGEMENT PLAN EXHIBIT • DEPOLLUTANT BASINS VICINITY MAP January 28, 2008 - vi - 021039-5 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 1.0 INTRODUCTION Federal, state and local agencies have established goals and objectives for storm water quality in the region. The proposed project is a priority project as defined in Order No. 2001-01 by the San Diego Region of the California Water Quality Control Board. As a result, the project is subject to SUSMP requirements. In addition, prior to the start of construction activities, the project will comply with all federal, state and local permits including the Stormwater Management Plan (SWMP) required under the County of San Diego Watershed Protection, Stormwater Management, and Discharge Control Ordinance (WPO) (section 67.871), the City of Carlsbad's Standard Urban Storm Water Mitigation Plan, and the National Pollution Discharge Elimination System (NPDES) from the Regional Water Quality Control Board (RWQCB). The purpose of this SWMP is to address the water quality impacts from the proposed improvements as shown on the Site Development Plan (S.D.P. 98-01(A)). This report will provide guidelines in developing and implementing post construction Best Management Practices (BMPs) for storm water quality. There are three distinctly separate storm drain systems on site. The offsite runoff is considered clean water. This water is clean because it is from the surrounding open space easements. In addition, this water is collected through out the greater La Costa Glen site and kept separate from improved area storm water runoff. The clean water is then discharged into the Encinitas Creek. The onsite runoff will be collected in the two other storm drain systems as shown in the Preliminary Drainage Study for La Costa Glen Skilled Nursing Center Expansion. These systems will be composed of drainage ditches, catch basins, curb inlets etc. The runoff will then ultimately discharge into two separate depollutant basins, one along Calle Barcelona and the other along Rush Rose Drive and Levante Street as outline on City of Carlsbad Plan 349-3 A. See Appendix J for depollutant basin locations. It is the assumption of this report that the project site and uses was taken into consideration when these depollutant basin were initially designed as part of City of Carlsbad Plan 349-3 A. 1.1 PURPOSE This Storm Water Management Plan (SWMP) is for the La Costa Glen Skilled Nursing Center Expansion. It has been written to the standards set forth in the City of Carlsbad Engineering Standards, Volume 4: Stormwater Best Management Practices (BMPs) (2004 Edition). This report will reference these standards as 'City Standards.' 1.2 LOCATION The project is located according to the vicinity map found in Appendix A. 2.0 PROJECT REVIEW & PERMITTING PROCESS In order to complete the Project Review & Permitting Process section of the City Standards the Storm Water requirements Applicability Checklist has been completed. January 28, 2008 -1 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION For reference, this document has been included in Appendix B: Storm Water Requirements Applicability Checklist. 2.1 DETERMINE APPLICABLE STORM WATER BMP REQUIREMENTS Based on the completed Storm Water Requirements Applicability Checklist completed for the project (see Appendix B: Storm Water Requirements Applicability Checklist) the following requirements apply to the project: 2.2 PRIORITY PROJECT PERMANENT STORM WATER BMP REQUIREMENTS Based on Section 1, Part A: Determine Priority Project Permanent Storm Water BMP Requirements of the Storm Water Requirements Applicability Checklist the following priority project categories apply to the project: • Attached residential development of 10 or more units. • Project discharging to receiving waters within Environmentally Sensitive Areas • Parking lots greater than or equal to 5,000 square feet or with at least 15 parking spaces, and potentially exposed to urban runoff Since the project subject to standard permanent storm water requirements the design should incorporate all applicable requirements identified in Sections IH.2 'Establish Permanent Storm Water Best Management Practices' (requirements 1 through 35) per the City Standards. This should include site design and source control BMPs; BMPs applicable to individual priority projects; and treatment control BMPs. Further guidance on these requirements can be found on page 7 of the City Standards. 2.3 STANDARD PERMANENT STORM WATER BMP REQUIREMENTS Based on Section 1, Part B: Determine Standard Permanent Storm Water BMP Requirements of the Storm Water Requirements Applicability Checklist the following apply to the project: • New impervious areas, such as rooftops, roads, parking lots, driveways, paths, and sidewalks • New pervious landscape areas and irrigation systems • Trash storage areas • Any grading or ground disturbance during construction • Any new storm drains, or alteration to existing storm drains Since the project is subject to standard permanent storm water requirements the design should incorporate site design and source control requirements identified in Sections IH.2.A and B (requirements 1 through 15) per Table 1 of the City Standards. January 28, 2008 - 2 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION For reference, this document has been included in Appendix B: Storm Water Requirements Applicability Checklist. 2.1 DETERMINE APPLICABLE STORM WATER BMP REQUIREMENTS Based on the completed Storm Water Requirements Applicability Checklist completed for the project (see Appendix B: Storm Water Requirements Applicability Checklist) the following requirements apply to the project: 2.2 PRIORITY PROJECT PERMANENT STORM WATER BMP REQUIREMENTS Based on Section 1, Part A: Determine Priority Project Permanent Storm Water BMP Requirements of the Storm Water Requirements Applicability Checklist the following priority project categories apply to the project: • Attached residential development of 10 or more units. • Project discharging to receiving waters within Environmentally Sensitive Areas • Parking lots greater than or equal to 5,000 square feet or with at least 15 parking spaces, and potentially exposed to urban runoff Since the project is subject to standard permanent storm water requirements the design should incorporate all applicable requirements identified in Sections ffl.2 'Establish Permanent Storm Water Best Management Practices' (requirements 1 through 35) per the City Standards. This should include site design and source control BMPs; BMPs applicable to individual priority projects; and treatment control BMPs. Further guidance on these requirements can be found on page 7 of the City Standards. 2.3 STANDARD PERMANENT STORM WATER BMP REQUIREMENTS Based on Section 1, Part B: Determine Standard Permanent Storm Water BMP Requirements of the Storm Water Requirements Applicability Checklist the following apply to the project: • New impervious areas, such as rooftops, roads, parking lots, driveways, paths, and sidewalks • New pervious landscape areas and irrigation systems • Trash storage areas • Any grading or ground disturbance during construction • Any new storm drains, or alteration to existing storm drains Since the project is subject to standard permanent storm water requirements the design should incorporate site design and source control requirements identified in Sections III.2.A and B (requirements 1 through 15) per Table 1 of the City Standards. January 28, 2008 - 2 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 2.4 CONSTRUCTION CRITERIA Based on Section 2, Part C: Determine Construction Phase Storm Water Requirements of the Storm Water Requirements Applicability Checklist the following apply to the project: • The project proposes grading or soil disturbance • Storm water runoff or urban runoff has the potential to contact any portion of the construction area, including washing and staging areas • The project uses construction materials that could negatively affect water quality if discharged from the site (such as paints, solvents, concrete, and stucco) Since the project is subject to construction storm water best management practices requirements the design should incorporate the standards set forth in Section IV, 'Construction Storm Water BMP Performance Standards,' of the City Standards, as applicable to the site. Further guidance on these requirements can be found on page 7 of the City Standards. 2.5 CONSTRUCTION SITE PRIORITY Based on Section 2, Part D: Determine Construction Site Priority of the Storm Water Requirements Applicability Checklist, the project is classified as a High Priority Construction Site. 2.6 STORM WATER STANDARDS TABLE 1 Table 1 from page 8 of the City Standards has been included in Appendix C: City of Carlsbad Standards Excerpts for reference. 3.0 PREPARE AND SUBMIT APPROPRIATE PLANS Based on the general categories of storm water requirements that are applicable to the project as described in section 2, the following categories from Table 1: Standard Development Project & Priority Project Storm Water BMP Requirements Matrix found on page 8 of the City Standards apply: 3.1 REQUIRED BMP ELEMENTS The following are required BMP elements for the project and one or more applicable BMPs must be utilized: • Site Design BMPs • Source Control BMPs • Applicable to Individual Priority Projects o Surface Parking Areas • Treatment Control BMPs 3.2 OPTIONAL BMP ELEMENTS The following are optional best management practices, or BMPs that may be required by City of Carlsbad Staff for the project: • Applicable to Individual Priority Projects January 28, 2008 - 3 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION o Surface Parking Areas • Treatment Control BMPs 3.3 TREATMENT CONTROL BMPS Because the project is a priority project one or more Treatment Control BMPs will be required. 4.0 PERMANENT BEST MANAGEMENT PRACTICES SELECTION This section will identify what permanent best management practices will apply to project: 4.1 IDENTIFY POLLUTANTS FROM THE PROJECT AREA Based on the general pollutant categories and project categories as described in Table 2: Anticipated and Potential Pollutants Generated by Land Use Type found on page 12 of the City Standards, the project has the following pollutants: 4.1.1 ANTICIPATED POLLUTANTS OF CONCERN The following are anticipated pollutants of concern for the project: • Sediment • Heavy Metal • Organic Compounds (petroleum hydrocarbons) • Trash & Debris • Oil & Grease 4.1.2 POTENTIAL POLLUTANTS OF CONCERN The following are potential pollutants of concern for the project: • Nutrients (due to landscaping) • Oxygen Demanding Substances (due to landscaping) • Pesticides (due to landscaping) 4.2 IDENTIFY POLLUTANTS OF CONCERN IN RECEIVING WATERS This section will identify the pollutants or concern, if any, in the receiving waters of the project proposed drainage pattern. 4.2.1 IDENTIFY THE HYDROLOGIC UNIT CONTRIBUTION The project is located in the Batiquitos Hydrologic Subarea (904.51) of the San Marcos Hydrologic Area of the Carlsbad Hydrologic Unit in the San Diego Region. According to the City of Carlsbad's Standard Urban Storm Water Mitigation Plan, Appendix B: Draft Environmentally Sensitive Areas Within the City of Carlsbad Map (page 34,4/3/2003 edition), the project is in an environmentally sensitive area. A copy of this map is provided in Appendix C. January 28, 2008 - 4 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION project is in an environmentally sensitive area. A copy of this map is provided in Appendix C. 4.2.2 IDENTIFY 303(d) IMPAIRMENTS IN THE RECEIVING WATERS In the 2002 CW Section 303(d) List of Water Quality Limited Segments, the Batiquitos Lagoon is not an impaired water body, but it is in an environmentally sensitive area. Portions of Carlsbad where construction sites have the potential to discharge into a tributary of a 303(d) or directly into a 303(d) water body or sites located within 200 feet of an ESA require additional BMP implementation. These 303(d) water bodies include the Pacific Ocean, Buena Vista Lagoon, Encinas Creek, Aqua Hedionda Lagoon, and Batiquitos Lagoon. A copy of the 2002 CWA Section 303(d) List of Water Quality Limited Segments in included in Appendix F. 4.3 BENEFICIAL USES OF RECEIVING WATERS The beneficial uses for the hydrologic unit are included in Appendix E and a summary of the applicable definitions are listed below. This information comes from the Water Quality Control Plan for the San Diego Basin. 4.3.1 BIOL - PRESERVATION OF BIOLOGICAL HABITATS OF SPECIAL SIGNIFICANCE This beneficial use includes uses of water that support designated areas or habitats, such as established refuges, parks, sanctuaries, ecological reserves, or Areas of Special Biological Significance (ASBS), where the preservation or enhancement of natural resources requires special protection. 4.3.2 REC-1 CONTACT RECREATION This beneficial use includes uses of water for recreational activities involving body contact with water, where ingestion of water is reasonably possible. These uses include, but are not limited to, swimming, wading, water-skiing, skin and SCUBA diving, surfing, white water activities, fishing, or use of natural hot springs. 4.3.3 REC-2 - NON-CONTACT RECREATION This beneficial use includes the uses of water for recreational activities involving proximity to water, but not normally involving body contact with water, where ingestion of water is reasonably possible. These include, but are not limited to, picnicking, sunbathing, hiking, camping, boating, tide pool and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above activities. 4.3.4 EST - ESTUARINE HABITAT This beneficial use includes the uses of water that support estuarine ecosystems including, but not limited to, preservation or enhancement of January 28, 2008 - 5 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION estuarine habitats, vegetation, fish, or wildlife (e.g., estuarine mammals, waterfowl, shorebirds). 4.3.5 MAR-MARINE HABITAT This beneficial use includes uses of water that support marine ecosystems including, but not limited to, preservation or enhancement or marine habitats, vegetation such as kelp, fish, shellfish, or wildlife (e.g., marine mammals, shorebirds). 4.3.6 WILD - WILDLIFE HABITAT This beneficial use includes uses of water that support terrestrial ecosystems including but not limited to, preservation and enhancement of terrestrial habitats, vegetation, wildlife, (e.g., mammals, birds, reptiles, amphibians, invertebrates), or wildlife water food and sources. 4.3.7 RARE - RARE, THREATENED, OR ENDANGERED SPECIES This beneficial use includes uses of water that support habitats necessary, at least in part, for the survival and successful maintenance of plant or animal species established under state or federal law as rare, threatened or endangered. 4.3.8 MIGR -MIGRATION OF AQUATIC ORGANISMS This beneficial use includes uses of water that support habitats necessary for migration, acclimatization between fresh and salt water, or other temporary activities by aquatic organisms, such as anadromous fish. 4.4 IDENTIFY CONDITIONS OF CONCERN In order to determine if the project proposed drainage patterns will effect the downstream conditions, a copy of the La Costa Skilled Nursing Center Expansion Preliminary Drainage Study is including in Appendix D: Site Drainage Study. This report is title 'Preliminary Drainage Study for La Costa Glen Skilled Nursing Center Expansion' by O'Day Consultants, Inc January 28, 2008. Based on the findings in this Preliminary drainage study, the onsite water will be treated per this report and storm water that does not come into contact with the project site will continue to be diverted to separate, and assumed clean, open space drainage ditches, structures, and storm drain lines. 5.0 ESTABLISH PERMANENT STORM WATER BEST MANAGEMENT PRACTICES Because the project is a Priority Project, all the applicable BMPs will be applied to the project. Where applicable, the project will incorporate storm water BMPs in the project design in the following progression: • Site Design BMPs • Source Control BMPs January 28, 2008 - 6 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 5.1 SITE DESIGN BMPS (LOW IMPACT DEVELOPMENT) Site Design BMPs are comprised of the following BMPS: • Maintain Pre-Development Rainfall Runoff Characteristics o Minimize Impervious Footprint o Conserve Natural Areas o Minimize Directly Connected Impervious Areas o Maximize Canopy Interception and Water Conservation Consistent with the Carlsbad Landscape Manual • Protect Slopes and Channels o Convey Runoff Safely From Tops of Slopes o Vegetate Slopes with Natural or Drought Tolerant Vegetation o Stabilize Permanent Channel Crossings o Install Energy Dissipaters 5.1.1 MAINTAIN PRE-DEVELOPMENT RAINFALL RUNOFF CHARACTERISTICS This Site Design BMP entails controlling post construction peak storm water discharge at the rate and velocities of the pre-developed condition. 5.1.2 MINIMIZE IMPERVIOUS FOOTPRINT This Site Design BMP and L.I.D. requirement entails minimizing the proposed site impervious footprint through increasing building densities, utilizing pervious construction materials on walkways, driveways, trails, patios, overflow parking areas, alleys and low traffic areas. Examples of materials that can be used are pervious concrete, porous asphalt, unit pavers, and granular materials. In addition, streets, sidewalks, and parking lot aisles can be designed to minimum widths, provided pedestrian safety is not compromised. And lastly, this can be accomplished through the minimization of use of impervious surfaces, such as decorative concrete in landscape design. The proposed design of the project will attempt to utilize this Site Design BMP by minimizing and maximizing the impervious footprint as much as possible. The building expansion itself will be multi-story and have a higher density then multiple single story buildings and parking will be limited to the site constraints. Furthermore, the increase of approximately 545 square-feet of impervious surface due to the building expansion will be mitigated by converting four existing asphalt paved parking stalls into pervious paved stalls (576 square-feet). See Storm Water Management Plan Exhibit in Appendix J for the location of proposed pervious parking stalls. 5.1.3 CONSERVE NATURAL AREAS This Site Design BMP entails concentrating or clustering development on the least environmentally sensitive portions of a site while leaving the remaining land in a natural, undisturbed condition and incorporates the use of natural drainage systems to the maximum extend practical. The project proposes to meet this Site Design BMP by clustering everything together January 28, 2008 - 7 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION and setting aside as much as possible for 'open space' as defined by the City of Carlsbad. 5.1.4 MINIMIZE DIRECTLY CONNECTED IMPERVIOUS AREAS This Site Design BMP entails minimizing directly connect impervious areas where landscaping is proposed and attempt to direct runoff from impervious surfaces such as sidewalks, parking lots, walkways, trails, and patios to the landscaping areas. 5.1.5 MAXIMIZE CANOPY INTERCEPTION AND WATER CONSERVATION CONSISTENT WITH THE CARLSBAD LANDSCAPE MANUAL This Site Design BMP entails maximizing canopy interception and water conservation consistent with the Carlsbad Landscape Manual to preserve existing native trees and shrubs, to plant additional native or drought tolerant trees, and to plant large shrubs in place of non-drought tolerant exotic species. The project will utilize this Site Design BMP by having the landscaping designer utilize the applicable City of Carlsbad Landscape Manual and any other applicable City of Carlsbad Standards. 5.1.6 CONVEY RUNOFF SAFELY FROM TOPS OF SLOPES This Site Design BMP entails conveying runoff safely from the tops of slopes and in channels. The project will utilize this Site Design BMP as much as possible. There are tops and bottoms of slopes on the project site. Each top and bottom of slope will be designed so that runoff will safely be conveyed away from them. 5.1.7 VEGETATE SLOPES WITH NATURAL OR DROUGHT TOLERANT VEGETATION This Site Design BMP entails the vegetation of slopes with native or drought tolerant vegetation where practically consistent with the Carlsbad Landscape Manual. The project will utilize this Site Design BMP by having the landscaping designer utilize the applicable City of Carlsbad Landscape Manual and any other applicable City of Carlsbad Standards. 5.1.8 STABILIZE PERMANENT CHANNEL CROSSINGS This site Design BMP entails the stabilization of permanent channel crossings. This Site Design BMP will not be applicable to the project due to no permanent channel crossing being present on the existing or proposed site designs. 5.1.9 INSTALL ENERGY DISSIPATERS This Site Design BMP entails installing energy dissipaters at the outlets of new storm drains, culverts, conduits, or channels that enter unlined channels. This is to be done in accordance with the applicable standards January 28, 2008 - 8 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION and specifications to minimize erosion. Energy dissipaters shall be installed in such a fashion as to minimize impacts to the receiving waters. The project will utilize this Site Design BMP as needed to protect the proposed and existing storm drain inlets, culverts, conduits, and channels. 5.2 SOURCE CONTROL BMPS Source Control BMPs are comprised of the following BMPS: • Design Outdoor Material Storage Areas to Reduce Pollution Introduction • Design Trash Storage Areas to Reduce Pollution Introduction • Use Efficient Irrigation Systems and Landscape Design • Provide Storm Water Conveyance System Stenciling and Signage 5.2.1 DESIGN OUTDOOR MATERIAL STORAGE AREAS TO REDUCE POLLUTION INTRODUCTION This Source Control BMP entails placing any and all potentially hazardous materials that have a potential to contaminate urban runoff in storage areas on site that are enclosed in structures such as, but not limited to, cabinets, sheds, or other similar structures that prevent and contain with rain, runoff, or spillage. In addition, secondary structures such as berms, dikes, or curbs will be utilized out side of the storage structure to further prevent contamination. The storage areas shall be paved with a sufficiently impervious material to contain leaks and spills, and shall have a roof or awning to minimize direct contact with precipitation within the secondary containment area. Because the project does not proposed any material storage areas this Source Control BMP will not be utilized. 5.2.2 DESIGN TRASH STORAGE AREAS TO REDUCE POLLUTION INTRODUCTION This Source Control BMP entails designing trash storage areas to reduce pollution introduction. Trash Storage Areas shall be paved with an impervious surface, designed not to allow runoff from adjoining areas, screened or walled to prevent off-site transportation of trash, and contain attached lids on all trash containers that protects them from precipitation. Alternatively, the trash enclosure can contain a roof or awning to minimize direct contact with precipitation. The project will utilize this Source Control BMP by designing and building the trash storage areas according to the City of Carlsbad Standard Drawing GS-16 and in accordance with CASQA SD-32: Trash Enclosures. These areas will be paved with an impervious surface, graded to drain away from the enclosure, and screened and walled to prevent off-site transport of trash. Trash containers will contain attached lids that exclude rain to minimize direct precipitation. A copy of each of these is provided in Appendix G. January 28, 2008 - 9 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 5.2.3 USE EFFICIENT IRRIGATION SYSTEMS AND LANDSCAPE DESIGN This Source Control BMP entails employing rain shutoff devices to prevent irrigation during precipitation and this requires all landscaping aspects to be designed per the Carlsbad Landscape Manual. The project will utilize this Source Control BMP by having the landscaping designer utilize the applicable City of Carlsbad Landscape Manual and any other applicable City of Carlsbad Standards. In addition, site irrigation will also be designed in accordance with CASQA SD-10: Site Design and Landscape Planning. A copy of this has been provided in Appendix G. 5.2.4 PROVIDE STORM WATER CONVEYANCE SYSTEM STENCILING AND SIGNAGE This Source Control BMP entails providing storm drain conveyance system stenciling and signage. This shall be done by providing concrete stamping, porcelain tile, insert permanent marking or approved equivalent as approved by the City of Carlsbad, of all storm drain conveyance system inlets and catch basins within the project area with prohibitive language (i.e. "No Dumping -1 Live Downstream') satisfactory to the City Engineer. In addition, signs shall be posted and prohibitive language and/or graphical icons, which prohibit illegal dumping at public access points along channels and creeks within the project area, trailheads, and parks shall be used. The project will utilize this Source Control BMP by utilizing CASQA SD-13: Storm Drain Stenciling. A copy of this is provided in Appendix G. 5.3 INDIVIDUAL PRIORITY PROJECT CATEGORIES Where identified in Table 1 of the City Standards, the following requirements shall be incorporated into priority projects: Surface Parking Areas. Surface parking areas (covered and uncovered) where landscaping is proposed shall incorporate landscape areas into the drainage design. Parking that is in excess of the project's minimum requirements (overflow parking) may be constructed with permeable paving subject to the City Engineer's approval. The project will utilize this Individual Priority Project Category BMP by incorporating the proposed landscaping areas in the drainage pattern as much as feasibly possible. 5.4 TREATMENT CONTROL BMPS Where identified in Table 1 of the City Standards, and after site design and source control BMPs have been incorporated into the project design, treatment control BMPs may then be utilized. January 28, 2008 -10 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 5.4.1 TREATMENT CONTROL BMP DESIGN STANDARDS Treatment Control BMPs shall be designed to infiltrate, filter, and/or treat runoff from the project footprint per Table 3: Numeric Sizing Treatment Standards. A copy of Table 3 is provided in Appendix C. There are four guidelines that need to be followed for Treatment Control BMPs: • All Structural Treatment Control BMPs shall infiltrate, filter, and/or treat the required runoff volume or flow prior to discharging to any receiving water body supporting beneficial uses. • Multiple post construction Structural Treatment Control BMPs for a single priority project shall collectively be designed to comply with the numeric sizing treatment standards. • Shared BMPs shall be operational prior to the use of any dependent development or phase of development. The shared BMPs shall only be required to treat the dependent developments or phases of development that are in use. • Interim storm water BMPs that provide equivalent or greater treatment than is required may be implemented by a dependant development until each shared BMP is operational. If interim BMPs are selected, the BMPs shall remain in use until permanent BMPs are operational. 5.4.2 TREATMENT CONTROL BMP SELECTION All projects classified as Priority Projects in the City of Carlsbad shall select a single or combination of treatment control BMPs from the categories listed in Table 4: Structural Treatment Control BMPs Selection Matrix. A copy of Table 4 is provided in Appendix C. This selection matrix will determine the most efficient removal BMP for the pollutants of concern from the project site. The most efficient device or combination of devices shall be utilized to maximize pollutant removal. 5.4.3 POLLUTANTS OF CONCERN Based on the above findings for the proposed site usage the project has the following pollutants of concern: • Sediment (Anticipated) • Nutrients (Potential by use) • Heavy Metals (Anticipated) • Organic Compounds (Anticipated) • Trash & Debris (Anticipated) • Oxygen Demanding Substances (Potential by use) • Oil & Grease (Anticipated) • Pesticides (Potential by use) January 28,2008 -11- 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION Based on the actual design of the project the following is the applicable pollutants of concern based on the site design and usage: • Sediment (Anticipated) • Heavy Metals (Anticipated) • Organic Compounds (Anticipated) • Trash & Debris (Anticipated) • Oil & Grease (Anticipated) The other pollutants of concern have not been accounted for because the project landscaping will be designed and installed per the City of Carlsbad Landscape Manual and will incorporate efficient irrigation, pest resistant species, and incorporate drought resistant native species of planting. 5.4.4 STRUCTURAL TREATMENT CONTROL BMP SELECTION Based on the pollutants of concern present from the project site and the removal efficiencies listed in Table 4: Structural Treatment Control BMP Selection Matrix, the Structural Treatment Control BMP with the most efficient removal efficiencies for the project are as follows (listed most to least efficient): • Filtration • Detention Basins • Wet Ponds or Wetlands • Biofilters • Infiltration Basins Based on the above mentioned removal efficiencies and limited space on site, the project shall incorporate a combination of filtration and drainage inserts on site; however, downstream of the project site are two permanent detention basin as well. Higher removal efficient structural treatment control devices could not be used on site due to the limited space to accommodate their proper design and implementation. In addition, these devices will also be designed and installed in accordance with CASQA MP-52: Drain Inserts, TC-40: Media Filters, and CASQA TC-60: Multiple System Fact Sheet. A copy of these has been provided in Appendix H. January 28, 2008 -12 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 5.4.5 TREATMENT CONTROL BMP INFORMATION Based on the above mentioned removal efficiencies, the project shall incorporate Suntree Technologies Curb Met Basket System (or approved equivalent) and Bioclean Environmental Services, Inc Bio-Sorb (or approved equivalent) products in the proposed curb inlets. In addition, the Permanent Basin that was designed and built by City of Carlsbad Plan 349-3A will also be used as a detention basin as that is the original end point for the project storm water runoff and was originally intended for this purpose. 5.4.6 STRUCTURAL TREATMENT LIMITED EXCLUSIONS No Structural Treatment Limited Exclusions apply to this project as defined in the City Standards. 5.5 PERMANENT BMPS APPLICABLE TO THE PROJECT SITE Based on the above findings, the following permanent BMPs will be established for the project: Site Design BMPs: • Maintain Pre-Development Rainfall Runoff Characteristics o Minimize Impervious Footprint o Conserve Natural Areas o Minimize Directly Connected Impervious Areas o Maximize Canopy Interception and Water Conservation Consistent with the Carlsbad Landscape Manual • Protect Slopes and Channels o Convey Runoff Safely From Tops of Slopes o Vegetate Slopes with Natural or Drought Tolerant Vegetation o Stabilize Permanent Channel Crossings o Install Energy Dissipaters Source Control BMPs: • Design Trash Storage Areas to Reduce Pollution Introduction • Use Efficient Irrigation Systems and Landscape Design • Provide Storm Water Conveyance System Stenciling and Signage Applicable to Individual Priority Projects • Surface Parking Areas Treatment Control BMPs: • Suntree Technologies Catch Basin Insert • Bioclean Environmental Services, Inc Bio-Sorb January 28, 2008 -13 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 6.0 CONSTRUCTION STORM WATER BMPS Based on the size of the project site the City of Carlsbad will require that a separate document be prepared. If the project site is less then one acre then the project will require a Water Pollution Control Plan. If the project site is one acre of more then a Storm Water Pollution Prevention Plan will be required. Since the project has a disturbed area less than one acre a WPCP will be required. Construction BMPs and any applicable design standards can be found in this separate document. . 7.0 IMPLEMENTATION & MAINTENANCE REQUIREMENTS Once the City of Carlsbad approves all the project BMPs, the applicants and the City Project Managers must ensure proper implementation of the selected BMPs. In order to accomplish effective implementation and maintenance the City of Carlsbad may require that some sort of Permanent BMP Maintenance Agreement be entered into. This will be at the discretion of the City of Carlsbad Staff. In the event that a Permanent BMP Maintenance Agreement is required by City Staff, the following items will need to be addressed: 7.1 OPERATION AND MAINTENANCE PLAN The applicant shall include and Operation & Maintenance Plan (O&M), prepared satisfactory to the City, with the approved maintenance agreement, which describes the designated responsible party to mange the storm water BMPs, employee's training program and duties, operating schedule, maintenance frequency, routine service schedule, specific maintenance activities (including maintenance of storm water conveyance system stamps), copies of resource agency permits, and any other necessary activities. At a minimum, maintenance agreements shall require the applicant to provide inspection and servicing of all permanent treatment BMPs on an annual basis. The project proponent or City- approved maintenance entity shall complete and maintain O&M forms to document all maintenance requirements. Parties responsible for the O&M plan shall retain records for at least 5 years. These documents shall be made available to the City inspector upon request at any time. In addition, CASQA Section 6: Long-term Maintenance of BMPs shall be utilized as guide. A copy of this is provided in Appendix H. 7.2 ACCESS EASEMENT/AGREEMENT If a permanent BMP requires access for maintenance, as part of the O&M plan, the applicant shall execute and record an access easement or agreement that shall be binding on the under lying land throughout the life of the project in favor of the party responsible for maintenance, until such time that the permanent treatment BMP requiring access for maintenance is removed or replaced. The City shall approve any changes to the permanent BMPs, O&M plans, or access agreements. The agreement shall include a provision that gives the City the right, but not the obligation to perform the maintenance. The party responsible for BMP maintenance will pay the City for any and all costs uncured by the City for maintaining any BMPs. The agreement will provide a cost recovery provision in favor of the City satisfactory to the City Attorney. January 28, 2008 -14 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 8.0 APPENDICES: The following Appendices are included: Appendix A: Vicinity Map Appendix B: Storm Water Requirement Applicability Checklist Appendix C: City of Carlsbad Standards Excerpts • Table 1: Standard Development Project & Priority Project Storm Water BMP Requirements Matrix (page 8) • Table 2: Anticipated and Potential Pollutants Generated by Land Use Type (page 12) • Table 3: Numeric Sizing Treatment Standards (page 20) • Table 4: Structural Treatment Control BMP Selection Matrix (page 21) • Appendix B: Draft Environmentally Sensitive Areas Within the City of Carlsbad Map (page 34) Appendix D: Site Drainage Study • Preliminary Drainage Study for La Costa Glen Skilled Nursing Center Expansion by O'Day Consultants, Inc date January 28,2008. Appendix E: Beneficial Uses of Receiving Waters Appendix F: 2002 CWA Section 303(d) List of Water Quality Limited Segments Appendix G: Source Control BMP Fact Sheets Carlsbad Standard Drawing GS-16: Refuse Bin Enclosures CASQA SD-10: Site Design and Landscape Planning CASQA SD-11: Roof Runoff Controls CASQA SD-12: Efficient Irrigation CASQA SD-13: Strom Drain Stenciling CASQA SD-32: Trash Enclosures Appendix H: Treatment Control BMP Fact Sheets CASQA MP-52: Drain Inserts CASQA TC-40: Media Filters CASQA TC-60: Multiple System Fact Sheet Section 6: Long-term Maintenance of BMPs Appendix I: Applicable Manufacturer's BMP Information January 28, 2008 -15 - 021039 PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION Appendix J: Map Exhibits • La Costa Glen Skilled Nursing Center Expansion Preliminary Storm Water Management Plan Post Construction BMPs Exhibit • Depollutant Basins Vicinity Map • City of Carlsbad Drawing 349-3 A, Existing Downstream Storm Drain Systems. January 28, 2008 -16 - 021039 APPENDIX A PRELIMINARY STANDARD URBAN STORM WATER MITIGATION PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX A: VICINITY MAP CITY OF OCEANSIDE CITY OF VISTA CAR1ISBA17•i CITY OF SAN MARCOS CITY OF ENCINITAS VICINITY MAP NO SCALE APPENDIX B I*-" STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX B: STORM WATER REQUIREMENT APPLICABILITY CHECKLIST Please see attached. DEVELOPMENT APPLICATION STORM WATER STANDARDS QUESTIONNAIRE INSTRUCTIONS: This questionnaire must be completed by applicant in advance of submitting for a development application (subdivision and land use planning approvals and construction permits). The results of the questionnaire determine the level of storm water pollution prevention standards applied to a proposed development or redevelopment project. Many aspects of project site design are dependent upon the storm water pollution protection standards applied to a project. Applicant responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts. City staff has responsibility for making the final assessment after submission of the development application. A staff determination that the development application is subject to more stringent storm water standards, than initially assessed by the applicant, will result in the return of the development application as incomplete. If applicants are unsure about the meaning of a question or need help in determining how to respond to one or more of the questions, they are advised to seek assistance from Engineering Department Development Services staff. A separate completed and signed questionnaire must be submitted for each new development application submission. Only one completed and signed questionnaire is required when multiple development applications for the same project are submitted concurrently. In addition to this questionnaire, applicants for construction permits must also complete, sign and submit a Construction Activity Storm Water Standards Questionnaire. To address pollutants that may be generated from new development, the City requires that new development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management Practices (BMPs) into the project design, which are described in Section 2 of the City's Storm Water Standards Manual This questionnaire should be used to categorize new development and significant redevelopment projects as priority or non-priority, to determine what level of storm water standards are required or if the project is exempt. 1. Is your project a significant redevelopment? Definition: Significant redevelopment is defined as the creation or addition of at least 5,000 square feet of impervious surface on an already developed site. Significant redevelopment includes, but is not limited to: the expansion of a building footprint; addition to or replacement of a structure; structural development including an increase in gross floor area and/or exterior construction remodeling; replacement of an impervious surface that is not part of a routine maintenance activity; and land disturbing activities related with structural or impervious surfaces. Replacement of impervious surfaces includes any activity that is not part of a routine maintenance activity where impervious material(s) are removed, exposing underlying soil during construction. Note: If the Significant Redevelopment results in an increase of less than fifty percent of the impervious surfaces of a previously existing development, and the existing development was not subject to SUSMP requirements, the numeric sizing criteria discussed in Section F.1.b. (2)(c) applies only to the addition, and not to the entire development. 2. If your project IS considered significant redevelopment, then please skip Section 1 and proceed with Section 2. 3. If your project IS NOT considered significant redevelopment, then please proceed to Section 1. SECTION 1 NEW DEVELOPMENT PRIORITY PROJECT TYPE Does you project meet one or more of the following criteria: 1. Home subdivision of 100 units or more. Includes SFD, MFD, Condominium and Apartments 2. Residential development of 10 units or more. Includes SFD, MFD, Condominium and Apartments 3. Commercial and industrial develooment greater than 100.000 sauare feet includina oarkina areas. Any development on private land that is not for heavy industrial or residential uses. Example: Hospitals, Hotels, Recreational Facilities, Shopping Malls, etc. 4. Heaw Industrial / Industry areater than 1 acre (NEED SIC CODES FOR PERMIT BUSINESS TYPES) SIC codes 5013, 5014, 5541, 7532-7534, and 7536-7539 5. Automotive repair shoo. SIC codes 5013, 5014, 5541 , 7532-7534, and 7536-7539 6. A New Restaurant where the land area of develooment is 5.000 sauare feet or more includina oarkina areas. SIC code 5812 7. Hillside development (1) greater than 5,000 square feet of impervious surface area and (2) development will grade on any natural slope that is 25% or greater 8. Environmentally Sensitive Area (ESA). Impervious surface of 2,500 square feet or more located within, "directly adjacent"2 to (within 200 feet), or "discharging directly to"3 receiving water within the ESA1 9. Parking lot. Area of 5,000 square feet or more, or with 15 or more parking spaces, and potentially exposed to urban runoff 10. Retail Gasoline Outlets - servina more than 100 vehicles per day Serving more than 100 vehicles per day and greater than 5,000 square feet 11. Streets, roads, highways, and freeways. Project would create a new paved surface that is 5,000 square feet or greater. 12. Coastal Development Zone. Within 200 feet of the Pacific Ocean and (1) creates more than 2500 square feet of impermeable surface or (2) increases impermeable surface on property by more than 10%. YES NO 1 Environmentally Sensitive Areas include but are not limited to all Clean Water Act Section 303(d) impaired water bodies; areas designated as Areas of Special Biological Significance by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); water bodies designated with the RARE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and Count of San Diego; and any other equivalent environmentally sensitive areas which have been identified by the Copermittees. 2 "Directly adjacent" means situated within 200 feet of the environmentally sensitive area. 3 "Discharging directly to" means outflow from a drainage conveyance system that is composed entirely of flows from the subject development or redevelopment site, and not commingled with flow from adjacent lands. Section 1 Results: If you answered YES to ANY of the questions above you have a PRIORITY project and PRIORITY project requirements DO apply. A Storm Water Management Plan, prepared in accordance with City Storm Water Standards, must be submitted at time of application. Please check the "MEETS PRIORITY REQUIREMENTS" box in Section 3. If you answered NO to ALL of the questions above, then you are a NON-PRIORITY project and STANDARD requirements apply. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3. SECTION 2 SIGNIFICANT REDEVELOPMENT: 1 . Is the project an addition to an existing priority project type? (Priority projects are defined in Section 1) YES A> / NO If you answered YES, please proceed to question 2. If you answered NO, then you ARE NOT a significant redevelopment and you ARE NOT subject to PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3 below. 2. Is the project one of the following: a. Trenching and resurfacing associated with utility work? b. Resurfacing and reconfiguring surface parking lots? c. New sidewalk construction, pedestrian ramps, or bike land on public and/or private existing roads? d. Replacement of damaged pavement? •J S f V' If you answered NO to ALL of the questions, then proceed to Question 3. If you answered YES to ONE OR MORE of the questions then you ARE NOT a significant redevelopment and you ARE NOT subject to PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3 below. 3. Will the development create or add at least 5,000 square feet of impervious surfaces on an existing development or, be located within 200 feet of the Pacific Ocean and (1)create more than 2500 square feet of impermeable surface or (2) increases impermeable surface on property by more than 10%? If you answered YES, you ARE a significant redevelopment, and you ARE subject to PRIORITY project requirements. Please check the "MEETS PRIORITY REQUIREMENTS" box in Section 3 below. 4f- you answered NO, you ARE NOT a significant redevelopment, and you ARE NOT subject to PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET PRIORITY Requirements" box in Section 3 below. SECTION 3 Questionnaire Results: MY PROJECT MEETS PRIORITY REQUIREMENTS, MUST COMPLY WITH PRIORITY PROJECT STANDARDS AND MUST PREPARE A STORM WATER MANAGEMENT PLAN FOR SUBMITTAL AT TIME OF APPLICATION. MY PROJECT DOES NOT MEET PRIORITY REQUIREMENTS AND MUST ONLY COMPLY WITH STANDARD STORM WATER REQUIREMENTS. Applicant Information and Signature Box This Box for City Use Only o Project Address Woodfurn Lane Assessors Parcel Number(s): 255-012-15 Project # (city use only): Complete Sections 1 and 2 of the following checklist to determine your project's permanent and construction storm water best management practices requirements. This form must be completed and submitted with your permit application. Section 1. Permanent Storm Water BMP Requirements: If any answers to Part A are answered "Yes," your project is subject to the "Priority Project Permanent Storm Water BMP Requirements," and "Standard Permanent Storm Water BMP Requirements" in Section III, "Permanent Storm Water BMP Selection Procedure" in the Storm Water Standards manual. If all answers to Part A are "No," and any answe$9-ftrPartBare "Yes," your project is only subject to the "Standard Permanent Storm Water BMP Requirement". If every question in Part A and B is answered "No," your project is exempt from permanent storm water requirements. Part A: Determine Priority Project Permanent Storm Water /Requirements. Does the project meet the definition of oine or more of the priority project categories?* 1 . Detached residential development of 1 (J or more/inits. / 2. Attached residential development of\10 orvmore units.A \ 3. Commercial development greater than 100,000 square feet. 4. Automotive repair shoV / 5. Restaurant. \. y 6. Steep hillside development greater than 5,000 square feet. 7. Project discharging to receiving waters within Environmentally Sensitive Areas. 2 8. Parking lots greater than or equal to 5,000 ft or with at least 15 parking spaces, and potentially exposed to urban runoff. 9. Streets, roads, highways, and freeways which would create a new paved surface that is 5,000 square feet or greater Yes / / / No / / / / / / * Refer to the definitions section in the Storm Water Standards for expanded definitions of the priority project categories. Limited Exclusion: Trenching and resurfacing work associated with utility projects are not considered priority projects. Parking lots, buildings and other structures associated with utility projects are priority projects if one or more of the criteria in Part A is met. If all answers to Part A are "No", continue to Part B. Part B: Determine Standard Permanent Storm Water Requirements. Does the project propose: 1 . New impervious areas, such as rooftops, roads, parking lots, driveways, paths and sidewalks? 2. New pervious landscape areas and irrigation systems? 3. Permanent structures within 100 feet of any natural water body? 4. Trash storage areas? 5. Liquid or solid material loading and unloading areas? 6. Vehicle or equipment fueling, washing, or maintenance areas? 7. Require a General NPDES Permit for Storm Water Discharges Associated with Industrial Activities (Except construction)?* 8. Commercial or industrial waste handling or storage, excluding typical office or household waste? 9. Any grading or ground disturbance during construction? 10. Any new storm drains, or alteration to existing storm drains? Yes / / / D ^ / 0 No W / / 0 W *To find out if your project is required to obtain an individual General NPDES Permit for Storm Water Discharges Associated with Industrial Activities, visit the State Water Resources Control Board web site at, www.swrcb.ca.gov/stormwtr/industrial.html Section 2. Construction Storm Water BMP Requirements: If the answer to question 1 of Part C is answered "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare a Storm Water Pollution Prevention Plan (SWPPP). If the answer to question 1 is "No," but the answer to any of the remaining questions is "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare a Water Pollution Control Plan (WPCP). If every question in Part C is answered "No," your project is exempt from any construction storm water BMP requirements. If any of the answers to the questions in Part C are "Yes," complete the construction site prioritization in Part D, below. Part C: Determine Construction Phase Storm Water Requirements. Would the project meet any of these criteria during construction? 1 . Is the project subject to California's statewide General NPDES Permit for Storm Water Discharges Associated With Construction Activities? 2. Does the project propose grading or soil disturbance? 3. Would storm water or urban runoff have the potential to contact any portion of the construction area, including washing and staging areas? 4. Would the project use any construction materials that could negatively affect water quality if discharged from the site (such as, paints, solvents, concrete, and stucco)? Yes / / W No / Part D: Determine Construction Site Priority In accordance with the Municipal Permit, each construction site with construction storm water BMP requirements must be designated with a priority: high, medium or low. This prioritization must be completed with this form, noted on the plans, and included in the SWPPP or WPCP. Indicate the project's priority in one of the check boxes using the criteria below, and existing and surrounding conditions of the project, the type of activities necessary to complete the construction and any other extenuating circumstances that may pose a threat to water quality. The City reserves the right to adjust the priority of the projects both before and during construction. [Note: The construction priority does NOT change construction BMP requirements that apply to projects; all construction BMP requirements must be identified on a case-by-case basis. The construction priority does affect the frequency of inspections that will be conducted by City staff. See Section IV. 1 for more details on construction BMP requirements.] \A) High Priority 1) Projects where the site is 50 acres or more and grading will occur during the rainy season 2) Projects 1 acre or more. 3) Projects 1 acre or more within or directly adjacent to or discharging directly to a coastal lagoon or other receiving water within an environmentally sensitive area 4) Projects, active or inactive, adjacent or tributary to sensitive water bodies B) Medium Priority 5) Capital Improvement Projects where grading occurs, however a Storm Water Pollution Prevention Plan (SWPPP) is not required under the State General Construction Permit (i.e., water and sewer replacement projects, intersection and street re-alignments, widening, comfort stations, etc.) 6) Permit projects in the public right-of-way where grading occurs, such as installation of sidewalk, substantial retaining walls, curb and gutter for an entire street frontage, etc. , however SWPPPs are not required. 7) Permit projects on private property where grading permits are required, however, Notice Of Intents (NOIs) and SWPPPs are not required. C) Low Priority 8) Capital Projects where minimal to no grading occurs, such as signal light and loop installations, street light installations, etc. 9) Permit projects in the public right-of-way where minimal to no grading occurs, such as pedestrian ramps, driveway additions, small retaining walls, etc. 10) Permit projects on private property where grading permits are not required, such as small retaining walls, single-family homes, small tenant improvements, etc. Owner/Agent/Engineer Name (Please Print): 6&>JS&£ &'/)/?# Signature: / >^~^/"^>?ftA fs/S&l/ Title: t/t/SC fiLl£MJ£&/£ Date: APPENDIX C PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX C: CITY OF CARLSBAD STANDARDS EXCERPTS Table 1: Standard Development Project & Priority Project Storm Water BMP Requirements Matrix Standard Projects Site Design BMPs(l) R Source Control BMPs(2) R BMPs Applicable to Individual Priority Project-Categories (3)a. Private RoadsO b. Residential Driveways & GuestParkingO O 0 CO I S •d O e. Vehicle Wash AreasO •£ <4- O f bh O h. Surface Parking AreasO i O eo 1 •«—» 0 Treatment Control BMPs(4) O Priority Projects: Detached Residential Development Attached Residential Development Commercial Development > 100,000 ft2 Automotive Repair Restaurants Hillside Development <5, 000 ft2 Parking Lots Streets, Highways, & Freeways R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R(5) R R R S S S S S S S S R = Required; select one or more applicable and appropriate BMPs from the applicable steps in Section III.2.a-d, or equivalent as identified in Appendix C. O = Optional or may be required by City Staff. As appropriate, applicants are encouraged to incorporate treatment control BMPs and BMPs applicable to individual priority project categories into the project design. City staff may require one or more of these BMPs, where applicable. S = Select one or more applicable and appropriate treatment control BMPs from Appendix C. (1) Refer to Section IH.2.A. (2) Refer to Section IH.2.B. (3) Priority Project categories must apply specific storm water BMP requirements, where applicable. Priority projects are subject to the requirements of all priority project categories that apply. (4) Refer to Section IH.2.D. (5) Applies if the paved area totals >5,000 square feet or with >15 parkign spaces and is potentially exposed to urban run-off. Source: City of Carlsbad Public Works Department Standard Urban Storm Water Mitigation Plan Storm Water Standards (April 2003, page 8) PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX C: CITY OF CARLSBAD STANDARDS EXCERPTS Table 2: Anticipated and Potential Pollutants Generated by Land Use Type Project Categories Detached Residential Development Attached Residential Development Commercial Development > 100,000 ft2 Automotive Repair Restaurants Hillside Development <5, 000 ft2 Parking Lots Streets, Highways, & Freeways Notes: General Pollutant Categories Sediments X X pd) X p(l) X Nutrients X X pd) X pd) pd)X Heavy Metals X X X Organic Compounds pro X(4)(5) X(4) Trash & Debris X X X X X X X - Oxygen Demanding Substances X pd) p(5) X X pd) p(5) Oil & Grease X p(2) X X X X X X Bacteria & Viruses X pd) p(3) X Pesticides X X p(5) X pd) X = Anticipated P = Potential (1) A potential pollutant if landscaping exists on-site. (2) A potential pollutant if the project includes uncovered parking areas. (3) A potential pollutant is land use involves food or animal waste areas. (4) Including petroleum hydrocarbons. (5) Including solvents. Source: City of Carlsbad Public Works Department Standard Urban Storm Water Mitigation Plan Storm Water Standards (April 2003, page 12) PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX C: CITY OF CARLSBAD STANDARDS EXCERPTS Table 3: Numeric Sizing Treatment Standards Volume 1. Volume-based BMPs shall be designed to mitigate (infiltrate, filter, or treat) the volume of run-off produced from a 24-Hour 85th percentile storm event, as determined from Isopluvial maps contained in the County of San Diego Hydrology Manual. OR Flow 2. Flow-based BMPs shall be designed to mitigate (infiltrate, filter, or treat) the maximum flow rate of run-off produced from a rainfall intensity of 0.2 inch of rainfall per hour for each hour of a storm event. Source: City of Carlsbad Public Works Department Standard Urban Storm Water Mitigation Plan Storm Water Standards (April 2003, page 20) PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX C: CITY OF CARLSBAD STANDARDS EXCERPTS Table 4: Structural Treatment Control BMP Selection Matrix Pollutant Of Concern Sediment Nutrient Heavy Metals Organic Compounds Trash & Debris Oxygen Demanding Substances Bacteria Oil& Grease Pesticides Treatment Control BMP Categories Biofilters M L M U L L U M U Detention Basins H M M U H M U M U Infiltration Basins (1) H M M U U M H U U Wet Ponds or Wetlands H M H U U M U U U Drainage Inserts L L L L M L L L L Filtration H M H M H M M H U Hydrodynamic Separator Systems (2) M L L L M L L L L Notes: (1) Including trenches and porous pavement. (2) Also known as hydrodynamic devices and baffle boxes L: Low removal efficiency M: Medium removal efficiency H: High removal efficiency U: Unknown removal efficiency Sources: Guidance Specifying Management Measures for Sources ofNonpoint Pollution in Coastal Waters (1993), National Stormwater Best Management Practices Database (2001), and Guide for BMP Selection in Urban Development Areas (2001). Source: City of Carlsbad Public Works Department Standard Urban Storm Water Mitigation Plan Storm Water Standards (April 2003, page 21) PRELIMINARY STANDARD URBAN STORM WATER MITIGATION PLAN LA COSTA GLEN OFFICES APPENDIX C: CITY OF CARLSBAD STANDARDS EXCERPTS Stomfi Water Standards Af'i'ENDiX B OMRONMEimLLY AENSfllVE AREAS WITHIN THE CITV OF CARLSSAD APPENDIX D PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX D: DRAINAGE STUDY Please see attached. PRELIMINARY DRAINAGE STUDY FOR LA COSTA GLEN SKILLED NURSING CENTER EXPANSION Original: January 28,2008 JN: 021039 Prepared by: O'Day Consultants, Inc. 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92010-6609 Tel: (760)-931-7770 Fax: (760)-931-8680 George O'Day RCE 32014 Date Exp. 12/31/08 PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION TABLE OF CONTENTS DECLARATION OF RESPONSIBLE CHARGE 1 1.0 INTRODUCTION 2 1.1 PURPOSE OF STUDY : 2 1.2 SITE CHARACTERISTICS 2 1.2.1 Existing Conditions , 2 1.2.2 Proposed Conditions 2 1.3 SOIL CLASSIFICATION 3 1.4 SITE VICINITY MAP 3 2.0 RATIONAL METHOD DESCRIPTION 4 3.0 RUNOFF CALCULATIONS 4 3.1 EXISTING CONDITION 4 3.2 PROPOSED CONDITION 5 3.3 EXISTING AND PROPOSED RUNOFF COMPARISON 5 4.0 CONCLUSION 6 5.0 REFERENCES 7 APPENDICES: APPENDIX A - EXHIBITS • EXISTING CONDITION HYDROLOGY MAP • PROPOSED CONDITION HYDROLOGY MAP • HYDROLOGIC SOILS GROUPS APPENDIX B - HYDROLOGY CHARTS • RAINFALL ISOPLUVIALS • INTENSITY DURATION DESIGN CHARTS • NOMOGRAPH FOR DETERMINATION OF TIME OF CONCENTRATION • RUNOFF COEFFICIENTS FOR URBAN AREAS APPENDIX C - CAPACITY CALCULATIONS • EXISTING STORM DRAIN CAPACITIES PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION DECLARATION OF RESPONSIBLE CHARGE I, hereby declare that I am the Civil Engineer of work for this project, that I have exercised responsible charge over the design of the project as defined in section 6703 of the business and professions code, and that the design is consistent with current design. I understand that the check of the project drawings and specifications by the regulating agency is confined to the review only and does not relieve me, as engineer of work, of my responsibilities for project design. George O'Day, RCE 32014 Date PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 1.0 INTRODUCTION 1.1 PURPOSE OF STUDY The purpose of this preliminary hydrology study is two-fold: 1) to determine the potential hydrologic impacts of the La Costa Glen Skilled Nursing Center Expansion proposed development; 2) to and verify the capacities of the existing drainage facilities to ensure accommodation of the proposed drainage conditions. This report compares the proposed development hydrology condition with the existing hydrology condition using the Rational Method as outlined in the County of San Diego Hydrology Manual, June 2003 (SD County 2003). This report analyzes 100-year six-hour storm event flows for the existing and proposed site conditions. The calculated Q values are used to determine the capacity of existing and proposed drainage structures in accordance with the City of Carlsbad Engineering Standards, 2004 to determine adequacy to accommodate run-off. 1.2 SITE CHARACTERISTICS 1.2.1 Existing Conditions The 4.53 acre site currently consists of a skilled nursing facility building with a footprint of approximately 67,308 square-feet (1.55 acres) and 91 on-grade parking stalls with private driveways along the front and rear of the building. Two separate on-site private drainage systems collect and convey runoff generated on- site to public storm drain systems that ultimately discharge into two separate depollutant basins downstream. See Appendix A for Existing Condition Hydrology Map. 1.2.2 Proposed Conditions The proposed expansion of the skilled nursing facility will increase the current building footprint area to approximately 68,353 square-feet, an increase of 1,045 square-feet. As a result of the larger building footprint, four existing parking stalls will be eliminated, the existing on-site private drainage system will be modified to accommodate expansion and the total impervious surface of the site will have a slight increase. Existing drainage patterns will remain relatively the same except for the said increase of impervious surface. See Appendix A for Proposed Condition Hydrology Map. PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 1.3 SOIL CLASSIFICATION The Soil Hydrologic Group for this preliminary drainage study is Type 'D' soil as determined by using the County of San Diego Hydrology Manual Soil Hydrologic Groups Map. A full size and project specific copy of the Soils Hydrologic Groups Maps are provided in Appendix A. 1.4 SITE VICINITY MAP CITY OF OCEANSIDE CITY OF ENCINITAS VICINITY MAP NO SCALE PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 2.0 RATIONAL METHOD DESCRIPTION The rational method, as described in the SD County 2003 manual, was used to generate surface runoff flows, which were then used to size the proposed drainage facilities and to verify the capacity of the existing drainage facilities. Rational equation: Q = CIA Q = peak discharge in cubic feet per second (cfs) C = runoff coefficient (varies with surface) I = intensity (varies with time of concentration) A = Area in acres The design storm for this project is the 100-year event; the corresponding 6-hour rainfall amount (Pe) and 24-hour rainfall amount (P^) were found using the Isopluvial Charts in Appendix B. The Pe and P^A values are given in the following table. 6-hour and 24-hour Rainfall 2-year 10-year 100-year P6 1.2 1.7 2.7 P24 1.9 3.1 4.5 P*P24(%) 63.2 54.8 60.0 Runoff coefficients for each area were obtained from the table included in Appendix B. For areas with a percentage of impervious area the coefficient was calculated using the formula: C = 0.9(% impervious) + Cp(l-% impervious). Areas (including % impervious) were measured from the hydrology maps shown in Appendix A. 3.0 RUNOFF CALCULATIONS 3.1 EXISTING CONDITION Based on the topography maps the existing site including tributary areas can be subdivided into two drainage areas. The existing drainage areas are illustrated on the Existing Hydrology Map in Appendix A. Corresponding runoff coefficients (C) and rainfall intensity (I) values were derived using the SD County 2003 manual. The table of coefficients and rainfall isopluvials are included in Appendix PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION B. These values were used to calculate the peak flow for the 2-year, 10-year, and 100-year flows (Q) using the Rational Method. The drainage areas and corresponding Q values are summarized below. Basin Existing Drainage Condition No Area C Iioo Qioo Al A2 0.96 acres 1.31 acres 0.74 5.00 in./hr. 0.73 4.67 in./hr. 3.5 cfs 4.5 cfs 3.2 PROPOSED CONDITION The proposed hydrology conditions for the project have been designed to preserve the existing drainage patterns to the maximum extent practicable. The proposed site drainage conditions are shown in Proposed Hydrology Map in Appendix A. The proposed drainage areas, and corresponding Q values are summarized below. Basin No Area C Iioo Qioo Al A2 0.96 acres 1.31 acres 0.75 0.74 5.00 in./hr. 4.91 in./hr. 3.6 cfs 4.7 cfs (1) Area of the proposed site development 3.3 EXISTING AND PROPOSED RUNOFF COMPARISON The difference between the existing and proposed hydrology conditions are shown below. Condition Al A2 QIOO Existing QIOO Proposed Difference 3.5 cfs 3.6 cfs +0.1 cfs 4.5 cfs 4.7 cfs +0.2 cfs Existing Conditions BASIN 1 Overland flow Soil Group D node 100-101 C = 0.49 A = 0.05 acres L = 40 feet S= 1.0 % From Figure 3-3 6.9 minutes From Figure 3-1 Pe = 2.7 inches P24 = 4.5 inches Pe/P24= 60 % Use Pe = 2.7 inches I = 7.44P6D*645 I = 5.76 inches/hour Q= CIA Q = 0.1 cfs Pipe Flow (6" PVC @ 1%) node 101-102 subarea addition = 0.96 acres L = 245 feet savg= 1.0 % assume Qav9= 0.1 cfs V = 2.4 fps T, = 1.7 minutes Tc = 8.6 minutes I = 5.00 inches/hour A1= 0.47 acres (Roof Top) A2= 0.49 acres (Landscape) C1= 1.00 acres (Roof Top) C2= 0.49 acres (Landscape & Hardscape, 30% impervious) C = ((C1 (A1 )+C2(A2))/(A1 +A2) = 0.74 A = 0.96 acres Q = 3.5 cfs Existing Conditions BASIN 2 Overland flow Soil Group D node 200-201 C = 0.35 A = 0.05 acres L = 75 feet S = 2.5 % From Figure 3-3 T= 1.8(1.1-CM.1* T| = 8.6 minutes From Figure 3-1 P6 = 2.7 inches P24 = 4.5 inches Pe/Poj— CQ W Use P6 = 2.7 inches I = 7.44P6D"° •845 I = 5.00 inches/hour Q= CIA Q= 0.1 cfs Pipe Flow (6" PVC @ 3.5%) node 201-202 L= 217 feet savg = 3.5 % assume Qavg = 0.1 cfs V = 3.8 fps Tt = 1.0 minutes Tc = 9.6 minutes I = 4.67 inches/hour A1= 0.41 acres (Roof Top) A2= 0.42 acres (AC Pvmt) A3= 0.48 acres (Landscape) C1= 1.00 acres (Roof Top) C2= 0.90 acres (AC Pvmt) C3= 0.35 acres (Landscape) C = ((C1 (A1 )+C2(A2)+C3(A3))/(A1 +A2+A3) = 0.73 A = 1.31 acres Q = 4.5 cfs Proposed Conditions BASIN 1 Overland flow node 100-1 01 C = A = L = S= Soil Group D 0.49 0.05 acres 40 feet 1.0 % From Figure 3-3 T= 1.8(1.1-GIL" I, = 6.9 minutes From Figure 3-1 P6 = P24 = Use P6 = 2.7 4.5 60 2.7 inches inches % inches Q = Q = r6l- 5.76 CIA 0.1 inches/hour cfs Pipe Flow (6" PVC @ 1%) node 101-102 >area iaddition L Savj assume Q^g V = T,= T0 = l = 2.4 1.7 8.6 5.00 = 0.96 245 1.0 0.1 fps minutes minutes acres feet % cfs inches/hour A1= 0.48 acres (Roof Top) A2= 0.48 acres (Landscape) C1= 1.00 acres (Roof Top) C2= 0.49 acres (Landscape & Hardscape, 30% impervious) C= ((C1(A1)+C2(A2))/(A1+A2) = 0.75 A = 0.96 acres Q = 3.6 cfs Proposed Conditions BASIN 2 Overland flow Soil Group D node 200-201 C = 0.35 A = 0.05 acres L = 30 feet S= 1.0 % From Figure 3-3 T= 1.8M.1-OL1'2 I, = 7.4 minutes From Figure 3-1 P6 = 2.7 inches ?24 = 4.5 inches Pe/P24= 60 % Use Pe = 2.7 inches I = 7.44P6D-°645 I = 5.53 inches/hour Q= CIA Q= 0.1 cfs Pipe Flow (6" PVC @ 1%) node 201-202 L = 78 feet sawg= 1.0 % assume Qavg = 0.1 cfs V = 2.4 fps Tn = 0.5 minutes Pipe Flow (6" PVC @ 3.5%) node 202-203 L= 217 feet Savg = 3.5 % assume Qavg = 0.1 cfs V = 3.8 fps T,2 = 1.0 minutes Tc = 8.9 minutes I = 4.91 inches/hour A1= 0.43 acres (Roof Top) A2= 0.41 acres (AC Pvmt) A3= 0.47 acres (Landscape) C1= 1.00 acres (Roof Top) C2= 0.90 acres (AC Pvmt) C3= 0.35 acres (Landscape) C = ((C1 (A1 )+C2(A2)+C3(A3))/(A1 +A2+A3) = 0.74 A = 1.31 acres Q = 4.7 cfs r***************************************** * O'Day Consultants, Inc. * * 2710 Loker Avenue West, Suite 100 * *: Carlsbad, CA 92008 * * Tel: 760-931-7700 Fax: 760-931-8680 * Inside Diameter ( 6.00 in.) * * * * * Water * ( 1.57 in.) ( 0.131 ft.) | * * I * v Circular Channel Section Flowrate 0.100 CFS Velocity 2.438 fps Pipe Diameter 6.000 inches Depth of Flow 1.572 inches Depth of Flow 0.131 feet Critical Depth 0.156 feet Depth/Diameter (D/d) 0.262 Slope of Pipe 1.000 % X-Sectional Area 0.041 sq. ft, Wetted Perimeter 0.537 feet ARA (2/3) 0.007 Mannings 'n1 0.011 Min. Fric. Slope, 6 inch Pipe Flowing Full 0.023 % * *l * ! * ************ O'Day Consultants, Inc. 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92008 Tel: 760-931-7700 Fax: 760-931-8680 r*************** * * * * Inside Diameter ( 6.00 in.) Water * ( 1.15 in.) ( 0.096 ft.) v Circular Channel Section Flowrate 0.100 CFS Velocity 3.789 fps Pipe Diameter 6.000 inches Depth of Flow 1.153 inches Depth of Flow 0.096 feet Critical Depth 0.157 feet Depth/Diameter (D/d) 0.192 Slope of Pipe 3 .500 % X-Sectional Area 0.026 sq. ft Wetted Perimeter 0.454 feet ARA(2/3) 0.004 Mannings ' n' 0.011 Min. Fric. Slope, 6 inch Pipe Flowing Full 0.023 % PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 4.0 CONCLUSION The net increase in storm water run-off due to the proposed building expansion is approximately 0.1 cfs for Basin Al and 0.2- cfs for Basin A2. Capacity calculations shown in Appendix C, for the existing drainage structures show that the downstream drainage structures are adequate to accommodate the net increase in the 100-year flow. PRELIMINARY DRAINAGE STUDY LA COSTA GLEN SKILLED NURSING CENTER EXPANSION 5.0 REFERENCES City of Carlsbad, Engineering Standards, 2004. San Diego County Hydrology Manual, County of San Diego Department of Public Works Flood Control Section, 2003. PRELIMINARY DRAINAGE STUDY LA COSTA GLEN OFFICES APPENDIX A - EXHIBITS • EXISTING CONDITION HYDROLOGY MAP • PROPOSED CONDITION HYDROLOGY MAP • HYDROLOGIC SOILS GROUPS PRELIMINARY DRAINAGE STUDY LA COSTA GLEN OFFICES APPENDIX B - HYDROLOGY CHARTS • RAINFALL ISOPLUVTALS • INTENSITY DURATION DESIGN CHARTS • NOMOGRAPH FOR DETERMINATION OF TIME OF CONCENTRATION • RUNOFF COEFFICIENTS FOR URBAN AREAS I f 32-301 - j-.j...i~t-4 " ' ••--•••• i •-County of San Diego Hydrology Manual Rainfall Isopluvials 2 Year Rainfall Event - 6 Hours Isopluvlal (Inches) <CV^^? SkHlwSaan,.CIS N "--H 303 Miles >—Xi 39-CO1 32-451 County of San Diego Hydrology Manual Rainfall Isopluvials 2 Year Rainfall Event-24 Hours Isopkwlal (Inches) DPW CIS N TSSSiXSSSS 303 Miles T t ?1 .- -Ti,_ ,4 ,--, i --«:- i .-,-, i-i f-!-' 1-i-i-jp.i-, ... . 33'HQ1 331S1 ayeo1 10 Year Rainfall Event - 6 Hours County of San Diego Hydrology Manual f 33-301 3T301 County of San Diego Hydrology Manual Rainfall Isopluvials 10 Year Rainfall Event- 24 Hours Isopluvlal (Inches) CIS 33-00- 32-4S1 (2-301 County of San Diego Hydrology Manual Rainfall Isopluvials 100 Year RainfaU Event- 6 Hours loopluvlal (kidws) 303 Miles 33°30< County of Saa Diego Hydrology Manual Rainfall Jsopluvials 100 Yew Rain&ll Event - 24 Hours Isopluvfal (Inches) CIS 303 Miles Address igj http://www.co.san-diego.ca.us/dpw/watersheds/pubs/susmp_85precip.pdf HEDIONDA LAGOON BAT1QUITOS LAGOON SANELUO LAGOON « 48X36in ] D -H !.? pAutodeSklandD..|jfiwocleskLandD...{ 0 10:45 AM 0.1 6 7 8 9 10 Directions for Application: (1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are included in the County Hydrology Manual (10,50, and 100 yr maps included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert). (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a line through the point parallel to the plotted lines. (5) This line is the intensity-duration curve for the location being analyzed. Application Form: (a) Selected frequency.year Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. isj JM JH300 - 2,83 -3.95 iUMili 1.68i2[53ltaTTi IMS! 0.41 J0.61 o.44HW*SM£ML-^.0.19 :0ifl!o.38 0.17 TfTM't SJZ7 4.24 3.37 2£» d^i5*817-90 MjTiM»Tr;«unsung &24J3.89J4.S4 li^'^^'iSoj J.^«|..k7?.L2;07]2.41 1.79 2.09 O88 fojaeti Jiz] iTiil :9^^J3JP-8Bil.«»I052 aesToTBToSit " i^'O^sJM? 4.-.J»|OJI8i 0>rr£56]0.6f1/1 asio.33To.42 .disbi" «• Ttirnr- ^ —-j-y- 67745758 6.1818784 11JB6J13.17J 14.49] 155T 10JMTfl.e®iT2:72| JW2Jft27fiO.111 TiTViFir 4.85 ',,^^J._. ] &13T5.60 3^!l!*-JlS 14.66 ]4:'98 3.10J J-32 5.39 " 3.45 ' 3179 I 4.13 2.98 i 3^8 '3.58 8j85j2.92T3li8 Zp4r_2.25i2.45. i.Tp i 1.87 ! 2.04 1.47 ; 1.62 ! 1.76 1.31 I i:44j'i.57 iiM- i.19 11.30 0.94 ; {.03 r i.13ae4': b792! 1.00 Intensity-Duration Design Chart - Example FIGURE 3-2 EQUATION = 7.44 P6 IT0-645 I = Intensity (in/hr) P6= 6-Hour Precipitation (in) 0 = Duration (min) Dinction* for Application: (1) From precipitation maps determine 6 hr and 24 hr amounts lor the selected frequency. These maps are inducted in the County Hydrology Manual (10,50, and 100 yr maps included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (not applicapte to Desert). (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a line through the point parallel to the plotted lines. (5) This line is the intensity-duration curve for the location being analyzed. Application Form: (a) Selected frequency 0) pe = /'2y in., PoxV ^••^^•^^™» £*T I.I(c) Wfc ,(2)s_ _min. io/hr. o/0<2) Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. 1?-S4J 11JS6JJ3.17! 14.48! 15.81isi Poiii^6i"!a78.42T 9i7"Tiai"i 90 0.41 ;0,61 Jki?.UJ"4J^i?.i.'f-«wi.06ji.33TT59:i.ae^LiMIiJssjixs 1-63JJ!:** T 2JM ! 2.25 I 2.4534«j±^i"?*TW'i2JM- 1.08'i"u9i 1.30 0.85 ! 0.94 1,03 Ti .13 a7'sTb.64':'a92 ! 1.00 Intensity-Duration Design Chart • Example F I G P R 3-2 1 | 10.0 : 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 i i|i-o 1 0.6 1 0.7 0.6 0.5 0.4 0.3 °-2 0.1 i ^"IS^^sT*1 Sx7Sx,L* w|X>v sHSJ" !• b 1i > i j | ^ ^ssJ" i s <i^*v 1i X i ! 1 \ : \ ! | i MM :\ ! i i ! ' i { > ,4_j— f- -H _L_ Zl" — ? E 1 s s N i_ . f" *vps ; S*,S Xi ^TS >si s! i i ! ! I ™-U -T- f :: hs * Ni V » S X » K, ~ _. j !b> h ^ ^^ > s > s •*, N t11 « N N X s N n ; k" s > v »( ^^S X T»• k^ *s 'N, !••• M«••a !••!•• 1 T j i I n *i/S! '| N' M;I((* ». '«? • v s « x t • * '.. > i :;".;j "••.] i ., ••hi! :i j -. -v !!• '"'I ' ^ "1" '? ^T I , t 1 IBBBIIIIIUIIUIIHIIIBII inaniii»i>iiiu>iiin«iiBi ::::::::: :j :: :::: -:::::.:. -t r » * T T " | T t f tt 1 = 7.' P6= 6*; " ' ' D = DI ', 'l. ll'l<\1'•!!'" ' > , N:""•' J1 1 ^ i: : :iJ N 1 IDfWH' s IflllllllllillllllllllllMi ( EOLATION M P6 0-0.645 tensity (in/hr) Hour Precipitation (in oration (min) s s s s ^ 1 ^ N ™ s s > s s s ™ J s >ss > Nh S >, N % ^ N . ^ N Ni - ™ ™ ;^j: 55i S ''r l(\ "s '"' ^ ' I N '"''' *'«, * • ^.^•••••1 •••••^^••l• •••••.^•1MHHMMHJI^*' > 6 T 8 9 10 15 20 30 40 50 1 2 34 Minutes Hours Duration i t !., Diractk • • (1) Fror fortl Couj inth (2)Adji )the "KK _ n\ pint (5) This oeki Applia t (a) Sefc '! M| (c)Adju ' 6.5 S ... ' ' 4'6 "s tel 1 - Imm 4JO | w . 3'5 ~ Note: T MIS for Application: n precipitation maps determine 6 hr and 24 hr amounts ne selected frequency. These maps are included in the nty Hydrology Manual (10, 50, and 100 yr maps included e Design and Procedure Manual). ist 6 hr precipitation (if necessary) so that it is within range of 45% to 65% of the 24 hr precipitation (not icaple to Desert). 6 hr precipitation on the right side of the chart. * a line through the point parallel to the plotted lines. line is the intensity-duration curve for the location g analyzed. ittonForm: «ted frequency J3i? year istedP6<2>=_s2JLin. 3>1L_ in-/hr. .,-, -^ ,„ "* 7 > f f his chart replaces the Intensity-Duration-Frequency urves used since 1965. w,..."^...l j.34. 2.0 5 : : ; : f: in iiiiiim ••^^^••••rn »••»"" ^^^^^•^^HaJ• ••••III! •••••••••• IIHIlBH^n 1 30 10 *"SO 60 120 ISO 180 6 300 360 2.63 ^3.95 ?r?2 .3.tf 1.68 i2^f 1^30 Tl.95 O.S3 ' 1 4D nrt"r~t""F~t~ir-rTi~-V"-i --\-f-\ • f SZTt 6.59:750(9^2110^4111,86! 13.17! 14.49; 15.81 jySi! &M i 646.7.421 8.48 f 9.54 i 10.60J 11.66'; 12.72 i3.37 ! 4.21 -5X3Si 5.90' 6.74 '• 7,S8'I SL42 i 9^27 M6 Vi 2.»|jL24T3.89j4.54! 5.19 i 5.84 i 6.49 ! 7.13 i 7.78 2.15! 2i69j3\23; 3.77! 4.31 '• 4.85! 5.39 f Slw 1 6.46"i tei ', 9 *i 1 1> an \ <t vrt i -rn ; A en i ~A e-j~?"~i!"i'<i'""='^n 083 i1J4!1.6Sl 2.07 12.49 !2.'90|.3.32'1 173 1 4.15 ! 4.56 4.98 0.69 :1.03]1.38li.72!.i07i2.4t! 2.76~; 3.10 3.45 3.79 413 ^ 0.60 ,090! 1.19" 1.49 i1.79i2.69! 2.39 | 2.69 '2.98 3.28 3.5S 0.53 (OjO 0.41 toll jBJ4.{0.5f 0.26 10.39 "6i22 ;6^» 0.19 IOJ28 1.06] 1.33 ; 1.59; 1.86i 2.12 j 2.39 2.65 ~ 2.92 3.18 JDUK: 1.02 iljaii^SJ" 1,63 j. 1,84 2.04 2J2S 2.45 0-e8jO.855l.02i1.t9i 1.36 i 1.53"1.70 1.87 2.04 OS»', 0.73 :OJ8i 1.03! 1.18 !"l'.32~ 1.47 162 176 a$2T0.65j6.78!6^iTi.04 ! 1.1JB 1.31 1.44 Y57 0.43 ! 0.54 : 0.65 ! 6.76] 6.87 I 0.98 " i .08 i! 19 1 .30 a38i647jb.56Vpj66! 0.76; 0^5 0.94 1.03 1.13 0.33. 0.42 0.50! 0.58; 6.67 : 0^75 0.84 0.92 1 00 Intensity-Duration Design Chart - Template FIGURE 3-1 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 6 of 26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use NRCS Elements Undisturbed Natural Terrain (Natural) Low Density Residential (LDR) Low Density Residential (LDR) Low Density Residential (LDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MDR) High Density Residential (HDR) High Density Residential (HDR) Commercial/Industrial (N. Com) Commercial/Industrial (G. Com) Commercial/Industrial (O.P. Com) Commercial/Industrial (Limited I.) ; Commercial/Industrial (General I.) County Elements Permanent Open Space Residential, 1.0 DU/A or less Residential, 2.0 DU/A or less Residential, 2.9 DU/A or less Residential, 4.3 DU/A or less Residential, 7.3 DU/A or less Residential, 10.9 DU/A or less Residential, 14.5 DU/A or less Residential, 24.0 DU/A or less Residential, 43.0 DU/A or less Neighborhood Commercial General Commercial Office Professional/Commercial Limited Industrial General Industrial Runoff Coefficient "C" %IMPER. 0* 10 20 25 30 40 45 50 65 80 80 85 90 90 95 A 0.20 0.27 0.34 0.38 0.41 0.48 0.52 0.55 0.66 0.76 0.76 0.80 0.83 0.83 0.87 Soil B 0.25 0.32 0.38 0.41 0.45 0.51 0.54 0.58 0.67 0.77 0.77 0.80 0.84 0.84 0.87 Type C 0.30 0.36 0.42 0.45 0.48 0.54 0.57 0.60 0.69 0.78 0.78 0.81 0.84 0.84 0.87 D 035) 0.41 0.46 0.49 0.52 0.57 0.60 0.63 0.71 0.79 0.79 0.82 ;~v0.85,/ 0.85 0.87 j The values associated with 0% impervious may be used for direct calculation of the i coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuity. is located in Cleveland National Forest). DU/A = dwelling units per acre NRCS = National Resources Conservation Service runoff coefficient as described in Section 3.1.2 (representing the . Justification must be given that the area will remain natural forev „ — pervious runoff natural forever (e.g., the area 3-6 PRELIMINARY DRAINAGE STUDY LA COSTA GLEN OFFICES APPENDIX C - CAPACITY CALCULATIONS • EXISTING STORM DRAIN CAPACITIES *********! * * * *' O'Day Consultants, Inc. 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92008 Tel: 760-931-7700 Fax: 760-931-8680 Inside Diameter ( 18.00 in.) Water 16.88 in.) 1.407 ft.) v Circular Channel Section Flowrate 24 .910 CFS ^ ••/*iAX« Velocity 14.468 fps Pipe Diameter 18.000 inches Depth of Flow 16.884 inches Depth of Flow 1.407 feet Critical Depth Greater than Pipe Diameter Depth/Diameter (D/d) 0.938 Slope of Pipe 4.860 % X-Sectional Area 1.722 sq. ft. Wetted Perimeter 3.957 feet ARA (2/3) 0.989 Mannings 'n' 0.013 Min. Fric. Slope, 18 inch Pipe Flowing Full 5.624 % APPENDIX E PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX E: BENEFICIAL USES OF COASTAL WATERS Please see attached. Table 2-3. BENEFICIAL USES OF COASTAL WATERS Coastal Waters Hydrologic Unit Basin Number BENEFICIAL USE I N D Coastal Lagoons - continued .... 2 Buena Vista Lagoon Loma Alta Slough Mouth of San Luis Rey River Santa Margarita Lagoon Aliso Creek Mouth San Juan Creek Mouth San Mateo Creek'Mouth San Onofre Creek Mouth 4.21 4.10 3.11 2.11 1.13 1.27 1.40 1.51 N A V R E C 1 • • • • • • • • R E C 2 • • • • • • • • C O M M B I 0 L • • E S T 0 • • W I L D R A R E : * • • • • • • • • • • ' • • • • • M A R A Q U A • • • • • • • • • M 1 G R • • • • ' • S P W N W A R M S H E L L • • • •• • ' Includes the tidal prisms of the Otay and Sweetwater Rivers. 2 Fishing from shore or boat permitted, but other water contact recreational (REC-1) uses are prohibited. • Existing Beneficial Use O Potential Beneficial Use Table 2-3 BENEFICIAL USES 2-48 March 12, 1997 APPENDIX F PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX F: 2002 CWA SECTION 303(d) LIST OF WATER QUALITY LIMITED SEDIMENT Please see attached. 2002 CWA SECTION 303(d) LIST OF WATER QUALITY LIMITED SEGMENT SAN DIEGO REGIONAL WATER QUALITY CONTROL BOARD t,,md ty U5EPA: July 2003 REGION TYPE NAME CALWATER POTENTIAL' WATERSHED POLLOTANT/ST&ESSOR' SOURCES TMDL ESTIMATED PROPOSED TMDL PRIORITY SIZE AFFECTED COMPLETION C Pacific Ocean Shoreline, San Diequito HU C Pacific Ocean Shoreline, San Joaquin Hills HSA 9 C Pacific Ocean Shoreline, San Luis Rey HU 4 •" 9 C Pacific Ocean Shoreline, San Marcos HA 9 C Pacific Ocean Shoreline, Scripps HA 9 C Pacific Ocean Shoreline, Tijuana HU 9 R Pine Valley Creek (Upper) 90511000 90111000 90311000 90451000 90630000 91111000 91141000 Bacteria Indicators Low Impairment located at San Dieguito Lagoon Mouth, Solana Beach. Nonpoint/Point Source 0.86 Miles Bacteria Indicators Low 0.63 Miles Impairment located at Cameo Cove at Irvine Cove Dr. /Riviera Way, Heisler Park-North Urban Runoff/Storm Sewers Unknown Nonpoint Source Unknown point source Bacteria Indicators Impairment located at San Luis Rey River Mouth. Nonpoint/Point Source Bacteria Indicators Impairment located at Moonlight State Beach. Nonpoint/Point Source Low Low 0.49 Miles 0.5 Miles Bacteria Indicators Medium 3.9 Miles Impairment located at La Jolla Shores Beach at El Paseo Grande, La Jolla Shores Beaob at Caminito Del Oro, La Mia Shores Beach at Vallecitos, La Jolla Shores Beach at Ave de la Play a, Casa Beach (Childrens Pool), South Casa Beach at Coast Blvd., Whispering Sands Beach at Ravina St., Windansea Beach at Vista de la Playa, Windansea Beach at Bonair St., Windansea Beach at Playa del Norte, Windansea Beach at Palomar Ave., Tourmaline Surf Park, Pacific Beach at Grand Ave. Nonpoint/Point Source Bacteria Indicators Low Impairment located from the border, extending north along the shore. Nonpoint/Point Source Enterococci Medium Grazing-Related Sources Concentrated Animal Feeding Operations (permitted, point source) Transient encampments 3 Miles 2.9 Miles Page 7 of 16 APPENDIX G PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX G: SOURCE CONTROL BMP FACT SHEETS Please see attached. 17.0'13.0',<-MORTAR FILLED BLOCK WALL PER CITY OF CARLSBAD MASONRY FENCE ^ACCESS WAY 6" STRIP (TYP.) WHEREAPPLICABLETRASH BIN (3 CY TYPICAL) 6"0 CONCRETE FILLED IRON POST,3"PROTECTION POST(MOO. W-16) 11 OPTION CONT OFJIN-4 I ^- 0.5% (TYP.) FERROUS METAL 12"x12" DRAIN ROLL OUT I ill IMI YCLABLE INSTEAD [0.5% (TYP.) -— REFUSE TRUCK LOADING APPROACH ->- 0.5X(TYP.) LEVEL LOADING AREA | (CONCRETE)REFUSE TRUCK LOADING APPROACH DRAIN AWAY (TYP.) TYPE A - DRIVE AND LOAD FRONT APPROACH 15.0'(MIN.) = rTL_ CLEAR OVERHEAD - CLEAROVERHEAD TO 25.0 FT. HEIGHT I3.5'(MIN.)'HEIGHT TYPE B - DRIVE AND LOAD SIDE APPROACH UN i x JnF X6"RETC OVER (MIN.) A.B. 13.0' •x8" FOUNDATION DRAIN TO BMP (TYP.) SECTION A-A 8" r24' (TYP.) (TYP.)SECTION B-B SHEET 1 OF 2 .EV.APPROVED DATE CITY OF CARLSBAD REFUSE BIN ENCLOSURE FOR 3 CUBIC YARDS BINS 6-04 CITY ENGINEER DATE SUPPLEMENTAL STANDARD NO. Site Design & Landscape Planning SD-10 Design Objectives SSSKSraSaSSS3!5aSiSSSiB3!SSS3S£SSS3SS£S£S3S^^ 0 Maximize Inflation 0 Provide Retention 0 Slow Runoff r* Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Description Each project site possesses unique topographic, hydrologie, and vegetative features, some of which are more suitable for development than others. Integrating and incorporating appropriate landscape planning methodologies into the project design is the most effective action that can be done to minimize surface and groundwater contamination from stormwater. Approach Landscape planning should couple consideration of land suitability for urban uses with consideration of community goals and projected growth. Project plan designs should conserve natural areas to the extent possible, maximize natural water storage and infiltration opportunities, and protect slopes and channels. Suitable Applications Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. Design Considerations Design requirements for site design and landscapes planning should conform to applicable standards and specifications of agencies with jurisdiction and be consistent with applicable General Plan and Local Area Plan policies. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com Iof4 SD-10 Site Design & Landscape Planning Designing New Installations Begin the development of a plan for the landscape unit with attention to the following general principles: • Formulate the plan on the basis of clearly articulated community goals. Carefully identify conflicts and choices between retaining and protecting desired resources and community growth. • Map and assess land suitability for urban uses. Include the following landscape features in the assessment: wooded land, open unwooded land, steep slopes, erosion-prone soils, foundation suitability, soil suitability for waste disposal, aquifers, aquifer recharge areas, wetlands, fioodplains, surface waters, agricultural lands, and various categories of urban land use. When appropriate, the assessment can highlight outstanding local or regional resources that the community determines should be protected (e.g., a scenic area, recreational area, threatened species habitat, farmland, fish run). Mapping and assessment should recognize not only these resources but also additional areas needed for their sustenance. Project plan designs should conserve natural areas to the extent possible, maximize natural water storage and infiltration opportunities, and protect slopes and channels. Conserve Natural Areas during Landscape Planning If applicable, the following items are required and must be implemented in the site layout during the subdivision design and approval process, consistent with applicable General Plan and Local Area Plan policies: • Cluster development on least-sensitive portions of a site while leaving the remaining land in a natural undisturbed condition. • limit clearing and grading of native vegetation at a site to the minitmipn amount needed to build lots, allow access, and provide fire protection. • Maximize trees and other vegetation at each site by planting additional vegetation, clustering tree areas, and promoting the use of native and/or drought tolerant plants. • Promote natural vegetation by using parking lot islands and other landscaped areas. • Preserve riparian areas and wetlands. Maximize Natural Water Storage and Infiltration Opportunities Within the Landscape Unit m Promote the conservation of forest cover. Building on land that is already deforested affects basin hydrology to a lesser extent than converting forested land. Loss of forest cover reduces interception storage, detention in the organic forest floor layer, and water losses by evapotranspiration, resulting in large peak runoff increases and either their negative effects or the expense of countering them with structural solutions. • Maintain natural storage reservoirs and drainage corridors, including depressions, areas of permeable soils, swales, and intermittent streams. Develop and implement policies and 2 of 4 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.ojm Site Design & Landscape Planning SD-10 regulations to discourage the clearing, filling, and channelization of these features. Utilize them in drainage networks in preference to pipes, culverts, and engineered ditches. • Evaluating infiltration opportunities by referring to the stonnwater management manual for the jurisdiction and pay particular attention to the selection criteria for avoiding groundwater contamination, poor soils, and hydrogeological conditions that cause these facilities to fail. If necessary, locate developments with large amounts of impervious surfaces or a potential to produce relatively contaminated runoff away from groundwater recharge areas. Protection of Slopes and Channels during Landscape Design m Convey runoff safely from the tops of slopes. • Avoid disturbing steep or unstable slopes. • Avoid disturbing natural channels. • Stabilize disturbed slopes as quickly as possible. • Vegetate slopes with native or drought tolerant vegetation. • Control and treat flows in landscaping and/or other controls prior to reaching existing natural drainage systems. • Stabilize temporary and permanent channel crossings as quickly as possible, and ensure that increases in run-off velocity and frequency caused by the project do not erode the channel. • Install energy dissipaters, such as riprap, at the outlets of new storm drams, culverts, conduits, or channels that enter unlined channels in accordance with applicable specifications to minimize erosion. Energy dissipaters shall be installed in such a way as to minimize impacts to receiving waters. • line on-site conveyance channels where appropriate, to reduce erosion caused by increased flow velocity due to increases in tributary impervious area. The first choice for linings should be grass or some other vegetative surface, since these materials not only reduce runoff velocities, but also provide water quality benefits from filtration and infiltration. If velocities in the channel are high enough to erode grass or other vegetative linings, riprap, concrete, soil cement, or geo-grid stabilization are other alternatives. • Consider other design principles that are comparable and equally effective. Redeveloping Existing Installations Various jurisdictional stonnwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of " redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations" above should be followed. January 2003 California Stormwater BMP Handbook 3 of 4 New Development and Redevelopment www.cabmphandbooks.com SD-10 Site Design & Landscape Planning Redevelopment may present significant opportunity to add features which had not previously been implemented. Examples include incorporation of depressions, areas of permeable soils, and swales in newly redeveloped areas. While some site constraints may exist due to the status of already existing infrastructure, opportunities should not be missed to maximize infiltration, slow runoff, reduce impervious areas, disconnect directly connected impervious areas. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of PubKc Works, May 2002. Stormwater Management Manual for Western Washington, Washington State Department of Ecology, August 2001. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14,2002. Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003. Ventura Counrywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 4 of 4 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Roof Runoff Controls SD-11 Design Objectives Maximize Infiltration Provide Retention Slow Runoff Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Rain Garden Description Various roof runoff controls are available to address stormwater that drains off rooftops. The objective is to reduce the total volume and rate of runoff from individual lots, and retain the pollutants on site that may be picked up from roofing materials and atmospheric deposition. Roof runoff controls consist of directing the roof runoff away from paved areas and mitigating flow to the storm drain system through one of several general approaches: cisterns or rain barrels; dry wells or infiltration trenches; pop-up emitters, and foundation planting. The first three approaches require the roof runoff to be contained in a gutter and downspout system. Foundation planting provides a vegetated strip under the drip line of the roof. Approach Design of individual lots for single-family homes as well as lots for higher density residential and commercial structures should consider site design provisions for containing and infiltrating roof runoff or directing roof runoff to vegetative swales or buffer areas. Retained water can be reused for watering gardens, lawns, and trees. Benefits to the environment include reduced demand for potable water used for irrigation, improved stormwater quality, increased groundwater recharge, decreased runoff volume and peak flows, and decreased flooding potential. Suitable Applications Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. Design Considerations Designing New Installations Cisterns or Rain Barrels One method of addressing roof runoff is to direct roof downspouts to cisterns or rain barrels. A cistern is an above ground storage vessel with either a manually operated valve or a permanently open outlet. Roof runoff is temporarily stored and then released for stormwater irrigation or infiltration between storms. The number of rain Association January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbook.cotn 1 of 3 SD-11 Roof Runoff Controls barrels needed is a function of the rooftop area. Some low impact developers recommend that every house have at least 2 rain barrels, with a minimum storage capacity of 1000 liters. Roof barrels serve several purposes including mitigating the first flush from the roof which has a high volume, amount of contaminants, and thermal load. Several types of rain barrels are commercially available. Consideration must be given to selecting rain barrels that are vector proof and childproof. In addition, some barrels are designed witit a bypass valve that filters out grit and other contaminants and routes overflow to a soak-away pit or rain garden. If the cistern has an operable valve, the valve can be closed to store stormwater for irrigation or infiltration between storms. This system requires continual monitoring by the resident or grounds crews, but provides greater flexibility in water storage and metering. If a cistern is provided with an operable valve and water is stored inside for long periods, the cistern must be covered to prevent mosquitoes from breeding. A cistern system with a permanently open outlet can also provide for metering stormwater runoff. If the cistern outlet is significantly smaller than the size of the downspout inlet (say ¥4 to ¥2 inch diameter), runoff will build up inside the cistern during storms, and will empty out slowly after peak intensities subside. This is a feasible way to mitigate the peak flow increases caused by rooftop impervious land coverage, especially for the frequent, small storms. Dry wells and Infiltration Trenches Roof downspouts can be directed to dry wells or infiltration trenches. A dry well is constructed by excavating a hole in the ground and filling it with an open graded aggregate, and allowing the water to fill the dry well and infiltrate after the storm event. An underground connection from the downspout conveys water into the dry well, allowing it to be stored in the voids. To minimize sedimentation from lateral soil movement, the sides and top of the stone storage matrix can be wrapped in a permeable filter fabric, though the bottom may remain open. A perforated observation pipe can be inserted vertically into the dry well to allow for inspection and maintenance. In practice, dry wells receiving runoff from single roof downspouts have been successful over long periods because they contain very little sediment. They must be sized according to the amount of rooftop runoff received, but are typically 4 to 5 feet square, and 2 to 3 feet deep, with a minimum of i-foot soil cover over the top (maximum depth of 10 feet). To protect the foundation, dry wells must be set away from the building at least 10 feet. They must be installed in solids that accommodate infiltration. In poorly drained soils, dry wells have very limited feasibility. Infiltration trenches function in a similar manner and would be particularly effective for larger roof areas. An infiltration trench is a long, narrow, rock-filled trench with no outlet that receives stormwater runoff. These are described under Treatment Controls. Pop-up Drainage Emitter Roof downspouts can be directed to an underground pipe that daylights some distance from the building foundation, releasing the roof runoff through a pop-up emitter. Similar to a pop-up irrigation head, the emitter only opens when there is flow from the roof. The emitter remains flush to the ground during dry periods, for ease of lawn or landscape maintenance. 2 of 3 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbook.com Roof Runoff Controls SD-11 Foundation Planting Landscape planting can be provided around the base to allow increased opportunities for stormwater infiltration and protect the soil from erosion caused by concentrated sheet flow coming off the roof. Foundation plantings can reduce the physical impact of water on the soil and provide a subsurface matrix of roots that encourage infiltration. These plantings must be sturdy enough to tolerate the heavy runoff sheet flows, and periodic soil saturation. Redeveloping Existing Installations Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of " redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations" above should be followed. Supplemental Information Examples • City of Ottawa's Water Links Surface -Water Quality Protection Program • City of Toronto Downspout Disconnection Program • City of Boston, MA, Rain Barrel Demonstration Program Other Resources Hager, Marty Catherine, Stormwater, "Low-Impact Development", January/February 2003. www.stormh2o.com Low Impact Urban Design Tools, Low Impact Development Design Center, Beltsville, MD. www.lid-stormwater.net Start at the Source, Bay Area Stormwater Management Agencies Association, 1999 Edition January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbook.com 3 of 3 Efficient Irrigation SD-12 Design Objectives 7"Maximize Infiltration Provide Retention Slow Runoff Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Description "~~ _~»»____~_.—__ Irrigation water provided to landscaped areas may result in excess irrigation water being conveyed into stormwater drainage systems. Approach Project plan designs for development and redevelopment should include application methods of irrigation water that minimize runoff of excess irrigation water into the stormwater conveyance system. Suitable Applications Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.) Design Considerations Designing New Installations The following methods to reduce excessive irrigation runoff should be considered, and incorporated and implemented where determined applicable and feasible by the Permittee: • Employ rain-triggered shutoff devices to prevent irrigation after precipitation. • Design irrigation systems to each landscape area's specific water requirements. • Include design featuring flow reducers or shutoff valves triggered by a pressure drop to control waterless in the event of broken sprinkler heads or lines. • Implement landscape plans consistent with County or City water conservation resolutions, which may include provision of water sensors, programmable irrigation times (for short cycles), etc. *£&&?"'' J% $ d A l -ttV^. ffy «•':. ^f- ^jjlpf! *?"^K;_, I California """"' Stormwater Quality Association January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com lof 2 SP-12 Efficient Irrigation •'<*• ^B—-—i——•«mmm^m••••—•_••_•i^^«««H»I • Design timing and application methods of irrigation water to minimize the runoff of excess irrigation water into the storm water drainage system. • Group plants with similar water requirements in order to reduce excess irrigation runoff and promote surface filtration. Choose plants with low irrigation requirements (for example, native or drought tolerant species). Consider design features such as: Using mulches (such as wood chips or bar) in planter areas without ground cover to minimize sediment in runoff Installing appropriate plant materials for the location, in accordance with amount of sunlight and climate, and use native plant materials where possible and/or as recommended by the landscape architect Leaving a vegetative barrier along the property boundary and interior watercourses, to act as a pollutant filter, where appropriate and feasible - Choosing plants that minimize or eliminate the use of fertilizer or pesticides to sustain growth • Employ other comparable, equally effective methods to reduce irrigation water runoff. Redeveloping Existing Installations Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) i ***"*" define "redevelopment" in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of" redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations" above should be foDowed. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002. Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 of 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Storm Drain Signage SD-13 Design Objectives Maximize Infiltration Provide Retention Slow Runoff Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Description Waste materials dumped into storm drain inlets can have severe impacts on receiving and ground waters. Posting notices regarding discharge prohibitions at storm drain inlets can prevent waste dumping. Storm drain signs and stencils are highly visible source controls that are typically placed directly adjacent to storm drain inlets. Approach The stencil or affixed sign contains a brief statement that prohibits dumping of improper materials into the urban runoff conveyance system. Storm drain messages have become a popular method of alerting the public about the effects of and the prohibitions against waste disposal. Suitable Applications Stencils and signs alert the public to the destination of pollutants discharged to the storm drain. Signs are appropriate in residential, commercial, and industrial areas, as well as any other area where contributions or dumping to storm drains is likely. Design Considerations Storm drain message markers or placards are recommended at all storm drain inlets within the boundary of a development project. The marker should be placed in clear sight facing toward anyone approaching the inlet from either side. All storm drain inlet locations should be identified on the development site map. Designing New Installations The following methods should be considered for inclusion in the project design and show on project plans: Provide stenciling or labeling of all storm drain inlets and catch basins, constructed or modified, within the project area with prohibitive language. Examples include "NO DUMPING - S €1 Jl Stormwater Quality Association January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com lof 2 SD-13 Storm Drain Signage DRAINS TO OCEAN" and/or other graphical icons to discourage illegal dumping. • Post signs with prohibitive language and/or graphical icons, which prohibit illegal dumping at public access points along channels and creeks within the project area. Note - Some local agencies have approved specific signage and/or storm drain message placards for use. Consult local agency stormwater staff to determine specific requirements for placard types and methods of application. Redeveloping Existing Installations Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. If the project meets the definition of "redevelopment", then the requirements stated under " designing new installations" above should be included in all project design plans. Additional Information Maintenance Considerations • Legibility of markers and signs should be maintained. If required by the agency with jurisdiction over the project, the owner/operator or homeowner's association should enter into a maintenance agreement with the agency or record a deed restriction upon the property title to maintain the legibility of placards or signs. Placement • Signage on top of curbs tends to weather and fade. • Signage on face of curbs tends to be worn by contact with vehicle tires and sweeper brooms. Supplemental Information Examples m Most MS4 programs have storm drain signage programs. Some MS4 programs will provide stencils, or arrange for volunteers to stencil storm drains as part of their outreach program. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002. Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 of 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Trash Storage Areas SD-32 Description Trash storage areas are areas where a trash receptacle (s) are located for use as a repository for solid wastes. Stormwater runoff from areas where trash is stored or disposed of can be polluted. In addition, loose trash and debris can be easily, transported by water or wind into nearby storm drain inlets, channels, and/or creeks. Waste handling operations that may be sources of Stormwater pollution include dumpsters, litter control, and waste piles. Approach This fact sheet contains details on the specific measures required to prevent or reduce pollutants in Stormwater runoff associated with trash storage and handling. Preventative measures including enclosures, containment structures, and impervious pavements to mitigate spills, should be used to reduce the likelihood of contamination. Design Objectives Maximize Infiltration Provide Retention Slow Runoff Minimize impervious Land Coverage Prohibit Dumping of Improper Materials J Contain Pollutants Collect and Convey Suitable Applications Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.) Design Considerations Design requirements for waste handling areas are governed by Building and Fire Codes, and by current local agency ordinances and zoning requirements. The design criteria described in this fact sheet are meant to enhance and be consistent with these code and ordinance requirements. Hazardous waste should be handled in accordance with legal requirements established in Title 22, California Code of Regulation. Wastes from commercial and industrial sites are typically hauled by either public or commercial carriers that may have design or access requirements for waste storage areas. The design criteria in this fact sheet are recommendations and are not intended to be in conflict with requirements established by the waste hauler. The waste hauler should be contacted prior to the design of your site trash collection areas. Conflicts or issues should be discussed with the local agency. Designing New Installations Trash storage areas should be designed to consider the following structural or treatment control BMPs: • Design trash container areas so that drainage from adjoining roofs and pavement is diverted around the area(s) to avoid run-on. This might include berming or grading the waste handling area to prevent run-on of Stormwater. Make sure trash container areas are screened or walled to prevent off-site transport of trash. SQA Stormwater Quality Association January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com lof 2 SD-32 Trash Storage Areas • Use lined bins or dumpsters to reduce leaking of liquid waste. • Provide roofs, awnings, or attached lids on all trash containers to minimize direct precipitation and prevent rainfall from entering containers. • Pave trash storage areas with an impervious surface to mitigate spills. • Do not locate storm drains in immediate vicinity of the trash storage area. • Post signs on all dumpsters informing users that hazardous materials are not to be disposed of therein. Redeveloping Existing Installations Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" hi terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of " redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations" above should be followed. Additional Information Maintenance Considerations The integrity of structural elements that are subject to damage (i.e., screens, covers, and signs) must be maintained by the owner/operator. Maintenance agreements between the local agency and the owner/operator may be required. Some agencies will require maintenance deed restrictions to be recorded of the property title. If required by the local agency, maintenance agreements or deed restrictions must be executed by the owner/operator before improvement plans are approved. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002. Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 of 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com APPENDIX H PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX H: TREATMENT CONTROL BMP FACT SHEETS Please see attached. Drain Inserts MP-52 Description Drain inserts are manufactured filters or fabric placed in a drop inlet to remove sediment and debris. There are a multitude of inserts of various shapes and configurations, typically falling into one of three different groups: socks, boxes, and trays. The sock consists of a fabric, usually constructed of polypropylene. -The fabric may be attached to a frame or the grate of the inlet holds the sock. Socks are meant for vertical (drop) inlets. Boxes are constructed of plastic or wire mesh. Typically a polypropylene "bag" is placed in the wire mesh box. The bag takes the form of the box. Most box products are one box; that is, the setting area and filtration through media occur in the same box. Some products consist of one or more trays or mesh grates. The trays may hold different types of media. Filtration media vary by manufacturer. Types include polypropylene, porous polymer, treated cellulose, and activated carbon. California Experience The number of installations is unknown but likely exceeds a thousand. Some users have reported that these systems require considerable maintenance to prevent plugging and bypass. Advantages • Does not require additional space as inserts as the drain inlets are already a component of the standard drainage systems. • Easy access for inspection and maintenance. • As there is no standing water, there is little concern for mosquito breeding. • A relatively inexpensive retrofit option. Limitations Performance is likely significantly less than treatment systems that are located at the end of the drainage system such as ponds and vaults. Usually not suitable for large areas or areas with trash or leaves than can plug the insert. Design and Sizing Guidelines Refer to manufacturer's guidelines. Drain inserts come any many configurations but can be placed into three general groups: socks, boxes, and trays. The sock consists of a fabric, usually constructed of polypropylene. The fabric may be attached to a frame or the grate of the inlet holds the sock. Socks are meant for vertical (drop) inlets. Boxes are constructed of plastic or wire mesh. Typically a polypropylene "bag" is placed in the wire mesh box. The bag takes the form of the box. Most box products are Design Considerations • Use with other BMPs • Fit and Seal Capacity within Inlet Targeted Constituents J Sediment •f Nutrients / Trash / Metals Bacteria / Oil and Grease / Organics Removal Effectiveness See New Development and Redevelopment Handbook-Section 5. A SO A Stormwater Quality Association January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com lof 3 MP-52 Drain Inserts one box; that is, the setting area and filtration through media occurs in the same box. One manufacturer has a double-box. Stormwater enters the first box where setting occurs. The stormwater flows into the second box where the filter media is located. Some products consist of one or more trays or mesh grates. The trays can hold different types of media. Filtration media vary with the manufacturer: types include polypropylene, porous polymer, treated cellulose, and activated carbon. Construction/Inspection Considerations Be certain that installation is done in a manner that makes certain that the stormwater enters the unit and does not leak around the perimeter. Leakage between the frame of the insert and the frame of the drain inlet can easily occur with vertical (drop) inlets. Performance Few products have performance data collected under field conditions. Siting Criteria It is recommended that inserts be used only for retrofit situations or as pretreatment where other treatment BMPs presented in this section area used. Additional Design Guidelines Follow guidelines provided by individual manufacturers. Maintenance Likely require frequent maintenance, on the order of several times per year. Cost • The initial cost of individual inserts ranges from less than $100 to about $2,000. The cost of using multiple units in curb inlet drains varies with the size of the inlet. • The low cost of inserts may tend to favor the use of these systems over other, more effective treatment BMPs. However, the low cost of each unit may be offset by the number of units that are required, more frequent maintenance, and the shorter structural life (and therefore replacement). References and Sources of Additional Information Hrachovec, R., and G. Minton, 2001, Field testing of a sock-type catch basin insert, Planet CPR, Seattle, Washington Interagency Catch Basin Insert Committee, Evaluation of Commercially-Available Catch Basin Inserts for the Treatment of Stormwater Runoff from Developed Sites, 1995 Larry Walker Associates, June 1998, NDMP Inlet/In-line Control Measure Study Report Manufacturers literature Santa Monica (City), Santa Monica Bay Municipal Stormwater/Urban Runoff Project - Evaluation of Potential Catch basin Retrofits, Woodward Clyde, September 24, 1998 2 of 3 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Drain Inserts MP-52 Woodward Clyde, June 11,1996, Parking Lot Monitoring Report, Santa Clara Valley Nonpoint Source Pollution Control Program. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 3 of 3 Media Filter TC-40 Design Considerations HSSS3K5SS3SKSS5SSESKSS& Aesthetics Hydraulic Head Description Stormwater media filters are usually two-chambered including a pretreatment settling basin and a filter bed filled with sand or other absorptive filtering media. As stormwater flows into the first chamber, large particles settle out, and then finer particles and other pollutants are removed as stormwater flows through the filtering media in the second chamber. There are a number of design variations including the Austin sand filter, Delaware sand filter, and multi-chambered treatment train (MCTT). California Experience Caltrans constructed and monitored five Austin sand filters, two MCTTs, and one Delaware design in southern California. Pollutant removal was veiy similar for each of the designs; however operational and maintenance aspects were quite different. The Delaware filter and MCTT maintain permanent pools and consequently mosquito management was a critical issue, while the Austin style which is designed to empty completely between storms was less affected. Removal of the top few inches of sand was required at 3 of the Austin filters and the Delaware filter during the third year of operation; consequently, sizing of the filter bed is a critical design factor for establishing maintenance frequency. Advantages • Relatively high pollutant removal, especially for sediment and associated pollutants. • Widespread application with sufficient capture volume can provide significant control of channel erosion and enlargement caused by changes to flow frequency relationships resulting from the increase of impervious cover in a watershed. Limitations Targeted Constituents 0 Sediment 0 Nutrients 0 Trash 0 Metals 0 Bacteria 0 Oil and Grease 0 Organics Legend (Removal Effectiveness) • Low • High A Medium 3anuary 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabrnphandbooks.com lof 17 TC-40 Media Filter B More expensive to construct than many other BMPs. • May require more maintenance that some other BMPs depending upon the sizing of tie filter bed. • Generally require more hydraulic head to operate properly (minimum 4 feet). • High solids loads will cause the filter to clog. • Work best for relatively small, impervious watersheds. • Filters in residential areas can present aesthetic and safety problems if constructed with vertical concrete walls. • Certain designs (e.g., MCTT and Delaware filter) maintain permanent sources of standing water where mosquito and midge breeding is likely to occur. Design and Sizing Guidelines • Capture volume determined by local requirements or sized to treat 85% of the annual runoff volume. • Filter bed sized to discharge the capture volume over a period of 48 hours. • Filter bed 18 inches thick above underdrain system. m Include energy dissipation in the inlet design to reduce resuspension of accumulated sediment. • A maintenance ramp should be included in the design to facilitate access to the sedimentation and filter basins for maintenance activities (particularly for the Austin design). • Designs that utilize covered sedimentation and filtration basins should be accessible to vector control personnel via access doors to facilitate vector surveillance and controlling the basins if needed. Construction/Inspection Considerations m Tributary area should be completely stabilized before media is installed to prevent premature clogging. Performance The pollutant removal performance of media filters and other stormwater BMPs is generally characterized by the percent reduction in the influent load. This method implies a relationship between influent and effluent concentrations. For instance, it would be expected that a device that is reported to achieve a 75% reduction would have an effluent concentration equal to 25% of the influent concentrations. Recent work in California (Caltrans, 2002) on various sand filter designs indicates that this model for characterizing performance is inadequate. Figure 4 presents a graph relating influent and effluent TSS concentrations for the Austin full sedimentation design. 2 of 17 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.coin Media Filter TC-40 Jflfl ?*»n - mt *I(\(\ _,H 300 «£• 95ft*••• &WV 1** fi) ^HA £ 4enIU luU COWlfl A -IUU in - V= 0 0046x + 7 4242 R2 a 0.0037 _ 0 100 200 300 400 500 TSS Influent (mg/L) Figure 4 Comparison of Influent and Effluent Concentrations for TSS It is clearly evident that the effluent concentration is relative constant and independent of influent concentration. Consequently, the performance is more accurately characterized by the effluent concentration, which is about 7.5 mg/L. Constant effluent concentrations also are observed for all other particle related constituents such as particulate metals (total - dissolved) and participate phosphorus. Hie small uncertainty in the estimate of the mean effluent concentration highlights the very consistent effluent quality for TBS produced by sand niters. In addition, it demonstrates that a calculated percent reduction for TSS and other constituents with similar behavior for Austin sand filters is a secondary characteristic of the device and depends primarily on the specific influent concentrations observed. The distinction between a constant effluent quality and a percent reduction is extremely important to recognize if the results are to be used to estimate effluent quality from sand filters installed at other sites with different influent concentrations or for estimating compliance with water quality standards for storms with high concentrations of particulate constituents. If the conventionally derived removal efficiency (90%) were used to estimate the TSS concentrations in the treated runoff from storms with high influent concentrations, the estimated effluent concentration would be too high. For instance, the storm with the highest observed influent concentration (420 mg/L) would be expected to have a concentration hi the treated runoff of 42 mg/L, rather than the 10 mg/L that was measured. In fact, the TSS effluent concentrations for all events with influent concentrations greater than 200 mg/L were 10 ing/L or less. The stable effluent concentration of a sand filter under very different influent TSS concentrations implies something about the properties of the influent particle size distribution. If one assumes that January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 3 of 17 TC-40 Media Filter only the smallest size fraction can pass through the filter, then the similarity in effluent concentrations suggests that there is little difference in the total mass of the smallest sized particles even when the total TSS concentration varies greatly. Further, the difference in TSS concentration must then be caused by changes in the relative amount of the larger size fractions. Further research is necessary to determine the range of particle size that is effectively removed in the filter and the portion of the size fraction of suspended solids that it represents in urban stormwater. Sand filters are effective stormwater management practices for pollutant removal. Conventional removal rates for all sand filters and organic filters are presented in Table i. With the exception of nitrates, which are always exported from filtering systems because of the conversion of ammonia and organic nitrogen to nitrate, they perform relatively well at removing pollutants. Table 1 Sand filter removal efficiencies (percent) rss IT IN Nitrate Vletals Jacteria Sand Filter (Click etal, 1998) 89 59 17 -76 72-86 65 Compost Filter System Stewart, 1992 95 41 - -34 61-88 - Leif,l999 85 4 - -95 44-75 - Multi-Chamber Treatment Train Pitt etal., *997 85 80 - - 65-90 - Pitt, 1996 83 - - 14 91-100 - Greb et al., 1998 98 84 - - 83-89 - From the few studies available, it is difficult to determine if organic filters necessarily have higher removal efficiencies than sand filters. The MCTT may have high pollutant removal for some constituents, although an evaluation of these devices by the California Department of Transportation indicated no significant difference for most conventional pollutants. In addition to the relatively high pollutant removal in media filters, these devices, when sized to capture the channel forming storm volume, are highly effective at attenuating peak flow rates and reducing channel erosion. Siting Criteria In general, sand filters are preferred over infiltration practices, such as infiltration trenches, when contamination of groundwater with conventional pollutants is of concern. This usually occurs in areas where underlying soils alone cannot treat runoff adequately - or ground water tables are high. In most cases, sand filters can be constructed with impermeable basin or chamber bottoms, which help to collect, treat, and release runoff to a storm drainage system or directly to surface water with no contact between contaminated runoff and groundwater. In regions where evaporation exceeds rainfall and a wet pond would be unlikely to maintain the required permanent pool, a sand filtration system can be used. 4 of 17 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 Media Filter TC-40 Hie selection of a sand filter design depends largely on the drainage area's characteristics. For example, die Washington, D.C. and Delaware sand filter systems are well suited for highly impervious areas where land available for structural controls is limited, since both are installed underground. They have been used to treat runoff from parking lots, driveways, loading docks, service stations, garages, airport runways/taxiways, and storage yards. The Austin sand filtration system is more suited for large drainage areas that have both impervious and pervious surfaces. This system is located at grade and is used to treat runoff from any urban land use. It is challenging to use most sand filters in very flat terrain because they require a significant amount of hydraulic head (about 4 feet), to allow flow through the system. One exception is the perimeter sand filter, which can be applied with as little as 2 feet of head. Sand filters are best applied on relatively small sites (up to 25 acres for surface sand filters and closer to 2 acres for perimeter or underground filters). Filters have been used on larger drainage areas, of up to 100 acres, but these systems can clog when they treat larger drainage areas unless adequate measures are provided to prevent clogging, such as a larger sedimentation chamber or more intensive regular maintenance. When sand filters are designed as a stand-alone practice, they can be used on almost any soil because they can be designed so that stormwater never infiltrates into the soil or interacts with the ground water. Alternatively, sand filters can be designed as pretreatment for an infiltration practice, where soils do play a role. Additional Design Guidelines Pretreatment is a critical component of any stormwater management practice. In sand filters, pretreatment is achieved in the sedimentation chamber that precedes the filter bed. In this chamber, the coarsest particles settle out and thus do not reach the filter bed. Pretreatment reduces the maintenance burden of sand filters by reducing the potential for these sediments to clog the filter. When pretreatment is not provided designers should increase the size of the filter area to reduce the clogging potential. In sand filters, designers should select a medium sand as the filtering medium. A fine aggregate (ASTM €-33) that is intended for use in concrete is commonly specified. Many guidelines recommend sizing the filter bed using Darcy's Law, which relates the velocity of fluids to the hydraulic head and the coefficient of permeability of a medium. The resulting equation, as derived by the city of Austin, Texas, (1996), is Af = WQVd/[kt(h+d)] Where: Af = area of the filter bed (ft2); d = depth of the filter bed (ft; usually about 1.5 feet, depending on the design); k = coefficient of permeability of the filtering medium (ft/day); t = time for the water quality volume to filter through the system (days; usually assumed to be 1.67 days); and January 2003 California Stormwater BMP Handbook 5 of 17 New Development and Redevelopment www.cabrnphandbooks.com TC-40 Media Filter h = average water height above the sand bed (ft; assumed to be one-half of the maximum head). Typical values for k, as assembled by CWP (1996), are shown in Table 2. Table 2 Coefficient of permeability values for storm water filtering practices (CWP, 1996} Filter Medium Sand Peat/Sand Compost Coefficient of Permeability (ft/day) 3-5 2.75 8.7 The permeability of sand shown in Table 2 is extremely conservative, but is widely used since it is incorporated in the design guidelines of the City of Austin. When the sand is initially installed, the permeability is so high (over too ft/d) that generally only a portion of the filter area is required to infiltrate the entire volume, especially in a "full sedimentation" Austin design where the capture volume is released to the filter basin over 24 hours. The preceding methodology results in a filter bed area that is oversized when new and the entire water quality volume is filtered in less than a day with no significant height of water on top of the sand bed. Consequently, the following simple rule of thumb is adequate for sizing the filter area. If the filter is preceded by a sedimentation basin that releases the water quality volume (WQV) to the filter over 24 hours, then Af=WQV/i8 If no pretreatment is provided then the filter area is calculated more conservatively as: Af = WQV/io Typically, filtering practices are designed as "off-line" systems, meaning that during larger storms all runoff greater than the water quality volume is bypassed untreated using a flow splitter, which is a structure that directs larger flows to the storm drain system or to a stabilized channel. One exception is the perimeter filter; in this design, all flows enter the system, but larger flows overflow to an outlet chamber and are not treated by the practice. The Austin design variations are preferred where there is sufficient space, because they lack a permanent pool, which eliminates vector concerns. Design details of this variation are summarized below. Summary of Design Recommendations (i) Capture Volume - The facility should be sized to capture the required water quality volume, preferably in a separate pretreatment sedimentation basin. 6 of 17 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 Media Filter TC-40 (2) Basin Geometry - The water depth in the sedimentation basin when fall should be at least 2 feet and no greater than 10 feet. A fixed vertical sediment depth marker should be installed in the sedimentation basin to indicate when 2.0% of the basin •volume has been lost because of sediment accumulation. When a pretreatment sedimentation basin is provided the minimum average surface area for the sand filter (Af) is calculated from the following equation: Af = WQV/l8 If no pretreatment is provided then the filter area is calculated as: Af-WQV/10 (3) Sand and Gravel Configuration - Hie sand filter is constructed with 18 indies of sand overlying 6 inches of gravel. The sand and gravel media are separated by permeable geotextile fabric and the gravel layer is situated on geotextile fabric. Four-inch perforated PVC pipe is used to drain captured flows from the gravel layer. A minimum of 2 inches of gravel must cover the top surface of the PVC pipe. Figure 5 presents a schematic representation of a standard sand bed profile, (4) Sand Properties - The sand grain size distribution should be comparable to that of "washed concrete sand," as specified for fine aggregate in ASTM C-33- (5) Underdrain Pipe Configuration - In an Austin filter, the underdrain piping should consist of a main collector pipe and two or more lateral branch pipes, each with a minimum diameter of 4 inches. The pipes should have a minimum slope of i% (1/8 inch per foot) and the laterals should be spaced at intervals of no more than 10 feet. There should be no fewer than two lateral branch pipes. Each individual underdrain pipe should have a cleanout access location. All piping is to be Schedule 40 PVC. The maximum spacing between rows of perforations should not exceed 6 inches. (6) Flow Splitter - The inflow structure to the sedimentation chamber should incorporate a flow-splitting device capable of isolating the capture volume and bypassing the 25-year peak flow around the facility with the sedimentation/filtration pond full. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 7 of 17 TC-40 Media Filter tend Bed {top of tout to be horizontal) Performtion Layout lmp*rme*bi* Uy»r Perforated 4* PVC Pipe A. SAND BED PROFILE (with Qf«v«l fUtftf) (7) (8) Sand Bed (top of bod to to horizontal) 4:1 ImpermMblo Uyw Perforated4- PVC Pipe B. SAND BED PROFILE (trench dwlfln) Figure 5 Schematic of Sand Bed Profile Basin Inlet - Energy dissipation is required at the sedimentation basin inlet so that flows entering the basin should be distributed uniformly and at low velocity in order to prevent resuspension and encourage quiescent conditions necessary for deposition of solids. Sedimentation Pond Outlet Structure - The outflow structure from the sedimentation chamber should be (i) an earthen berm; (2) a concrete wall; or (3) a rock gabion. Gabion outflow structures should extend across the full width of the facility such that no short- circuiting of flows can occur. The gabion rock should be 4 inches in diameter. The 8 of 17 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 Media Filter TC-40 ast**' receiving end of the sand filter should be protected (splash pad, riprap, etc.) such that erosion of the sand media does not occur. When a riser pipe is used to connect the sedimentation and filtration basins (example in Figure 6), a valve should be included to isolate the sedimentation basin in case of a hazardous material spill in the watershed. The control for the valve must be accessible at all times, including when the basin is full. The riser pipe should have a minimum diameter of 6 inches with four i-inch perforations per row. The vertical spacing between rows should be 4 inches (on centers). (9) Sand Filter Discharge - If a gabion structure is used to separate the sedimentation and filtration basins, a valve must installed so that discharge from the BMP can be stopped in case runoff from a spill of hazardous material enters the sand filter. The control for the valve must be accessible at all times, including when the basin is full. Maintenance Even though sand filters are generally thought of as one of the higher maintenance BMPs, in a recent California study an average of only about 49 hours a year were required for field activities. This was less maintenance than was required by extended detention basins serving comparable sized catchments. Most maintenance consists of routine removal of trash and debris, especially in Austin sand filters where the outlet riser from the sedimentation basin can become clogged. Most data (ie. Clark, 2001) indicate that hydraulic failure from dogging of the sand media occurs before pollutant breakthrough. Typically, only the very top of the sand becomes clogged while the rest remains in relative pristine condition as shown in Figure 7. The rate of clogging has been related , to the TSS loading on the filter bed (Urbonas, 1999); however, the data are quite variable. Empirical observation of sites treating urban and highway runoff indicates that clogging of the filter occurs after 2-10 years of service. Presumably, this is related to differences in the type and amount of sediment in the catchment areas of the various installations. Once dogging occurs the top 2-3 inches of filter media is removed, which restores much, but not afl, of the lost permeability. This removal of the surface layer can occur several times before the entire filter bed must be replaced. The cost of the removal of the surface layer is not prohibitive, generally ranging between $2,000 (EPA Fact Sheet) and $4,000 (Caltrans, 2002) depending on the size of the filter. Media filters can become a nuisance due to mosquito and midge breeding in certain designs or if not regularly maintained. "Wet" designs (e,g., MCTT and Delaware filter) are more conducive to vectors than others (e.g., Austin filters) because they maintain permanent sources of standing water where breeding is likely to occur. Caltrans successfully exduded mosquitoes and midges from accessing the permanent water in the sedimentation basin of MCTT installations through use of a tight-fitting aluminum cover to seal vectors out. However, typical wet designs may require routine inspections and treatments by local mosquito and vector control agencies to suppress mosquito production. Vector habitats may also be created in "dry" designs when media filters dog, and/or when features such as level spreaders that hold water over 72 hours are included in the installation. Dry designs such as Austin filters should dewater completely (recommended 72 hour residence time or less) to prevent creating mosquito and other vector habitats. Maintenance efforts to prevent vector breeding in dry designs will need to focus on basic housekeeping practices such as removal of debris accumulations and vegetation management (in filter media) to prevent clogs and/or pools of standing water. January 2003 California Stormwater BMP Handbook 9 of 17 New Development and Redevelopment www.cabmphandbooks.com TC-40 Media Filter •Perforated (T Schedule « PVC Rfacrwith Rraovabla Solid C*f (1* Hot«*> I.JT K l^1 Oiiranisad tafte Ira traitSaefc Support «*t into Cone»*t« ~ * B«nov«Ue Tmb lUek made« W«U*d «r» Ftbrlc.Sti« I* X I" of S" -3* Crawl 1/2* X St**p vttln Aactor Bolt - *' Concrete Pad sifter Pip* Stet*e •*( la VaU/«ith. Vturpraf Seal Side View of Biaer r^ o • Trash Rack Support -Trash Rack >lo«At* SpUo* n««r SupportSpile* witfc Ctlvanix«i) V Clip* Top View of Riser (Square Design) Figure 6 Detail of Sedimentation Riser Pipe 10 of 17 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 Media Filter TC-40 Figure 7 Formation of Clogging Crust on Filter Bed Recommended maintenance activities and frequencies include: • Inspections senii-annuaUy for standing water, sediment, trash and debris, and to identify potential problems. • Remove accumulated trash and debris in the sedimentation basin, from the riser pipe, and the filter bed during routine inspections. • Inspect the facility once during the wet season after a large rain event to determine whether the facility is draining completely within 72 hr. • Remove top 50 mm (2 in.) of sand and dispose of sediment if facility drain time exceeds 72 hr. Restore media depth to 450 mm (18 in.) when overall media depth drops to 300 mm (12 in.). • Remove accumulated sediment in the sedimentation basin every 10 yr or when the sediment occupies 10 percent of the basin volume, whichever is less. Cost Construction Cost There are few consistent published data on the cost of sand filters, largely because, with the exception of Austin, Texas, Alexandria, Virginia, and Washington, D.C., they have not been widely used. Furthermore, filters have such varied designs that it is difficult to assign a cost to filters in general. A study by Brown and Schueler (1997) was unable to find a statistically valid relationship between the volume of water treated in a filter and the cost of the practice. The EPA filter fact sheet indicates a cost for an Austin sand filter at $18,500 (1997 dollars) for a 0.4 hectare- (i acre-) January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 11 of 17 TC-40 Media Filter drainage area. However, the same design implemented at a 1.1 ha site by the California Department of Transportation, cost $240,000. Consequently, there is a tremendous uncertainly about what the average construction cost might be. It is important to note that, although underground and perimeter sand filters can be more expensive than surface sand filters, they consume no surface space, making them a relatively cost-effective practice in ultra-urban areas where land is at a premium. Given the number of facilities installed in the areas that promote their use it should be possible to develop fairly accurate construction cost numbers through a more comprehensive survey of municipalities and developers that have implemented these filters. Maintenance Cost Annual costs for maintaining sand filter systems average about 5 percent of the initial construction cost (Schueler, 1992). Media is replaced as needed, with the frequency correlated with the solids loading on the filter bed. Currently the sand is being replaced in the D.C. filter systems about every 2 years, while an Austin design might last 3-10 years depending on the watershed characteristics. The cost to replace the gravel layer, filter fabric and top portion of the sand for D.C. sand filters is approximately $1,700 (1997 dollars). Caltrans estimated future maintenance costs for the Austin design, assuming a device sized to treat runoff from approximately 4 acres. These estimates are presented in Table 3 and assume a fully burdened hourly rate of $44 for labor. This estimate is somewhat uncertain, since complete replacement of the filter bed was not required during the period that maintenance costs were recorded. Table 3 Expected Annual Maintenance Costs for an Austin Sand Filter Activity Inspections Maintenance Vector Control Administration Direct Costs Total Labor Hours 4 36 o 3 - 43 Equipment and Materials ($) o 125 o o 888 $1,013 Cost 176 1,706 o 132 888 $2,902 References and Sources of Additional Information Barton Springs/Edwards Aquifer Conservation District. 1996. Final Report: Enhanced Roadway Runoff Best Management Practices. City of Austin, Drainage Utility, LCRA, TDOT. Austin, TX. 200 pp. Bell, W., L. Stokes, L.J. Gavan, andT.N. Nguyen. 1995. Assessment of the Pollutant Removal Efficiencies of Delaware Sand Filter BMPs. Final Report. Department of Transportation and 12 of 17 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 Media Filter TC-40 ****" Environmental Services. Alexandria, VA. 140 pp. Also in Performance of Delaware Sand Filter Assessed. Watershed Protection Techniques. Center for Watershed Protection. Fall 1995. Vol. 2(1): 291-293. Brown, W., andT. Schueler. 1997. The Economics ofStormwaterBMPs in the Mid-Atlantic Region. Prepared for the Chesapeake Research Consortium, Edgewater, MD, by the Center for Watershed Protection, Eflicott City, MD. Caltrans, 2002, Proposed Final Report: BMP Retrofit Pilot Program, California Dept. of Transportation Report CTSW-RT-oi-oso, Sacramento, CA. Center for Watershed Protection (CWP). 1996. Design of Stormwater Filtering Systems. Prepared for the Chesapeake Research Consortium, Solomons, MD, and U.S. EPA Region 5, Chicago, IL, by the Center for Watershed Protection, Ellicott City, MD. Center for Watershed Protection (CWP). 1997. Multi-Chamber Treatment Train developed for stormwater hot spots. Watershed Protection Techniques 2(3):445~449. City of Austin, TX. 1990. Removal Efficiencies of Stormwater Control Structures. Final Report. Environmental Resource Management Division. 36 p. Also in: Developments in Sand Filter Technology to Improve Stormwater Runoff Quality. Watershed Protection Techniques. Center for Watershed Protection. Summer 1994. Vol. 1(2): 47-54. City of Austin, TX. 1996. Design of Water Quality Controls. City of Austin, TX. (%**" Clark, S.E., 2000, Urban Stormwater Filtration: Optimization of Design Parameters and a Pilot- Scale Evaluation, Ph.D. Dissertation, University of Alabama at Birmingham. CSF Treatment Systems, Inc. (CSF). 1996. Stormwater management promotional brochure. CSF Treatment Systems, Inc., Portland, OR Curran, T. 1996. Peat Sand Efficiency Calculations for McGregor Park Unpublished data. Lower Colorado River Authority. Austin, TX. Galli,F. 1990. Peat-Sand Filters: A Proposed Stormwater Management Practice for Urban Areas. Metropolitan Washington Council of Governments, Washington, DC. Click, Roger, Chang, George C., and Barrett, Michael E., 1998, Monitoring and evaluation of stormwater quality control basins, in Watershed Management: Moving from Theory to Implementation, Denver, CO, May 3-6,1998, pp. 369 - 376. Greb, S., S. Corsi, and R Waschbush. 1998. Evaluation of Stormceptor© and Multi-Chamber Treatment Train as Urban Retrofit Strategies. Presented at Retrofit Opportunities for Water Resource Protection in Urban Environments, A National Conference. The Westin Hotel, Chicago, IL, February 10-12,1998. Harper, H., and J. Herr. 1993. Treatment Efficiency of Detention With Filtration Systems. Environmental Research and Design, Inc. Final Report Submitted to Florida Department of Environmental Regulation. Orlando, FL. 164 pp. January 2003 California Stormwater BMP Handbook 13 of 17 New Development and Redevelopment www.cabmphandboolcs.com TC-40 Media Filter Homer, R.R. and Homer, C.R., 1999, Performance of a Perimeter ("Delaware") Sand Filter in Treating Stormwater Runoff from a Barge Loading Terminal. Proc. of the Comprehensive Stormwater and Aquatic Ecosystem ManagementConf, Auckland, N.Z., Feb. 1999, pp. 183-192. Homer, R.R., and C.R. Homer. 1995. Design, Construction and Evaluation of a Sand Filter Stormwater Treatment System. Part II. Performance Monitoring. Report to Alaska Marine Lines, Seattle, WA. 38 p. Also in Performance of Delaware Sand Filter Assessed. Watershed Protection Techniques. Center for Watershed Protection. Fall 1995. Vol. 2(1): 291-293. Keblin, Michael V., Barrett, Michael E., Malina, Joseph E, Jr., Charbeneau, Randall J, 1998, The Effectiveness of Permanent Highway Runoff Controls: Sedimentation/Filtration Systems, Research Report 2954-1, Center for Transportation Research, University of Texas at Austin. King County, Washington, Department of Natural Resources. 2000. King County Surface Water Design Manual. http://spIash.metrokc.gov/wlr/dss/mamial.htm.Last updated March 6,2000. Accessed January 5,2001. Leif, T. 1999. Compost Stormwater Filter Evaluation. Snohomish County, Washington, Department of Public Works, Everett, WA Maryland Department of the Environment (MDE). 2000. Maryland Stormwater Design Manual. http://www.mde.state.md.us/environment/wma/stormwatennanual. Accessed May 22,2001. Metzger, M. E., D. F. Messer, C. L. Beitia, C. M. Myers, and V. L. Kramer. 2002. The fvBMPs. Stormwater 3(2): 24-39. Pitt, R. 1996. The Control of Toxicants at Critical Source Areas. Presented at the ASCE/Engineering Foundation Conference, Snowbird, UT, August 1996. Pitt, R., M. Lilbuni, and S. Burian. 1997. Storm Drainage Design for the Future: Summary of Current US. EPA Research. American Society of Civil Engineers Technical Conference, Gulf Shores, AL, July 1997. Robertson, B., R. Pitt, A. Ayyoubi, and R. Field. 1995. A Multi-Chambered Stormwater Treatment Train. In Proceedings of the Engineering Foundation Conference: Stormwater NPDES-Related Monitoring Needs, ML Crested Butte, Colorado, August 7-12,1994, American Society of Civil Engineers, New York, New York. Schueler, T. 1994. Developments hi sand filter technology to improve Stormwater runoff quality. Waters/led Protection Techniques i(2):47~54. Schueler, T. 1997. Comparative Pollutant Removal Capability of Urban BMPs: A Reanalysis. Watershed Protection Techniques 2(43:515-520. Stewart, W. 1992. Compost Stormwater Treatment System. W&H Pacific Consultants. Draft Report. Portland, OR. Also in Innovative Leaf Compost System Used to Fflter Runoff at Small Sites in the Northwest. Watershed Protection Techniques. Center for Watershed Protection. February 1994. Vol. 1(1): 13-14. 14 of 17 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Media Filter TC-40 Urbonas, B.R, 1999, Design of a sand filter for stormwater quality enhancement, Water Environment Research, V. 71, No. i, pp. 102-113. U.S. EPA, 1999, Stormwater Technology Fact Sheet: Sand Filters, Report EPA 832-F-99-OO7 http://www.epa.gov/owm/mtb/sandfitr.pdfj Office of Water, Washington, DC Washington State Department of Ecology (DOE). 1992. Stormwater Management Manual for the Puget Sound Basin, Washington State Department of Ecology, Otympia, WA. Watershed Management Institute (WMI). 1997. Operation, Maintenance, and Management of Stormwater Management Systems. Prepared for U.S. EPA Office of Water, Washington, DC, by Watershed Management Institute. Welborn, C., and J. Veenhuis. 1987. Effects of Runoff Controls on the Quantity and Quality of Urban Runoff in Two Locations in Austin, TX. USGS Water Resources Investigations Report. 87- 4004. 88 pp- Young, G.K., et al., 1996, Evaluation and Management of Highway Runoff Water QuaRty, Publication No. FHWA-PD-96-O32, U.S. Department of Transportation, Federal Highway Administration, Office of Environment and Planning. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 15 of 17 TC-40 Media Filter C3EZ PtAH Full Sadtmantation Basin FiltrationBasin Schematic of the "Full Sedimentation" Austin Sand Filter Separated FiccutLH»wU»Uflfcg Point*Weir Between SednaeolPoolindFUttr Curb Inlet*•tPtvemcBt Overflow Wter 0.4<HnSandPiter Uqwr Q.tS-mDndiiBed Schematic of a Delaware Sand Filter (Young et at., 1996) 16 of 17 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 Media Filter TC-40 Main Settfing Chamber •packed column -sorbentprilows aerators - fine bubble aerators -tube settlers I" Filtering Chamber "Sorbent filter fabric - mixed media filter layer (sand and peat) •fitter fabric • gravel packed underdrain e-~> <r-a d2Irtr*jgf y^Sf»**« **? »» »%m £'"-£;.'"'' *•':-'"^'-' '^''^.'^'•''•''-^'•"•^ ^•<?;'--v:-^''5" ".':!•'•£•• :!• '£ '*»tP|9vP9 OflanH*wwvwBflooflvvwvw fisDOa ^"^^•^^^^^^j^Ssa Ck. Schematic of a MCTT (Robertson et ai., 1995) January 2003 California Stomnwater BMP Handbook New Development and Redevelopment www.cabrnphandbooks.com 17 of 17 Multiple System Fact Sheet TC-60 Description A multiple treatment system uses two or more BMPs in series. Some examples of multiple systems include: settling basin combined with a sand filter; settling basin or biofilter combined with an infiltration basin or trench; extended detention zone on a wet pond. California Experience The research wetlands at Fremont, California are a combination of wet ponds, wetlands, and vegetated controls. Advantages • BMPs that are less sensitive to high pollutant loadings, especially solids, can be used to pretreat runoff for sand filters and infiltration devices where the potential for clogging exists. • BMPs which target different constituents can be combined to provide treatment for all constituents of concern. • BMPs which use different removal processes (sedimentation, filtration, biological uptake) can be combined to improve the overall removal efficiency for a given constituent. • BMPs in series can provide redundancy and reduce the likelihood of total system failure. Limitations • Capital costs of multiple systems are higher than for single devices. • Space requirements are greater than that required for a single technology. Design and Sizing Guidelines Refer to individual treatment control BMP fact sheets. Performance • Be aware that placing multiple BMPs in series does not necessarily result in combined cumulative increased performance. This is because the first BMP may already achieve part of the gam normally achieved by the second BMP. On the other hand, picking the right combination can often help optimize performance of the second BMP since the influent to the second BMP is of more consistent water quality, and thus more consistent performance, thereby allowing the BMP to achieve its highest performance. Design Considerations • Area Required • Slope • Water Availability • Hydraulic Head • Environmental Side-effects Targeted Constituents 0 Sediment 0 Nutrients 0 Trash 0 Metals 0 Bacteria 0 08 and Grease 0 Organics Legend (Removal Effectiveness) • Low • High A Medium January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com lof 2 TC-60 Multiple System Fact Sheet « When addressing multiple constituents through multiple BMPs, one BMP may optimize removal of a particular constituent, while another BMP optimizes removal of a different constituent or set of constituents. Therefore, selecting the right combination of BMPs can be very constructive in collectively removing multiple constituents. Siting Criteria Refer to individual treatment control BMP fact sheets. Additional Design Guidelines • When using two or more BMPs in series, it may be possible to reduce the size of BMPs. • Existing pretreatment requirements may be able to be avoided when using some BMP combinations. Maintenance Refer to individual treatment control BMP fact sheets. Cost Refer to individual treatment control BMP fact sheets. Resources and Sources of Additional Information Refer to individual treatment control BMP fact sheets. 2 of 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 6 Long-term Maintenance of BMPs 6.1 Introduction The long-term performance of BMPs hinges on ongoing and proper maintenance. In order for this to occur detailed maintenance plans are needed that include specific maintenance activities and frequencies for each type of BMP. In addition, these should include indicators for assessing when "as needed" maintenance activities are required. The fact sheets included in this volume contain the basic information needed to develop these maintenance plans, but municipalities and other regulatory agencies also need to identify the responsible party and potentially to address funding requirements. The following discussion is based primarily on data developed by Horner et al. (1994) and information available at http://www.stormwatercenter.net/ 6.2 Critical Regulatory Components Critical regulatory components identified by Horner et al. (1994) include: • Regulations should officially designate a responsible party, frequently the development site owner, to have ultimate responsibility for the continued maintenance of stormwater facilities. This official designation provides the opportunity for appropriate preparation and budgeting prior to actually assuming responsibilities. It also facilitates enforcement or other legal remedies necessary to address compliance or performance problems once the facility has been constructed. • Regulations should clearly state the inspection and maintenance requirements. Inspection and maintenance requirements should also comply with all applicable statutes and be based on the needs and priorities of the individual measure or facility. A clear presentation will help owners and builders comply and inspectors enforce requirements. • Regulations should contain comprehensive requirements for documenting and detailing maintenance. A facility operation and maintenance manual should be prepared containing accurate and comprehensive drawings or plans of the completed facility and detailed descriptions and schedules of inspection and maintenance. • The regulations should delineate the procedure for maintenance noncompliance. This process should provide informal, discretionary measures to deal with periodic, inadvertent noncompliance and formal and severe measures to address chronic noncompliance or performance problems. In either case, the primary goal of enforcement is to maintain an effective BMP - the enforcement action should not become an end in itself. • Regulations should also address the possibility of total default by the owner or builder by providing a way to complete construction and continue maintenance. For example, the public might assume maintenance responsibility. If so, the designated public agency must be alerted and possess the necessary staffing, equipment, expertise, and funding to assume this responsibility. Default can be addressed through bonds and other performance January 2003 California Stormwater BMP Handbook 6-1 New Development and Redevelopment www.cabmphandbooks.com Section 6 Long-term Maintenance ofBMPs guarantees obtained before the project is approved and construction begins. These bonds can then be used to fund the necessary maintenance activities. • The regulations must recognize that adequate and secure funding is needed for facility inspection and maintenance and provide for such funding. 6.3 Enforcement Options A public agency will sometimes need to compel those responsible for facility construction or maintenance to fulfill their obligations. Therefore, the maintenance program must have enforcement options for quick corrective action. Rather than a single enforcement measure, the program should have a variety of techniques, each with its own degree of formality and legal weight. The inspection program should provide for nonconforming performance and even default, and contain suitable means to address all stages. Prior to receiving construction approval, the developer or builder can be forced to provide performance guarantees. The public agency overseeing the construction can use these guarantees, usually a performance bond or other surety in an amount equal to some fraction of the facility's construction cost, to fund maintenance activities. Enforcement of maintenance requirements can be accomplished through a stormwater maintenance agreement, which is a formal contract between a local government and a property owner designed to guarantee that specific maintenance functions are performed in exchange for permission to develop that property (http://www.stonnwatercenter.net/). Local governments benefit from these agreements in that responsibility for regular maintenance of the BMPs can be placed upon the property owner or other legally recognized party, allowing agency staff more time for plan review and inspection. 6.4 Maintenance Agreements Maintenance agreements can be an effective tool for ensuring long-term maintenance of on-site BMPs. The most important aspect of creating these maintenance agreements is to clearly define the responsibilities of each party entering into the agreement. Basic language that should be incorporated into an agreement includes the following: 1. Performance of Routine Maintenance Local governments often find it easier to have a property owner perform all maintenance according to the requirements of a Design Manual. Other communities require that property owners do aesthetic maintenance (i.e., mowing, vegetation removal) and implement pollution prevention plans, but elect to perform structural maintenance and sediment removal themselves. 2. Maintenance Schedules Maintenance requirements may vary, but usually governments require that all BMP owners perform at least an annual inspection and document the maintenance and repairs performed. An annual report must then be submitted to the government, who may then choose to perform an inspection of the facility. 6-2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 6 Long-term Maintenance ofBMPs 3. Inspection Requirements Local governments may obligate themselves to perform an annual inspection of a BMP, or may choose to inspect when deemed necessary instead. Local governments may also wish to include language allowing maintenance requirements to be increased if deemed necessary to ensure proper functioning of the BMP. 4. Access to BMPs The agreement should grant permission to a local government or its authorized agent to enter onto property to inspect BMPs. If deficiencies are noted, the government should then provide a copy of the inspection report to the property owner and provide a timeline for repair of these deficiencies. 5. Failure to Maintain In the maintenance agreement, the government should repeat the steps available for addressing a failure to maintain situation. Language allowing access to BMPs cited as not properly maintained is essential, along with the right to charge any costs for repairs back to the property owner. The government may wish to include deadlines for repayment of maintenance costs, and provide for liens against property up to the cost of the maintenance plus interest. 6. Recording Of The Maintenance Agreement An important aspect to the recording of the maintenance agreement is that the agreement be recorded into local deed records. This helps ensure that the maintenance agreement is bound to the property in perpetuity. Finally, some communities elect to include easement requirements into their maintenance agreements. While easement agreements are often secured through a separate legal agreement, recording public access easements for maintenance in a maintenance agreement reinforces a local government's right to enter and inspect a BMP. Examples of maintenance agreements include several available on the web at: http://www.stormwatercenter.net/ 6.5 Public Funding Sources If local agencies are willing to assume responsibility for stormwater BMPs, it is essential to identify the long-term funding sources. Several of these are described below: General Tax Revenues Tax revenues are an obvious source of funding, particularly for the long-term inspection and maintenance of existing runoff and drainage facilities. The benefits and protection to the public from continued safe and effective operation of the facility justifies using revenues from general funds. To use tax revenues, particularly from a general fund, the inspection and maintenance program must annually compete with all other programs included in the government's annual operating budget. This inconsistent and unreliable funding makes securing a long-term financial January 2003 California Stormwater BMP Handbook 6-3 New Development and Redevelopment www.cabmphandbooks.com Section 6 Long-term Maintenance ofBMPs commitment to inspection and maintenance difficult and subject to political pressures. Nevertheless, tax revenues remain a popular funding source because the collection and disbursement system is already in place and familiar. Utility Charges Using utility charges to fund inspection and maintenance is a somewhat recent application of an already established financing technique. In addition, several municipalities and counties throughout the country have runoff management, drainage, and flood control authorities or districts to provide residents with runoff related services. Using utility charge financing has several advantages. By addressing only runoff needs and benefits, utility funding avoids competing with other programs arid needs. Utility funding also demonstrates a direct link between the funding and the services it provides. This approach can require an entirely new operating system and organization that needs legal authorization to exist, operate, and assess charges. The effort required to create such an entity can deter many, although the continued success of established authorities and growth of new ones have done much to allay concerns over the effort required. In a runoff utility, the user charges are often based on the need for services rather than the benefits derived from them. While charges are based on actual costs to inspect and maintain runoff facilities and measures within the service area, the assessed rate structure should relate to site characteristics. These include property area size, extent of impervious coverage, and other factors with a direct and demonstrable effect on runoff. To be fair, the rate structure should also remain simple and understandable to the ratepayer. To finance the stormwater utility in Prince William County, Virginia, residential and nonresidential owners of developed property pay based on the amount of impervious area (rooftops, paved areas, etc.) on their property. Residents pay $10.38 billed twice a year ($20.76 total annual fee) for detached singe-family homes. Town home and condominium owners will pay $7.785 billed twice a year ($15.57 total annual fee). Nonresidential property owners pay $0.84 per 1,000 ft2 of impervious area per month. Fee adjustments or credits may be available if a stormwater management system is already in place. The fee will be on the real estate bills. Fees for the stormwater utility in Austin, Texas are higher with residential users billed $5.79/mo, while commercial users pay $94.62/mo/acre of impervious cover. These fees cover not only maintenance of existing BMPs, but also capital improvement projects related to the drainage infrastructure. Permit Fees Collecting permit fees to finance runoff inspection and maintenance is a long standing funding procedure. Most governmental entities local, county, and state can establish and collect fees and other charges to obtain operating funds for programs and services. Many inspection services, most notably the construction inspection of both ESC measures and permanent drainage and runoff management facilities, are financed at least in part through fees collected by permitting agencies. Unlike taxes or some utility charges, inspection costs are borne by those who need them. 6-4 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 6 Long-term Maintenance ofBMPs The permit fee collection program should have a demonstrable link to the runoff management or drainage systems. The public agency should demonstrate a direct link between the permit fees collected and the permitted project one method is using dedicated accounts for individual projects and facilities. Finally, the rate structure should reflect site characteristics such as area size or imperviousness that directly relate to the measure or facility by affecting runoff or erosion. Dedicated Contributions Public agencies at times have used developer contributions to fund long-term facility maintenance. This approach is particularly appropriate in single-family residential subdivisions, where numerous individual property owners served by a single runoff facility can result in confusion over who has maintenance responsibility. The exact funding technique depends on many factors, including community attitude and knowledge, economic and political viability, and program needs and costs. Some techniques, including permit fees and dedicated contributions, may be more appropriate for short-term activities, such as construction inspection. Others utility charges and specialized tax revenues may apply to all phases of an inspection and maintenance program but require considerable effort and special legal authorization to operate. January 2003 California Stormwater BMP Handbook 6-5 New Development and Redevelopment www.cabmphandbooks.com APPENDIX I PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX I: APPLICABLE MANUFACTURER'S BMP INFORMATION Please see attached. ENVIRO-SAFE HIGH CAPACITY GRATE INLET SKIMMER CALIFORNIA CURB SHELF BASKET WATER CLEANSING SYSTEM SAN DIEGO REGIONAL STANDARD CURB INLET CATCH BASIN WALL SHOT Ofi/MTflWmom OF INLET WILL VARY FIGURE 2 DETAIL Of INSTALLATION FIGURE 1 DETAIL OF PARTS REMOVABLE BASKET CATCHES EVERYTHING AND MAY BE REMOVED THROUGH MANHOLE WITHOUT ENTRY. GRATE FLOW DIVERTER FLOW RATES per J FT. Basket Coarse Semen Ued Scnon Fine Screen TOTAL SO .62 .36 .68 .84 1.X 1.02 h(ft) 0.146 0.75 1.167 1.06 3.53 4.01 8.6 The above flow rates are based on unobstructed screens. FIGURE J DETAIL OF PROCESS BOX MANUFACTURED FROM MARINE GRADE FIBERGLASS & GEL COATED FOR UV PROTECTION 5 YEAR MANUFACTURERS WARRANTY PATENTED ALL FILTER SCREENS ARE STAINLESS STEEL NOTES: 1.SHELF SYSTEM PROVIDES FOR ENTIRE COVERAGE OF INLET OPENING SO TO DIVERT ALL FLOW TO BASKET. 2.SHELF SYSTEM MANUFACTURED FROM MARINE GRADE FTBERGLASS.GEL COATED FOR UV PROTECTION. 3.SHELF SYSTEM ATTACHED TO THE CATCH BASIN WITH NON-CORROSIVE HARDWARE. 4.FILTRA7TON BASKET STRUCTURE MANUFACTURED OF MARINE GRADE FIBERGLASS.GEL COATED FOR UV PROTECTION. 5.FTLTRATTON BASKET FINE SCREEN AND COARSE CONTAINMENT SCREEN MANUFACTURED FROM STAINLESS STEEL 6.FILTKATTON BASKET HOLDS BOOM OF ABSORBENT MEDIA TO CAPTURE HYDROCARBONS. BOOM IS EASILY REPLACED WITHOUT REMOVING MOUNTING HARDWARE. 7.F)LTTWnON BASKET LOCATION IS DIRECTLY UNDER MANHOLE FOR EASY MAINTENANCE. EXCLUSIVE CALIFORNIA DISTRIBUTOR:BIO CL.EAN ENVIRONMENTAL. SERVICE P.O. BOX 369. OCEANSIDE. CA. 32O-4-9 TEL.. 7BO — 4-33—7B4-O FAX:76O — 4-33 — 3 1 76 Email: tnfo&btocloanonvlronmontal.rntt SMWREF QUMJ1Y PRODUCE ARE BUILT FOR BST CLEWHS AND ARE DESKNEO TO BE PEKHUWTINFOWRUCTURE AND SHOULD LAST FOK DECADES. 798 CLEARLAKE RD. SUITE #2COCOA FT.. 32922 TEL. 321—e37—7SSZ FAX 321—637—7SS4- CURB INLET BASKET SYSTEM DATE: O4-/1 2/O4- SCAL.E:SF — IS Part / GISB-18-18-12 18 TOP VIEW FLOW SCHEMATIC SIDE VIEW STORM BOOM SKIMMER THROAT TURBULENCE DEFLECTOR Flow Specifications Description of filter opening SkimmerprotectedEly— Pass Coarse Screen 3/4-" x 1-3/4-" stainless steel flattened expanded Medium Screen 1Ox1O mesh stainless steel Fine screen 14 x IB mesh stain/ess steel Percent Open Buttt anScnm MlMMfaM -100X 62X sex 68X THROAT FLOW RATE Total:.Bcfs Total Square Inches per Unit 48.0 48.0 48.0 49.0 Square Inches of Total Unobstructed Openings 48.0 29.7 26.8 49.0 FlowRate (Cubic Feet per Second) 1.7 cfs 1.3 cfs 1.3 cfs 1.8 cfs TREATED FLOW RATE Total: 4.4cfs FLOW RATES BASED ON UNOBSTRUCTED OPENINGS GRATE SKIMMER PROTECTED BYPASS COARSE SCREEN FINE SCREEN BOX MANUFACTURED FROM MARINE GRADE FIBERGLASS & GEL COATED FOR UV PROTECTION 5 YEAR MANUFACTURERS WARRANTY CONCRETE STRUCTURE PATENTED REMOVE GRATE INSERT GISB REINSTALL GRATE ALL FILTER SCREENS ARE STAINLESS STEEL EXCLUSIVE CALIFORNIA DISTRIBUTOR:BIO CLEAN ENVIRONMENTAL. SERVICE P.O. BOX 869, OCEANSIDE. CA. 92O-4-9TEL.. 7GO — 4-33—764-O FAX:76O — -4-33 — 3 1 76 Email: fn^oObfoc/aananvfron mental, nat SUNIREE OUHJIY PRODUCTS MS BOLT FOR BSf OJEHtHS MO AK£ DESIGNED TO BE KOUNEHT HFWSmKWK AM) SHOULD LAST FOR DECADES. 798 CLEARLAKE RD. SUITE #2COCOA PL. 32922 TEL. 321—S37—7SS2 FAX 321 — 837— 7SS4 GRATE INLET SKIMMER BOX GISB— 18— IB— 12 DATE: O4-/1 2/O4-\SCAL.E:Sr — 75 APPENDIX J PRELIMINARY STORM WATER MANAGEMENT PLAN LA COSTA GLEN SKILLED NURSING CENTER EXPANSION APPENDIX J: MAP EXHIBITS Please see attached. DEPOLLUTANT BASINS VICINITY MAP MLS.