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SANTA CLARA COUNTY CODE OF ORDINANCES: CHAPTER V. STORM WATER POLLUTION PREVENTION REQUIREMENTS FOR THE SAN FRANCISCO BAY WATERSHED

Copyrighted by SANTA CLARA COUNTY CODE & Municipal Code Corporation, 1998.

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CHAPTER V.
STORM WATER POLLUTION PREVENTION REQUIREMENTS FOR THE SAN FRANCISCO BAY WATERSHED

Sec. B11 1/2-15. Purpose of chapter.

The purpose of this chapter is to provide minimum requirements designed to control, reduce, and prevent the discharge of pollutants into the storm water system of Santa Clara County from public and private land development projects, in compliance with applicable provisions of the Federal Clean Water Act and any National Pollutant Discharge Elimination System (NPDES) Storm Water Discharge Permits issued to the County of Santa Clara. This chapter only applies to properties located within the unincorporated area and also within the watershed of the San Francisco Bay and that meet the criteria stated herein.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-16. Project criteria.

Projects are determined to be Group 1, Group HMP, Group 2A, or Group 2B development or redevelopment projects by their size and the date deemed complete. (See Watershed Map, on file with the Development Services Office)

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-17. Permanent storm water pollution prevention measures required for certain development projects located within the San Francisco Bay Watershed.

A. Site Design and Source Control BMP Requirements. The projects shall include, where practicable as determined by the Development Services Office, appropriate site design and source control BMPs in order to reduce the water quality impacts of storm water runoff from the site, for the life of the project.

B. Requirements and Effective Dates for Storm Water Treatment BMPs.

1. In addition to site design and source control BMPs, Group 1, Group 2A, and Group 2B project applicants are required to design and implement permanent storm water treatment measures sufficient to reduce the water quality impacts of storm water runoff from the site for the life of the project.

2. Any Group 1 defined project for which a land use application to the County was deemed complete by the Planning Office prior to October 15, 2003, is not required to implement storm water treatment measures.

3. Any Group 2A defined project for which an application to the County was deemed complete by the Planning Office prior to October 20, 2005 is not required to implement storm water treatment measures. Group 2A is superseded by Group 2B effective August 15, 2006.

4. Any Group 2B defined project for which an application to the County was deemed complete by the Planning Office prior to August 15, 2006 is not required to implement storm water treatment measures.

5. When a project application or building permit has expired, even when previously deemed complete, any re-application or new application must conform to the provisions of this ordinance that are in effect at the time of re-application. This section shall not apply to applications that are extended under the provisions of a county ordinance, prior to the land use application expiration date.

C. Hydromodification Management Plan (HMP) BMP Requirements and Exemptions.

1. In accordance with the County's NPDES Municipal Storm water Discharge Permit, all Group 1 Projects are required to implement permanent Hydromodification Management BMPs, except for the following projects:

a. Projects that do not create an increase in impervious surface over pre-project conditions.

b. Transit-oriented developments located within a one-half mile radius of existing or planned transit stations and/or major transfer points.

c. Projects located in sub-watershed areas that are 90 percent or more built-out relative to zoning and have more than 65 percent impervious surface. (Please see red colored area on HMP Map, on file with the Developments Services Office.)

d. Projects that are less than 50 acres in total project size that are located in sub-watershed areas that are 90 percent or more built-out relative to zoning and have less than 65 percent impervious surface. (Please see yellow colored area on HMP Map, on file with the Developments Services Office.)

e. Projects located within areas that drain to stream channels within the tidally influenced area, projects located within areas that drain to non-earthen stream channels that are hardened on three sides and extend continuously upstream from the tidally influenced area, and projects draining to an underground storm drain that discharges directly to San Francisco Bay. (Please see purple colored area on HMP Map, on file with the Developments Services Office.)

f. Projects that demonstrate, through stream-specific modeling studies consistent with the HMP that there will be no increase in erosion potential or other adverse impact to the beneficial uses to any waters of the State of California.

2. HMP projects that are located on sites less than or equal to 20 acres in size (small site projects) that are not part of a larger phased development shall comply with the HMP requirements through the use of appropriate site design, source control, and treatment control measures with flow control benefits to the maximum extent practicable. In addition, where available, off-site and/or in-stream controls should be considered in meeting the management standard.

To demonstrate compliance with the maximum extent practicable criterion, small site projects may use small-scale, distributed storm water management techniques such as bio-retention facilities, infiltration trenches, filter strips, vegetated swales, and multi-functional landscape areas to achieve treatment and flow reduction. Runoff volume reduction and time of concentrations for small-scale facilities can be computed using a discrete storm event approach until other simplified tools based on continuous simulation modeling are available for sizing flow control BMPs. Small site projects may demonstrate that this performance criterion is being met by matching pre- and post-project runoff volume and time of concentration (based on the two- and ten-year storms) to the maximum extent practicable.

3. Determination of impracticability. Meeting the HMP requirements will be considered impracticable if the combined construction cost of both required storm water treatment and hydromodification management BMPs exceeds two percent of the project construction cost, excluding land costs, soil disposal fees, hauling, contaminated soil testing, mitigation, disposal, or other normal site enhancement costs such as landscaping or grading that are required for other development purposes.

If a developer demonstrates that the total cost to fully comply with the HMP and other storm water treatment requirements will exceed this cost threshold, a determination may be made by Manager of the Development Services Office or designee that the project shall comply with the HMP requirements by either (1) implementing hydromodification management controls on-site to the maximum extent practicable, or (2) by contributing to an in-stream or off-site solution, if available, up to a maximum cost for all controls of two percent of the project cost. (The in-stream or off-site solution may be located within another jurisdiction or on land controlled by the Santa Clara Valley Water District.)

D. Group 1, Group 2A, and Group 2B projects that result in an increase of, or replacement of, more than 50 percent of the impervious surface of a previously existing development shall include permanent BMPs sufficient to reduce water quality impacts of storm water runoff from the entire site for the life of the project. These permanent BMPs should include site design, source control, storm water treatment measures, and if applicable, hydromodification management measures.

E. Group 1, Group 2A, and Group 2B projects that result in an increase of, or replacement of fifty (50) percent or less of the impervious surface of a previously existing development shall include permanent BMPs sufficient to reduce water quality impacts to storm water runoff from the increased or replaced portion of the site, for the life of the project. These permanent BMPs should include site design, source control, storm water treatment measures, and if applicable, hydromodification management measures.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-18. Design and Selection of Best Management Practices.

A. Storm water quality best management practices shall be selected and designed to the satisfaction of the Manager of the Development Services Office or designee in accordance with the requirements contained in the most recent versions of the following documents:

1. NPDES Municipal Storm Water Discharge Permit issued to the County of Santa Clara by the San Francisco Bay Regional Water Quality Control Board;

2. Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP.) "Guidance for Implementing Storm Water Regulations for New and Redevelopment Projects";

3. California BMP Handbooks developed by the California Storm Water Quality Agencies Association (CASQA);

4. "Start at the Source" Design Guidance Manual developed by the Bay Area Storm Water Management Agencies Association (BASMAA) ;

5. Bay Area Storm water Management Agencies Association "Using Site Design Standards to Meet Development Standards for Storm Water Quality - A Companion Document to Start at the Source"; and

6. The SCVURPPP Hydromodification Management Plan, as approved by the San Francisco Bay Regional Water Quality Control Board.

B. Numeric sizing criteria used to design storm water treatment systems shall be in accordance with the County's NPDES Municipal Storm Water Discharge Permit.

1. Storm water treatment measures depending on volume capacity, such as detention/retention units or infiltration structures, shall be designed to treat storm water runoff equal to:

a. The maximized storm water quality capture volume for the area, based on historical rainfall records, determined using the formula and volume capture coefficients set forth in Urban Runoff Quality Management, WEF Manual of Practice No. 23/ASCE Manual of Practice No. 87, (1998), pages 175-178 (e.g. approximately the 85th percentile 24-hour storm runoff event); or

b. The volume of annual runoff required to achieve 80 percent or more capture, determined in accordance with the methodology set forth in Appendix D of the California Storm water Best Management Practices Handbook for New Development and Redevelopment (2003), using local rainfall data.

2. Storm water treatment measures whose primary mode of action depends on flow capacity, such as swales, sand filters, or wetlands, shall be sized to treat:

a. Ten percent of the 50-year peak flow rate; or

b. The flow of runoff produced by rain equal to at least two times the 85th percentile hourly rainfall intensity for the applicable area, based on historical records of hourly rainfall; or

c. The flow of runoff resulting from rain equal to at least 0.2 inches per hour intensity.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-19. Storm water treatment questionnaire required for Group 1, Group 2A, and Group 2B Project Applications.

A. Initial land use permit or building permit application requirements. Applications for Group 1, Group 2A, or Group 2B projects shall be accompanied by a Storm Water Treatment Questionnaire. The Questionnaire is available from the Department of Planning and Development.

B. Questionnaire information. The storm water treatment questionnaire shall include the following information:

1. Project name (if any), common address, parcel number of the site, building permit application plan check number, County land use application file number, applicant's name (include all persons having an interest in the property).

2. Whether the project is a subdivision, multi-family residential, commercial, industrial, or a governmental project.

3. Data for total site area, total disturbed area, existing impervious area, proposed new and/or replacement impervious surface area, total impervious surface area, and percent of increase of new or replacement impervious area.

4. The type of pesticide use reduction strategy to be utilized.

5. The general type of proposed storm water treatment measures, proposed site design measures, and proposed source control measures to be utilized.

6. A list of any other applicable water quality related permits, if any, that will be required for the project and the permitting agencies (examples: Santa Clara Valley Water District Permit, State Department of Fish and Game Stream Alteration Agreement, Regional Water Quality Control Board Water Quality Certification, Army Corps of Engineers Water Quality Certification, etc.).

7. A listing of existing or proposed water related resources at the site, including watercourses, streams, wetlands, springs, seeps, water wells, impoundments, on-site sewage disposal systems, etc.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-20. Storm water treatment design information to be included with final building and/or final grading plan submittals.

A. For projects where storm water treatment and/or H.M.P measures are required, the following items shall be submitted for plan checking prior to issuance of building permits and/or grading permits:

1. Hydrologic computations, including drainage area maps depicting existing and post-development runoff flow paths and land use.

2. Hydraulic computations for existing and post-development conditions.

3. If a grading permit is involved, an erosion prevention and sediment control plan must be submitted, as required by the County Grading Ordinance, County Ordinance Code, Division C12, Chapter III.

4. Structural and construction details for all components of the proposed drainage system or systems and storm water management facilities.

5. If landscaping is required, submit a landscaping plan showing disposition of existing vegetation and any vegetative site stabilization and/or landscape-based storm water management measures.

6. Cost estimates for all proposed on-site storm water treatment facilities.

1. A statement of the particular reasons for the applicability of the HMP requirements to the specific project.

2. Hydrologic and hydraulic calculations for any hydromodification management BMPs, including an explanation of how these BMPs will function as the required flow controls.

3. If the applicant is applying for an exemption from HMP requirements, hydraulic calculations and construction cost data must be submitted in order to justify the requested exemption.

4. This information shall be prepared, signed, and stamped by a private professional civil engineer who is registered by the State of California.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-21. Preparation and submittal of storm water treatment, pesticide reduction, and HMP certifications.

A. Group 1, Group 2A, and Group 2B project storm water treatment designs. Design certifications and calculations shall be prepared and submitted for any Group 1, Group 2A, or Group 2B project for plan checking prior to building or grading permit issuance, and shall be prepared by a private professional civil engineer who is registered by the State of California. The certification will verify whether the design meets the requirements of the County's NPDES Permit with regard to storm water treatment. The professional civil engineer shall submit the original signed and stamped certification form.

B. Group 1, Group 2A, and Group 2B project pesticide reduction landscape designs. Design certifications and a list of species proposed shall be prepared and submitted for any Group 1, Group 2A, or Group 2B project for plan checking prior to building or grading permit approval, and shall be prepared by a licensed landscape architect who is registered by the State of California. The certification will verify whether the landscape design meets the intent of the County's NPDES Permit with regard to reducing pesticide needs. The licensed landscape architect shall submit the original signed and stamped certification form.

C. HMP project certifications. Design certifications and calculations for group 1 projects that are also HMP projects shall be prepared and submitted by a private professional civil engineer who is registered by the State of California. The certification will verify whether the design meets the requirements of the SCVURPPP Hydrograph Modification Plan requirements. The professional civil engineer shall submit shall submit the original signed and stamped certification form.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-22. Operation and maintenance responsibility for storm water treatment and HMP measures.

A. For the life of the project, all on-site storm water management facilities shall be operated and maintained in good condition and promptly repaired by the property owner(s), a Homeowners' Association, or other legal entity approved by the County.

B. Any repairs or restoration and maintenance shall be in accordance with the original County- approved plans.

C. The property owner(s) of Group 1, Group 2A, and Group 2B projects shall at the minimum follow the inspection schedule specified in Section B11 1/2-24.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-23. Storm water treatment measures operation and maintenance agreement for Group 1 (including Group 1 HMP Projects), Group 2A, and Group 2B projects.

A. Prior to the issuance of any building or grading permit for a Group 1 (including Group 1 HMP Projects), Group 2A, or Group 2B project, the owner(s) of the site shall enter into a formal written storm water BMP operation and maintenance agreement with the County. The County shall record this agreement with reference to the property or properties involved with the Clerk-Recorder of the County of Santa Clara, and it shall be binding on all subsequent owners of land served by the required storm water treatment BMPs.

B. The storm water BMP operation and maintenance agreement shall require that the BMPs not be modified without the permission of the Development Services Office of the County Department of Planning and Development, and that BMP maintenance activities not alter the design or function of the facility from the original approved plan, unless approved by the Development Services Office prior to the commencement of the proposed modification or maintenance activity.

C. Prior to building or grading permit issuance, the owner shall provide the Development Services Office with a signed and notarized recordable copy of the storm water BMP operation and maintenance agreement and payment in the amount of the recording fee .

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-24. Storm water treatment measures inspection responsibility.

A. The property owner(s) of Group 1 (including Group 1 HMP projects), Group 2A, and Group 2B projects shall be responsible for having all storm water management facilities periodically inspected for condition and function by a privately employed professional civil engineer who is registered by the State of California. (Alternatively, maintenance of landscape-based storm water treatment designs may also be inspected by a landscape architect who is licensed by the State of California.)

B. Unless otherwise required by the Development Services Office, storm water facility inspections shall be inspected according to the following schedule:

1. Landscape based facilities: once every three years (i.e., vegetated swales).

2. Detention based facilities: once every two years (i.e., detention ponds).

3. Growing (or green) roof systems: once every year (i.e., roofs that are covered with vegetation designed to trap storm water pollutants).

4. Proprietary devices, installed either underground or at the surface, that use filtration, baffles, chambers, or inverts to trap sediment: once every year (i.e., concrete chambers or flow devices designed for storm water treatment).

5. Infiltration based devices: once every three years (i.e. shallow rock filled dry wells, infiltration trenches, or pervious pavement).

6. Devices that use multiple methods of storm water treatment: once every year (i.e. a combination of a detention pond and an infiltration trench).

7. Devices that utilize powered pumping equipment: once every six months (i.e. any storm water treatment device where the discharge is higher than the inlet, requiring the pumping to a higher elevation of the treated storm water discharge).

C. Written records shall be kept of all inspections and shall include, at minimum, the following information:

1. Site address.

2. Date and time of inspection.

3. Name and signature of the person conducting the inspection.

4. Name, signature, and stamp of the privately employed professional civil engineer, or landscape architect for landscape-based designs, who is registered by the State of California, and who is responsible for the inspection.

5. List of storm water facilities inspected.

6. Condition of each storm water facility inspected.

7. Description of any needed maintenance or repairs.

8. As applicable, the need for site re-inspection prior to the next routine inspection.

9. Any noted violations of this ordinance or of the NPDES Storm Water Discharge Permit.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-25. Records of maintenance and inspection activities.

On or before May 15th of each year, the party responsible for the operation and maintenance of on-site storm water management facilities of Group 1 (including Group 1 HMP Projects), Group 2A, and Group 2B projects shall provide the Development Services Office with records of all inspections, maintenance and repairs for the just completed rainy season (October 15th through April 15th).

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-26. Failure to maintain storm water treatment and HMP facilities.

If the property owner fails or refuses to meet the requirements of the storm water BMP operation and maintenance agreement, the County, after 30 days' written notice, may correct a violation of the design standards or maintenance requirements by performing the necessary work to place the facility or practice in proper working condition. The County will invoice the owner(s) of the property for the cost of repair work and any administrative costs, pursuant to Section B11 1/2-10.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-27. Approved storm water pollutant source control BMPs.

A. Storm drain inlet labeling. Storm drain inlets for all Group 1, Group 2A, and Group 2B projects shall be clearly marked with the words "No Dumping - Flows to Bay," or the equivalent.

B. Waste plumbing drains and other drains.

1. Interior floor drains shall not be directly or indirectly connected to the storm drainage system.

2. Exterior drains within the following areas shall not be connected to the storm drain (Provide vermin proof grate or screen, and gas tight cap for external drains):

a. Equipment or vehicle washing areas.

b. Areas where chemicals, hazardous materials, or other uncontained materials are stored, unless secondary containment is provided.

c. Equipment or vehicle fueling areas or fluid changing areas.

d. Loading docks where chemicals, hazardous materials, grease, oil, or waste products are handled.

3. Roof runoff shall be directed first to landscaped areas or naturally vegetated areas, unless deemed infeasible by the Manager of the Development Services Office or a designee. Appropriate energy dissipation shall be provided.

4. Nonresidential facilities shall either: (a) provide secondary containment for all roof-mounted equipment, tanks, and piping containing liquids other than potable water; or (b) connect all covered equipment roof drains and equipment discharge lines to the sanitary sewer, with an appropriate backflow prevention device or air gap separation.

5. Boiler drain plumbing lines shall be connected to the sanitary sewer system with an appropriate backflow prevention device or air gap separation, and may not be discharged to the storm drainage system.

6. Cooling systems shall not be connected to or allowed to drain to the storm drainage system.

7. Cooling system condensate lines shall not be connected to or allowed to drain directly to the storm drainage system. The first choice discharge shall be the sanitary sewer with an appropriate backflow prevention device or air gap separation, and the second choice for discharge shall be to a landscaped or naturally vegetated area if the first choice is not practicable.

C. Swimming pool and spa discharges.

1. It shall be unlawful to discharge water from pools, hot tubs, and spas to the storm drainage system.

2. When draining a pool, a hose or other temporary system shall be directed into a sanitary sewer clean out. To prevent a cross connection from occurring, an air gap of two times the receiving sewer pipe diameter shall be provided.

3. For swimming pools located on premises where a sanitary sewer connection exists, a sewer clean out shall be installed in a readily accessible area. Such a cleanout shall not be provided when the site is served by an on-site sewage disposal system.

4. During periods without rainfall, swimming pool and spa discharges may be directed to landscaped areas for percolation and/or evaporation, provided this does not generate runoff to the storm drainage system and does not cause a nuisance to adjacent property owners or neighbors.

D. Vehicle and equipment fueling facilities. Vehicle or equipment fueling facilities shall be designed to prevent the run-on of storm water and runoff of spills. This shall be accomplished by:

1. Paving the fueling area with concrete or other impervious surface.

2. Covering the fueling area and the fuel pumps.

3. Grading the area (i.e., sloping inwardly) or installing a berm or curb around the perimeter of the fueling area. Storm drains shall be prohibited within these fueling areas, unless they drain to a permitted oil/water separator device.

E. Garbage and refuse receptacles serving food service facilities.

1. New food service facilities shall have a sink or other area for cleaning floor mats, containers, and equipment, which is connected to a grease removal device and thence to the sanitary sewer or an approved on-site sewage disposal system. The sink or cleaning area shall be large enough to clean the largest mat or piece of equipment to be cleaned.

2. New buildings constructed to house food service facilities shall include a covered area for a dumpster. The area shall be designed with slope or berms to prevent storm water run-on to the area and storm water runoff from the area.

3. Drains that are installed beneath covered dumpsters serving food service facilities must be connected to a the sanitary sewer or an approved on-site sewage disposal system.

F. Garbage and refuse receptacles. ("dumpsters") serving residences.

1. New residential buildings and all commercial and industrial buildings, except for single-family, duplex, and triplex residences, shall provide a covered-area for a dumpster.

2. The dumpster storage area shall be designed to prevent both storm water runon and storm water runoff under the cover.

3. Any drains that are installed beneath covered dumpsters must be connected to the sanitary sewer or an approved on-site sewage disposal system.

(Ord. No. NS-517.74, § 1, 10-17-06)

Sec. B11 1/2-28. Approved storm water pollutant site design BMPs.

A. Minimize land disturbance.

B. Minimize impervious surfaces.

C. Minimize the impact of parking lots, including parking space maximization within a given area, use of landscaping as a storm water treatment feature, and give consideration to the use of pervious pavement, etc.

D. Cluster structures and pavement to preserve open space and/or vegetated areas.

E. Connect roof downspouts to splash blocks or "bubble-ups", and conduct storm water to vegetated or landscaped areas, instead of directly to the street gutter or storm drain.

F. Installation of micro-detention areas, including landscape detention and the use of cisterns or dry wells for infiltration, where conditions allow.

G. Preserving open space.

H. Maintaining and/or restoring riparian areas and wetlands as project amenities, including establishing vegetated buffer zones to reduce runoff into waterways, allow for potential stream channel changes, and other mitigations.

I. Incorporating supplemental controls to minimize changes in the volume, flow rate, timing, and duration of runoff, for a given precipitation event or events. These changes may include mitigating the cumulative hydromodification caused by site development. Measures may include landscape-based measures or other features to reduce the runoff velocity, increase runoff detention, and/or increase runoff infiltration.

(Ord. No. NS-517.74, § 1, 10-17-06)