§ 23.04.450. Stormwater Management.

a.

Purpose. The requirements in this Section are intended to reduce pollutant discharges to the Maximum Extent Practicable and to prevent stormwater discharges from causing or contributing to a violation of receiving water quality standards, also known as post-construction stormwater management. These requirements also emphasize protecting and, where degraded, restoring key watershed processes to create and sustain linkages between hydrology, channel geomorphology, and biological health necessary for healthy watersheds. Maintenance and restoration of watershed processes impacted by stormwater management is necessary to protect water quality and the beneficial uses of surface and groundwater.

b.

Applicability.

(1)

Where applicable. The requirements of this section are applicable only where a project will drain to those areas designated by the State Water Resources Control Board (SWRCB) as traditional or non-traditional Municipal Separate Storm Sewer Systems (MS4s), as shown in Figures 4-A through 4-G. MS4s consist of areas designated as "urbanized" in the most recent decennial US Census, as well as other outlying areas with a population of 10,000 or more or a population density greater than 1,000 people per square mile.

Designated MS4 areas include, but are not limited to, the following:

(i)

All areas within an Urban Reserve Line (URL) or the Callender-Garrett Village Reserve Line (VRL), as designated in the County General Plan.

(ii)

Any other areas identified as being subject to the stormwater standards, as indicated in Figures 10-5 through 10-13.

(2)

Limited exemption. Projects which have received approval of a zoning clearance, land use permit or land division prior to March 6, 2014 are exempt from the standards of this Section, unless such approval has expired.

(3)

Regulated Projects. Regulated projects include all new development or redevelopment projects, both discretionary and ministerial, that create and/or replace at least 2,500 square feet of impervious surface (collectively over the entire project site).

c.

Stormwater Control Plan (SWCP) Required. Prior to acceptance of an application for a construction permit, grading permit, land use permit or subdivision application associated with a Regulated Project, as defined in Subsection A.3, the applicant shall submit a Stormwater Control Plan that demonstrates compliance with the Post Construction Requirements for the Central Coast Region, adopted by the Central Coast Regional Water Quality Control Board under Order R3-2013-0032.

(1)

Site Design Checklist. The SWCP for all projects subject to this Section shall demonstrate that the following design strategies have been pursued in order to reduce runoff:

(i)

Limit disturbance of creeks and natural drainage features.

(ii)

Minimize compaction of highly permeable soils.

(iii)

Limit clearing and grading of native vegetation at the site to the minimum area needed to build the project, allow access, and provide fire protection.

(iv)

Minimize impervious surfaces by concentrating improvements on the least-sensitive portions of the site, while leaving the remaining land in natural, undisturbed state.

(v)

Implement at least one of the following strategies:

(a)

Direct roof runoff into cisterns, rain barrels, underground storage, or a similar mechanism for reuse.

(b)

Direct roof runoff onto vegetated areas safely away from building foundations and footings, consistent with the California Building Code.

(c)

Direct roof runoff from sidewalks, walkways, and/or patios onto vegetated areas safely away from building foundations and footings, consistent with the California Building Code.

(d)

Direct runoff from driveways and/or uncovered parking lots onto vegetated areas safely away from building foundations and footings, consistent with the California Building Code and Title 19 of the County Code.

(e)

Construct bike lanes, driveways, uncovered parking lots, sidewalks, walkways, and patios with permeable surfaces.

(2)

Plan documents and details. The SWCP for all Regulated Projects, as defined in Subsection A.3, shall provide the following documents and details:

(i)

Project name, application number, location, and assessor's parcel number.

(ii)

Name of the applicant.

(iii)

Identification of which project phase, if the project is being constructed in phases.

(iv)

Project type (e.g. commercial, industrial, multi-unit residential, mixed use, public) and description.

(v)

Total project site area.

(vi)

Total new impervious surface area, total replaced impervious surface area, total new pervious area, and calculation of Net Impervious Area.

(vii)

Identification of all structural and non-structural Best Management Practices (BMPs) proposed as part of the stormwater conveyance system.

(viii)

A certification from a qualified professional (e.g. a Registered Civil Engineer, licensed architect, or other individual deemed to be qualified by the Director) that appropriate Best Management Practices (BMPs) have been incorporated into the plan to the maximum extent practicable.

(ix)

A preliminary drainage plan, consistent with of Section 22.52.110.

(x)

A preliminary erosion and sedimentation control plan, consistent with Section 22.52.120.

(xi)

If needed to demonstrate compliance with the stormwater quality standards in Subsection D, drainage calculations prepared by a Registered Civil Engineer.

d.

Stormwater Quality Standards. Stormwater Control Plans shall be reviewed for consistency with the post-construction stormwater control standards identified in Central Coast Regional Water Quality Control Board Order R3-2013-0032. Standards contained in this order include, but are not limited to, the following:

(1)

Site Design. All Regulated Projects, as defined in Subsection A.3, are subject to this standard.

(2)

Water Quality Treatment. All projects resulting in at least 5,000 square feet of net impervious area, other than single-family residences, shall comply with this standard. Single- family residence projects shall comply with this standard if they involve at least 15,000 square feet of impervious area.

(3)

Runoff Retention. All projects resulting in at least 15,000 square feet of net impervious area shall comply with this standard.

(4)

Peak Management. All projects resulting in at least 22,500 square feet of net impervious area shall comply with this standard.

(5)

Special Circumstances. Projects subject to the performance standards identified in Subsection D.3 and D.4, but discharging to watercourses with special circumstances.

e.

Source Control Standards for Specific Uses. The Stormwater Control Plan must address source control of any applicable pollutants associated with the proposed use that could enter the stormwater conveyance system. The following source control Best Management Practices (BMPs) are required for projects that propose any of the following features:

(1)

Outdoor material storage. Where proposed projects include outdoor storage areas for storage of materials that may contribute pollutants to the stormwater conveyance system, the following structural or treatment BMPs are required:

(i)

Materials with the potential to contaminate stormwater must be:

(a)

Placed in an enclosure such as, but not limited to, a cabinet, shed, or similar structure that prevents contact with runoff or spillage to the stormwater system; or

(b)

Protected by secondary containment structures, such as berms, dikes, or curbs.

(ii)

The material storage area shall be sufficiently impervious to contain leaks and spills.

(iii)

Where secondary containment is necessary, storage areas shall have a roof or awning to minimize collection of stormwater, or another approved method.

(iv)

For storage areas involving the storage of motor vehicles, site design shall comply with Subsection E.7.

(2)

Loading and unloading dock areas. To minimize the potential for material spills to be transported to the stormwater conveyance system, the following is required:

(i)

Loading dock areas shall be covered, or drainage shall be designed to minimize run- on or runoff of stormwater; and

(ii)

Connections to storm drains from depressed loading docks (truck wells) are prohibited. An approved structural source control measure and/or treatment control measure shall be used to prevent stormwater pollution.

(3)

Repair and maintenance bays. To minimize the potential for oil/grease, car battery acid, coolant, and gasoline to be transported to the stormwater conveyance system, design plans for repair/maintenance bays shall include the following:

(i)

Repair/maintenance bays shall be indoors or designed in such a way that does not allow stormwater run-on or runoff; and

(ii)

The drainage system for the repair/maintenance bays shall be designed to capture all washwater, leaks, and spills. Drains shall be connected to a sump for collection and disposal. Direct connection to the storm drain system is prohibited. If required by the Regional Water Quality Control Board, an Industrial Waste Discharge Permit shall be obtained.

(4)

Vehicle and equipment wash areas. To minimize the potential for metals, oil/grease, solvents, phosphates, and suspended solids to be transported to the stormwater conveyance system, the area for washing/steam cleaning of vehicles and equipment shall be designed to the following specifications:

(i)

Self-contained and/or covered, equipped with a clarifier, or other pre-treatment facility; and

(ii)

Properly connected to a sanitary sewer or other appropriately permitted disposal facility.

(5)

Restaurants. An area for washing/steam cleaning of equipment and accessories shall be included on the plans. To minimize the potential for metals, oil and grease, solvents, phosphates, and suspended solids to be transported to the stormwater conveyance system, the area for washing/steam cleaning of equipment and accessories shall be designed to the following specifications:

(i)

Self-contained, equipped with a grease trap, and properly connected to the sanitary sewer; and

(ii)

If the wash area is to be located outdoors, it must be covered, paved, have secondary containment, and be connected to the sanitary sewer or other appropriately permitted disposal facility.

(6)

Fueling areas. To minimize the potential for oil/grease, solvents, car battery acid, coolant, and gasoline to be transported to the stormwater conveyance system, the project plans shall include all of the following BMPs:

(i)

The fuel dispensing area shall be covered with an overhanging roof structure or canopy. Provide containment limits on the plans (i.e. grade break, berm, etc.). The canopy's minimum dimensions shall be equal to or greater than the containmentlimits. The canopy shall not drain onto the fuel dispensing area, and the canopy downspouts shall be routed to prevent drainage across the fueling area.

(ii)

The fuel dispensing area must be paved with Portland cement concrete (or equivalent smooth impervious surface), and the use of asphalt concrete shall be prohibited.

(iii)

The fuel dispensing area must have a two percent minimum slope to prevent ponding, and must be separated from the rest of the site by a grade break that prevents run-on of stormwater to the maximum extent practicable.

(iv)

At a minimum, the concrete fuel dispensing area must extend 6.5 feet from the corner of each fuel dispenser, or the length at which the hose and nozzle assembly may be operated plus 1 foot, whichever is less.

(7)

Parking lots. Parking lots with an area of 5,000 square feet or more, or 25 parking spaces or more, shall minimize potential for oil, grease, and other water insoluble hydrocarbons from vehicle drippings and leaks from entering the stormwater conveyance system. Plans shall provide for the following:

(i)

Treat to remove oil and petroleum hydrocarbons; and

(ii)

Ensure adequate operation and maintenance of treatment systems, particularly sludge and oil removal and system fouling and plugging prevention control. At a minimum, this shall include a maintenance program which is funded and carried out by the property owner.

f.

Maintenance. Long-term maintenance of BMPs shall be established through the recordation of a maintenance agreement and/or Covenants, Conditions, and Restriction (CC&Rs), unless the project does not include structural or treatment control BMPs. This agreement shall be recorded prior to or concurrent with issuance of a construction permit. In order to verify that BMPs will be maintained, the agreement shall do the following:

(1)

Designate responsibility. Identify the party who is responsible for long-term maintenance of structural and treatment control BMPs.

(2)

Address transfer of responsibility. Address how BMPs will be maintained once property has been transferred to private landowners, a homeowners association, or a public entity.

(3)

Reference educational materials. Educational materials shall be required to accompany the first deed transfer. These materials shall provide information on what stormwater management facilities are present, signs that maintenance is needed, how the necessary maintenance can be performed, and assistance that the applicant can provide to the new landowner. The transfer of this information shall also be required with any subsequent sale of the property.

(4)

Address operations and maintenance reporting. Address how and when long-term operations and maintenance will be verified and reported to the County.

g.

Alternative Compliance. The alternative compliance process specified in Central Coast Regional Water Quality Control Board Order R3-2013-0032 may be followed at the discretion of the Director. Such a process may be available in the following circumstances:

(1)

Special Circumstances. Where the project discharges to receiving waters with special circumstances (e.g. highly altered channels, intermediate flow control facilities, and historic lakes and wetlands). In these cases, projects may follow the performance standard identified in Subsection D.5 rather than the performance standards in Subsections D.3 and D.4.

(2)

Technical infeasibility. Where technical infeasibility limits or prevents the use of structural stormwater control measures.

(3)

Approved watershed or regional plan. Where the project falls under a watershed or regional plan that has received approval from the Executive Director of the Central Coast Regional Water Quality Control Board.

(4)

Approved urban sustainability area. Urban infill redevelopment projects located within an Urban Sustainability Area that has been approved by the Executive Director of the Central Coast Regional Water Quality Control Board.

(5)

Other circumstances. In other circumstances as approved by the Executive Director of the Central Coast Regional Water Quality Control Board.

Figure 4-A: Stormwater Management—Cambria

Figure 4-B: Stormwater Management—Cayucos

Figure 4-C: Stormwater Management—Los Osos

Figure 4-D: Stormwater Management—Morro Bay

Figure 4-E: Stormwater Management—Oceano

Figure 4-F: Stormwater Management—Avila Beach

Figure 4-G: Stormwater Management—Pismo Beach

[Added 2013, Ord. 3253]