Stormwater and Water Quality Protection. Developers shall be required to meet all measures for stormwater pollution control, waste management, and provide public utility connections that comply with the city and other service providers. The United States Environmental Protection Agency has promulgated regulations requiring permits for stormwater discharges from small municipal separate storm sewer systems (MS4s). The city of King is an MS4 and therefore projects within the city shall meet the standards established by the Central Coast Regional Water Quality Control Board (RWQCB). Since impermeable surfaces (such as paving and buildings) as well as bare unvegetated soil greatly increases runoff and the potential for erosion and pollution of waters within streams and the Salinas River, mitigation measures have been deemed necessary to reduce runoff and increase percolation within the urban area of the city.
Development in the city will be required to include best management practices (BMPs), including erosion and sediment control, during construction and grading and include low impact development (LID) design practices in the design and layout of the project. According to the RWQCB, LID “is an effective approach to managing stormwater to minimize the adverse effects of urbanization and development on watershed processes and beneficial uses resulting from changes in stormwater runoff conditions. LID strategies can achieve significant reductions in pollutant loading and runoff volumes as well as greatly enhanced groundwater recharge rates. The proper implementation of LID techniques results in greater benefits than single purpose stormwater and flood control infrastructure.”
Therefore, controlling urban runoff pollution by using a combination of on-site source control and LID BMPs augmented with treatment control BMPs before the runoff enters the MS4 is important and will be required of each development project (unless specifically exempted by the RWQCB). Also, according to the RWQCB, “the risks associated with infiltration can be properly managed by many techniques, including: (1) designing landscape drainage features that promote infiltration of runoff, but do not “inject” runoff (injection bypasses the natural processes of filtering and transformation that occur in the soil); (2) taking reasonable steps to prevent the illegal disposal of wastes; (3) protecting footings and foundations; and (4) ensuring that each drainage feature is adequately maintained in perpetuity. However, in some circumstances, site conditions (e.g., historical soil contamination) and the type of development (i.e., urban infill) can limit the feasibility of retaining, infiltrating, and reusing stormwater at sites.” (Source: Resolution No. R3-2013-0032, Approving Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast Region, Central Coast Regional Water Quality Control Board.)
The City Engineer shall review each project, unless exempted by the RWQCB, to assure compliance with these requirements, including the RWQCB “Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast Region.” These RWQCB standards include BMPs for erosion and sediment control during project construction and after completion of the project. LID measures include, but are not limited to: limiting disturbance of creeks and natural drainage features, minimizing compaction of highly permeable soils, limiting removal of native vegetation at the site to the minimum area needed to build the project, limiting impermeable surfaces, including buildings and paving, and the use of innovative design layout that further increases permeable surfaces and landscaping.
Development shall minimize stormwater runoff by implementing one or more of the following site design measures identified by the RWQCB:
(1) Direct roof runoff into cisterns or rain barrels for reuse;
(2) Direct roof runoff onto vegetated areas safely away from building foundations and footings, consistent with California Building Code;
(3) Direct runoff from sidewalks, walkways, and/or patios onto vegetated areas safely away from building foundations and footings, consistent with California Building Code;
(4) Direct runoff from driveways and/or uncovered parking lots onto vegetated areas safely away from building foundations and footings, consistent with California Building Code;
(5) Construct bike lanes, driveways, uncovered parking lots, sidewalks, walkways, and patios with permeable surfaces;
(6) The directing of runoff to bioretention basins; and
(7) Other similar measures as determined by the city engineer.
(Ord. 715 § 3, 2015)