35.25.140 Regulations | Clallam County Code

35.25.140 Regulations.

(1) All shoreline uses and developments shall use effective temporary erosion and sediment control (TESC) methods during project construction. Project proponents shall submit a TESC plan for Administrator review and approval prior if they meet any of the following criteria:

(a) Disturb 7,000 square feet or more of land;

(b) Result in slopes over 25 percent and greater than five feet in height;

(d) Result in the diversion of existing drainage courses; or

(e) Involve clearing and grading in an erosion hazard area or on slopes steeper than 25 percent.

(2) To protect water quality, shoreline uses and developments shall comply with the following standards based on the type and scale of the proposed development:

(a) Tier 1 Developments. Residential development with up to 2,000 square feet of new or replaced impervious surface:

(i) All new, replaced, and disturbed topsoil must be amended with organic matter, which shall not include biosolids (industrial, human, and/or hospital wastes) and shall be certified to be free of invasive weeds.

(ii) Roof runoff must be routed to a dry well or, if a dry well is not appropriate for site conditions, runoff must be dispersed to a vegetated area, a rain garden or bioswale, an infiltration system or permeable pavement.

(iii) Project proponents must submit a one-page drainage plan showing how stormwater runoff will be controlled and design standards implemented.

(b) Tier 2 Developments. Single-family residential development with more than 2,000 square feet of new or replaced impervious surface, other residential development which disturbs more than 7,000 square feet of land or generates 2,000 to 5,000 square feet of impervious surface, and all commercial development smaller than 5,000 square feet in size that do not use hazardous substances:

(i) All Tier 2 developments shall provide for on-site stormwater management controls, in accordance with best management practices identified by the County and/or Washington Department of Ecology Stormwater Management Manual for Western Washington, as amended.

(ii) In addition to other requirements, all new, replaced, and disturbed topsoil must be amended with organic matter, which shall not include biosolids (industrial, human, and/or hospital wastes) and shall be certified to be free of invasive weeds.

(c) Tier 3 Developments. All industrial development; commercial and residential development which generates more new or replaced impervious surface than is allowed in Tier 2, converts three-quarters acre or more of native vegetation to lawn or landscaped areas, or converts two and one-half acres or more of native vegetation to pasture; and all commercial projects that use hazardous materials:

(i) A stormwater management site plan prepared by a licensed engineer must be prepared in accordance with the most current edition of the Ecology Stormwater Management Manual for Western Washington, as amended.

(3) To avoid water quality degradation by malfunctioning or failing septic systems located within shoreline jurisdiction, on-site sewage systems shall be located and designed to meet all applicable water quality, utility, and health standards. On-site sewage systems shall comply with the shoreline and critical area buffer requirements of this Program, and shall be a minimum of 100 feet landward of the ordinary high water mark and any water body. On shorelines which, according to the State’s water quality assessment, exceed allowances for nitrogen contamination, the County shall require new septic systems to provide denitrification.

(4) All building materials that may come in contact with surface waters shall be composed of nontoxic materials, such as wood, concrete, approved plastic composites, or steel that will not adversely impact water quality or aquatic plants or animals. Materials used for docks or similar structures shall be approved by applicable State agencies for contact with water to avoid discharge of pollutants from wave splash, rain, or runoff. Wood treated with creosote, copper chromium arsenate, or pentachlorophenol is prohibited in shoreline water bodies.

(5) Solid and liquid wastes and untreated effluents shall not be allowed to enter any groundwater or surface water or to be discharged onto land. The release of oil, chemicals, genetically modified organisms, or hazardous materials onto land or into the water is prohibited.

(6) Illicit nonstormwater discharges to the stormwater system are prohibited. This includes direct discharges of wastewater (e.g., from sinks, washing machines) to stormwater conveyance systems such as drainage ditches, and discharge of wastes from incidental sources such as spills from road accidents into stormwater drainage.