Chapter 12.14 EROSION AND SEDIMENT CONTROL

Chapter 12.14
EROSION AND SEDIMENT CONTROL

Sections:

12.14.010 Minor developments.

12.14.020 Major developments.

12.14.030 Erosion and sedimentation control plan required.

12.14.040 Major development erosion and sedimentation control minimum requirements.

12.14.050 Erosion control design storm event.

12.14.010 Minor developments.

(a) All minor developments, as defined in this title, shall be required to control erosion and sedimentation during construction, to permanently stabilize soil exposed during construction, and to comply with the minor development requirements described in subsection (b)(1) through (5) of this section.

(b) Minor Development Requirements.

(1) Construction Access Route. Construction vehicle access shall be, whenever possible, limited to one route. Access points shall be stabilized with quarry spall or crushed rock to minimize the tracking of soils and debris onto public roads.

(2) Stabilization of Denuded Area. All exposed soils shall be stabilized by suitable application of BMP’s, including but not limited to, sod or other vegetation, mat covering, mulching or application of compacted ground base material on areas to be paved. All BMP’s shall be selected, designed and maintained in accordance with the manual. From October first to April thirtieth, no soils shall remain unstabilized for more than two days. From May first to September thirtieth, no soils shall remain unstabilized for more than seven days.

At all times of the year, the contractor shall have sufficient materials, equipment and labor on-site to stabilize and prevent erosion from all denuded areas within twelve hours as site and weather conditions dictate.

(3) Protection of Adjacent Properties. Adjacent properties shall be protected from sediment deposition by appropriate use of vegetative buffer strips, sediment barriers or filters, dikes or mulching, or by a combination of these measures and other appropriate BMP’s.

(4) Maintenance. All erosion and sediment control BMP’s shall be regularly inspected and maintained to ensure continued performance of their intended function.

(5) Other BMP’s. Any adverse effects of increased runoff resulting from land disturbing and/or land development activities shall be controlled by appropriate BMP’s.

(Ord. 199 (1996) §§ 5.10, 5.11, 1996)

12.14.020 Major developments.

Any new development meeting the definition of a major development, shall comply with Section 12.14.040. For any redevelopment project meeting the definition of a major development, those portions of the site that are being redeveloped shall comply with Section 12.14.040.

(Ord. 199 (1996) § 5.20, 1996)

12.14.030 Erosion and sedimentation control plan required.

Compliance with the erosion and sedimentation control requirements of Section 12.14.040 shall be demonstrated through the implementation of an approved erosion and sedimentation control plan.

(Ord. 199 (1996) § 5.21, 1996)

12.14.040 Major development erosion and sedimentation control minimum requirements.

(1) Stabilization and Sediment Trapping. All exposed and unworked soils, including soil stockpiles, shall be stabilized by suitable application of BMP’s which protect soil from the erosive forces of raindrop impact and flowing water. Applicable practices include, but are not limited to vegetative establishment, mulching, plastic covering, and the early application of gravel base on areas to be paved. From October first to April thirtieth, no soils shall remain unstabilized for more than two days. From May first to September thirtieth, no soils shall remain unstabilized for more than seven days.

(2) Delineation of Clearing and Easement Limits. Clearing limits, setbacks, buffers and sensitive or critical areas such as steep slopes, wetlands and riparian corridors shall be clearly marked in the field and inspected by the Kitsap County department of community development prior to commencement of land clearing activities.

(4) Timing and Stabilization of Sediment Trapping Measures. Sediment ponds and traps, perimeter dikes, sediment barriers and other BMP’s intended to trap sediment on-site shall be constructed as a first step in grading. These BMP’s shall be functional before additional land disturbing activities take place. Earthen structures such as dams, dikes and diversions shall be stabilized according to the timing indicated in subsection (1) of this section.

(5) Slope Stabilization. Cut and fill slopes shall be constructed in a manner that will minimize erosion. Roughened soil surfaces are preferred to smooth surfaces. Interceptors should be constructed at the top of long, steep slopes which have significant areas above that contribute runoff. Concentrated runoff should not be allowed to flow down the face of a cut or fill slope unless contained within an adequate channel or pipe slope drain. Wherever a slope face crosses a water seepage plane, adequate drainage or other protection should be provided. In addition, slopes should be stabilized in accordance with subsection (1) of this section.

(6) Controlling Off-Site Erosion. Properties and waterways downstream from development sites shall be protected from erosion due to increases in the volume, velocity, and peak flow rate of storm water runoff from the development site by the implementation of appropriate BMP’s to minimize adverse downstream impacts.

(7) Stabilization of Temporary Conveyance Channels and Outlets. All temporary on-site conveyance channels shall be designed, constructed and stabilized to prevent erosion from the expected flow velocity from a two-year frequency, twenty-four-hour duration storm for the post-development condition. Stabilization adequate to prevent erosion of outlets, adjacent streambanks, slopes and downstream reaches shall be provided at the outlets of all conveyance systems.

(8) Storm Drain Inlet Protection. All storm drain inlets made operable during construction shall be protected so that storm water runoff shall not enter the conveyance system without first being filtered or otherwise treated to remove sediment. After proper written application, the requirement for inlet protection may be waived by the director on a site-specific basis when the conveyance system downstream of the inlet discharges to an appropriate on-site sediment control BMP, including but not limited to sediment ponds or traps, and the conveyance system will be adequately cleaned following site stabilization.

(9) Underground Utility Construction. The construction of underground utility lines shall be limited, where feasible, to no more than five hundred feet of open trench at any one time. Where consistent with safety and space considerations, excavated material shall be placed on the uphill side of the trench. Dewatering devices shall discharge to an appropriate sediment trap or pond, preceded by adequate energy dissipation, prior to runoff leaving the site.

(10) Constructed Access Routes. Wherever construction vehicle access routes intersect paved roads, provisions must be made to minimize the transport of sediment (mud) onto the paved road by use of appropriate BMP’s such as a stabilized construction entrance. If sediment is transported onto a road surface, the roads shall be cleaned thoroughly, as a minimum, at the end of each day. Sediment shall be removed from roads by shoveling or sweeping and be transported to a controlled sediment disposal area. Street washing shall be allowed only after sediment is removed in this manner.

(11) Removal of Temporary BMP’s. All temporary erosion and sediment control BMP’s shall be removed within thirty days after final site stabilization is achieved or after the temporary BMP’s are no longer needed. Trapped sediment shall be removed or stabilized on-site. Disturbed soil areas resulting from removal of temporary BMP’s shall be permanently stabilized. The removal of temporary erosion and sediment control BMP’s may not be required for those projects, such as single-family plats, that will be followed by additional construction under a different permit. In these circumstances, the need for removing or retaining the measures will be evaluated on a site-specific basis.

(12) Dewatering Construction Sites. Dewatering devices shall discharge into an appropriate sediment trap or pond designed to accept such a discharge, preceded by adequate energy dissipation, prior to runoff leaving the site.

(13) Control of Pollutants Other Than Sediment on Construction Sites. All pollutants other than sediment that occur on-site during construction shall be handled and legally disposed of in a manner that does not cause contamination of surface waters. Pollutants of concern include, but are not limited to, fuels, lubricants, solvents, concrete byproducts and construction materials.

(14) Maintenance. All temporary and permanent erosion and sediment control BMP’s shall be maintained and repaired as needed to assure continued performance of their intended function. All maintenance and repair shall be conducted in accordance with the manual. The applicant shall be responsible for assuring that any such facilities damaged during floods, storms or other adverse weather conditions are immediately returned to normal operating condition.

(15) Financial Liability. A performance covenant or performance surety shall be required for all projects, to ensure compliance with the approved erosion and sediment control plan, as outlined in Chapter 12.12.

(Ord. 199 (1996) § 5.30, 1996)

12.14.050 Erosion control design storm event

Facilities designed for the control of erosion and sedimentation shall be designed for the erosion and sedimentation control design storm event, defined as the two-year, twenty-four-hour duration storm.

(Ord. 199 (1996) § 5.40, 1996)