HomeMy WebLinkAboutWet Season Requirements.pdfSECTION D.2 GENERAL CSWPP REQUIREMENTS
D.2.4.2 WET SEASON REQUIREMENTS
Any site with exposed soils during the wet season (October 1 to April 30) shall be subject to the special
provisions below. In addition to the ESC cover measures (see Section D.2.1.2), these provisions include
covering any newly seeded areas with mulch and identifying and seeding as much disturbed area as
possible prior to September 23 in order to provide grass cover for the wet season. A "wet season ESC
plan" must be submitted and approved by the City before work proceeds or continues.
Wet Season Special Provisions
All of the following provisions for wet season construction are detailed in the referenced sections. These
requirements are listed here for the convenience of the designer and the reviewer.
The allowed time that a disturbed area may remain unworked without cover measures is reduced to
two consecutive working days, rather than seven (Section D.2.1.2).
2. Stockpiles and steep cut and fill slopes are to be protected if unworked for more than 12 hours
(Section D.2.1.2).
3. Cover materials sufficient to cover all disturbed areas shall be stockpiled on site (Section D.2.1.2).
4. All areas that are to be unworked during the wet season shall be seeded within one week of the
beginning of the wet season (Section D.2.1.2.6).
5. Mulch is required to protect all seeded areas (Section D.2.1.2.2).
6. Fifty linear feet of silt fence (and the necessary stakes) per acre of disturbance must be stockpiled on
site (Section D.2.1.3.1).
7. Construction road and parking lot stabilization are required for all sites unless the site is underlain by
coarse -grained soil (Section D.2.1.4.2).
Sediment retention is required unless no offsite discharge is anticipated for the specified design flow
(Section D.2.1.5).
9. Surface water controls are required unless no offsite discharge is anticipated for the specified design
flow (Section D.2.1.6).
10. Phasing and more conservative BMPs must be evaluated for construction activity near surface waters
(Section D.2.4.3).
11. Any runoff generated by dewatering may be required to discharge to the sanitary sewer (with
appropriate discharge authorization), portable sand filter systems, or holding tanks (Section D.2.2).
D.2.4.3 CRITICAL AREAS RESTRICTIONS
Any construction that will result in disturbed areas on or within a stream or associated buffer, a wetland or
associated buffer, or within 50 feet of a lake shall be subject to the special provisions below. These
provisions include, whenever possible, phasing the project so that construction in these areas is limited to
the dry season. The City may require more conservative BMPs, including more stringent cover
requirements, in order to protect surface water quality. Any project proposing work within 50 feet of a
steep slope hazard area shall evaluate the need for diverting runoff that might flow over the top of the
slope.
Critical Areas Special Provisions
Any project that disturbs areas on or within a stream or associated buffer, wetland or associated buffer, or
within 50 feet of a lake has the potential to seriously damage water resources, even if the project is
relatively small. While it is difficult to require specific measures for such projects because the CSWPP
plan must be very site specific, the following recommendations shall be incorporated into the plan where
appropriate:
12/12/2016 2017 City of Renton Surface Water Design Manual
D-106