HomeMy WebLinkAboutRS-ErosionControlPlan pg2-4-MFP25006681-101193402SECTION D.2 GENERAL CSWPP REQUIREMENTS
6/22/2022 2022 City of Renton Surface Water Design Manual
D-20
Maintenance Standards for Plastic Covering
1. Torn sheets must be replaced and open seams repaired.
2. If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and
replaced.
3. When the plastic is no longer needed, it shall be completely removed.
D.2.1.2.5 STRAW WATTLES
Code: SW Symbol:
Purpose
Wattles are erosion and sediment control barriers consisting of straw wrapped in biodegradable tubular
plastic or similar encasing material. Wattles may reduce the velocity and can spread the flow of rill and
sheet runoff, and can capture and retain sediment. Straw wattles are typically 8 to 10 inches in diameter
and 25 to 30 feet in length. The wattles are placed in shallow trenches and staked along the contour of
disturbed or newly constructed slopes.
Conditions of Use
1. Install on disturbed areas that require immediate erosion protection.
2. Use on slopes requiring stabilization until permanent vegetation can be established.
3. Can be used along the perimeter of a project, as a check dam in unlined ditches and around temporary
stockpiles
4. Wattles can be staked to the ground using willow cuttings for added revegetation.
5. Rilling can occur beneath and between wattles if not properly entrenched, allowing water to pass
below and between wattles
Design and Installation Specifications
1. It is critical that wattles are installed perpendicular to the flow direction and parallel to the slope
contour.
2. Narrow trenches should be dug across the slope, on contour, to a depth of 3 to 5 inches on clay soils
and soils with gradual slopes. On loose soils, steep slopes, and during high rainfall events, the trenches
should be dug to a depth of 5 to 7 inches, or ½ to 2/3 of the thickness of the wattle.
3. Start construction of trenches and installing wattles from the base of the slope and work uphill.
Excavated material should be spread evenly along the uphill slope and compacted using hand tamping
or other method. Construct trenches at contour intervals of 3 to 30 feet apart depending on the
steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches
should be constructed. Vertical distance between wattles is not to exceed 10 feet.
4. Install the wattles snugly into the trenches and abut tightly end to end. Do not overlap the ends.
5. Install stakes at each end of the wattle, and at 4 foot centers along the entire length of the wattle.
6. If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and
into the soil.
7. At a minimum, wooden stakes should be approximately ¾ x ¾ x 24 inches. Willow cuttings or
3/8 inch rebar can also be used for stakes.
8. Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake protruding
above the wattle.
D.2.1 ESC MEASURES
2022 City of Renton Surface Water Design Manual 6/22/2022
D-21
Maintenance Standards
1. Inspect wattles prior to forecasted rain, daily during extended rain events, after rain events, weekly
during the wet season, and at two week intervals at all other times of the year.
2. Repair or replace split, torn, raveling, or slumping wattles
3. Remove sediment accumulations when exceeding ½ the height between the top of the wattle and the
ground surface.
SECTION D.2 GENERAL CSWPP REQUIREMENTS
6/22/2022 2022 City of Renton Surface Water Design Manual
D-22
FIGURE D.2.1.2.E STRAW WATTLES
1. STRAW ROLL INSTALLATION REQUIRES THE PLACEMENT AND SECURE STAKING
OF THE ROLL IN A TRENCH, 3" x 5" (75-125mm) DEEP, DUG ON CONTOUR.
2. RUNOFF MUST NOT BE ALLOWED TO RUN UNDER OR AROUND ROLL.
ROLL SPACING DEPENDS ON SOIL
TYPE AND SLOPE STEEPNESS
STRAW ROLLS MUST BE PLACED
ALONG SLOPE CONTOURS
3'-4'
1.2m)
10'-25'
3-8m)
3"-5"
75-125mm)
ADJACENT ROLLS
SHALL TIGHTLY ABUT
SEDIMENT, ORGANIC MATTER,
AND NATIVE SEEDS ARE
CAPTURED BEHIND THE ROLLS
LIVE STAKE
1" x 1" STAKE
8"-10" DIA.
200-250mm)
NOTES:
STRAW WATTLES
NTS