METHODS OF DEWATERING SEDIMENT BASINS

The dewatering methods shown here are inexpensive and operate automatically.

METHOD

COMMENTS

B. Same as "A" except for skimming device, detailed below:

C.

CROSS-SECTION

D.

CROSS-SECTION

Bags must be disposed of according to manufacturer's instructions. Bags may not be reused. SEDIMENT CONTROL BAG FOR DEWATERING

N.T.S.

Table 27-1: Lengths of Construction Exits on Sloping Roadbeds

STONE SIZE – NO. 2 (2–1/2" TO 1–1/2") OR NO. 3 (2 TO 1 INCH) CLEAN. CRUSHED, ANGULAR STONE

Use ECMDS\circledR for more accurate staple pattern selection.

Individual lot entrance and egress- After interior roadways are paved, individual lot ingress/egress points may require a stabilized construction entrance consisting of no. 3 stone (1" to 2") to prevent or minimize tracking of sediments. Width of the stone ingress/egress shall be equal to lot entrance width and shall be a minimum of ten feet in length.

Tire washing - If space is limited, vehicle tires may be washed with clean water before entering a paved area. A wash station must be located such that wash water will not flow onto paved roadways or into unprotected storm drainage systems.

When the construction access exits onto a major roadway, a paved transition area may be installed between the major roadway and the stoned entrance to prevent loose stones from being transported out onto the roadway by heavy equipment entering or leaving the site.

Maintenance

The entrance shall be maintained in a condition which will prevent tracking or flowing of sediment onto roadways. This may require periodic top dressing with additional stone or additional length as conditions demand and repair and/or cleanout of any measures used to trap sediment. All sediment spilled, dropped, washed, or tracked onto roadways (public or private) or other impervious surfaces must be removed immediately.

Where accumulation of dust/sediment is inadequately cleaned or removed by conventional methods, a power broom or street sweeper will be required to clean paved or impervious surfaces. All other access points which are not stabilized shall be blocked off.

STABILIZED CONSTRUCTION ACCESS

N.T.S.

C. Requirements for silt fence:

Fence posts shall be spaced 8 feet center-to-center or closer. They shall extend at least 2 feet into the ground and extend at least 2 feet above ground (Fig. 23-2). Posts shall be constructed of hardwood with a minimum diameter thickness of 1 1/2 inches.

2. "Super" silt fence - A metal fence with 6 inch or smaller mesh openings and at least 2 feet high may be utilized, fastened to the fence posts, to provide reinforcement and support to the geotextile fabric. Posts may be spaced less than 8 feet on center and may be constructed of heavier wood or metal as needed to withstand heavier sediment loading. This practice is appropriate where space for other practices is limited and heavy sediment loading is expected. "Super" silt fence is not to be used in place of properly designed diversions (pg. 15-1) which may be needed to control surface runoff rates and velocities.
3. A geotextile fabric, recommended for such use by the manufacturer, shall be buried at least 6 inches deep in the ground. The fabric shall extend at least 2 feet above the ground. The fabric must be securely fastened to the posts using a system consisting of metal fasteners (nails or staples) and a high strength reinforcement material (nylon webbing, grommets, washers etc.) placed between the fastener and the geotextile fabric. The fastening system shall resist tearing away from the post. The fabric shall incorporate a drawstring in the top portion of the fence for added strength.

Maintenance

1. Sediment shall be removed from the upstream face of the barrier when it has reached a depth of 1/2 the barrier height.
2. Repair or replace barrier (fabric, posts, bales etc.) when damaged.
3. Barriers shall be inspected daily for signs of deterioration and sediment removal.

FLOATING RISER DETAIL

N.T.S.