3875Water Treatment

3875.1SCOPE

Provide water treatment methods to minimize turbid water levels from dewatering practices that discharge to receiving waters.

3875.2REQUIREMENTS

A Passive Use passive dewatering treatment methods, using time and gravity to settle out sediments, if draining basins, traps, ditches, or sumps to prepare the construction site for the next storm event. A.1 Rock Weepers Provide rock weepers for vegetated or impermeable lined channels per 3874.2C, “Type 3 – Rock Weeper System” A.2 Perforated Riser (Standpipe) Provide a riser pipe in a pond, basin, or trap outlet Structure meeting the following requirements or characteristics:

Structure

riser pipe

Install a trash guard on the top overflow. A.3 Floating Head Skimmer Provide a schedule 40 PVC pipe at least 1.5 inch diameter for the floating head skimmer. Provide a flocculant per 3898, “Flocculants” with a floating head skimmer for additional treatment, if shown in the Plans. A.4 Portable Sediment Tanks Provide prefabricated portable sediment tanks meeting the following requirements and characteristics:

capacity

access

other filter media to meet the Project pollutant load

Provide additional tanks to meet item (2) above or, if outfall water is not visibly clear. B Active Provide pumps, hoses, pressurized tanks, or a combination of these items to depress the water table allowing for construction Work to be completed in dry soil conditions. B.1 Rock Barrel Provide a 55 gallon barrel with 12 inch slits cut into the base. Install a sleeved 8 inch diameter perforated pipe in the barrel. Provide a flocculant sock per 3898, “Flocculants,” and place the sock at the bottom of the barrel and around the base of the perforated pipe. Surround the slits in the bottom of the barrel with clean rock with a diameter from 1 inch to 2 inches. Place the clean rock on a 1:2 (Vertical:Horizontal) slope around the barrel. B.2 In-line Flocculant Sock Provide a flocculant per 3898, “Flocculants,” in the hose connecting one containment facility to another. Locate the flocculant sock after the pump. B.3 In-line Pressurized Filter Systems Provide a portable water quality monitoring system consisting of sand media, pressurized bags, or cartridges to produce required turbidity or chemical reduction. Use liquid flocculants in accordance with 3898, “Flocculants,” if necessary. Provide a portable water quality monitoring system meeting the discharge requirements shown on the P lans.

3875.3SAMPLING AND TESTING – BLANK