Reasons for Exemption
Work under this project consists of installation of small new equipment at an existing wastewater treatment plant, and falls under both Class 1 and Class 3. Class 1 consists of the operation, repair, maintenance, permitting, leasing, licensing, or minor alteration of existing public or private structures, facilities, mechanical equipment, or topographical features, involving negligible or no expansion of existing or former use. All new equipment will be installed at an existing wastewater treatment plant, and an existing renewable natural gas plant within that wastewater treatment facility. Modifications will be made to existing equipment and piping, and new equipment will be placed on existing concrete or in an existing biodigester. For these reasons, work under this project will have no significant impact on the environment and falls within 15301. Class 3 consists of construction and location of limited numbers of new, small facilities or structures; installation of small new equipment and facilities in small structures; and the conversion of existing small structures from one use to another where only minor modifications are made in the exterior of the structure. There are five components to the work. First, an existing thickener unit will be replaced. The new unit will be placed on existing concrete, and will be approximately 24 square feet. Pumps, piping, and a filter will be placed on existing lines. Second, a new membrane holder and piping will be installed, next to an existing membrane holder. The new membrane holder will be approximately 300 square feet. Third, modifications will be made to existing piping in an existing renewable natural gas (RNG) plant within the existing wastewater treatment facility. Small electronic controls and instrumentation, new piping, valves, and membranes on existing racks will all be added. The new membranes are approximately 12” x 36”. Fourth, a microgrid controller – i.e., a computer – will be added at the RNG plant. Fifth, two mixers will be added to an existing anaerobic digester. Each mixer is approximately 900 pounds, with a 1.5-meter blade diameter. The result of these upgrades and additions of small new equipment will be to increase throughput without changing use, while simultaneously reducing biogas flaring. For these reasons, work under this project will have no significant impact on the environment and falls within 15303.