To assist in addressing the 12,000 ac-ft of annual overdraft in the Pajaro Basin to decrease the downstream impacts of surface flow generated from impermeable surfaces and directed from surrounding developed neighborhoods onto the Watsonville airport, the project will install an intake structure for a MaxWell Plus Drainage (drywell) system in an existing swale. The inlet design consists of a prefabricated 2' by 3' concrete drop inlet placed within the bed of the swale and connected to an adjustable "Agridrain" prefabricated weir control box located on higher ground nearby. Water will enter the system through the top of the grated inlet and then discharge through an 8-inch diameter pipe to the weir box. At very low flows, water should be stopped at the weir and water in the weir box would equilibrate with standing water in the channel. As flows within the swale increase during storm events, the water surface elevation in the swale rises above the elevation of the weir crest. Water is then allowed to pass over the weir and on to the drywell system through a second pipe located on the other side of the weir box. The weir crest length was sized at 2.5 feet, allowing 0.4 cfs to pass over the weir as the water surface in the channel raises by 1.5 inches. Low flows continue to bypass the inlet and flow downstream within the watershed. The intake structure will be connected to a drywell array in the adjacent field. A mobile drill-rig will be used to drill three-holes for the MaxWell Plus drywells. Spoils will be disposed off-site. A backhoe or excavator will be used to dig 12" wide ranches for the 8" PVC supply lines to the drywell array.
The project will not have signigicant adverse impact on species or their habitat and wil not have a significnt cumulative impact to the environment and therefore shall be exempt from the provisions of CEQA.