Through word of mouth marketing, Torrent was asked to evaluate the potential of using a MaxWell® Plus on a Southern California Edison (SCE) site in Ontario, CA. The existing site contained a stormwater retention basin that had stopped draining because the surface soils had been completely impacted by the introduction of silt and fine material over the years. With new improvements in the works, the site had to meet current stormwater requirements, which include draining within 48 hours after a storm.
Torrent used information from previous drywell installations in the vicinity of the subject site to affirm that using a drywell would be feasible and provided a design for a single MaxWell Plus. Having previously worked on SCE projects, Torrent had all the proper approvals/clearances and coordinated, designed, and installed the drywell in the failing basin within 90 days.
The 1.66 acre site generated a water quality volume of 13,187 ft3 and the sub-surface soils allowed for an infiltration rate of 9 in/hr at the projected depth. After applying a 50% factor of safety, the final drywell design included a 15’ primary settling chamber, 15’ drywell chamber, and an overall depth of 55’. The surface area of the gravel pack beneath the drywell chamber allowed the system to easily drain away the volume storm within 48 hours.
With its deep sump, internal filter screens, and oil sorbent pillows, the MaxWell Plus provides excellent pre-treatment of influent stormwater. The introduction of a drywell into this failing retention basin has provided a positive means of eliminating accumulated stormwater within the time allowed while allowing for periodic maintenance. A side benefit of adding the drywell includes groundwater recharge of pre-treated stormwater that used to only disappear over a long period of time through evaporation.
Torrent Resources has a geological database with over 12,000 drywell excavations in Southern California to help you estimate the anticipated soil conditions in a specific area. We can size the right product to meet your design criteria. CLICK HERE to design your drywell.