HomeMy WebLinkAboutWSA-WVWD_EPALetterReWVWD-Discharge_Feb2016
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION IX
75 Hawthorne Street
San Francisco, CA 94105
SENT VIA EMAIL AS PDF
February 8, 2016
Tom Crowley
General Manager
West Valley Water District
855 W. Baseline
Rialto, CA 92377
Dear Mr. Crowley:
Subject: WVWD Startup and Operational Discharges to the Cactus Avenue Flood Control Basins
We have reviewed the January 27, 2016 Technical Memorandum related to the West Valley
Water District’s (the District) planned discharge of treated water from the District's Groundwater
Wellhead Treatment System Project into Cactus Avenue Flood Control Basins #1 and #2. The
Cactus Basins are operated by the San Bernardino County Flood Control District.
The Memorandum states that discharges are planned during initial plant startup and potentially,
after startup. The estimated discharge volume during startup is 336 acre-feet, assumed to occur
over a period of 40 days. Subsequent discharges, after startup, are estimated at up to 128 acre
feet per year. The discharged water is expected to recharge the Cactus Basins and infiltrate into
the underlying groundwater. After startup, the treated groundwater will be used as drinking
water and discharges to the Cactus Basins are expected to be infrequent.
Given the relatively small volumes of water and the limited duration of the planned discharges,
we do not expect the discharges to have a significant effect on the distribution or movement of
contaminated groundwater in the Rialto-Colton groundwater basin. Cactus Basins #1 and #2 are
located near the western edge of the groundwater plumes associated with the Rockets, Fireworks,
and Flares Superfund Site (formerly known as the B.F. Goodrich Superfund Site).
EPA previously reached this same conclusion about discharges that occurred during earlier
testing of the project. The earlier discharges were similar in magnitude, estimated at 270 acre-
feet, to the currently proposed discharges.
The shallow groundwater beneath Cactus Basins #1 and #2 is not known to be contaminated.
Near the Cactus Basins, significant groundwater contamination (i.e., contaminant concentrations
exceeding Maximum Contaminant Levels) first appears deeper in the aquifer (e.g., at more than
R
100 feet below the water table at nearby groundwater monitoring well 1S/5W-3A). We expect
that the planned discharge will have a negligible effect, if any, on this deeper groundwater.
Please call or email at 415-972-3181 or praskins.wayne@epa.gov with any questions.
Sincerely,
Wayne Praskins
Project Manager
cc: Kurt Berchtold, Santa Ana Regional Water Quality Control Board