Perchlorate Occurrence in Ventura and Los Angeles Counties Dennis A. Dickerson Executive Officer California Regional Water Quality Control Board Los Angeles Region
Perchlorate Detections • Since 1997 perchlorate has been increasingly identified in regional groundwater • Occurrence closely associated with defense and aerospace sites • Highest levels of contamination most likely from “legacy” sources • new sources not being created • In some locations, incidental contamination resulting from other sources cannot be ruled out, e.g., fireworks, road flares, fertilizers
Where do we find the highest concentrations of perchlorate in groundwater? • Greatest concentrations in groundwater are found closely associated with aerospace and defense sites • Aerojet (Baldwin Park) • JPL (Pasadena) • Santa Susana Field Lab (Boeing)
Significant Source Sites in Ventura County • Boeing’s Rocketdyne SSFL • Santa Susana Field Lab • near surface 48 ppb (ES-11) • Chatsworth 1,600 ppb (HAR-16) • Off-site 4-5 ppb, single detects not repeated • San Nicholas Island • US Navy 16 ppb • Maximum concentrations in groundwater
Other Perchlorate Detections in Ventura County • Simi Valley • 17 detections in groundwater • all less than 20 ppb • 7 of the 17 detections less than 6 ppb • no definable plume • at present, no clear connection to SSFL as the source • Ahmanson Ranch • 28 ppb (MW-1) • split sample showed non-detect • pending additional round of sampling • Maximum concentrations in groundwater
Significant Source Sites in Los Angeles County • Whittaker Bermite Site • Santa Clarita - 310,000 ppb • DTSC Order • NASA/JPL • Pasadena - 1,500 ppb • USEPA Order (Superfund Site) • Aerojet • Azusa - 2,180 ppb • Regional Water Board Order • Maximum concentrations in groundwater
Perchlorate found in USEPA Multi-port monitoring wells across the Baldwin Park Operable Unit (BPOU) in Azusa, California
Other Perchlorate Detections in Los Angeles County • Central Basin • sporadic detections have been reported in Vernon, Commerce, Norwalk and Bellflower. • San Gabriel Basin • perchlorate has been detected basin-wide, inside and outside designated Superfund areas. • Pomona Valley • the City of Pomona has reported perchlorate detections as high as 19 ppb in 23 production wells.
Perchlorate Impacts • Ventura County • No drinking water wells impacted
Perchlorate Impacts • Los Angeles County • Numerous drinking water wells impacted (over 130 total) • Drinking water wells in the Cities of Santa Clarita, Valencia, Saugus and and Newhall have been affected. • City of Pasadena shut down 9 of their 13 drinking water wells due to perchlorate impact
Operable Unit 1: Source Removal JPL Facility Operable Unit 2 0 400 800 SCALE IN FEET Operable Unit 3: Plume Containment ClO4– > 500 ppb ClO4– > 10 ppb Figure 8
Treatment Options • Treatment is possible but costly • Current wellhead treatment systems not designed for perchlorate • retrofits are required
Regional Board Actions Source Identification Efforts: 1997– Directed the City of El Monte, water supply companies and some dischargers to sample for perchlorate. Analytical results ranged from 1 to 5 ppb. 1998 - Assisted USEPA with the identification of perchlorate contaminant sources in the Azusa/Baldwin Park Area. 1998 - Assisted USEPA with the revision of the 1994 Record of Decision for the Baldwin Park Operable Unit amended to include perchlorate.
Regional Board Actions Source Identification Efforts: 1999 - Directed PRPs in El Monte Operable Unit to sample for perchlorate. 2000 - Directed Lockheed (in San Fernando Basin) and NASA/JPL (Raymond Basin) to sample for perchlorate. 2001 - Directed some dischargers in Monrovia and South El Monte to sample for perchlorate.
Regional Board Actions Source Identification Efforts: 2002 - USEPA and the Regional Board direct PRPs in South El Monte and Puente Valley Operable Units to sample for perchlorate and other emergent chemicals. 2002 - Regional Board issues 13267 investigation letters to Boeing (Santa Susana Field Lab) and Ahmanson 2003 - Regional Board staff send out 433 letters to NPDES dischargers requesting a one time sampling for perchlorate, NDMA, 1,4-dioxane and hexavalent chromium.
Recent Regional Board Actions • Current focus is on investigation • orders issued to determine extent of contamination • Future actions • Cleanup and Abatement Orders where warranted • increase source identification efforts • work with USEPA on significant sites
Conclusions • A number of distinct and significant sources of contamination are known. • Many sources remain to be identified • Most identified source sites have not yet been remediated. • The occurrence of perchlorate in groundwater poses a significant additional economic burden to conduct wellhead treatment of drinking water resources.