perchlorate occurrence in ventura and los angeles counties dennis a. dickerson executive officer...
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Perchlorate Occurrence in Ventura and Los Angeles Counties
Dennis A. DickersonExecutive 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 Monitoring Wells in Azusa (BPOU)
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
0 400 800
SCALE IN FEET
ClO4– > 500 ppb
ClO4– > 10 ppb
JPLFacility
JPLFacility
Operable Unit 2
Operable Unit 1:Source RemovalOperable Unit 1:Source Removal
Operable Unit 3:Plume ContainmentOperable Unit 3:Plume Containment
Figure 8
Treatment Options
• Treatment is possible but costly
• Current wellhead treatment systems not designed for perchlorate– retrofits are required
Regional Board ActionsSource 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 ActionsSource 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 ActionsSource 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.
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