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HomeMy WebLinkAboutMINUTES - 01271987 - T.5 THE BOARD OF SUPERVISORS OF CONTRA COSTA COUNTY, CALIFORNIA Adopted this Order on January 27, 1987 by the following vote: AYES: Supervisors Powers, Fanden, Schroder, Torlaskon, McPeak NOES: None ABSENT: None ABSTAIN: None ------------------------------------------------------------------- ------------------------------------------------------------------- SUBJECT: Report Status of GBF Toxic Waste Site in Antioch This being the time for hearing on the report of the County Health Services Director on the status of the GBF Toxic Waste Site in Antioch; and Dr. Wendel Brunner, Assistant Health Services Director, Public Health) appeared and reviewed the contents of his January 26 , 1987 report, a copy of which is attached hereto and by reference incorporated herein. IT IS BY THE BOARD ORDERED THAT the aforesaid report is accepted and is HEREBY REFERRED to the Hazardous Materials Commission and to the newly established Containment, Clean-up and Coordinating Committee. I hereby codify that this is a treat and correct copy of an action taken and erterad on the minutes of the Board of Supervisors on tha date shown.� ATTESTED: Z ---�U_ _ PHIL BA .HE!CP', 1,%.rk tr the Board of Supe sears ant County Administrator By ._...._._:..,Deputy cc: Health Services Director County Administrator Hazardous Materials Commission (Via CAO) Containment, Clean-up and Coordinating Committee via Supervisor Torlakson CONTRA COSTA COUNTY HEALTH SERVICES DEPARTMENT c COUNT Board of Supervisors To: via Phil Batchelor Date: January 26, 1987 County Administrator From: Mark Fi nucane 11-411 Subject: Current Status of GBF Health Services Director Toxic Waste Site in by Wendel Brunner, M.D.'l/y Antioch Assistant Health Services Director Public Health Enclosed is a report prepared by staff from the Public and Environmental Health Divisions describing the current status of the investigations into the leaking of toxic chemicals from the GBF hazardous waste site in Antioch. In August 1986 the Central Valley Regional Water Quality Control Board disco- vered that the closed GBF site had leaked toxic chemicals into the groundwater in the immediate vicinity of the site. Our Health Department was primarily con- cerned about the possibility of exposure of the community to these hazardous chemicals through drinking water or air. The City of Antioch, including the subdivisions in the immediate vicinity of the site, are served by a public water system. That system is regularly tested for trace toxic contaminants, and our survey of those test records indicated that the public drinking water system is not contaminated. With the cooperation of the City of Antioch the County Health Department identified existing domestic wells within three miles of the GBF site. We selected seven wells closest to the site for testing; those wells are all free of toxic contamination. The Bay Area Air Quality Management District conducted measurements of ambient air both up and downwind of the GBF site on two separate days. The level of toxic air contaminants downwind of the GBF site is less than the average measured by the BAAQMD at their nine monitoring sites throughout the Bay Area, and is in particular less than the values obtained on the corresponding days at the nearest monitoring site in Pittsburg. The monitoring data for air and water has been reviewed by the County Health Department and representatives of the State Department of Health Services Toxic Substances Control Divisions and Epidemiological Studies Section, Bay Area Air Quality Management District staff, and Solid Waste Management Division staff. That group believes that the data shows no current human exposure to leaking materials from the hazardous waste site. That group further recommended, however, that additional water samples be taken from Markley Creek and that additional soil gas samples be obtained between the waste site and the nearby subdivisions. That further sampling will be completed within several weeks. There is still a need to expedite the characterization of the groundwater con- tamination plume to identify potential future contamination of drinking water sources. The more definitive abatement of the site is the primary respon- sibility of the regulatory agencies with jurisdiction, State Health Services Department and Regional Water Quality Control . WpB�:,rm E11� A-41 * CURRENT STATUS OF GBF TOXIC WASTE SITE IN ANTIOCH This report summarizes the information that has been assembled by the County Health Services Department regarding the GBF land site and the potential for an adverse public health impact in the community from the migration of toxic chemi - cals from that site. We have focused on identifying possible exposures from water, air, soil gas migration, and direct physical contact. To assemble the information required for such an evaluation we made a physical site inspection and sampled water from existing wells in the community. To evaluate possible air exposure, the Bay Area Air Quality Management District (BAAQMD) made measurements of ambient air both up and downwind of the site to identify any off gassing of toxic materials. The BAAQMD also performed soil gas measurements on the dump site for toxic constituents. In addition to the BAAQMD, we received assistance in this evaluation from the State Department of Health Services, Central Valley Regional Water Quality Control Board, (CVRWQCB) , the Antioch Maintenance Services Department, and the California Waste Management Board. The GBF site in Antioch was used for disposal of toxic and hazardous materials between World War II and 1974. Beginning in 1960 the site came under the mana- gement of Industrial Tank Corporation, an ancestor of the current IT toxic waste management corporation. In the late 60' s and early 70' s the site consisted of ten ponds covering approximately 60 acres: Although no detailed manifests were kept at the time, a large quantity of hazardous wastes were disposed of in these ponds. Existing records indicate that the waste included oils, solvents, acids, beryllium metal , and polychlorinated biphenyls (PCB' s) . Later apparently some phosphorous ordinance, either grenades or mortar shells, were dumped in the area. The ponds were completely unlined; in fact, they were designed as "Percolation and evaporation ponds", deliberately intended to allow the waste to evaporate into the air or percolate into the ground. The concentration of orga- nics into the pond was apparently on occasion high enough to burn, and there are at least three documented major fires that occurred there during the early 701s. A State Health Services Department report mentions that at other times the vapors from the ponds were thick enough to be mistaken for smoke. The GBF site ceased accepting hazardous waste in 1974 and began a closure proce- dure under the direction of the State Department of Health Services -and the Regional Water Quality Control Board. The closure was one of the first closures of a hazardous waste facility in the nation, and was portrayed as a model of state of the art closure technology at the time. The closure procedure con- sisted of filling the ponds with ordinary garbage to absorb the hazardous waste and then covering the top over with earth. Finally the site was sealed with a cap of presumably impermeable clay. A series of shallow wells were installed around the perimeter of the site to monitor for leachate migrating off the faci- lity. Dutifully logged reports from quarterly inspections of the collection wells indicated that they were always dry. In May of 1986 six deeper groundwater monitoring wells were installed at the GBF land fill site in Antioch under new Calderon legislation which required moni - toring of actual groundwater in the vicinity of toxic waste sites. Samples from the groundwater monitoring wells were collected or analyzed in August. The results indicated a significant contamination of groundwater in the immediate vicinity of the site by toxic chemicals. The Contra Costa County Health Services Department learned of the results in September, although official noti- fication from the Central Valley RWQCB did not occur until October. A summary of the well monitoring data gathered in August appears in Table 1. -1- The first concern of the Health Department was to determine whether any drinking water supplies had been contaminated by leakage from the hazardous waste site. The subdivisions in the immediate vicinity of the site are served by an Antioch public water system which draws its source from the Contra Costa Canal . A review of the records of the Antioch water system, as well as the other water systems in the county which are all tested regularly for trace toxic con- taminants, indicated that none of the public water systems in the county have been contaminated by toxic chemicals. The Health Department next surveyed for existing domestic wells in the vicinity of the GBF site. Wells were identified from well permit records from the Environmental Health Division, an inventory of crossflow protection devices maintained by the Antioch Maintenance Services Department, and information from local citizens knowledgeable about well locations in the area. A total of more than 30 domestic wells in the vicinity of the landfill were identified, with three wells located within two miles of the site being used for drinking. Seven of the domestic wells nearest the site were sampled by the Contra Costa Health Department between August 31 and December 3. Most of these wells were within one and one-half miles of the site; the closest was three-quarters of a mile away. The seven wells sampled include the three that were used for drinking purposes. The water samples were analyzed for purgeable halocarbons, purgeable aromatics, and acetone. All seven wells sampled were free of toxic contaminants down to very low detection limits. An additional small water system within two miles of the waste site was tested during spring 1986 by the County Health Department in the course of implementing AB1803. The well feeding that system was also free of organic chemical contaminants. The Contra Costa County Health Services Department convened two meetings in November with representatives of the CVRWQCB, BAAQMD, State Department of Health Services, including Toxics Control Division and Epidemiological Studies Section, and the California Waste Management Board. The first meeting on November 5, 1986 focused on the domestic well sampling program described above as well as plans for accelerating the schedule for requiring the site responsible party to develop further information to characterize the extent of contamination of groundwater from the site. As a result of the requirement of the CVRWQCB, GBF 's consultants submitted a work plan on December 1, 1986 for characterization of the extent of the groundwater contamination plume. The plan, which has been approved by the Water Board, requires the installation of seven additional groundwater monitoring wells. Those new wells will be the first in a series of additional wells to define the extent of the groundwater contamination. The second meeting held November 13 included representatives of the Epidemiological Studies Section of the State Health Services Department and focused on identifying potential paths of current exposure that could impact public health in the vicinity of the site. As the water exposure routes had been largely handled at the previous meeting and by our Health Departments well water sampling program, the second meeting focused on possible airborne exposure to the population. An ambient air and soil gas monitoring program was discussed and planned, and the BAAQMD agreed to perform the indicated measurements. A visit to the GBF site was organized and conducted on November 16 by staff from DOHS, BAAQMD, and our Health Department. During that visit soil gas monitoring wells were observed and it was determined that fencing and other measures were intact to prevent children or others coming into direct contact with the waste site. -2- Air sampling was conducted by BAAQMD on December 11 and again on December 17, 1986., Six hour samplings of ambient air were taken both upwind and downwind of the GBF site on both days. Those samples were analyzed at the BAAQMD labora- tories for trace toxic air contaminants. In addition, soil gas samples from the monitoring wells throughout the dump site, including the areas used primarily for solid waste sanitary landfill , were collected and analyzed. The results are presented in Table 2. The results in Table 2 indicate that the level of toxic air contaminants in the vicinity of the GBF dump site both up and downwind are lower than the average level of air contaminants identified at the nine monitoring stations throughout the Bay Area maintained by the BAAQMD. In particular, the concentrations in the vicinity of the GBF site were lower than the concentrations obtained on the corresponding days at the nearest BAAQMD monitoring site in Pittsburg. On January 13, 1987 the Contra Costa Health Services Department called a meeting of representatives of the Department of Health Services Toxic Substances Control Division and Epidemiological Studies, BAAQMD, and California Waste Management Board to discuss the public health significance of the data collected to date, and to identify any further measures that should be immediately taken to assure that there is not current exposure to the population in Antioch to toxic chemi - cals from the site. The consensus from the agencies was that public health is not being impacted through exposure to ambient air or groundwater, although it was recommended that Markley Creek should be sampled if there is surface water flowing past the landfill . The agencies also agreed to a monitoring plan to rule out exposure of the nearby subdivision due to soil gas migration. Such an exposure did occur at the BKK site in Southern California, although the houses impacted in that case were immediately adjacent to that toxic waste site. In Antioch the nearest homes are three hundred feet away. The California Waste Management Board has agreed to install temporary soil gas monitoring wells, and the BAAQMD has again offered the services of their laboratory and technical expertise. Sampling is expected to be completed in the next few weeks to rule out the unlikely possibility of soil gas migration toward the subdivision. With the completion of the soil gas and creek monitoring described above, we can confirm that there is not current human exposure to toxic chemicals from the GBF site. That conclusion was in particular discussed with Dr. K. Goldsmith repre- senting the Epidemiological Studies Section of the State Department of Health Services; she has reviewed our data and methodology and concurs in our conclu- sions. It is still of some health importance to expedite the characterization of the groundwater contamination plume so as to identify potential future sour- ces of drinking water contamination. Following the completion of the pending soil gas measurements, and in particular after characterization of the ground- water plume, the Contra Costa County Health Services Department will become less actively involved in the GBF site issues. Further site characterization and mitigation is mainly a matter of public policy and enforcement by the regulatory agencies having primary jurisdiction, State Health and Regional Water Quality Control Board. The Contra Costa County Health Services Department would like to become involved regarding any future land use planning proposal involving the GBF site. -3- 1/16/87 20gbfrpt TABLE 1 GBF GROUNDWATER MONITORING RESULTS Sampling Date: August 11 - August 12 Test: EPA Method 624/625 Units: PPB Constituent Monitoring Well 1 2 3 4 5 6 Acetone 3200 440,000* Chloroform 5 2,200* 250* 1,1-Dichloroethene 16* 1,1-Dichlorethane 5 24* 6 1,2-Dichloroethane 18* Trans-1,2-Dichloroethene 6 - 26* 1,2-Dichloropropane 5 3700* 14* Trichloroethene (TCE) 26* 680* 3 48* 170* Benzene 23* 110* 5* Tetrachloroethene (PCE) 31* 190* 2-Hexanone 210 Toluene 22 Xylene 52 Carbon Tetrachloride 9* 1,2-Dichlorobenzene 26 *Above action level L CU C\3 3: to 4-) co (o r4 O C6 1c) O 0% > r-4 ct 1-4 Oj >)V-4 - S- 4- C) C; C\J04 Ln m "4 E m %0 CD -4 --4 C> P-4 %0 C:) -4 00 ep Ul a) r- 4-J u (0 CD C:; c, O C1 O a, O O c; Q 4J I -X; O S- u C71 lt:r C7% co C� &-E (a Co to C)� -4 C) -4 -4 to S— o cu •C-4 C=; C5 NNci > N/ to to c 00 --- Ul) LO C14 Ch C%j Itr E (::I to r4 v-4 t0 N CD to a to C-1; C=; CO C; CO O cl* C; 4- C%j IV V I/ cr- -i V) to as co cic vel **,% N = (D 1-4 CD LO O v-4 -tr r-4 r-4 C) V-4 -% r4 ; 8 CO 8 8 8 6 03 C N N/ V v U- V) a_ ¢ r-4 CL c C4 to Ca p r- co 3: m O a 00 C%j 0% 4-; V) LLI 0 CO r-4 0-4 LO " CD --cr CO N C%j LLJ V) 4-) 01 o V) V) >1 > r-4 O O O C) 0 O N O (D Ilzr ct LLI S- NN/ CU CD +j L -4 a o tom. >< (1) tj C9 ul >< to C) LLj 03 to 0% co C%s 00 r- 0 cl o O to C) -4 C> O CD O C) 0 -3 = -r-U V-4 V_; Cl 8 40* 8 8 r; C; 8 4 4- C%j %e v v v V (a LU ca -j LA- tm I co NC) CD CO m 1-4 rl% (D " LA- -4 CO C; O v_: O G C4 8 1; c 4-a ro 03 cli v v %Ile 3: 4-3 4 P tJ -- 4.3 r4 0*r (Lr) Q m 4-) 406 4-b 41 >I# W c MLn s- 4- > S- t0 +Lj 0 -r- :3 m 00 C LL- -0 c \ d Mr. Icr C) C114 ln' (L) >% (A.- -4 C) co Cl r-4 Kr 1-4 cli N O N to U 4.J 4- W 4J S- r-4 +j o 4.J C%j IV v w -4 a 4- 44 U (A 4) 0 IA-- 39 C to 4J C-4 4J Cj 4-3 (A S- u LLJ a) -r- 0 -19 a -j _0 r- 44 L O 43 43) cj 41 CL. 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