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PUBLIC HEALTH ASSESSMENT

SYNERTEK (BUILDING 1)
SANTA CLARA, SANTA CLARA COUNTY, CALIFORNIA


SUMMARY

Synertek Building #1 is in an industrial and commercial area ofSanta Clara, California. Synertek was placed on the U.S.Environmental Protection Agency's National Priorities List inSeptember 1989. The California Regional Water Quality ControlBoard (RWQCB), San Francisco Bay Region, is the lead agency foroverseeing investigation and remediation at the site. One solventstorage tank and a three tank neutralization system leaked variousorganic solvents into subsurface soils and groundwater. Thoseunderground tanks were removed in 1985, along with contaminatedsubsurface soil around the tanks. Several organic compounds,principally 1,1,1-trichloroethane (1,1,1-TCA), trichloroethylene(TCE), 1,1-dichloroethane (1,1-DCA), 1,1-dichloroethylene(1,1-DCE), vinyl chloride, and 1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113) have been detected in shallow on-and off-site groundwater at levels of health concern.

None of the contaminated groundwater has been used or is currentlybeing used as public water supply, and the city of Santa Clara hasno plans to use it for that purpose. However, under the RWQCBWater Quality Plan, the shallow groundwater at the Synertek site isconsidered a potential source of drinking water. Because of that,the RWQCB is required to take action to protect such potentiallybeneficial use. On-site groundwater extraction and treatment torestore water to acceptable drinking water standards have been inoperation since 1987; off-site groundwater extraction began in1989. The RWQCB adopted a Final Remedial Action Plan for Synertek#1 (Board Order 91-051) on March 20, 1991. EPA's AssistantRegional Administrator signed the Record of Decision for Synertek#1 on June 28, 1991. The clean up plan for the site is expected totake about 25 years to reach targeted clean up levels.

Based on information reviewed, the Agency for Toxic Substances andDisease Registry (ATSDR), and the California Department of HealthServices (CDHS) consider this site an indeterminate public health hazard due to incomplete information on possible air contamination. Specifically, there is insufficient information to evaluate thepossible effect on indoor air quality of emissions from the airstripper stacks located near the air intake vents for Building #1,or the effect of possible accumulation of volatile organiccompounds in enclosed spaces in industrial or commercial buildingsover the groundwater contaminant plume (the contaminant plume isnot near a residential area). Direct exposure to groundwatercontaminants is unlikely since no water wells will be permitted inareas of known contamination until the groundwater extraction andtreatment system reduces concentrations of contaminants to a pointbelow levels of health concern.

ATSDR and CDHS recommend evaluating the potential effect of airstripper emissions on air within Synertek Building #1 due toproximity of intake vents to the air stripper stacks. Further,ATSDR and CDHS recommend that remedial action be taken ifnecessary. We also recommend that an indoor air model be developedand that direct indoor air monitoring be carried out to determineconcentrations of volatile organic compounds in Synertek Building#1 in order to determine whether contaminated soil gas is effectingthe indoor air quality in buildings over the groundwatercontaminant plume. ATSDR and CDHS will evaluate additionalinformation on exposure point concentrations as it becomesavailable, and will assess the likelihood of an effect on workers'health. This site is not being considered at this time for follow-up health activities. As additional information becomes available, ATSDR and CDHS will re-evaluate this site for any indicated follow-up activities.


BACKGROUND

A. Site Description and History

Synertek, Inc., Building #1 (Synertek), is at 3050 CoronadoBoulevard in Santa Clara, California. Synertek manufacturedsemiconductor products in five buildings on a 3.5-acre site from1974 to 1985. Honeywell, Inc., acquired Synertek in 1978. TheRREEF Funds purchased the property from Honeywell and they arecurrently leasing the property to Honeywell. The property wasvacant from 1985 until it was subleased in 1989 to a printingcompany. Figure 1 shows the important features on and near thesite.

Site Vicinity Map of Synertek Building #1 Showing Perimeters of A aquifer and B aquifer plumes
FIGURE 1. SITE VICINITY MAP OF SYNERTEK BUILDING #1 SHOWING PERIMETERS OF A AQUIFER AND B AQUIFER PLUMES

The U.S. Environmental Protection Agency (EPA) placed Synertek onthe National Priorities List (NPL) in September 1989. Sites on theNPL are the most serious of all known sites. The CaliforniaRegional Water Quality Control Board (RWQCB), San Francisco BayRegion (Region 2), is the lead agency regulating the Synertekcleanup under a formal agreement with EPA. Honeywell and the RREEFFunds are the only identified responsible parties. Honeywell hasaccepted sole responsibility for the site cleanup.

Staff members from the Agency for Toxic Substances and DiseaseRegistry (ATSDR) conducted a site visit in February 1989, andreleased the Preliminary Health Assessment for Synertek in August1990 (1). ATSDR, in Atlanta, Georgia, is part of the U.S. PublicHealth Service within the Department of Health and Human Services. ATSDR is mandated by the Comprehensive Environmental Response,Compensation, and Liability ACT of 1980 (CERCLA), to conduct healthassessments at hazardous waste sites. This health assessment isbeing prepared by the California Department of Health Services(CDHS) under a cooperative agreement with ATSDR, and serves toupdate the preliminary health assessment.

The ATSDR/CDHS health assessment is a mechanism for 1) determiningif there have been exposures to hazardous substances from aparticular hazardous waste site at levels that could pose a healththreat; 2) determining if it is possible to use health-related datato better define what effect the site may have had on thecommunity; 3) determining whether all relevant current or futureexposure pathways are being sufficiently addressed in the RemedialInvestigation, Baseline Risk Assessment and Feasibility Study(RI/FS) required by CERCLA (2-3); and 4) providing the communitywith that information, and for addressing specific community healthconcerns.

In 1982, Synertek completed a RWQCB questionnaire that providedinformation on the underground neutralization system and wastesolvent storage tank located on the west side of Building #1. Based on the information provided, the RWQCB required that soilsampling be done to determine if the tanks had leaked. Soilsamples in the vicinity of the tanks showed contamination withvolatile organic compounds (VOCs). The first groundwater analysesshowing contamination were performed in 1983. The solvent tank andthe neutralization system tanks were removed in 1985, along withcontaminated subsurface soil around the tanks.

After that, three on-site and two off-site groundwater extractionwells were installed, along with an air stripping tower to treatthe extracted groundwater. The on-site groundwater extractionsystem has been in operation since 1987. The off-site groundwaterextraction wells, which are connected to the on-site treatmentsystem, began operation in 1989. Treated groundwater is dischargedinto the storm sewer system tributary of San Tomas Aquino Creek, aspermitted by the RWQCB under the National Pollutant DischargeElimination System. Conestoga-Rovers & Associates, Limited, thecontractor for Honeywell, submitted the final RemedialInvestigation and Baseline Risk Assessment to the RWQCB September29, 1990 (2), and the Feasibility Study on November 30, 1990 (3).

B. Site Visit

On January 17, 1991, staff members from the CDHS/ATSDR Projectvisited the site, along with a representative from Honeywell. There was a well-maintained building, an asphalt parking lot on thewest side of the building, and a fenced air stripping tower in theparking lot adjacent to the west side of the building. The areaswhere the underground storage tanks were formerly located (i.e.,the parking lot on the west side of the building) are covered byasphalt (Figure 1).

C. Demographics, Land Use, and Natural Resources

Demographics

The nearest residential areas are 2,800 feet south of the site,upgradient of the contaminant plume. The nearest residence north(hydraulically downgradient) of the site is a mobile home park,about 3,500 feet northeast of the site and about 2,500 feet fromthe identified edge of the plume. Census figures from 1980,adjusted through a comparison of aerial photographs from 1980 and1990, estimate the mobile home park's population at about 500persons (4).

Land Use

Synertek has been subleased and occupied since 1989 by twodifferent printing companies, Media Publications, Incorporated, andWestmar Printing Company. The site is in the city of Santa Clara,in an industrial park dominated by the electronics industry,particularly semiconductor manufacturing. As such, the majority ofthe area is developed, with large paved areas for streets andparking lots. The area around the site does not support abundantwildlife and is not used for hunting.

Natural Resources

Surface water is controlled by the storm sewer system which directsrunoff to San Tomas Aquino Creek (the nearest surface water body),approximately 7,000 feet north of the site. In the vicinity of thesite, subsurface soils consist of clays and silts, with sand andgravel interbeds. Below the water table, the sand and graveldeposits form aquifers that transmit groundwater, and the clays andsilts act as aquitards or aquicludes that restrict the movement ofgroundwater. Aquifers are generally only a few feet thick, but mayrange up to about 30 feet in thickness (2).

Two shallow water-bearing zones, the A and B aquifers, exist belowthe site. The A aquifer is 10 - 20 feet below ground, and the Baquifer is 30 - 40 feet below ground surface. Based on informationfrom two soil borings, there appears to be a layer of mostly claysand silt, which acts as an aquitard or aquiclude below the Baquifer down to a depth of about 100 feet. A deeper water-bearingzone, the B1 aquifer, is located at a depth of about 100 to 108feet below ground surface. The regional aquifer, located between171 and 465 feet below ground surface, is separated from the B1aquifer by a clay regional aquitard or aquiclude and by numerousnarrow bands of water-bearing material. This lower, regionalaquifer is the source for public drinking water wells in the area.

Based on water table elevation data, the direction of groundwaterflow in the A and B aquifers is towards the north-northeast. Thegroundwater speed is approximately 209 feet per year in the Aaquifer, and only about 20 feet per year in the B aquifer (2). Groundwater in the A and B aquifer zones is believed to dischargeinto the San Tomas Aquino Creek. Groundwater flow in the deepregional aquifer is also northward, toward San Francisco Bay, aboutthree miles north of the site.

An estimated 200,000 persons within a three mile radius of the siteare served by groundwater from the regional aquifer. However, awell use survey in 1986 indicated that there were no active privateor public supply wells within 1/2-mile of the site (5). A 1990survey extended the well search to one mile downgradient of thesite. There are nine municipal wells within two miles of the site,two of which are downgradient of the site. These last two wellsare approximately 1.6 and 1.8 miles downgradient of the site.

D. Health Outcome Data

On January 1, 1988, the state's cancer reporting system, theCalifornia Tumor Registry, began collecting data for the regionthat includes the Synertek site and surrounding areas. The statereleased the data for 1988 on February 18, 1991 (6). TheCalifornia Birth Defects Monitoring Program began collecting datafor Santa Clara County in 1983. The pertinence of these data basesto the Synertek site will be discussed in the Public HealthImplications section of the health assessment.


COMMUNITY HEALTH CONCERNS

The Community Relations Coordinator from the CDHS/ATSDR Projectelicited community information about Synertek from the director ofthe Silicon Valley Toxics Coalition, city officials from SantaClara, officials from the Santa Clara County Health Department, aSanta Clara County Board of Supervisors staff member, and communityrelations staff from EPA, the RWQCB, and the California StateToxics Substance Control Program. The RWQCB indicated that someconcern had been expressed by the company currently leasingSynertek Building #1 regarding the emissions from the air stripperstack that is near the building's air intake vents. This potentialexposure pathway was not considered in the Baseline Public HealthEvaluation. That is the only community health concern reportedabout this site.

Following the discovery of the contamination at the Fairchild andIBM facilities in South San Jose in the early 1980s, the communitybecame concerned about groundwater contamination in Santa ClaraCounty. In November, 1982, a group of environmental, labor andother organizations upset about groundwater contamination formedThe Silicon Valley Toxics Coalition. The Coalition was able toorganize residents living around some of the hazardous waste sites,which enabled the general populace to be better informed about theissues of water contamination in the region.

In recent years, the intensity of community concern appears to havelessened. As the lead agency on the site, the RWQCB, in January1991, released their Santa Clara Community Relations Plan,incorporating into a single plan concerns about the five Superfundsites in the city of Santa Clara (7). The five sites were AppliedMaterials, Intel Santa Clara 3, MicroStorage/Intel Magnetics,Synertek, and National Semiconductor. The plan identified sevenmain historical concerns in the Santa Clara area as being: 1)concern about the quality of drinking water; 2) concern aboutwhether the extent of the problem had been determined; 3) concernabout what would happen if the contamination spread; 4) concernabout what is being done to clean up the soil and groundwater; 5)concern about what happened to the contaminated groundwater thatwas pumped out; 6) concern about what the schedule for clean-up is,and 7) concern about how property values would be affected.

RWQCB staffers have written two fact sheets addressing thecommunity concerns in general, and specifically informing thoseinterested in the Synertek site of RWQCB's activities and timelines. For this site, they developed a 500-person mailing listincluding residents around the site, elected officials, and countyofficials, community organizations, and industry representatives. A Fact Sheet prepared in January 1991, described the proposedRemedial Action Plan, and delineated the four clean-up alternativesthat were considered (8). A public meeting held on January 17,1991, was sparsely attended. Questions asked at the public meetingwere primarily related to cleanup alternatives. The low communityinterest regarding this site may be due to the fact that the siteis in an industrial park, and the contaminated groundwater is notnear a residential area.


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

This section discuses the contaminants of concern at Synertek. Their listing does not necessarily imply that a health threatexists. The health assessment evaluates these contaminants insubsequent sections in order to determine whether exposure to themhas public health significance. ATSDR/CDHS selects thesecontaminants based on the following factors: 1) concentrations ofcontaminants on and off site; 2) field data quality, laboratorydata quality, and sample design, and 3) comparison of site-relatedconcentrations with ATSDR health based comparison values (forexample, Environmental Media Evaluation Guides [EMEGs] fornoncarcinogenic endpoints, and media-specific lifetime cancercomparison levels, if available, for carcinogenic endpoints), andother appropriate criteria.

A. On- and Off-site Contamination

Sub-surface Soil

Subsurface soils were sampled and analyzed for VOCs during the tankexcavation operations in 1985. The bottoms of the undergroundstorage tanks were apparently only a few feet from where the Aaquifer zone begins. Hence, VOCs would probably be transportedrelatively quickly into the aquifer. Removal of contaminated soilduring tank excavation in 1985 eliminated the source contamination.

Groundwater

Elevated levels of several VOCs are present in shallow groundwater. Based on available groundwater monitoring data, the contaminationappears to be confined to the A and B aquifer zones, extending toa depth of about 48 feet. The contaminant plume in the A aquiferextends about 1,200 feet north (downgradient) from the site. TheB aquifer contamination extends about 250 feet north of the source,and has not affected neighboring properties. Currently, there area total of 37 wells at the Synertek site. There are 27 wells inthe A aquifer: 23 monitoring wells and 4 water extraction wells. The B aquifer has seven monitoring wells and two extraction wells. Extraction wells for each of the aquifers appear in Figure 1.

Monitoring data indicate that the extraction and treatment systemhas substantially captured the A aquifer plume, and additional on-and off-site migration of groundwater contamination should beretarded. The B aquifer plume is believed to be captured by thetwo B aquifer extraction wells. There is one B1 aquifer monitoringwell. Samples from that well have not shown any contamination todate. Based on the concentrations seen, on distance from the B1aquifer, and on geological considerations, the RWQCB has determinedthat one B1 aquifer monitoring well is adequate. Groundwatermonitoring wells at the site are currently sampled on a quarterlybasis. For two sampling rounds, all wells are sampled. For theother two quarters, a selection of wells is sampled to determinethe horizontal and vertical extent of the plume. Data on totalVOCs in the influent to the air stripping tower from 1987 through1990 indicate that levels have been below 1,000 micrograms VOC perliter (ug/L) of groundwater (2-3).

TABLE 1. CHEMICALS OF CONCERN IN GROUNDWATER AT SYNERTEK BUILDING #1a

Chemical EPA Weight of Evidence Ratingb Max. Conc. (ug/L)c Average Conc. of Detects (ug/L)d Drinking Water Criteria (ug/L) Drinking Water Criteria Sourcee Proposed Cleanup Standard (ug/L)
Acetone
Benzene
Di(2-ethylhexyl)phthalate
1,1-Dichloroethane (1,1-DCA)
1,1-Dichloroethene (1,1-DCE)
cis-1,2-Dichloroethene (cis-1,2-DCE)
Ethylbenzene
Styrene
Toluene
1,2,4-Trichlorobenzene
1,1,1-Trichloroethane (1,1,1-TCA)
Trichloroethene (TCE)
Freon 113
Vinyl Chloride
Xylenes
D
A
B2
C
C
D
D
B2
D
D
D
NA
NA
A
D
3,200
4
16
1,400
800
55
54
9
24
39
25,000
33,000
1,900
40
74
311
3
7
67
49
10
15
7
6
21
389
709
131
14
84
1,200
1
4
5
6
6
680
5
100
9
200
5
1,200
0.5
1,750
IRIS
CA MCL
CA MCL
CA MCL
CA MCL
CA MCL
CA MCL
EPA MCL
CA AL
CA MCL
PR
CA MCL
CA MCL
CA MCL
CA MCL
1,200
1
4
5
6
6
680
5
100
 
200
5
1,200
0.5
175

a Concentrations based on well data (both on and off-site) from 1983 through October 1989.
b EPA Weight of Evidence Rating:

A = Known Human Carcinogen
B1 = Probable Human Carcinogen (limited evidence in humans)
B2 = Probable Human Carcinogen (sufficient evidence in animal studies, no human)
C = Possible Human Carcinogen
D = Not Classified (insufficient evidence to classify)
E = No evidence of Carginogencity in Humans

c ug/L=microgram per liter or parts per billion
d Average concentrations calculated by including only positively detected results
e CA MCL = California State Maximum Contaminant Level (MCL) for Drinking Water
IRIS = EPA's Integrated Risk Information System
EPA MCL PR = Proposed EPA Maximum Contaminant Level (MCL) for Drinking Water
CA AL = California DHS Action Level
NA = Not available

Surface Water

As of June 1990, the five extraction wells have extracted 17.1million gallons of groundwater from the A and B aquifers, fromwhich the treatment system has removed 92 pounds of VOCs (9). Aspart of the NPDES Permit, the water treated by the air stripper issampled on a monthly basis. No individual VOC can exceed aconcentration of 5 ug/L in the effluent. The air stripper has beentreating VOC-contaminated groundwater to levels below 2 ug/L totalVOCs (3). The groundwater treated by the air stripper isdischarged into the storm sewer system tributary of San TomasAquino Creek.

Soil Gas

A soil gas survey conducted off site in 1986 indicated that soilgases contained VOCs. The survey was initiated in order to assistin planning off-site well placements. The information is limitedbecause no soil gas samples were taken on the Synertek propertynear the source of contamination. The maximum concentration anddetection frequency for each of the four VOCs analyzed for in soilgas appears in Table 2.

TABLE 2. MAXIMUM CONCENTRATION AND DETECTION FREQUENCY FOR CONTAMINANTS IN SOIL GAS OFF SITE AT SYNERTEK BUILDING #1a

Chemical
Maximum Concentration (mg/m3)b
Detection Frequencyc
1,1,1-Trichloroethane (TCA)
Trichloroethene (TCE)
1,1-Dichloroethane (1,1-DCA)
1,1-Dichloroethene (1,1-DCE)
2
1
ND
0.1
22/22
22/22
0/22
4/22

a Results taken from Remedial Investigation/Baseline Public Health Evaluation for Synertek (2).

b Maximum concentration detected in milligrams chemical per cubicmeter soil gas.

c Number of samples with the contaminant above the detection limit, divided by the total number of samples analyzed.

Air

No ambient or indoor air monitoring has been done at SynertekBuilding #1.

Toxic Chemical Release Inventory (TRI) search

To identify other possible releases that could contribute toambient air pollution, the CDHS/ATSDR Project staff searched theToxic Release Inventory (TRI) for the years 1987, 1988, and 1989(the years for which TRI data were available on line at the timethis health assessment was written). The TRI contains informationon estimated annual releases (emission rates) of toxic chemicals tothe environment (via air, water, soil, or underground injection),and it is based on data submitted to EPA by certain industries(Standard Industrial Classification codes 20 through 39, with 10 ormore full-time employees). The estimates are mainly based upontheoretical mass balance equations and assumed leakage ratesdeveloped by EPA. Some environmental monitoring data are reportedby industry, and are incorporated into TRI. The TRI databasecontains information on releases from active industrial facilitiesfrom 1987 to present.

No information was contained in TRI on the two printing companiescurrently leasing the former Synertek building. In order to get acrude estimate of contaminant releases to the environment in thearea around the site, TRI was searched using the area's zip code95051. In 1987, companies within the 95051 zip code released atotal of 20,150 pounds of chemicals into the environment; 18,250pounds were released to air, and 1,900 pounds were released to thesoil. In 1988, companies in that zip code reported to TRI releasestotalling 95,467 pounds of chemicals to the air. No chemicals werereported released to water or soil in 1988. In 1989, 25,980 poundsof chemicals were reported released to the air. No chemicals werereported released to water or soil in 1989. These reports wereissued by seven separate companies. Chemicals reported released bythe seven companies included acetone, ammonia, copper, Freon 113,hydrochloric acid, hydrogen fluoride, lead, nitric acid, phosphoricacid, sodium hydroxide, sulfuric acid, toluene, and xylenes.

B. Quality Assurance and Quality Control

In preparing this health assessment, ATSDR and CDHS relied on theinformation provided in the referenced documents and assumed thatadequate quality assurance and quality control measures werefollowed with regard to chain-of-custody, laboratory procedures,and data reporting. The validity of the analysis and conclusionsdrawn for this health assessment are determined by thecomprehensiveness and reliability of the referenced information.

C. Physical and Other Hazards

Observations made at the time of the site visit did not detect anyphysical or other hazards that would be expected to present athreat to public health.


PATHWAYS ANALYSES

To determine whether on-site workers or nearby residents areexposed to contaminants migrating from the site, ATSDR/CDHSevaluates the environmental and human components that lead to humanexposure. This pathway analysis consists of five elements: 1) asource of contamination, 2) transport through an environmentalmedium, 3) a point of exposure, 4) a route of human exposure, and5) an exposed population. ATSDR/CDHS identify exposure pathways ascompleted, potential, or eliminated. Completed pathways requirethat the five elements exist, and indicate that exposure to acontaminant has occurred in the past, is currently occurring, orwill occur in the future. A pathway is classified as a potentialpathway if one or more of the five elements is missing, but couldexist. Potential pathways indicate that exposure to a contaminantcould have occurred in the past, could be occurring now, or couldoccur in the future. If based only on contaminant fate andtransport modeling, or if it is questionable due to a lack ofsampling data whether significant exposure is occurring, a pathwaymay be labeled as potential (but indeterminate) until additionalinformation becomes available. Eliminated pathways require that atleast one of the five elements be missing and that it will never bepresent. Pathways may be eliminated from further assessment whenthey are unlikely to exist.

Soil Pathways

Remediation has removed contaminated soils. No exposure pathwaysinvolving soil are identified.

Groundwater Pathways

There are no private or municipal wells in the affected area;therefore, this does not present a current pathway. The likelihoodof a well being placed within the confines of Synertek'scontaminant plume is low. At this time, sufficient water formunicipal use is available from other aquifers having higher waterquality and yield. In addition, regulatory barriers exist toprohibit installation of shallow private wells.

The nearest municipal well downgradient of the plume is city ofSanta Clara Well 33. That well, installed in 1988, isapproximately 1.6 miles beyond the current edge of the contaminantplume. Well 33 and other municipal wells in the area are screenedat levels below 250 feet beneath the ground surface. Public waterwells in the region of the site are monitored on at least a yearlybasis for various organic compounds.

Exposure to groundwater contaminants in the future will not occurif: 1) the groundwater extraction and treatment system reducesconcentrations of contaminants to a point below levels of healthconcern, and 2) no future drinking water wells are placed in areasof known contamination until remediation has reduced contaminantconcentrations to a point below levels of concern. The RWQCB'sFinal Remedial Action Plan for Synertek #1 contains a task thatrequires Honeywell to obtain a deed restriction prohibiting the useof A and B aquifer groundwater as a source of drinking water.

Air Pathways

Volatilization of organic chemicals in shallow groundwater to thesoil above has occurred and will continue to occur, as indicated bythe soil gas survey of 1986. The asphalt that covers the parkingarea acts as a significant barrier to the volatilization of organicchemicals from sub-surface soil and groundwater. Contaminated soilgases will be rapidly diluted when they reach the ambient air abovethe groundwater contaminant plume. The emissions into the ambientair from the air stripping treatment system in the parking lot onthe west side of Synertek Building #1 are very low due to lowinfluent VOC concentrations and flow rates. The concentration oftotal VOCs in the influent to the air stripping tower has been lessthan 1,000 ug/L since August 1987. Emissions are regulated underthe air permit issued yearly by the Bay Area Air Quality ManagementDistrict (BAAQMD). About 0.05 pounds of total VOCs are emitted perday, which is below the BAAQMD criteria of 1.0 pound per day fornew sources (3). Some concern has been expressed by the companycurrently leasing Building #1 (see Community Concerns Section)regarding the possible impact on indoor air from air stripperemissions due to the proximity of the stack to the building's airintake vents, even though those emissions are rapidly diluted inthe ambient environment. That potential exposure pathway was notconsidered in the RI/FS.

The potential exists for organic contaminants transported via soilgas to accumulate within confined areas in Synertek Building #1,and possibly in other buildings overlying the plume. Althoughsubsurface soil contamination appears to have been remediated, highlevels of VOCs in the shallow aquifer have volatilized and willcontinue to volatilize and migrate to the surface. A soil gassurvey conducted in an off-site industrial area in 1986 indicatedthat soil gases contained VOCs. The survey was initiated in orderto assist in planning off-site well placements. The informationprovided is limited because no soil gas samples were taken on theSynertek property near the source of contamination. The off-sitesoil gas survey detected 1,1-DCE at 0.1 mg/m3. The concentrationof 1,1-DCE in soil gas closer to the source of contamination couldbe significantly higher. The ATSDR comparison value (EMEG) for1,1-DCE in air is 0.08 mg/m3; the OSHA Permissible Exposure Limit(PEL) for 1,1-DCE in air is 4.0 mg/m3.

This would be an exposure pathway of concern if: 1) contaminatedsoil gas migrates through openings in the structure, 2)contaminants accumulate in enclosed spaces, and 3) workers are inthose locations for significant periods of time. No soil gas orair samples have been taken near the source or in Synertek Building#1. A soil gas transport model and/or indoor air monitoring willbe required to determine the significance of this potentialexposure pathway. The RI/FS does not consider the volatilizationof organic chemicals from shallow groundwater a pathway of concern.

At the time the ATSDR Preliminary Health Assessment (PHA) forSynertek was written, Building #1 was vacant. The PHA concludedthat "If the site of the former Synertek Building #1 is used inthe future for commercial purposes, potential exists for inhalationof VOCs, especially in enclosed spaces." The PHA recommended thatinstitutional controls be implemented to prevent occupation ofSynertek Building #1 unless monitoring shows that humans would notbe exposed to VOCs at levels of public health concern (1).

A. Completed Exposure Pathways

Evaluation of existing information and data for Synertek did notfind any pathways resulting in past or current exposures tosignificant levels of site-related contaminants.

B. Potential Exposure Pathways

This health assessment found one potential exposure pathway ofconcern. Indoor air exposure to site-related contaminants couldhave occurred in the past, could be occurring now, and could occurin the future. This indoor air pathway may or may not be complete. It is classified as a potential pathway because soil gas dataindicate that there is a potential for low levels of volatileorganic chemicals to enter buildings over the contaminant plume,although no transport modeling or air monitoring has been done toevaluate that possible pathway.


PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

The only exposure pathway of concern identified is the possibleimpact of volatile organic chemicals on indoor air quality due toshallow groundwater contamination and the proximity of the airstripper to air intake vents. The concentration of volatileorganic compounds, if any, to which workers may be exposed inSynertek Building #1 is currently unknown. Modeling information ormonitoring data will be necessary to determine possible exposurepoint contaminant concentrations, thereby allowing the assessmentof risks from this exposure pathway. Also, without additionalinformation on dispersion of the chemicals and possibleconcentrations at points of human contact, it is not possible toassess the implications of the release information contained in theToxic Chemical Release Inventory data base. The reported releasesvary substantially from year to year, and the accuracy of theinformation is unknown.

B. Health Outcome Data Evaluation

It is unknown whether workers in buildings over the plume ofcontaminated groundwater have been exposed or are being exposed viainhalation. Additional information or data on possible exposurepoint concentrations will be necessary to assess the likelihood ofan effect on employee health. This information will then allow adetermination of whether it is possible or necessary to betterdefine possible health effects using health related data. Asdiscussed under the section of "Health Outcome Data," theCalifornia Tumor Registry began collecting data in 1988 for theregion that includes the Synertek site. This cancer incidenceinformation may ultimately be useful in a cancer investigation, butwith only one year of data, it should be viewed carefully sincebackground cancer rates for that population are undefined, and thefirst year of cancer reporting usually results in underreporting.

C. Community Health Concerns Evaluation

As indicated previously, the only health concerns identified bytalking with local officials and reviewing the site literature camefrom the company currently leasing Synertek Building #1. Theconcern expressed was whether emissions from the air stripper stacklocated near the building's air intake vents were affecting indoorair quality. Honeywell is currently planning to evaluate thepotential effect of contaminated soil gas and air stripperemissions on air quality within the building. These data will besubmitted to the CDHS/ATSDR for review.

The Health Assessment for Synertek was released for public commentfrom November 13 until December 11, 1991. Comments were receivedfrom Honeywell, Inc., the city of Santa Clara, and from RWQCB. Nocomments were received from local residents. Comments fromHoneywell included corrections and updates on the current number ofgroundwater wells at the site. As stated above, Honeywellindicated that they were currently planning to conduct airmonitoring at the site to evaluate indoor air quality. Thatinformation has been incorporated into the report. The city ofSanta Clara requested that the city have an opportunity to reviewfuture draft health assessments before public distribution. In thefuture, we will include the city in the review process. Inaddition, the city presented editorial recommendations, many ofwhich have been incorporated into the report. Editorialrecommendations by RWQCB have been incorporated into the report.


CONCLUSIONS

Based on information reviewed, the Agency for Toxic Substances andDisease Registry (ATSDR) and the California Department of HealthServices (CDHS) consider this site to be an indeterminate publichealth hazard due to incomplete information on possible aircontamination. Specifically, there is insufficient information toevaluate the potential effect of emissions from the air stripperstacks near the air intake vents for Building #1 on indoor airquality, and the possible accumulation of volatile organiccompounds in enclosed spaces in buildings over the groundwatercontaminant plume. Direct exposure to groundwater contaminants isunlikely since no water wells will be permitted in areas of knowncontamination until the groundwater extraction and treatment systemreduces concentrations of contaminants to a point below levels ofhealth concern.


RECOMMENDATIONS

A. Cease/Reduce Exposure Recommendations:

  1. The potential effect of air stripper emissions on air withinSynertek Building #1 due to the proximity of intake vents tothe air stripper stacks should be evaluated, and remedialaction should be taken if necessary.


  2. Deed restrictions prohibiting the use of A and B aquifergroundwater as a source of drinking water should remain ineffect until groundwater cleanup standards have been attained.

B. Site Characterization Recommendations:

  1. An indoor air model should be developed, and/or direct indoorair monitoring should be carried out to determineconcentrations of volatile organic compounds in SynertekBuilding #1 (and neighboring buildings if appropriate) toevaluate whether contaminated soil gas is affecting the airquality inside buildings over the groundwater contaminantplume.

C. Health Activities Recommendation Panel (HARP) Recommendations:

  1. In accordance with the Comprehensive Environmental Response,Compensation, and Liability Act of 1980, as amended, theSynertek site has been evaluated for follow-up healthactivities. The available environmental and exposure pathwayinformation is insufficient to determine whether or not humanshave been exposed to site contaminants at levels of publichealth concern. Therefore, this site is not being consideredfor follow-up health activities at this time. As additional ornew information on potential exposure pathways such as airbecomes available, ATSDR and CDHS will re-evaluate this sitefor any indicated follow-up activities.

PUBLIC HEALTH ACTIONS

Based on the recommendation of the ATSDR Health ActivitiesRecommendation Panel, this site is not being considered at thistime for follow-up health studies. In the near future, Honeywellplans to monitor Synertek Building #1 to: 1) evaluate the potentialeffect of contaminated soil gas on air quality within the building,and 2) determine the effect of the air stripper emissions on airwithin the building. CDHS will review those data and consider anyappropriate public health action. In addition, the information maybe issued as an addendum to this public health assessment in thefuture.


PREPARERS OF REPORT

Environmental and Health Effects Assessors:

David J. Borgeson, M.S.
Epidemiologist
Impact Assessment, Inc., Consultant to
Environmental Epidemiology and Toxicology Program
California Department of Health Services

Diana M. Lee, M.P.H.
Research Scientist
Environmental Epidemiology and Toxicology Program
California Department of Health Services

Community Relations Coordinator:

Jane Riggan, M.S.W.
Impact Assessment, Inc., Consultant to
Environmental Epidemiology and Toxicology Program
California Department of Health Services


ATSDR REGIONAL REPRESENTATIVES

Gwendolyn Eng
Regional Operations, Region IX
Office of the Assistant Administrator

William Nelson
Regional Operations, Region IX
Office of the Assistant Administrator


ATSDR TECHNICAL PROJECT OFFICER

Burt J. Cooper, M.S.
Environmental Health Scientist
Division of Health Assessment and Consultation
Remedial Programs Branch, State Programs Section


CERTIFICATION

This public health assessment was prepared by the CaliforniaDepartment of Health Services under a cooperative agreement withthe Agency for Toxic Substances and Disease Registry (ATSDR). Itis in accordance with approved methodology and proceduresexisting at the time the public health assessment was initiated.

Burt J. Cooper
Technical Project Officer, SPS, RPB, DHAC


The Division of Health Assessment and Consultation, ATSDR, hasreviewed this public health assessment and concurs with itsfindings.

Director, DHAC, ATSDR


REFERENCES

  1. ATSDR. 1990. Preliminary Health Assessment for Synertek,Inc. (Building 1), Cerclis No. CAD990832735, Santa Clara,Santa Clara County, California, August 27, 1990.


  2. Conestoga-Rovers and Associates, Limited (1990). RemedialInvestigation / Baseline Public Health Evaluation forSynertek Building 1, September 1990, Santa Clara, California


  3. Conestoga-Rovers and Associates, Limited (1990). Feasibility Study for Synertek Building 1, November 1990,Santa Clara, California.


  4. Bureau of the Census, 1980. Census of Housing. U.S.Department of Commerce.


  5. EMCON Associates (1986). Potential for Leakage to DeepAquifers: Report on Water Wells Within One Half-Mile of theSynertek Site, Santa Clara, California.


  6. Department of Health Services. Cancer Incidence andMortality in California, 1988.


  7. California Water Quality Control Board. Community RelationsPlan for Superfund Sites in the city of Santa Clara,California. January 1990.


  8. California Water Quality Control Board. Synertek Building#1 Superfund Site, Fact Sheet #2. January 1991.


  9. California Regional Water Quality Control Board, SanFrancisco Bay Region, Tentative Order for Site CleanupRequirements for Honeywell Inc. and The RREEF Funds, FormerSynertek #1 Facility. December 26, 1990.

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