PUBLIC HEALTH ASSESSMENT
STATE ROAD 114 GROUNDWATER PLUME
LEVELLAND, HOCKLEY COUNTY, TEXAS
The State Road 114 Groundwater Plume site consists of a contaminated groundwater plume in theOgallala aquifer along the western boundary of the City of Levelland, Hockley County, Texas. Water wells along State Highway 114 (SH 114) and Farm to Market 1490 (FM 1490) have beenaffected, and additional water wells are in the migration path of the contaminated groundwaterplume.
In the past 1,2-dichloroethane and other contaminants of concern posed a public health hazard tothose using contaminated well water. Currently the plume of contaminated groundwater poses noapparent public health hazard either because wells are on individual treatment systems orexposure to the contaminants of concern in wells without a treatment system are not high enough toresult in health problems. In the future, contaminants could migrate toward additional wells. Ongoing sampling has been initiated by the Texas Natural Resource Conservation Commission to track the migration of the groundwater plume.
The U.S. Environmental Protection Agency is working with state agencies and local representativesto develop a plan for treating the contaminated groundwater plume. The Texas Department ofHealth and the Agency for Toxic Substances and Disease Registry will evaluate additional well water data as they become available.
|CATEGORY A. |
URGENT PUBLIC HEALTH HAZARD 1
|CATEGORY B. |
PUBLIC HEALTH HAZARD 1
|CATEGORY C. |
This category is used for sites in which"critical" data are insufficient with regard toextent of exposure and/or toxicologicproperties at estimated exposure levels.
|CATEGORY D. |
NO APPARENT PUBLIC HEALTH HAZARD 1
This category is used for sites where humanexposure to contaminated media may beoccurring, may have occurred in the past,and/or may occur in the future, but theexposure is not expected to cause anyadverse health effects.
NO PUBLIC HEALTH HAZARD
This category is used for sitesthat, because of the absence ofexposure, do NOT pose apublic health hazard.
2 Such as environmental and demographic data; health outcome data; exposure data; community health concerns information; toxicologic, medical, and epidemiologic data.
The Agency for Toxic Substances and Disease Registry (ATSDR) was established under themandate of the Comprehensive Environmental Response, Compensation, and Liability Act(CERCLA) of 1980. This act, also known as the "Superfund" law, authorized the U.S.Environmental Protection Agency (EPA) to conduct clean up activities at hazardous waste sites. EPA was directed to compile a list of sites considered hazardous to public health. This list is calledthe National Priorities List (NPL). The 1986 Superfund Amendments and Reauthorization Act(SARA) directed ATSDR to prepare a Public Health Assessment (PHA) for each NPL site. (Note:Appendix A provides a listing of abbreviations and acronyms used in this report.)
In conducting the PHA, three types of information are used: environmental data, community healthconcerns, and health outcome data. The environmental data are reviewed to determine whetherpeople in the community might be exposed to hazardous materials from the NPL facility. If peopleare being exposed to these chemicals, ATSDR will determine whether the exposure is at levelswhich might cause harm. Community health concerns are collected to determine whether healthconcerns expressed by community members could be related to exposure to chemicals released fromthe NPL site. If citizens raise concerns about specific diseases in the community, health outcomedata (information from state and local databases or health care providers) can be used to address thecommunity concerns. Also, if ATSDR finds that harmful exposures have occurred, health outcomedata can be used to determine if illnesses are occurring which could be associated with the hazardouschemicals released from the NPL site.
In accordance with the Interagency Cooperative Agreement between ATSDR and the TexasDepartment of Health (TDH), ATSDR and TDH have prepared this PHA for the State Road 114Groundwater Plume site. This PHA presents conclusions about whether exposures are occurring,and whether a health threat is present. In some cases, it is possible to determine whether exposuresoccurred in the past; however, often a lack of appropriate historical data makes it difficult toquantify past exposures. If it is found that a threat to public health exists, recommendations are made to stop or reduce the threat to public health.
The State Road 114 Groundwater Plume site consists of a contaminated groundwater plume in the Ogallala aquifer along the western boundary of the City of Levelland, Hockley County, Texas (Figure 1) . The plume extends west to east for approximately 1.5 miles along State Highway 114 (SH 114) from the former Motor Fuels Corporation property west of Evening Tower Road, to the City of Levelland municipal park (Figure 2). The plume is approximately one mile wide, bounded roughly by Ellis Road to the north and Houston Avenue to the south [1, 2]. Water wells along SH 114 and Farm to Market Road 1490 (FM 1490) have been affected and additional water wells are in the migration path of the contaminated groundwater plume.
In June 1990, the Texas Department of Health (TDH) first detected groundwater contamination inwell water at the Farmer's Co-op Elevator Association. Benzene was measured at 77 microgramsper liter (µg/L) and 1,2-dichloroethane was measured at 11 µg/L. Subsequent sampling of this wellby the Texas Water Commission (TWC) in 1991 and by the Texas Natural Resource ConservationCommission (TNRCC) in 1995 indicated that concentrations of benzene, 1,2-dichloroethane, andother contaminants in the water were increasing . As a result, the use of water from this well wasrestricted.
Investigations conducted by the TNRCC and the U.S. Environmental Protection Agency (EPA)between 1997 and the present (2000) identified contamination in 28 area water wells (19 residentialwells, five business wells, an irrigation well, and three City of Levelland municipal wells) [1, 2, 3,4].
Several potential sources of the contaminated groundwater plume have been investigated by theTNRCC. Among them are the former Motor Fuels Corporation facility, the Farmers Co-op ElevatorAssociation, and oil field service related businesses along the south side of SH 114 .
The Motor Fuels Corporation site was a former petroleum products refinery that operated from mid-1939 to 1954. The site consisted of approximately 64 acres. The refinery and aboveground storagetanks were demolished and removed and in 1958 the land was sold off in parcels . Among thecurrent owners of this property are the Farmer's Co-op Elevator Association, Edward's Transport,Inc., and Well-Co Oil Service, Inc. The TNRCC documented contamination in soil at the formerMotor Fuels Corporation property and in off- site well water during investigations conducted inOctober 1995 and March 1997 .
At the request of the TNRCC, TDH completed several health consultations for the site [6,7,8, 9,10]. The TNRCC notified individual well owners of the groundwater contamination and TDHprovided written information about the contaminants of concern and how exposure could beminimized. The TNRCC and the EPA have temporarily addressed the hazard posed by the use ofthe contaminated well water by installing and maintaining groundwater filtration systems for thesewells . The wells continue to be sampled quarterly and maintenance of the wells' filtrationsystems is ongoing as EPA and TNRCC work to develop a plan to address the groundwatercontamination.
The State Road 114 Groundwater Plume site was proposed to the National Priorities List ofSuperfund Sites on July 22, 1999, and was added to the National Priorities List on October 22, 1999 .
We (TDH) visited the State Road 114 Groundwater Plume site on November 19, 1999  and met with the EPA Project Manager and representatives of the Farmer's Co-op both to brief them onthe ATSDR public health assessment process and obtain current site information. We spent aboutone and one-half hours examining the area over the plume and the surrounding properties. Wevisited the Farmer's Elevator Co-op Association property, the neighborhood along FM 1490 whereprivate water wells have been affected, the area around the nearest municipal water wells, and theformer Motor Fuels Corporation property.
Some of the businesses along SH 114 were fenced, thus limiting access to the former Motor FuelsCorporation property. However, the former Motor Fuels Corporation property was not fenced andwas accessible from SH 114 via the Edwards Transport property and from Evening Tower Road viathe Farmer's Co-op Association property (Figure 2).
We saw a 900 by 900-foot playa basin on the northwest part of the former Motor Fuels property,five tarry pits east and south of the playa, and two long excavated areas near the pits (Figure 3). The surface of the playa was dry and crusted over. Dark liquid oozed from the surface of the playabasin as we walked over the surface . We did not see any standing water; however, the two longexcavated areas and the tarry pits contained dark-stained soil and liquid. There was tall vegetationsurrounding the dry playa basin, but the plants growing around the tarry pits appeared to be stunted.
We did not see any bodies of water (ponds, stock tanks, etc.) or residences on the former MotorFuels property, but we did see what appeared to be an injection well, south of the playa, on theproperty.
The area around the site is flat, and there were agricultural crops of cotton and milo, oil wells, andbrine injection wells throughout the area .
The closest occupied household is north of SH 114 across from the Farmer's Co-op Association. We saw a daycare facility along the north side of SH 114 in the path of the contaminatedgroundwater plume (Figure 2). There were horses on some of the properties along FM 1490.
Closed City Water Well #18 is near the intersection of SH 114 and FM 1490, and there is an oilwell approximately 100 yards south of the city well .
The City of Levelland has a population of 13,986, and the population of Hockley County isestimated to be 23,374 [13, 14]. Approximately 320 people live within one mile of the State Road114 Groundwater Plume site and 37 of them are age 6 years or younger. Two hundred (200) peoplework in the vicinity of the site [13, 15]. Currently there are 11 full-time workers at the Farmer'sCo-op [1, 15]. Within the area of the contaminated groundwater plume, private wells serve 60people, and the public water supply wells in the migration path of the plume serve 3,007 people .
Exposure to, or contact with chemical contaminants drives the ATSDR public health assessmentprocess. The release or disposal of chemical contaminants into the environment does not alwaysresult in exposure or contact. Chemicals have the potential to cause adverse health effects only ifpeople actually come into contact with them. People may be exposed to chemicals by breathing,eating, or drinking a substance containing the contaminant or by skin (dermal) contact with asubstance containing the contaminant.
When people are exposed to chemicals, the exposure does not always result in adverse health effects. The type and severity of health effects that may occur in an individual from contact withcontaminants depend on the toxicologic properties of the contaminants, how much of thecontaminant to which the individual is exposed, how often and/or how long exposure is allowed tooccur, the manner in which the contaminant enters or contacts the body (breathing, eating, drinking,or skin/eye contact), and the number of contaminants to which an individual is exposed(combinations of contaminants). Once exposure occurs, characteristics such as age, sex, nutritionalstatus, genetics, life style, and health status of the exposed individual influence how the individualabsorbs, distributes, metabolizes, and excretes the contaminant. These factors and characteristicsinfluence whether exposure to a contaminant could or would result in adverse health effects.
To assess the potential health risks associated with contaminants at this site, we comparedcontaminant concentrations to health assessment comparison (HAC) values. HAC values aremedia-specific contaminant concentrations that are used to screen contaminants for furtherevaluation. Non-cancer HAC values are called environmental media evaluation guides (EMEGs) orreference dose media evaluation guides (RMEGs) and are respectively based on ATSDR's minimalrisk levels (MRLs) or EPA's reference doses (RfDs). MRLs and RfDs are estimates of a dailyhuman exposure to a contaminant that is unlikely to cause adverse non-cancer health effects. Cancer risk evaluation guides (CREGs) are based on EPA's chemical specific cancer slope factorsand an estimated excess lifetime cancer risk of one-in-one-million persons exposed for a lifetime. We used standard assumptions to calculate appropriate HAC values .
In some instances, we compare contaminant concentrations in water to EPA's maximumcontaminant levels (MCLs). MCLs are chemical-specific maximum concentrations allowed in waterdelivered to the users of a public water system; they are considered protective of public health over alifetime (70 years) of exposure at an ingestion rate of two liters per day. The setting of MCLs mayalso be influenced by available technology and economic feasibility. Although MCLs only apply topublic water supply systems, we often use them to help assess the public health implications ofcontaminants found in water from other sources.
While exceeding a HAC value does not necessarily mean that a contaminant represents a publichealth threat, it does suggest that the contaminant warrants further consideration. The public healthsignificance of contaminants that exceed HAC values may be assessed by reviewing and integratingrelevant toxicological information with plausible exposure scenarios. Estimated exposures may becompared to reported No Observable and Lowest Observable Adverse Effects Levels (NOAELs andLOAELs) and to known effect levels in humans, when available. Contaminants whereconcentrations were below ATSDR's HAC values were excluded from further consideration.
The TNRCC collected soil samples during the Expanded Site Investigation for the Motor FuelsCorporation site March 10-12, 1997 . Soil samples were analyzed for volatile organiccompounds, semivolatile organic compounds, pesticides, PCBs, and metals . Since groundwatercontamination had been identified in the water well at the Farmer's Co-op, which is on the formerMotor Fuels Corporation property, in August 1998 the TNRCC sampled additional water wells inthe vicinity of this property . Samples were analyzed for volatile organic compounds,semivolatile organic compounds, and metals . Water wells were resampled in July and August of1999. The public health significance of the above mentioned sampling events was addressed inprevious health consultations prepared by TDH for ATSDR [6, 7, 8, 9, 10].
Between January and March 2000 by Daniel B. Stephens & Associates, Inc. (DBS&A), a contractor for the TNRCC collected water samples from residential, business, and municipal wells [17, 18]. These samples were analyzed for volatile organic compounds and metals [17, 18]. The public health significance of the results from these samples is addressed in this public health assessment. In reviewing these data, we relied on the information provided in the referenced documents and assumed that adequate Quality Assurance and Quality Control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The conclusions in this public health assessment are valid only if the referenced information is valid and complete.
To determine whether people in the community could be exposed to (or come into contact with) contaminants from the site, we evaluated the possible pathways for exposure to contaminants at the State Road 114 Groundwater Plume National Priorities List site. Exposure pathways consist of five elements: 1) a source of contamination, 2) transport through an environmental medium, 3) a point of exposure, 4) a plausible manner (route) for the contaminant to get into the body, and 5) an identifiable, potentially exposed population. Exposure pathways can be complete, potential, or eliminated. For a person to be exposed to a contaminant, the exposure pathway must be complete. An exposure pathway is considered completed when all five elements in the pathway are present and exposure has occurred, is occurring, or will plausibly occur in the future. A potential pathway is missing at least one of the five elements but possibly may be complete in the future as more data become available or site conditions change. Eliminated pathways are missing one or more of the five elements and will never be complete. The completed and/or potential exposure pathways considered in our evaluation of this site are summarized in Table 1.
|CONTAMINANTS OF CONCERN||EXPOSURE PATHWAY SELEMENTS||TIME||COMMENTS|
|POINT OF |
|ROUTE OF |
|Unknown source, possibly tarry pits and playa basin that received discharge from the former Motor Fuels Corp. site|| |
|Residences and businesses using water wells along FM 1490 and SH 114||Ingestion Inhalation Dermal contact||Individuals using contaminated wells along FM 1490 and SH 114||Past||There is sufficient evidence indicating that prior to the installation of individual treatment systems, approximately 60 people used water from the contaminated groundwater plume. In the past the contaminants in the groundwater presented a public health hazard.|
|None||Present||TNRCC has installed individual treatment systems to remove contaminants from the water prior to use. Exposure to contaminants in groundwater currently poses no public health hazard at this time.|
|Future||Future use of groundwater wells west of Levelland, prior to treatment, could pose a public health hazard if water is not treated and/or additional wells become contaminated.|
|Soil||Petroleum constituents||Motor Fuels Corp. operations|| |
|Playa basin, excavated pits, tarry pits on Motor Fuels site||Incidental ingestion |
| Past |
|Because of the low likelihood of exposure we have classified this pathway as posing no apparent public health hazard.|
|Air||Volatile petroleum |
|Motor Fuels Corp. operations|| |
|Motor Fuels Corp. site and vicinity||Inhalation||Workers |
|Past||Because of the lack of ambient air data during the time that the MFC facility was operating, the air pathway is an indeterminate public health hazard.|
|Because the MFC is no longer operating this exposure pathway is eliminated.|
The State Road 114 Groundwater Plume site is located over the Ogallala aquifer which providesapproximately 20 to 30 percent of the City of Levelland's drinking water and serves as the principalsource of drinking water for numerous individual well owners in Hockley County [2,19]. TheOgallala consists of the saturated sediments of the Ogallala Formation and is generally under watertable conditions (unconfined). In the area of the contaminated groundwater plume the Ogallalaaquifer ranges in thickness from 50 to 300 feet and the depth to groundwater ranges from 120 to150 feet below ground surface [2, 4]. The water in the aquifer flows toward the east (Figure 2)[2,19]. Area water wells generally are screened between 100 and 260 feet below ground surface. High chlorides and sulfates are commonly found in the alkaline playa basins of HockleyCounty and affect area water quality. Water quality of the Ogallala ranges from good to slightly salty.
Within four miles of the contaminated groundwater plume there are 60 private wells, 13 businesswells, 17 municipal wells, and 47 irrigation wells [2, 3]. Between January 21, 2000 and March 4,2000, a contractor for the TNRCC sampled 22 residential water wells, nine business wells, and fourCity of Levelland municipal water supply wells (Figure 2). Samples were analyzed for volatileorganic compounds and total metals. Constituents exceeding HAC values are shown in Appendix C; Table 2.
Water from privately owned wells along the length of FM 1490 between Ellis Road and SH 114contained 1,2-dichloroethane, arsenic, manganese, and vanadium at concentrations exceeding theirrespective HAC values . Disinfection by-products (bromodichloromethane, bromoform,chloroform, and dibromochloromethane) were detected in one of the wells but were below themaximum concentration level for total trihalomethanes of 100 µg/L (Table 2). Individual watertreatment systems designed to remove the contaminants of concern from the water prior to householduse have been installed on each well in which contaminants were measured at concentrations ofpotential public health concern. Prior to the installation of the treatment systems, people using waterfrom these wells could have been exposed to the contaminants of concern through ingestion (1,2-dichloroethane, arsenic, manganese, and vanadium), inhalation (1,2-dichloroethane), and/or dermalcontact (1,2-dichloroethane). The public health significance of possible past exposures to sitecontaminants is addressed in Appendix-D.
Currently, the contaminants measured in water from the residential wells pose no apparent publichealth hazard either because the wells are on individual treatment systems or exposure to thecontaminants of concern in wells without treatment systems would not be expected cause adverseeffects. In the future the migration of contaminants in the groundwater could affect additional wells.
Benzene has been detected in water from the well at the Farmer's Co-op at concentrations morethan one hundred times higher than EPA's maximum contaminant level of 5 µg/L and over 500times higher than the CREG value for benzene. Benzene was detected in water from one otherbusiness well at a concentration of 2 µg/L; however, the results were questionable since benzene wasdetected in the sample collected after the water was treated but was not in the sample collecteddirectly from the well . Benzene has not been detected in any of the other wells sampled. Othercontaminants (1,2-dichloroethane, arsenic, manganese, and vanadium) were detected at levels at orabove their respective HAC values in business wells (Table 2). Individual water treatment systemsdesigned to remove the contaminants of concern from the water prior to use have been installed oneach well in which contaminants were measured at concentrations of potential public health concern. Prior to the installation of the treatment systems, individuals using water from these wells couldhave been exposed to site contaminants through ingestion (benzene, 1,2-dichloroethane, arsenic,manganese, and vanadium), inhalation (benzene, 1,2-dichloroethane), and/or dermal contact(benzene, 1,2-dichloroethane). Currently, the contaminants measured in water from the businesswells poses no apparent public health hazard either because the wells are on individual treatmentsystems or exposure to the contaminants of concern in wells without treatment systems would not beexpected cause adverse effects. In the future the migration of contaminants in the groundwatercould affect additional wells. The public health significance of possible past exposures to site contaminants is addressed in Appendix-D.
Low concentrations of volatile organic compounds associated with chlorination by-products weremeasured in City Well #21 but were below the maximum concentration level for totaltrihalomethanes of 100 µg/L (Table 2). Lead was detected in one sample from City Well #21 at aconcentration of 37 µg/L. Manganese was measured at concentrations above its child-based HACvalue (500 µg/L) in water from City Wells #15 (1,390 µg/L) and #23 (1,190 µg/L) . Vanadium was measured in water from City Wells #10, #15, and #23 at concentrations at or aboveits HAC value . Since water from the municipal wells is blended with treated water from LakeMeredith at a ratio of approximately one-third municipal well water to two-thirds treated lake water,the actual concentration of the contaminants delivered to the end users of the municipal water systemis much lower than those measured at any one individual well. According to available records, theCity of Levelland drinking water supply meets all the standards of the Safe Drinking Water Act. Atthe present time, we do not consider this to be a significant exposure pathway and have classified it as posing no apparent public health hazard.
In the past, volatile and semi-volatile organic compounds were detected in soil from the Motor FuelsCorporation property at three depths (four, six, and eight feet below ground surface) . The playabasin reportedly received wastewater from the former petroleum refinery. While it is not likely thatvolatile organic compounds remain in the surface soil, it is possible that other contaminants still mayremain in the surface soils. While this pathway could be considered to be an indeterminate publichealth hazard because of the general lack of surface soil data, the property is somewhat remote. Inour professional judgement, the likelihood that people are receiving significant exposures is low. We have therefore classified this pathway as posing no apparent public health hazard.
Due to discharges to the playa basin, spills, and other site-related activities, volatilization ofpetroleum constituents into the air may have occurred during the time that the Motor FuelsCorporation facility was operating. Due to a lack of air sampling data during the time that thefacility was operating, we were not able to evaluate this pathway; therefore, past exposure to air inthe vicinity of the Motor Fuels Corporation facility is an indeterminate public health hazard. Currently, the Motor Fuels Corporation facility is not operating. Thus, at the present time we do notconsider this to be a significant exposure pathway and have eliminated it from further consideration.
ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and childrendemand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardous substancesemitted from waste sites and emergency events. They are more likely to be exposed because theyplay outdoors and they often bring food into contaminated areas. They are shorter than adults,which means they breathe dust, soil, and heavy vapors close to the ground. Children are alsosmaller, resulting in higher doses of chemical exposure per body weight. The developing bodysystems of children can sustain permanent damage if toxic exposures occur during critical growthstages. Most important, children depend completely on adults for risk identification andmanagement decisions, housing decisions, and access to medical care.
ATSDR evaluated the likelihood for children living in the vicinity of the State Road 114Groundwater Plume site to be exposed to 1,2-dichloroethane and other contaminants at levels ofhealth concern. In the past children may have been exposed to contaminants in the groundwateralthough data were insufficient to evaluate possible past exposures. Children currently are notexposed to contaminants in the groundwater since individual treatment systems have been installedon each of the affected wells.
The private well at the daycare (Figure 2) had no measurable concentrations of volatile organiccompounds. The metal vanadium was measured at 30 µg/L and all other metals were belowdetection. A child (15kg) drinking water with this concentration of vanadium would not be likely to experience any adverse health effects .
Health outcome data (HOD) record certain health conditions that occur in populations. These datacan provide information on the general health of communities living near a hazardous waste site. Italso can provide information on patterns of specified health conditions. Examples of health outcomedatabases are tumor registries and vital statistics. Information from local hospitals and other healthcare providers also may be used to investigate patterns of disease in a specific population.
To collect community health concerns related to the State Road 114 Groundwater Plume site, wecontacted several different agencies and individuals including the Texas Department of HealthRegion 1, the Texas Natural Resource Conservation Commission, and the U.S. EPA Region 6. Inaddition, we contacted the City Manager for the City of Levelland and representatives from the Farmer's Co-op. We received the following concerns:
- Could the well water affect my horses?
- There are a lot of people on thyroid medicine in our area, could this be due to the water?
- There have been a lot of hysterectomies, is this due to the water problem?
- There seems to be a lot of brain cancer in our area as well as cancer of the lung, kidneys, and breast.
Just as in people, many factors will determine whether harmful health effects will occur andwhat the type and severity of those health effects will be. These factors include the amountand type of contaminant, the dose, the duration and route of exposure and individualcharacteristics such as age and overall state of health. Generally, the concentrations of 1,2-dichloroethane and vanadium in the groundwater are low; however, we did not find any specific literature with respect to the effects of these contaminants on horses.
We were unable to find any specific toxicological studies evaluating the effects of exposureto the contaminants of concern on the thyroid; however, thyroid disorders are reportedly verycommon. According to the Thyroid Foundation of America, 13 million people have someform of thyroid dysfunction. Thyroid disease is up to eight times more common in womenthan in men. There seems to be a genetic component to thyroid disease although otherfactors such as age and stress also are related. There are some contaminants such asperchlorate which are known to affect the thyroid. To our knowledge, perchlorates have not been associated with this site.
We are not aware of any associations between the contaminants of concern andhysterectomies.
An analysis of incidence and mortality data by the Texas Department of Health CancerRegistry Division did not show an excess of these cancers in Hockley County.