Skip directly to search Skip directly to A to Z list Skip directly to site content




The Williams Pipe Line Disposal Pit (WPL) site is located on the northeast corner of theWilliams Pipe Line Terminal facility in Minnehaha County, Sioux Falls, South Dakota. Fertilizers, petroleum products, and pesticides were dumped and periodically burned at thedisposal or burn pit. The disposal pit and the contaminants from it have been identified as aNational Priorities List (NPL) site by the U.S. Environmental Protection Agency (EPA). TheWilliams Pipe Line Terminal facility in Sioux Falls has a long history of spills of petroleumproducts which have lead to extensive contamination of area ground water. This contaminationwas the source of exposure to hexane, benzene and pentane in the old Hayward School and aresidence which posed fire, explosion, and health hazards. The school and residence have beenleveled and the groundwater in the area is being treated. A new Hayward School was built to thenorthwest of WPL.

Because spills of petroleum products alone are not covered under the Superfund laws, thecontamination due to those spills is not considered part of the NPL site. However, this publichealth assessment evaluates the possible health impact of the entire Williams Pipe Line Terminalfacility.

Private drinking water wells on the northeast (1 well) and south (4 wells) of the site and ambientair in the Hayward School are considered completed exposure pathways. The contaminants ofconcern in the northeast private drinking water exposure pathway are bromodichloromethane,chloromethane, and nitrate. Nitrate is the only contaminant of concern in the south privatedrinking water exposure pathway. The contaminants of concern in ambient air pathway arebenzene, hexane, and pentane. There are community health concerns about learning disabilities,health effects of contaminated water, and the health and explosion hazards of vapor accumulationin their homes.

The WPL site is considered a public health hazard based on the exposure to nitrate in severalprivate drinking water wells south of the site. The maximum concentrations of nitrates couldresult in methemoglobinemia in children less than six months old. The exposures in September1986 of students and staff of Hayward Elementary School to benzene, hexane, and pentanevapors was an urgent public health hazard. However, no long-term health effects should occur. None of the other contaminants of concern represent a public health hazard.

Data on infant mortality, cancer deaths, and learning disabilities (LD) were reviewed. Noconclusions could be made on the infant mortality and cancer death data. The percent LD for thenew Hayward School in 1990 was 10.2 %, which is the second highest percentage in the SiouxFalls School District. This percent LD is not statistically greater than other schools in thenorthern half of the district, but is greater than the average percent LD for the whole district. Data on LD for the years between 1986 - 1990 and by grade is needed to fully evaluate thepossible relationship between the incident in 1986 and LD. While solvents are known to causeneurotoxic effects, it is not known whether exposure to these chemicals can contribute to theonset of LD.

The Agency for Toxic Substances and Disease Registry (ATSDR) recommends that EPA, incooperation with the South Dakota Department of Water and Natural Resources (SDDWNR),better characterize off-site groundwater, soil, and air.

ATSDR's Health Activities Recommendation Panel (HARP) has evaluated the data andinformation developed in the Williams Pipe Line Disposal Pit Public Health Assessment. Thepanel determined that no further health education appears necessary at this time, but may beappropriated in the future. No health studies or investigations are indicated at this time.


The Williams Pipe Line Twelfth Street facility (WPL) in Sioux Falls, Minnehaha County, SouthDakota has a long history of spills of petroleum products which have lead to extensivecontamination of area ground water. Spills of petroleum products alone are not covered underthe Comprehensive Environmental Response, Compensation, and Liability Act of 1980(CERCLA). Fertilizers, petroleum products, and pesticides were dumped and periodicallyburned at the disposal or burn pit located on the northeast corner of the facility. The disposal pitand the contaminants were proposed as a National Priorities List (NPL) site by the U.S.Environmental Protection Agency (EPA) in 1990. Because it is not possible to precisely identifywhether contaminants are from the disposal pit or from other sources, this public healthassessment will evaluate the possible health impact of the entire Williams Pipe Line Terminalfacility.

A. Site Description and History

The WPL terminal facility is located at West Twelfth Street in Sioux Falls, South Dakota, SE1/4, Section 14 Township 101N, Range 50 West and is owned by Williams Pipe Line Company,of Minneapolis, Minnesota, a subsidiary of the Williams Companies. The site was owned until1966 by Great Lakes Pipeline Company. The site was built in the 1940s. This site is currentlyused for the transport and the storage of petroleum products. In the past fertilizers were alsotransported and stored. Capacity at this facility is 25,326,000 gallons. Tanks range in size from2,000 barrels (84,000 gallons) to 40,000 barrels (1,680,000 gallons) (1). Fertilizers, petroleumproducts, and pesticides were dumped and periodically burned at the disposal or burn pit locatedon the northeast corner of the facility. The terminal facility is fenced and has a security guard onthe premises.

Currently there are nine workers on the site. They perform different materials handling,inspection, oversight, and security functions. There are also transient work crews that performmaintenance activities on the site, environmental consultants, and workers who service thevarious recovery systems on the site (3).

History of Contamination

Six major contamination events have been reported to the South Dakota Department of Waterand Natural Resources (SDDWNR). In 1981 a spill from tank 4007 resulted in approximately10,500 gallons of #2 diesel fuel being spilled on to frozen ground which limited the extent ofcontamination. WPL states that they recovered nearly all of the spill. In March 1983 a brokencoupling resulted in the spill of approximately 300 gallons of #2 diesel fuel. WPL states thatthey recovered the majority of this spill by pumping with the rest being collected by absorbentmaterial. In October 1983 an underground pipeline failed in the southeast corner of the WPLproperty near the truck loading rack with a resulting loss of 107 barrels (4,494 gallons) of #1 fueloil. Remedial actions near the truck loading rack have resulted in the recovery of well over 6,900gallons of product. In July 1984 a spill of 10,500 gallons #2 diesel fuel to soil and ground wateroccurred. Over half of that spill had been recovered in two years of remediation (1).

In 1984 hydrocarbons and nitrates were found in a water sample collected at Hayward School bya 6th grade class for a special project. Hydrocarbons were present at 5 parts per million (ppm)and nitrate-nitrogen was detected at 21 milligrams per liter (mg/L). The school discontinued theuse of well water and was connected to the Sioux Falls municipal water supply in September1984 (4).

In May 1986 a gasoline leak from Tank 1341 on the southwest corner of the WPL propertyoccurred. The gasoline entered the ground water and caused the evacuation of a residence nearthe southwest corner of the WPL property. The exact amount of the spill was not established. This contamination was the source of exposure to hexane, benzene and pentane in the oldHayward School and a residence which posed fire, explosion, and health hazards (1, 5, 6). Theschool and residence have been leveled and the groundwater in the area is being treated. A newHayward School was built to the northwest of WPL.

The final source of contamination investigated by the SDDWNR is the area known as the burnpit or disposal pit. In 1979, a monitoring well north of the northeast corner of WPL property showed hydrocarbon contamination. An investigation of the site showed an open dumping areain the northeast corner of the property called the burn pit or disposal pit. The burn pit is an open,unlined pit measuring 9 feet by 9 feet by 7 feet deep. The pit served as a collection for runofffrom the WPL site and as a repository for condensate and sludges from the tanks. Trucks mayhave also dumped clean-out wastes in the burn pit before changing the products that to betransported. EPA believes that pesticides were also dumped in the pit in this way. Periodicallythe material in the pit was burned. SDDWNR notified WPL in 1986 that corrective measuresmust be taken immediately on the burn pit. The pit is currently inactive with a plastic cover on it(1).

Remedial Activities

Remedial actions at WPL include the installation of recovery systems to remove free product onthe water surface, ground-water extraction wells to remove and treat contaminated aquifer waterand hydraulic control and extraction wells to prevent the spread of contaminant plumes (7). These remedial actions were initiated by WPL and their environmental consultants, Bay West(1986-1988) and Leggette, Brashears and Graham, Inc. (1988-present) to comply with SDDWNRviolation orders and a 1989 settlement agreement (8, 9).

In the northeast section of the property and off-site at Golden Sun Feeds, a recovery-well systemremoves free petroleum products from the shallow aquifer and treatment systems treat recoveredground water to remove hydrocarbon contamination. The treated water is disposed of into thesanitary sewer system. On the east and southeast corner of the WPL property recovery wellshave been constructed. In addition, an interceptor trench, consisting of a French Drain system inthe shallow aquifer, has also been installed to capture contaminants at the property boundary inthe aquifer.

Recovery wells have also been placed adjacent to the old Hayward School. A line of wells wasestablished to create a dynamic barrier to ground-water movement through the area. TheHayward School treatment system consists of an oil/water separator and an air-stripping column. Partially treated water is discharged into the sanitary sewer system but notes made on the systemin 1987 state that the water was to be sufficiently treated to remove all hydrocarbons and allowthe treated water to be infiltrated back into the Skunk Creek Aquifer (9).

Combustible-gas monitoring at Old Hayward School was also conducted by Bay West. Acontinuous, combustible-gas monitoring system was installed at the Golden Sun Feed (GSF)warehouse by GSF. GSF installed explosion-proof sump pumps and the sump areas were sealedto prevent infiltration of explosive vapors into the rest of the building (9).

B. Site Visits

On September 22, 1986, Mr. Joseph M. Posid of ATSDR, visited the old Hayward School inresponse to a request from the National Institute of Occupational Safety and Health (NIOSH) andthe State of South Dakota to investigate complaints of illness, noxious odors and explosiveconditions at the school. The principal of the school had called the Sioux Falls fire departmentwho recorded the levels of explosive vapors in the school. The school had been evacuated onSeptember 18, 1986. Mr. Posid met with representatives from the SDDWNR, the hydrologistfrom the South Dakota Geologic Survey, and the Sioux Falls Director of Public Health. He alsospoke with the Sioux Falls Fire Marshall and conducted a public meeting with the state and localofficials. He was asked to provide assistance on establishing safe or re-entry levels of vapors forschool and he proceeded to the regional EPA headquarters to discuss possible EPA involvement(10).

On October 1-3, 1986, Dr. William Cibulas, Jr. and Mr. Clifford Moseley of ATSDR conducteda site visit to the old Hayward School to provide technical support the State and local officials inestablishing the re-entry criteria for the school. Their second purpose of their trip was to evaluate any impact of the WPL spill on the surrounding community and assess possibilities forconducting an exposure assessment. They met with representatives from the EPA ERT,SDDWNR and the local fire department who was measuring the explosive levels of vapors insidethe school. These tests were conducted with the school's ventilation system turned on. Mr.Moseley entered the school and turned off the ventilation system and determined throughorganoleptic testing (tasting and smelling) that the crawlspace under the school filled quicklywith vapors (5).

Mr. Moseley and Dr. Cibulas also met with representatives from the Sioux Falls Public HealthDepartment the Superintendent of the Sioux Falls School District. The EPA-ERT collected soilgas samples and reported the preliminary values to the ATSDR representatives (5).

On October 8 & 9, 1986, Dr. Jeffrey A. Lybarger and other ATSDR staff sampled the air atvarious locations inside old Hayward School. These included samples collected in studentoccupied and normally unoccupied areas. Measurements were taken with and without thebuilding ventilation system operating. Sampling equipment was provided by NIOSH andconsisted of battery-operated vacuum pumps and activated charcoal sampling tubes. The tubeswere analyzed by NIOSH personnel. Air patterns were detected with standard smoke tubes andreal-time organic vapor measurements were taken with a Century Organic Vapor Analyzer. Nodiscussion was made of the calibration procedures for these instruments. Air sampling indicatedthe presence of benzene, n-hexane and elevated total hydrocarbon vapors in and under the school. The ATSDR representatives recommended that a qualified engineering firm be enlisted todevelop a means to control soil vapors beneath the school and that the effectiveness of thecontrol systems be evaluated once they are in place (6).

On August 1-2, 1990, Dr. John Crellin, Ms. Rosalyn Lee, and Glenn Tucker of ATSDRconducted a site visit of WPL along with Lisa Reed from EPA. Contact was made with therepresentatives of the SDDWNR and the Sioux Falls City Health Department and City Attorney. Representatives of WPL and their environmental consultants, Leggette, Brashears & Graham,Inc., gave a tour of the facility to the ATSDR and EPA staff. They explained the operation of theinterceptor trench and treatment facilities and showed ATSDR and EPA staff the burn pit. Theold Hayward School recovery facilities were also toured. An interview a local TV reporter wasgiven by Dr. Crellin, which included information on how to contact ATSDR with site specificproblems (11).

ATSDR representatives made the following observations on the 1990 site visit.

  • The WPL site itself is well fenced and a guard is on the site.
  • While driving by the WPL-owned old Hayward School recovery site (school now evacuated)they observed that the fence was open and no WPL personnel appeared to be in the area.
  • To the east and west of WPL are small stores, gasoline stations, storage facilities, and lightindustry. Large residential areas lie to the north and south within 1000 feet of the site.

The ATSDR representatives also conducted a search of the SDDWNR files for informationpertinent to the public health assessment at that time (11).

In March 1991, Dr. Robin Brothers of the Oak Ridge National Laboratory, an ATSDRcontractor, made an informal site tour of the WPL area with representatives of SDDWNR whileon private business in South Dakota. At this time she observed the following from outside theWPL fence:

  • No additional remedial activities (i.e., removal or treatment of soil) had taken place on theburn pit.
  • The old Hayward School had been demolished and the area once covered by the school wasbare soil with only a small shed covering the recovery well operation.
  • The area once occupied by the residence on the southwest corner of the WPL property wasgrass covered and a small shed stood on this site also. This is now part of WPL property.
  • Many large gravel pits are in very close proximity (less than 1/4 mile) to the WPL property. Many of these pits extended below the water level and had water standing in the bottom of them.

Dr. Brothers also learned that recently some other governmental agencies had been conductingcommunity concerns surveys in the area regarding WPL. Upon her return to Tennessee, sheinvestigated this comment and learned that the EPA regional office had been conducting theseinterviews and was able to obtain a copy of them (12).

C. Demographics, Land Use and Natural Resources


The City of Sioux Falls population was 81,600 in the 1980 census. More recent census data werenot available from the state or local officials at the time of the writing of this document due todisputes in the validity of the 1990 census data. The Director of Planning and Building Servicesfor the City of Sioux Falls states that the population of Sioux Falls consists of approximately96% Caucasian, 2.5% American Indian, 0.5% Black, and the remaining 1% consisting ofOriental and Hispanic persons. The area immediately surrounding the WPL property consists ofa higher percentage of Caucasian persons as the minority population is primarily closer to thecenter of the city (13).

Land Use

The area around the WPL site (site refers to the entire WPL Twelfth Street Terminal property)consists of mixed residential, commercial and industrial uses. Large residential areas lie within1000 feet to the north and south of the site. The residential area to the south is an older area withsmall low-to-middle-income-class, wooden dwellings, most of which are well maintained. Tothe north of the site lies a large mobile home park and middle class neighborhoods of brick andwood homes (11). The area is zoned for further residential development to the north and to thesouth. West Twelfth Street consists of a 400 foot commercial frontage and immediately north ofthe WPL property is another 400 foot commercial frontage. To the east is industrial commercialdevelopment and to the west residential development (13). Approximately 1 mile to thesouthwest is a large mobile home park that utilizes private well water (14). A survey of wellusers in the area of WPL identified approximately 150 businesses or residences within theimmediate vicinity of the property (15). A conservative estimate of the total number of personsrepresented by this figure would be 300. This is probably an underestimate of the potentiallyaffected population as the well survey was limited and residential development is continuing togrow in the area (14).

The distance from the site to the nearest residence is approximately 500 feet. The distance fromthe site to the nearest private well (in a business) is approximately 100 feet or less (17). A newschool has been constructed within 1 mile of the site (11).

Immediately to the south of the WPL property is a gasoline station which was thought to becontributing to the south-side off-site contamination. This station's tanks were determined to betight and any leakage that may have come from this location was due to possible leaks in the pipefittings at or near the tops of the tanks (4).

Natural Resource Use

Within the Skunk Creek Aquifer there are several possible sites affecting the water quality. Approximately 4 miles northwest of the site a former gravel pit was used as a dump site formanure. There is an increased nitrate nitrogen content in the ground water at this location. Approximately 1 mile to the northeast of WPL is a land fill which is also now resulting in anincrease in calcium, sodium, chloride, dissolved solids, iron and manganese in the area groundwater. Rubble is still being dumped into abandoned gravel pits at this site (20). Gravel pitoperations with 0.5 miles of the WPL property may impact water flow characteristics and groundwater quality (20).

The City of Sioux Falls has a municipal well in the Skunk Creek Aquifer approximately 1 milefrom the WPL site. This well pumps a million gallons per day during the peak water use periodsin the summer. It is mixed with finished water from other municipal wells before use. The citymaintains a monitoring well approximately 0.5 miles from the site. Other city municipal wellsare located in the Big Sioux Aquifer approximately 3 miles from the WPL property and themunicipal system also uses some surface water from the Big Sioux River when the flow issufficient (21, 22). Surface water from the Big Sioux River is also used to recharge the Big Sioux Aquifer (21).

Homes and businesses in the immediate vicinity of WPL use either municipal water or privatewell water or a combination of the two. The homes and businesses in the area have municipalwater available to them via a curbside connection but their is no requirement to attach to thewater line even though a property assessment is made for the connection (13, 14). These privatewells are constructed in the Skunk Creek Aquifer, a shallow unconfined aquifer consisting ofglacial till (4).

Skunk Creek, the nearest surface water body, is approximately 1 mile from the WPL site. SkunkCreek has been classified by the State of South Dakota as useful for marginal fish lifepropagation and limited contact recreation. This designation spans from its confluence with theBig Sioux River to approximately 4 miles upstream of the WPL site. In addition all streams inSouth Dakota must also be useable for irrigation, wildlife propagation, and stock watering (23).

The prevailing winds for the area taken at Foss Field Airport (less than 3 miles from the site)reported for the years 1971-1985 were from the south at 11 miles per hour. There is a distinctseasonal shift in wind direction with the months of November through April having prevailingwind from the northwest (24). The average annual precipitation for the area for 1987 was 24.12inches (water-equivalent) with 48 inches of snow and ice (25).

D. State and Local Health Data

Health Data

Using state and local health databases it may be possible to determine whether the occurrence ofcertain health effects are greater than expected in the area surrounding the WPL site. Thissection identifies the relevant, available databases; their evaluation occurs in the Public Health Implications section. Although several contaminants of concern at the site are carcinogens, theState of South Dakota does not have a tumor registry (26). The State Registrar of Vital Recordsdoes publish an annual report of Vital Statistics and Health Status (27). A listing of cancerdeaths by system by county are available from the State Registrar of Vital Records (26). Tumorregistries are maintained by the following hospitals in Sioux Falls: McKennan Hospital (28),Sioux Valley Hospital (29), and the Veterans Administration Hospital (30). Access to theseregistries may be gained by submission of a letter stating the information desired and theintended use. Central Plains Clinic, a large medical clinic in Sioux Falls, cooperates with theNorth Central Cancer Treatment Group out of the Mayo Clinic in Rochester, MN. They do havea cancer data manager and all patients are followed until death (31). The annual report of VitalStatistics and Health Status lists the infant mortality for the state by county (27).

Learning Disabilities

Because of the complaints of possible learning disabilities (LD), the sources for information oneducational outcomes was pursued. The City of Sioux Falls School Superintendent's Office wasable to provide a 1990 listing of all schools in the city and their number of students with LD. The city did not have a historical record of the learning disabilities from previous years (32, 33). The State of South Dakota, Division of Elementary and Secondary Education, Office of SpecialEducation maintains individual student files but compiles all data from individual schools inschool districts into district wide reports (34).


The following community health concerns have been gathered from site visits by ATSDR (11)and EPA personnel (35), well surveys conducted by SDDWNR (36), the city fire department(37), a transcript of a radio program about the WPL site (38), and personal communication withconcerned residents (39).

    1. Did the children and staff of the old Hayward School suffer any long-term health effects as aresult of exposure to vapors in the school?

    2. Will the exposure to vapors in the old Hayward School impair the children's learning ability inany way? Is the rate of learning disabilities 42% for children from old Hayward School?

    3. Is the off-site soil contamination high enough to warrant concern?

    4. Is it possible for site contaminants to pollute garden fruits and vegetables? Is it safe for me togarden?

    5. Are the levels of vapors in residences and business high enough to be a concern?

    6. Are workers on the WPL site in any great danger?

    7. Is the municipal well in the Skunk Creek Aquifer safe now and for future consumption?

    8. Will the residents and employees of the school and businesses in the area who consumed wellwater have any long-term health effects?

    9. Should residents in the area continue using private wells?

    10. Has the source of pesticide contamination in the burn pit area and off site been identified?

    11. Is there any relation of the WPL site to dead trees to the west of the site?

    12. Will children at a day care facility off the south side of the WPL site suffer any health effectsfrom the site?

Next Section       Table of Contents The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

A-Z Index

  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #