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HEALTH CONSULTATION

NORTH MANKATO DUMP
NORTH MANKATO, NICOLLET COUNTY, MINNESOTA


I. SUMMARY OF BACKGROUND AND HISTORY

The Minnesota Department of Health (MDH) received a request from the Minnesota Pollution ControlAgency (MPCA) to evaluate potential public health concerns regarding the North Mankato Dump, locatedin the city of North Mankato, Nicollet County, Minnesota (the site). The site was identified by the MPCAthrough its Dump Assessment Program as an "action site," indicating that the site warranted furtherevaluation due to its potential to adversely impact public health or the environment. This healthconsultation is based on a site visit conducted by MDH staff on April 27, 2000, private water supply wellsampling conducted by MDH staff on June 14, 2000, a review of previous MDH documents, andinformation provided to MDH by the MPCA and its consultant, STS Consultants, LTD (STS 2000a, STS2000b).

The site is located just north of the intersection of Webster Avenue and Sherman Street within the citylimits of North Mankato, approximately 1/4 mile west of U.S. Highway 169. The site is located on landowned by the City of North Mankato that is currently used as a city maintenance and highway garage. Several buildings have been constructed on top of the buried wastes. Access to the site is restricted onthree sides by a low fence, and the site is in use by the city during daylight hours. The site location isshown in Figure 1, and a site map is presented in Figure 2. The dump area is rather large, occupyingapproximately 11 acres. The dump itself is not readily visible, except for small amounts of exposed waste along its edges. However, these areas abut a public park, and are located outside of the site fence.

The dump apparently began accepting wastes in 1950, and operated until 1973 when it was closed andcovered by the city. Some demolition wastes (dirt, concrete, etc.) may have been added by the city sincethat time on an irregular basis. The area surrounding the site is primarily residential and parkland. Severalponds, including an old meander channel or oxbow lake formed by the nearby Minnesota River, are locatednorth and south of the site. Some homes near the site have shallow private wells, while some homes havebeen connected to municipal water that is available in this area. The nearest homes are locatedapproximately 500 feet west of the site. Several municipal water supply wells for the city of NorthMankato are located approximately one mile southwest of the site. Several of the wells are reportedly 700feet deep, although one is less than 100 feet deep.

As a public dump, the site likely accepted all types of wastes. A 1971 U.S. Public Health Serviceinspection report documents the acceptance of household, industrial, commercial, institutional, andagricultural wastes at the site, and indicates that problems with leachate and drainage existed (STS2000a). Many businesses were located just east of the site, and may have used the site for disposal of theirwastes. Wastes were reportedly burned until 1964. Some wastes may have been disposed of in marshlandor small ponds. A 1973 memorandum from the MPCA noted contamination in the oxbow lake north ofthe site. Based on a Phase II site investigation, the volume of waste at the site is estimated to beapproximately 125,000 cubic yards. The horizontal extent of the waste was not defined, however.

Two petroleum releases associated with the city's maintenance and highway garage have been reported atthe site (STS 2000a). One involved a release associated with a 560 gallon used oil underground storagetank (UST), while the other was found during the removal of two 10,000 gallon USTs used for gasolineand diesel fuel. Approximately 120 cubic yards of petroleum contaminated soil were removed from the site, and contamination was found in groundwater at the site. The files on both releases were closed by the MPCA in the mid-1990s.

Geology/Hydrogeology

Based on available geologic information, surface soils at the site are composed primarily of fine to mediumgrained sand deposits associated with the nearby Minnesota River, with little gravel (STS 2000a). Theuppermost bedrock is expected to be Cambrian sandstone and shale at depths of between 50 to 100 feetbelow ground. Soil borings conducted by STS showed a layer of fill materials (sand and gravel) on top ofwaste materials mixed with soil (STS 2000b). The wastes were underlain by native soils ranging from siltyclay to fine sand. The location of the borings is illustrated in Figure 2, and cross-sections of the dump prepared by STS are presented in Figure 3.

The surficial groundwater is expected to flow east and southeast toward the Minnesota River. At the site,groundwater was encountered between 4.5 to 14.5 feet below grade. Groundwater was found within thewaste materials in some borings. Only temporary monitoring wells were installed to collect water samples,so flow direction beneath the site could not be determined.

Site Visit

On May 15, 2000, Jim Kelly and Ginny Yingling of MDH visited the site. The site is primarily covered bythe city maintenance facility (parking lots, buildings, dirt, sand, and gravel piles) and a ball field on thenorthwest corner. The north and western edges of the dump are partially defined by a recently establishednature trail, and the toe of the dump encroaches on a pond area to the north. Access to the site itself isrestricted by a fence on three sides, although some wastes are exposed outside of the fence along the edgeof the dump.

Exposed wastes were observed next to the nature trail and in the ponds, and consisted of concrete, scrapmetal, one 55-gallon drum, tires, bottles, cans, and tile. The walkway across the pond in the nature areanorth of the dump was built from recycled asphalt that is in contact with the water. This waste may not bedirectly related to the dump.

Surrounding land use is primarily residential, parks, commercial, and light industrial. A public swimmingpond (which appears to be man-made) is located in the park to the south across Webster Street. Peoplefish and reportedly swim in the adjacent ponds to the north.

Site Investigation

Sixteen soil borings were advanced by STS at the site in July 2000 using a hollow-stem auger, with ninecompleted as temporary monitoring wells. The boring locations are shown in Figure 2. The boringsencountered up to 11.5 feet of waste materials in some areas. Solid wastes encountered in the boringsincluded glass, metal, concrete, and wood. Soil vapor measurements were collected during drilling using aphoto ionization detector (PID) equipped with a 10.6 eV lamp calibrated to a benzene standard, and anexplosive gas meter. Organic vapors were detected at levels ranging from 1 to 45 PID units. Methane gaswas detected using the explosive gas meter at levels of up to 25.5%. The methane gas monitoring results,along with measurements of carbon dioxide and oxygen levels, are presented in Table 1.

Surface soil from two locations was analyzed for metals, polychlorinated biphenyls (PCBs), polyaromatichydrocarbons (PAHs), diesel range organics (DRO), pesticides, and herbicides. One metal, chromium,slightly exceeded its MPCA Soil Reference Value (SRV) in one sample, collected in the smaller dump area. The SRVs represent the concentration of a contaminant in residential soil at or below which normal dermal contact, inhalation, and/or ingestion is unlikely to result in an adverse human health effect. While thechromium level exceeded its SRV, it should be noted that no attempt was made to determine the species ofthe chromium. The SRV is based on the more toxic chromium VI species, while the analysis was for totalchromium, which includes both chromium VI and the more commonly found (and less toxic) chromium III. No other metals exceeded their SRV, nor their MPCA Soil Leaching Values (SLVs). The SLVs represent theconcentration of a contaminant in soil above which leaching could contaminate the groundwater to levelsabove established standards. DRO was detected in both samples at concentrations of 61 and 29milligrams per kilogram (mg/kg) respectively. There are currently no formal soil screening criteria forDRO. No PCBs, PAHs, pesticides, or herbicides were detected. The analytical results and MPCA soilscreening criteria are presented in Table 2.

Samples of buried waste materials were collected at depths ranging from 2.5 to 17 feet below grade fromfive borings. The samples were analyzed for metals, volatile organic compounds (VOCs), PCBs, PAHs,DRO, pesticides, and herbicides. High levels of metals, including arsenic and lead, and DRO were found inseveral of the samples. PCBs were detected in 4 samples at levels below the SRV. Low levels of VOCs(primarily petroleum related VOCs) and several pesticides were also found. One pesticide, chlordane,exceeded its SRV in boring B-2. No PAHs or herbicides were found. The waste sample analytical resultsare presented in Table 3.

Soil samples from beneath the waste were collected in five borings to determine if contaminants had leachedfrom the waste materials into native soils. The soil samples were also analyzed for metals, VOCs, PCBs,PAHs, DRO, pesticides, and herbicides. Low levels of chromium, DRO, PCBs, and gamma-chlordane weredetected in three of the soil samples.

Groundwater samples were collected by STS from nine temporary monitoring wells installed in soil boringsB-1 through B-9, and were analyzed for VOCs, metals, PCBs, PAHs, DRO, pesticides, and herbicides. DRO was detected in all of the samples, at concentrations ranging from 180 micrograms per liter (g/L)to 1,400 g/L. Many of the samples exceeded the MDH Health-Based Value (HBV) for DRO of 200g/L. Low levels of VOCs (again, primarily petroleum related VOCs) were found in several of thegroundwater samples at levels below the MDH Health Risk Limits (HRLs) for groundwater. The HRLs havebeen promulgated into rule and represent levels of contamination in drinking water from private wells thatMDH considers safe for daily human consumption over a lifetime. The HBVs are similar to the HRLs, buthave not been promulgated. High levels of arsenic, barium, and selenium were also detected in many of thegroundwater samples. Arsenic levels in excess of the federal Maximum Contaminant Level (MCL) for publicwater supplies of 50 g/L was found in five of the nine samples. There is currently no HRL for arsenic. NoPAHs, PCBs, pesticides, or herbicides were detected. The groundwater analytical results are presented in Table 4.

STS collected a surface water sample from the man-made swimming pond located directly south of the site,across Webster Avenue. The pond is reported to be unlined, and may serve as a discharge point forgroundwater. The sample was analyzed for metals (both total and dissolved), VOCs, PCBs, PAHs, DRO,pesticides, and herbicides. Low levels of several halogenated methanes were found, which is indicative ofchlorination of the water in the swimming pond. Very low levels of several metals were also found. NoDRO, PCBs, PAHs, pesticides, or herbicides were found, although the detection limit for DRO was high(110 g/L).

MDH staff collected water samples from two private wells near the site; the well locations are shown on Figure 1. The wells are located in a likely upgradient location from the site; no wells were identified in thepresumed downgradient direction. The samples were analyzed for the presence of 68 volatile organicchemicals (VOCs), eight metals, nitrate, and four potential indicator parameters. Low levels of metals(including barium, lead, manganese, and zinc) were detected in both of the wells. None exceeded theirrespective HRLs. Levels of nitrate were also well below the HRL in both wells. Indicator parameters were generally within normal background ranges. Owners of the private wells were notified of the results.


II. DISCUSSION

Dumps may pose a potential human health risk when people come into contact with chemicals in soil, water,or air at levels of health concern, or when people are exposed to physical hazards such as sharp objects oruneven ground. This requires that both the chemicals (or hazards) are present and that people are incontact with them.

Waste materials in old dumps are often buried beneath a thin layer of whatever type of soil is easily availableat the time. This is the case at the North Mankato dump, where soils from a nearby street constructionproject were reportedly used for cover materials (STS 2000a). When cover materials are thin or absent,wastes and contaminants are exposed and people or animals may come into contact with them. Over time,compaction and degradation of the waste can result in settling and the emergence of large, sharp objectssuch as scrap steel, which can pose a physical hazard.

Organic waste materials in the dump (if it was not burned regularly) often degrade and generate methaneand other gases. Low levels of chemical solvents may also be present in gas produced by old dumps. Together, these gases are referred to as "landfill gases." These gases are frequently explosive and canmigrate up to a few hundred feet from the dump site, depending on local conditions. This gas migration canresult in explosive levels of methane and concentrations of solvents above health concerns in nearby homesor buildings, especially in basement areas. High levels of methane were found at the site, and other organicvapors were detected in soil at the site at very low levels. Buildings at the site may therefore be at riskfrom infiltration of methane or other gases, although most of the buildings appear to be relatively open andwell-ventilated and do not have basements. The degradation of solid waste also produces leachate wheninfiltrating water contacts the waste and dissolves chemicals from it. Leachate may discharge to surfacewater or infiltrate into groundwater. Groundwater contaminated by leachate usually does not have anydistinguishing appearance, color, or taste, and people are rarely aware of any problem unless the water istested. Soil with contaminant concentrations below the SLVs is not expected to generate leachate at levelsthat would be above groundwater or surface water criteria.

The North Mankato dump is somewhat unusual because it is located in a town near a populated area, andhas since been developed. It accepted all types of wastes, and had few if any controls. Some wastematerials are exposed at the dump surface, especially around the margins of the dump, and it appears thatthe dump may still be used by the city from time to time for disposal of excess soil or concrete. Thereappears to be little chemical risk due to direct contact with surface soil associated with this site, aside fromone metal detected in surface soil samples at a concentration slightly exceeding its Soil Reference Value in asingle sample. The number of surface soil samples collected was very limited; however, and other areas ofcontaminated soil may exist. Samples were not collected from areas of exposed waste that are outside of thefence. Exposed chemical wastes may also be carried from the site in runoff, and into the adjacent marsh orponds. Physical hazards are present from exposed wastes in some areas.

Samples from within the waste materials showed high levels of metals and DRO, as well as low levels ofVOCs and PCBs, indicating significant contamination is present within the bulk of the dump site. The bulkof the contamination appears to be petroleum related. Releases of petroleum from the 3 leaking USTs likelycontributed to this contamination. While direct human exposure to buried waste materials is unlikely at thistime, disturbance of the waste materials by humans or animals could bring them to the surface whereexposures could occur. They may also contribute to groundwater contamination. The finding of DRO andother compounds in soil beneath the waste indicates that they may be capable of leaching intogroundwater.

The analytical results clearly show that groundwater contamination is associated with the dump, some ofwhich is no doubt related to the petroleum UST releases. High levels of DRO are present in groundwateracross a wide area of the site, and numerous petroleum-related VOCs were found. High levels of arsenicand several other metals were also found. General groundwater flow is assumed to be east towards theMinnesota River. Municipal water is available in this area and few or no wells are located there. Contaminated groundwater from the site may also discharge to the ponds located in the park immediatelynorth of the site. The concentrations of contaminants detected in the groundwater would not represent ahealth risk to people who swim or fish in these ponds. However, the amount of data collected is limited andconditions could change over time.

There were no detections of VOCs or arsenic in two private wells located approximately 500 feet west ofthe site in a likely upgradient location. Only low levels of metals were found in the swimming pond locateddirectly south of the site; however, laboratory detection limits for DRO were high so the possible presence of DRO cannot be ruled out.

Agency for Toxic Substances and Disease Registry (ATSDR) Child Health Initiative

ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children make themof special concern to communities faced with contamination of their water, soil, air, or food. Children areat greater risk than adults from certain kinds of exposures to hazardous substances at waste disposal sites.They are more likely to be exposed because they play outdoors and they often bring food into contaminatedareas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors close to theground. Children also weigh less, resulting in higher doses of chemical exposure per body weight. Thedeveloping body systems of children can sustain permanent damage if toxic exposures occur during criticalgrowth stages. Most importantly, children depend completely on adults for risk identification andmanagement decisions, housing decisions, and access to medical care.

Children may be attracted to exposed debris at the site due to the presence of bottles, shiny metal objects,exposed dirt, etc. The location of the dump adjacent to a park and trail system may attract children. While the site itself is fenced, some exposed wastes are located outside of the fence and are accessible.


III. CONCLUSIONS

Based on a review of available information in MPCA and MDH files, a site visit conducted on April 27,2000, and analysis of private water supply samples, it appears that this site poses an indeterminate publichealth hazard. The hazards involve physical hazards from exposed wastes, and potential fire or explosionhazards from the production of methane gas by decaying wastes. Chemical hazards from potential contactwith contaminated surface soils or wastes could occur; however, information on exposure is lacking. Thepotential for contaminants detected at the site to impact private and public water supply wells in the area is minimal based on data collected so far.


IV. RECOMMENDATIONS

  1. All exposed wastes at the site should be removed, and cover soil should be placed on theseareas to prevent exposure to physical hazards and potentially contaminated soils. Cover soilsacross the remainder of the site should be properly graded and maintained. This would alsolikely help to reduce the amount of contamination potentially entering the nearby ponds as aresult of runoff. The cover material should be able to support vegetation and graded to promoterunoff without excessive erosion.

  2. All buildings on the site should be screened for the possible presence of methane gas, andany obvious points of gas entry should be sealed.

  3. Institutional controls such as a notice filed with the property deed should be considered torecord the location of the dump for future reference.

V. PUBLIC HEALTH ACTION PLAN

MDH's Public Health Action Plan for the site will consist of:

  1. A letter to the MPCA and to city and county authorities advising them of ourconclusions and recommendations; and

  2. A review of any additional available data, and participation in any meetings or otherpublic outreach activities.

VI. REFERENCES

STS 2000a. Draft Phase I Environmental Site Assessment, STS Consultants, LTD. June 27, 2000.

STS 2000b. Draft Phase II Environmental Site Assessment, STS Consultants, LTD. October 19,2000.


PREPARERS OF REPORT

James Kelly
Health Assessor
Site Assessment and Consultation Unit
Minnesota Department of Health
tel: (651) 215-0913

Ginny Yingling
Hydrologist
Site Assessment and Consultation Unit
Minnesota Department of Health
tel: (651) 215-0917

Alan Yarbrough
Technical Project Officer
Division of Health and Consultation
State Program Section
Agency for Toxic Substances and Disease Registry


CERTIFICATION

This North Mankato Dump Health Consultation was prepared by the Minnesota Department ofHealth under a cooperative agreement with the Agency for Toxic Substances and Disease Registry(ATSDR). It is in accordance with approved methodology and procedures existing at the time thehealth consultation was begun.

Alan W. Yarbrough
Technical Project Officer, SPS, SSAB, DHAC, ATSDR


The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.

Sven E. Rodenbeck
for Richard Gillig
Chief, Superfund Site Assessment Branch, DHAC, ATSDR


FIGURES

North Mankato Dump Location
Figure 1. North Mankato Dump Location

Site Map
Figure 2. Site Map

Cross Sections
Figure 3. Cross Sections


TABLES

Table 1.

Soil Boring Vapor Observations
North Mankato Dump
Boring No. Methane Gas (%) Carbon Dioxide (%) Oxygen (%)
B-1 4.3 3.1 16.2
B-2 15.1 16.2 3.0
B-3 11.5 8.9 12.3
B-4 14.1 10.0 9.9
B-5 0.5 1.3 16.9
B-6 24.0 3.8 11.2
B-7 6.0 3.7 16.2
B-8 16.8 7.5 11.4
B-9 3.6 7.5 12.4
B-10 4.1 1.7 16.7
B-11 0.0 1.9 16.8
B-12 0.0 2.8 15.2
B-13 1.3 1.7 17.1
B-14 10.9 8.5 12.1
B-15 0.0 0.7 17.5
B-16 25.5 12.7 6.3

Source: STS 2000B


Table 2.

Surface Soil Analytical Results North Mankato Dump Concentrations in mg/kg
  SS-01
(3 ft.)
SS-02
(0-1 ft.)
SLV SRV
Diesel Range Organics - DRO 61** 29** NE NE
Metals EPA 6010        
Arsenic 2.86 3.47 15.1 10
Barium 193 70 842 1,200
Cadmium 0.706 0.609 4.4 35
Chromium* 18.6 9.5 18* 71*
Copper 19.8 13.5 400 100
Lead 26.5 20.8 525 400
Nickel 17.4 12 88 520
Selenium 0.931 0.322 1.5 170
Silver 2.32 <0.608 3.9 170
Polychlorinated Biphenyls - PCBs EPA
8082
No detects for all compounds analyzed 2.1 1.2
Polyaromatic Hydrocarbons - PHAs EPA
8270
No detects for all compounds analyzed varies varies
Pesticides EPA 8081 No detects for all compounds analyzed NE varies
Herbicides (MDA List 1) No detects for all compounds analyzed varies varies

** - Re-extracted sample result
* = Chromium (total) results conservatively compared to Chromium VI SLV and SRV
SLV = MPCA Soil Leaching Value, Tier 1
SRV = MPCA Soil Reference Value
NE = Not Established
Bold = Concentration above detection limits

  = Concentration exceeds SLV

 

= Concentration exceeds SRV

Source: STS 2000b


Table 3.

Waste Analytical Results North Mankato Dump Concentrations in mg/kg
  B-2
S-07
(15-17 ft.)
B-4
S-02
(4-5.5 ft.)
B-6
S-05
(10-12 ft.)
B-8
S-02
(2.5-4.5 ft.)
B-9
S-05(10-12 ft.)
SLV SRV
Volatile Organics Compounds - VOCs
EPA 8260 Methonal Extraction
Ethylbenzene < 0.39 <0.28 0.74 <0.34 <0.33 4.7 200
1,2,4 - Trimethylbenzene 0.46 <0.28 <0.3 <0.34 <0.33 NE 5
Napthalene 0.54 <0.28 <0.3 <0.34 <0.33 7.5 10
4-Methyl-2-Pentanone <0.39 <0.28 0.54 <0.34 <0.33 NE NE
M&P Xylene <0.77 <0.56 9.4 <0.67 <0.66 45 110
O-Xylene <0.39 <0.28 1.3 <0.34 <0.33 45 110
Diesel Range Organics - DRO 530 49 <12 130 450** NE NE
Metals EPA 6010
Arsenic 3.74 2.9 57.1 2.42 4.81 15.1 10
Barium 883 49.8 307 893 93.3 842 1,200
Cadmium 9.28 0.166 5.78 0.316 0.417 4.4 35
Chromium (VI)* 55.2 7.82 28.1 31.2 12.7 18* 71*
Copper 301 8.04 125 9.03 14.3 400 100
Lead 578 30.1 1470 739 29.9 525 400
Mercury (EPA 7471) <0.0258 <0.0448 0.0575 <0.0512 <0.0493 1.6 0.7
Nickel 24.1 8.51 25.7 13.3 14.5 88 520
Selenium <1.81 0.3 1.43 0.562 0.598 1.5 170
Silver 4.28 <0.56 1.5 <0.662 <0.658 3.9 170
Polychlorinated Biphenyls - PCBs
EPA 8082
Arochlor 1016 <0.051 <0.037 <0.04 <0.043 0.18 2.1 1.2
Arochlor 1254 <0.051 0.081 0.06 0.098 <0.039 2.1 1.2
Polyaromatic Hydrocarbons - PAHs
EPA 8270
No detects for all compounds analyzed
Pesticides EPA 8081
Dieldrin <0.26 <0.037 0.0082 <0.043 <0.039 NE 0.8
Chlordane 21 <0.74 <0.08 <0.88 <0.79 NE 13
gamma-Chlordane 3.8 <0.019 <0.002 <0.22 <0.02 NE 13
alpha-Chlordane 2.4 <0.019 <0.002 <0.22 <0.02 NE 13
Herbicides (MDA List 1) No detects for all compounds analyzed varies varies

** - Re-extracted sample result
* = Chromium (total) results conservatively compared to Chromium VI SLV and SRV
SLV = MPCA Soil Leaching Value, Tier 1
SRV = MPCA Soil Reference Value
NE = Not Established
Bold = Concentration above detection limits

  = Concentration exceeds SLV

 

= Concentration exceeds SRV


Table 4.

Groundwater Analytical Results North Mankato Dump Concentrations in ug/l
  B-1
W-01
B-2
W-03
B-3
W-05
B-4
W-06
B-5
W-08
B-6
W-10
B-7
W-07
B-8
W-09
B-9
W-11
B-20
W-02 (dup. B-1)
Standard Source
Volatile Organics Compounds -
VOCs EPA 465E
 
Dichlorodifluoromethane <1 <1 <1 <1 <1 1.2 <1 <1 <1 <1 1,000 HRL
Diethyl Ether 12 10 44 16 <10 <10 <10 <10 <10 12 NE HRL, MCL, HBV
Acetone 8.8 <5 12 5.1 <5 <5 21 <5 <5 11 700 HRL
Benzene 3.3 <1 1.7 <1 <1 <1 <1 <1 <1 3.4 10 HRL
Chlorobenzene <1 <1 <1 1.8 <1 <1 <1 <1 1 <1 100 HRL
M&P Xylene 13 <2 5.3 <2 <2 <2 <2 <2 <2 11 10,000 HRL
O-Xylene 2.6 <1 <1 <1 <1 <1 <1 <1 <1 2.3 10,000 HRL
Isopropylbenzene 2.1 <1 <1 <1 <1 <1 <1 <1 <1 1.7 300 HRL
n-Propylbenzene 3.5 <1 <1 <1 <1 <1 <1 <1 <1 2.7 NE HRL, MCL, HBV
1,3,5-Trimethylbenzene 1.7 <1 <1 <1 <1 <1 <1 <1 <1 1.3 NE HRL, MCL, HBV
1,2,4-Trimethylbenzene 21 <1 3.8 <1 <1 <1 <1 <1 <1 16 NE HRL, MCL, HBV
p-Isopropyltoluene <1 <1 <1 <1 <1 <1 <1 1 <1 <1 NE HRL, MCL, HBV
1,4-Dichlorobenzene 2.8 1.3 <1 1.4 <1 <1 <1 <1 <1 2.3 10 HRL
Naphthalene 8 5.4 3.5 <1 <1 <1 3.3 <1 <1 7.4 300 HRL
Diesel Range Organics - DRO 1100 430 190 510 400 180 370 300 320 1400 200 HBV
Metals EPA 6010    
Arsenic 30.6 12.1 25.3 121 <5 96.9 71.2 63.8 100 28 50* MCL
Barium 781 868 950 1,010 445 532 1,080 908 483 783 2,000 HRL
Nickel <20 <20 <20 <20 33.6 <20 <20 <20 <20 <20 100 HRL
Selenium 22 21.4 10.6 14.9 18.5 15.3 19.1 16.2 13.5 22.6 30 HRL
Polyaromatic Hydrocarbons -
PAHs EPA 8270
No detects for all compounds analyzed varies varies
Polychlorinated Biphenyls - PCBs
EPA 8082
No detects for all compounds analyzed 0.04 HBV
Pesticides EPA 8081 No detects for all compounds analyzed varies varies
Herbicides (MDA List 1) No detects for all compounds analyzed varies varies
 

* = Interim MCL; under evaluation
< = Less than laboratory limit of detection
HRL = Health Risk Limit for Groundwater, Minnesota Department of Health
HBV = Health Based Value For Groundwater, Minnesota Department of Health
MCL = Maximum Contaminant Level, U.S. Environmental Protection Agency
NE = Not Established
Bold = Concentration above detection limits

  = Concentration exceeds HRL/HBV/MCL

Source: STS 2000b


Table of Contents

  
 
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