PUBLIC HEALTH ASSESSMENT
NAVAL INDUSTRIAL RESERVE ORDNANCE PLANT
FRIDLEY, ANOKA COUNTY, MINNESOTA
This Public Health Assessment addresses contaminated media (soil, water, and air) at two NationalPriorities List (NPL) Superfund sites: the Fridley, Minnesota, Naval Industrial Reserve OrdnancePlant (NIROP) and FMC Superfund Site. These superfund sites are separated by United DefenseLimited Partnership (UDLP) property. FMC was purchased by UDLP. There is an apparentcompleted groundwater pathway via the Mississippi River to the Minneapolis Water Works(MWW). For this reason, groundwater is the media most discussed in this assessment. These twoSuperfund properties include 2 RCRA Sites: Storage Area C and UDLP Subsurface (belowbuilding) Source Areas.
NIROP and UDLP properties are located approximately 1 mile south of Interstate 694 and East River Road on the east side of the Mississippi River. The NIROP and the UDLP properties consist of several small buildings and one large manufacturing facility that contain approximately 1.9 million square feet. The large manufacturing facility is jointly owned by the United States Navy (NAVY) and UDLP, but the Navy owns more than half. Access to NIROP and UDLP properties is limited. Land in the area is designated as industrial, excluding Anoka County Riverfront Park. The Minneapolis Water Works (MWW) drinking water intakes are located approximately one mile down stream from NIROP and UDLP/FMC on the Mississippi River. Groundwater discharges from NIROP and UDLP to the Mississippi River is not permitted to exceed 5 micrograms per liter (µg/l) of trichloroethylene (TCE). NIROP TCE groundwater monitoring wells near the river exceed the clean-up standard of 5 µg/l. Limited FMC Superfund Site monitoring data indicates detections of 5 µg/l TCE off the UDLP property.
Based on sampling data of the treated (finished) water from the MWW from 1984 to the present, MDH concludes that any impact from these sites on the MWW's treated water is not a human health hazard or concern under current (or past) conditions: people are not being exposed to NIROP or UDLP/FMC related contaminants above health-based standards. TCE has been detected in the MWW finished water 27 times in the past 16 years. However, all the TCE detections have been substantially below the Maximum Contaminant Level (MCL) of 5 µg/l. The finished water is sampled quarterly for volatile organic compounds (including TCE). No other volatile organic compounds have been detected in the finished water. The raw water has been sampled for TCE annually by UDLP for the past 8 years with no detections using the Maximum Contaminant Level for TCE (5 µg/l) or 2.1 µg/l as the detection limit. In other words, TCE may have been present at levels similar to those found in the finished water but was not detected in the raw water because the detection limit was too high.
There may be potential for TCE concentrations in drinking water to exceed health-based standards. This possibility is suggested by TCE contamination found in groundwater at the Anoka CountyRiverfront Park, and fluctuations in TCE concentrations in monitoring wells near the MississippiRiver. These wells are indicators of what may be discharging to the river. Plume migrationunderground from NIROP and the FMC Superfund Sites is in the direction of the Mississippi River.A portion of the FMC Superfund Site groundwater plume has reached has reached MWW property.If and where the contaminated groundwater from the FMC Superfund Site is discharging into theMississippi River is not known. It is generally believed that contaminated groundwater that is notcaptured by NIROP's groundwater extraction system (the majority is captured) or is beyond it'scapture zone is discharging into the Mississippi in the southern portion of Anoka County Park. Inaddition, all source areas for groundwater contamination at the superfund sites need to be identifiedto achieve better understanding of the horizontal and vertical extent of contaminated groundwater. Increased monitoring of the MWW raw water intakes as a safety measure is also recommended.
The NIROP site contains three operable units. Operable Unit 1 (OU1) consists of facility wide contaminated groundwater, including off site contaminated groundwater in Anoka County Riverfront Park. A two-phase approach is being implemented for the extraction and treatment of OU1 groundwater. In phase one, a groundwater extraction system discharges groundwater contaminated with TCE to the sanitary sewer system for treatment at the local waste water treatment plant. The Navy has successfully implemented phase two, where a water treatment system is used to lower TCE concentrations in groundwater to 5 µg/l or less and discharge the treated water into the Mississippi River, as required by a National Pollution Discharge Elimination System (NPDES) permit. A recent cone penetrometer investigation in Anoka County Riverfront Park has found groundwater contamination ranging from not detectable to 37,300 micrograms per liter (µg/l) (see figure 4, sample W1-6). The current extraction system will not remove contaminated groundwater from Anoka County Riverfront Park. Also, there is only one Prairie du Chien monitoring well (No. 43) down gradient from the NIROP/UDLP facility which has not been adequately monitored. The Prairie du Chien is the main Twin Cities drinking water aquifer. Thus, there are groundwater issues that still need to be resolved.
Operable Unit 2 (OU2) consists of on-site subsurface source areas (unsaturated zone) outside of theNIROP manufacturing building. The source areas for OU2 include buried drums and contaminatedsoil containing varying amounts of solvents and poly aromatic hydrocarbons (PAHs). Completedremoval actions included excavation and proper disposal of more than thirty 55 gallon drumscontaining spent solvents. Contaminated soil was also removed. However, during a MississippiRiver sampling event in 1997, buried drums were discovered in the Anoka County Riverfront Park. The drums are part of an old NIROP/UDLP dump which has not been characterized.
Operable Unit 3 (OU3) includes on-site subsurface source areas (saturated and unsaturated zone) beneath the NIROP manufacturing building. Remedial investigation field work has been completed. A complete remedial investigation report will be available in 1999. Preliminary findings include TCE concentrations in soil up to 100,000 micrograms per kilogram (µg/kg) and 140,000 µg/l in groundwater underneath the plating shop. Other contaminants were also found in the soil.
UDLP property currently has two operating remedial systems: one for soil and another forgroundwater. In 1983, the Minnesota Pollution Control Agency (MPCA) issued a Consent Order toUDLP/FMC that resulted in the cleanup and treatment of waste in a Containment and TreatmentFacility (CTF). The CTF is a vault filled with TCE contaminated soil. The vault includes leachatecollection and vapor extraction systems. UDLP/FMC also operates a groundwater extraction systemthat discharges contaminated groundwater to the sanitary sewer system for treatment at the localwaste water treatment plant. The UDLP groundwater plume needs to be further investigated; thecurrent monitoring well network does not adequately describe the horizontal and vertical extent ofgroundwater contamination.
Although TCE is the main contaminant of concern at both sites, other contaminants have beendetected above health protective standards - Maximum Contaminant Levels (MCLs) and MDHHealth Risk Limits (HRLs) - for contaminants in drinking water. Groundwater exceedances of HRLs and MCLs are listed in Appendixes D and E.
This Public Health Assessment (PHA) evaluates potential exposures to contaminants found at theFridley, Minnesota, Navy Industrial Reserve Ordnance Plant (NIROP) National Priority List (NPL)superfund site, United Defense Limited Partnership (UDLP [formerly FMC Corporation.]), FridleyMinnesota, NPL Site, and two Resource Conservation and Restoration Act Sites located on NIROPand UDLP properties. These properties are individually evaluated in this public health assessment. This document examines contaminated media (water, air and soil), transport mechanisms and routesof exposure (ingestion, inhalation and dermal contact) to determine the likelihood of individualsbeing exposed to contamination. Minnesota Pollution Control Agency (MPCA), United States Navy(Navy) and UDLP project files along with electronic documents provided to Minnesota Departmentof Health (MDH) were reviewed. These documents and a site visit, form the basis for this PHA. Health effects that might be associated with any exposures are also discussed. This Public HealthAssessment discusses data and results collected prior to April 1998. Most of the recent results havenot been reviewed by MDH, although some of these results are sometimes referred to whenappropriate.
MDH, under a cooperative agreement with the Agency for Toxic Substances and Disease Registry(ATSDR), evaluated the public health significance of contamination associated with NIROP andUDLP properties. More specifically, MDH and ATSDR cooperated to determine whether healtheffects are possible and to make recommendations to reduce or prevent possible health effects. ATSDR, located in Atlanta, Georgia, is a federal agency within the U.S. Department of Health andHuman Services and is authorized by the Comprehensive Environmental Response, Compensation,and Liability Act of 1980 (CERCLA; also known as Superfund) to conduct health assessments athazardous waste sites.
The Naval Industrial Reserve Ordnance Plant (NIROP, CERCLIS number MN3170022914) andUnited Defense Limited Partnership (UDLP, CERCLIS number MND006481543) facilities arecontiguous, and located in the northern portion of the Minneapolis/St. Paul metropolitan area withinthe city limits of Fridley, Minnesota. These sites are situated approximately one-quarter mile east ofthe Mississippi River and less than 1 mile south of Interstate 694 (Figures 1 and 2). TheNIROP/UDLP plant is used for the design and manufacture of advanced naval weapons systems. The plant was the first government owned/contractor operated (GOCO) facility in the United States.
The northern portion (NIROP) of the plant is owned by the Navy but operated by UDLP. NIROPconsists of approximately 80.3 acres, including approximately 36 acres under roof and an estimated14 acres paved. NIROP property is occupied by buildings containing approximately 1,753,000square feet of space. NIROP is contiguous to buildings/plant and property to the south owned byUDLP. The UDLP portion of the plant contains approximately 9.5 acres with 326,000 square feetunder a roof. Both NIROP and UDLP are superfund sites with their respective environmentalliabilities. A groundwater plume consisting mostly of trichloroethylene (TCE) emanates from under the NIROP facility. The FMC Superfund Site includes the unconfined aquifer plume and the confined aquifer plume on UDLP property south of the main facility, and any off-site areas of plume migration.
The plant was built in 1940 by the Northern Pump Company using U.S. War Department Funds. In1941, the plant was in full production making 5 inch gun mounts. In June 1942, the NorthernPump Company established Northern Ordnance Incorporated as a subsidiary. The Navy financedadditional buildings on private land for use as manufacturing facilities for Northern OrdnanceIncorporated. In 1947, the U.S. acquired 80.3 acres of land underlying Navy owned buildings.During the 1950s, production changed to guided missile launching systems. In 1964, NorthernOrdnance was acquired by the FMC Corporation (FMC). On January 1, 1994, FMC's defensebusiness entered into a limited (currently 60% ownership) partnership with Harsco Corporation'sdefense business to form United Defense, Limited Partnership (UDLP). Currently, the ArmamentSystems Division of UDLP operates the facility, which continues to produce gun mounts and missilelaunching systems and is currently owned by the Carlyle Group (1). In this document, UDLP andFMC are considered one and the same unless otherwise noted.
The Environmental Protection Agency (EPA) and the Minnesota Pollution Control Agency (MPCA)have determined that past disposal practices of hazardous substances at the NIROP and UDLPfacilities have resulted in releases of hazardous substances causing extensive ground watercontamination on and off NIROP and UDLP properties.
For this Public Health Assessment, NIROP and UDLP are considered one site due to the closeproximity and physical arrangement of the two sites, and potential for mixing of their respectivegroundwater plumes. Because of the long history and large size of the facility, there are numerousAreas of Concern (AOC) and Solid Waste Management Units (SWMU) that still need to beinvestigated. AOCs include any areas where hazardous wastes may have been stored, spilled, usedor disposed (including above and below ground storage tanks). SWMUs include any areas wheresolid wastes (hazardous and nonhazardous) were stored, dumped or buried. State supervised sitecharacterization has been an ongoing effort, spanning 16 years beginning with the MPCA's issuanceof a Request For Response Action in 1984 under the authority of the Minnesota EnvironmentalResponse and Liability Act (MERLA)(1). Figure 3 depicts past industrial process areas within thefacility and notes those production areas have changed over time. Thus, many AOC and SWMUlocations have also changed over time making them beyond the scope of this report. The emphasisof this document is on recent site related activities, and any known AOCs/SWMUs that may havecontributed to the groundwater contamination. NIROP's and UDLP's operable units (OU) arelisted separately to aid the reader in distinguishing between the two. UDLP's hazardous waste treatment systems are also listed separately.
A.1 Naval Industrial Reserve Ordnance Plant (NIROP) Superfund Site
NIROP property contains five sites that have been identified as Navy Installation Restoration Program (IRP) Sites. These sites are divided into three major work areas called Operable Units (OU1, OU2 and OU3). OU1 consists of plant wide groundwater. OU2 includes all contaminated soil and buried drum sites (1). OU3 includes source areas beneath the factory building.
A.1.a NIROP Operable Unit 1 (OU1) plant wide groundwater
A Record of Decision (ROD) for groundwater at NIROP was finalized on March 1991 (2). The ROD describes how the Navy plans to remedy the contaminated groundwater by hydraulic containment, recovery, and treatment. The proposed remedy includes installation and operation of a groundwater containment and extraction system. A two phased approach for disposal of the contaminated groundwater from the system has been implemented.
Under Phase I, the extracted groundwater was initially pretreated before being discharged directly tothe existing sanitary sewer system, and treated at the Pig's Eye wastewater treatment facility. Aftereffluent TCE concentrations dropped, the extracted groundwater was discharged directly to thesanitary sewer. This discharge is permitted by the Metropolitan Council Environmental Services(MCES) Industrial Discharge Permit (No. 2154 ) (1). The monitoring well system consists of 81wells completed in the shallow, intermediate and deep surficial aquifers and the Prairie duChien/Jordan Dolomite aquifer. Forty-four of the wells are sampled on a regular basis as part of theRemedial Action Monitoring Plan (RAMP). There is a total of six extraction wells, two of whichwere part of a 1995 upgrade. To date, a true zone of capture has not been firmly established (21).However, substantial capture of the groundwater plume is occurring.
In phase II, the groundwater treatment facility will lower extracted groundwater TCE concentrationsto 5 micrograms per liter (µg/l) (maximum contaminant level) or less and discharge it to theMississippi River under a National Pollutant Discharge Elimination System Permit (NPDES),(Permit No: MN0000710). The groundwater treatment facility is currently in operation . The riverdischarge limits (daily maximums, not averages) are listed in the following table.
|Daily Max (µg/l)||Measurement Frequency||Sample Type|
|Methylene Chloride||5.0||Twice Monthly||Grab|
|Carbon Disulfide||700||Twice Monthly||Grab|
|1,1 dichloroethene||6.0||Twice Monthly||Grab|
|1,1 dichloroethane||70||Twice Monthly||Grab|
|1,2 dichloroethane (cis)||70||Twice Monthly||Grab|
|1,2 dichloroethane (trans)||100||Twice Monthly||Grab|
|1,1,1 Trichloroethane||200||Twice Monthly||Grab|
|Trichlorethylene (TCE)||5.0||Twice Monthly||Grab|
|Tetrachloroethene (PERC)||3.8||Twice Monthly||Grab|
It should be noted that monitoring frequency is subject to change after the first year if contaminantsare consistently well below the discharge limits. A reduction in monitoring must be approved by theCommissioner of the MPCA. The groundwater remedy will continue until groundwater TCE levelsreach 5 µg/l or asymptotic conditions are reached (21).
The contaminated groundwater in Anoka County Riverfront Park is included in OU1. A Cone Penetrometer Test investigation was completed in December 1997. See Figure 4 for preliminary findings of TCE concentrations from the cone penetrometer investigation in Anoka County Park. The cone penetrometer investigation was a one time sampling event that revealed TCE concentrations as high 37,300 parts per billion (ppb) in the park (21).
A. 1.b NIROP Operable Unit 2 (OU2) Unsaturated Zone Outside Building
OU2 consists of on-site subsurface source areas (unsaturated zone) outside of the NIROP manufacturing building. The source areas for OU2 included buried drums and contaminated soil containing varying amounts of solvents and polycyclic aromatic hydrocarbons (PAHs). OU2 had three completed and separate removal actionsinitiated in 1983, 1991 and 1996 in the North Forty. The North Forty is approximately 22 acres of land north of the main building.
The area contains the following: buildings 58, 50, and 37; three 17,300 gallon propane tanks; one90,000 gallon propane tank. Figure 5 shows the locations of all the removal actions and buildingsin the North Forty.
The North Forty site was identified in 1983 during an Initial Assessment Study (IAS) conducted aspart of the Navy Assessment and Control of Installation Pollutants Program. The IAS revealed thatdrummed wastes were disposed of in the northern portion of the NIROP in varying length trenchesranging from 8 to10 feet deep.
Following the completion of the IAS, a geophysical survey was conducted by the U.S. Army Corpsof Engineers (USACE) in the suspected disposal areas. Based on numerous magnetic anomalies,nine areas were selected for excavation (test pits) and a total of 43 drums and 1,200 cubic yards ofcontaminated soil were recovered and disposed of in 1984.
Subsequent geophysical, soil gas, and soil boring investigations led to the conclusion that another drum disposal area mightexist. These findings led to a removal action in 1991, which included theexcavation, sampling and overpacking of 31 drums. Analysis with field screening instrumentsindicated that 21 of the drums were contaminated with Volatile Organic Compounds (VOCs). Approximately 900 cubic yards of soil and debris were removed during the excavation, along withthe drums. The debris consisted of a mixture of trash, rubble, and demolition. Based on datedmaterials found at the NIROP site, it can be concluded that some of the disposal took place duringthe early 1970s. The soil was mechanically separated from the debris and returned to the excavationas backfill (700-750 cubic yards) (5). The drum wastes were incinerated at an EnvironmentalProtection Agency (EPA) Resource Conservation and Recovery Act (RCRA) licensed facility. Thedebris disposal was either at a sanitary landfill or at a RCRA secure landfill, based on itscontaminant concentrations.
The most recent removal action began in April 1996, and ended in June of the same year. Ageophysical investigation consisting of an electromagnetic survey of the North Forty identifiedfifteen anomalies. Results suggested the presence of buried metallic materials. All 15 excavatedanomalies contained scrap metal, and several had drums and debris. The debris consisted of amixture of trash, scrap metal, tires, construction and demolition rubble, metal casting waste,equipment parts, and cast concrete structures. In all, a total of twenty-three 55-gallon drums and 12smaller containers were excavated from four of the 15 anomalies. Contents of 13 drums and 8containers were sampled, analyzed, and overpacked for hazardous waste disposal at the Port Arthur(Texas) incinerator (6). The remaining10 drums and 4 containers were found to have no detectablecontamination using a field screening gas chromatograph with both photoionization and flameionization detectors. The contents of these drums and containers were emptied and landfilled, andthe containers were disposed of as scrap metal.
Soil contaminated with Volatile Organic Compounds (VOC) from one of the excavations wasemptied into two steel overpack drums. Soil was incinerated at Port Arthur. Approximately 12cubic yards of soil with asbestos containing siding, insulation and paraffin sludge was containerizedand disposed of at the Voyager Landfill in Canyon, Minnesota. Another 100 cubic yards of soil notsuitable for backfill was disposed of at Pine Bend Landfill, also in Minnesota.
Soil samples were collected from the bottom of each excavation and analyzed for VOCs,semivolatile organic compounds (SVOC), total organic halides (TOH), phenolics, total cyanide,sulfur, and metals. Samples were collected from the approximate center of each 1/2 or 1/3 area comprising the bottom of the excavation.
A.1.c NIROP Building In Saturated Zone (OU3)
OU3 includes on-site subsurface source areas (saturated and unsaturated zone) beneath the NIROP manufacturing building, and on-site subsurface source areas (saturated zone) outside of the NIROP manufacturing building. The remedial investigation and feasibility study field work are complete pending MPCA and EPA approval. Preliminary findings include TCE concentrations in soil up to 100,000 µg/kg and 140,000 µg/l in groundwater underneath the plating shop (21). The final remedial investigation report should be complete 1999. This report will include soil boring data that will help characterize source areas located under the NIROP manufacturing building. In addition, 18 nested monitoring wells have been installed within the building from which groundwater samples will be collected. This operable unit is suspected to be a very prominent source area based on the TCE isoconcentration maps provided in the NIROP 1996 and 1997 Annual Monitoring Reports (Figure 6 and 7). To date, other source areas (buried drums and contaminated soil) identified and removed on NIROP and UDLP properties outside the building are much less significant. This conclusion is based on the extent and concentrations of the groundwater plume emanating from under the NIROP/UDLP facility, in comparison with other source area contamination.
A.1.d NIROP Storage Area C RCRA Site
FMC operated a Navy owned hazardous waste storage facility known as Storage Area C on NIROP property. The concrete storage area was constructed in 1972 and metal building was added in 1985. Storage Area C could house a maximum of 144 55-gallon drums. The building was dismantled in 1988. An initial excavation of the concrete pad was conducted in January 1989. During closure activities at Storage Area C, it was discovered that the sump in the pad was a "dry well". The dry well was constructed with a 48-inch concrete pipe filled with crushed rock to the depth of approximately 11 feet. The bottom of the dry well was open to the underlying soil. Soil samples from the dry well indicated the presence of VOCs, primarily TCE and tetrachloroethylene (PERC). Maximum soil concentrations associated with Storage Area C were 6,300 µg/kg for TCE and 500 µg/kg for PERC. More than 200 cubic yards of contaminated soil were excavated and disposed off site. Remaining soils with TCE concentrations of 100 µg/kg were treated with an in-situ soil vapor extraction system. The site included approximately 4,750 cubic yards of potentially contaminated soil.
The soil gas extraction system began operating in 1993 and was deactivated in mid 1997. Thesystem consisted of several gas wells, associated subsurface piping, and a soil vapor extractionbuilding that housed pumps and filters. Contaminated groundwater associated with the Storage Area C site is part of the NIROP Superfund Site.
A.2.a Groundwater Remedial Action Operable Unit
This operable unit consists of 18 acres on the southern portion of the UDLP property. Thirteen acres of this land belongs to UDLP and five acres were sold to Glacier Park Company, a subsidiary of Burlington Northern Railroad (BNR) (Figure 8). The land due west of UDLP was sold to Anoka County and is now part of the Anoka County Riverfront Park. This park was developed as part of the federally funded Great River Road Project (7). The UDLP portion of the plant is privately owned and operated. In April 1981, an FMC investigation revealed historical use of the FMC and BNRlands for waste disposal. Investigators found groundwater contamination on site as well as contamination in the Minneapolis Water Works (MWW) water intakes(7).
The remedial action for this site consists of a ground water extraction system and discharge ofuntreated groundwater to a sanitary sewer for treatment at the Pig's Eye Water Treatment Plant, aPublicly Owned Treatment Works (POTW) (8).
The groundwater extraction system (GWS) began operating in December 1987. The GWS consistsof five extraction wells (RW1-RW5), related piping, and mechanical components. Wells RW-1 andRW-2 are installed on the BNR property. These wells are completed in the upper, unconfined sandunit of the alluvial aquifer. Extraction well RW-1 has not been in service since 1987 due to a lackof groundwater recharge at the well. The MPCA questions if RW-2 provides adequate hydrauliccontainment (12). Extraction wells RW-3, RW-4, and RW-5 are located on the UDLP property andare completed in the lower, confined sand unit of the alluvial aquifer. According to MPCA (23), "Itis expected that portions of both the unconfined and confined plumes exist beyond the capture abilityof the groundwater pumping system and that the plumes are present down gradient of East RiverRoad between the road and the Mississippi River. Given deficiencies in the current off-sitemonitoring network, it is difficult to evaluate the horizontal and vertical extent and concentration ofthe offsite plume." These deficiencies include the number and location of wells and the lack ofdiscrete vertical aquifer characterization. Some of the monitoring wells were constructed with verylong screened intervals (70-100 foot screens) which make the interpretation of data from the wellsincluding contaminant concentrations and hydraulic heads uncertain (23). In monitoring wellsnearest the Mississippi River (MW-21, MW-39), in 1996, TCE concentration data did not exceed5µg/l. However, these two wells are sampled only once a year and data may not be representative ofconcentrations in the off-site confined plume in general. No appropriately screened down gradientwells exist to monitor compliance with water quality standards in the confined aquifer near the river(23). Based on groundwater flows, it is reasonable to expect ground water discharge for theseplumes to be up gradient of the MWW's intakes. In addition, extraction wells RW-2 and RW-3have consistently exceeded the MDH Health Risk Limit (HRL) (0.2 µg/l) and EnvironmentalProtection Agency's MCL (2.0 µg/l) for vinyl chloride (see Appendix E). The HRL is an MDHstandard entirely based on health considerations that is used to give advice to government agenciesand private citizens, concerning safe levels of contaminants in drinking water. The MCL is aregulatory standard for public water supplies. It is meant to protect public health, but other factorsmay also be considered, such as cost, best available technology, and so forth. Figures 9 and 10 showthe 1996 TCE isoconcentration contours for the unconfined and confined aquifers. The pipingsystem conveys extracted groundwater to a combined gravity drain system and discharges it into a15-inch diameter sanitary sewer (Figure 11). The sewer line traverses the site and discharges into an existing manhole along the southern site boundary.
Groundwater discharge to the sanitary sewer is monitored by UDLP and regulated by theMetropolitan Council Environmental Services. Treatment of extracted groundwater is accomplishedat the POTW. The Metropolitan Environmental Council Service (MECS) Special Discharge Permit2020 restricts VOC effluent concentrations greater than 10 parts per million (ppm) total, with nogreater than 3 ppm for any one VOC (16).
The United States Environmental Protection Agency (USEPA) and the MPCA has set the boundaryof compliance for groundwater remediation at UDLP at the property boundary (8). The cleanupstandard for groundwater in the ROD was set at the MCL of 5 µg/l for TCE (13). The HRL forTCE is 30 µg/l.
Long term monitoring and implementation of institutional controls assure that ground water betweenthe site and the Mississippi River will not be used until the groundwater plume has sufficientlydissipated (8). These institutional controls consist of Minnesota Well Code (MWC) restrictions onthe placement of wells near contaminant sources (MWC 4725.4450), and the City of Fridleyordinance requiring connection to municipal water system when feasible (Rule 207.13). See Figure8 for the location of the water main. Institutional controls for soil include zoning restrictions for industrial land use.
A.2.b UDLP/FMC Containment and Treatment Facility (CTF) Site
FMC excavated 38,625 cubic yards of soil contaminated with Volatile Organic Compounds (VOCs) (source areas for groundwater TCE) from waste burning and disposal pits (7). The soil was placed in an on-site RCRA designed Containment and Treatment Facility (CTF), (Figure 12). Soils contaminated with 1 mg/kg of VOCs were excavated and deposited in the CTF. VOCs detected in the soils included: 1,1- dichloroethane; 1,2-dichloroethane; 1,1,1-trichloroethane; 1,1,2-trichlorothane; 1,1-dichloroethylene; 1,2-dichloroethylene; tetrachloroethylene (PERC); benzene; toluene; xylene; and trichloroethylene (TCE), (8). TCE accounts for 98% of the contaminant loading to the groundwater under the site (7). In addition, 44 drums of hazardous waste were excavated, overpacked, and disposed of off site in a RCRA approved landfill.
The CTF is double lined, has a leachate collection, leak detection, and gas collection/treatmentsystem. Components of the CTF include: 1) clay floors and walls, 2) high density polyethylene(HDPE) liner, 3) sand drainage liner, 4) Supac 6WM filter fabric above the top sand drainageblanket and below the contaminated soils, 5) leachate collection system with a leak detection systemunderneath, 6) nine gas collection wells, 7) gas treatment system with activated carbon filters (Figures 13-16), (7). The following table lists amounts of leachate removed from the CTF.
|Year||Quantity Removed In Gallons|
To put the leachate numbers into perspective, (MPCA calculations based on 1991 AnnualMonitoring Report for CTF) (22), the leachate collection system removed 40 milliliters of TCE forthe year and the gas extraction system removed 2 gallons of TCE for the year. The TCE emissionrate from the gas extraction system is well below the MPCA Emission Screening Rate for TCE of26,247 (µg/sec) (22). Leachate is discharged to the sanitary sewer under a MCES issued a SpecialIndustrial Discharge Permit (#2049) and treated at the Pig's Eye Treatment Plant. The discharge limitations are listed in the following table.
| Additional Limitations: |
For Leachate and Contaminated Groundwater
|Any (individual) toxic organic||3.0|
|Combined total toxic organics||10.0|
|Total hydrocarbons (petroleum discharges)||100.0|
|*Parameters: TCE, trans-1,2-dichloroethylene, 1,1,1-trichloroethane, Tetrachloroethylene, 1,1-dichloroethane.|
*Adapted from Reference (15).
A.2.c Resource Conservation and Recovery Act (RCRA) Subsurface Source Area Investigation (Under UDLP's Portion of Building)
An RCRA Permit modification dated November 5, 1997, (number MN3170022914) requires permittee UDLP to characterize the nature and extent of contamination under UDLP's portion of the main industrial building. (1) The permit also requires the permittees to identify and locate all known Solid Waste Management Units (SWMUs) and Areas of Concern (AOCs) located within the facility boundary, identify releases or potential releases from these units, and submit an Investigative Work Plan proposing investigative activities at each of the SWMUs and AOCs. (1)
A subsurface source area investigation under UDLP's portion of the main facility is critical tounderstanding and characterizing the large TCE plume emanating from under the NIROP/UDLPfacility. UDLP has begun an investigation under its portion of the main building.
B. Site Visit
A site visit was conducted on April 22, 1997, by representatives from MDH, Southern Division Naval Facilities Engineering Command, NAVSEA Department of the Navy, Navy Environmental Health Center, and ATSDR. The purpose of the visit was for MDH and ATSDR representatives to meet with Navy staff to discuss current site conditions, tour the site, briefly discuss various site related topics, and identify any potential health hazards. Topics included drum storage removal operations, groundwater model, site history, sampling well locations, and groundwater treatment plant design. Information obtained from this site visit is used throughout this document to provide history, physical descriptions, and spatial perspective about the areas of concern. The following observations were made on the site tour:
- Access to the NIROP/UDLP facilities is restricted by a chain-link fence on all sides of theproperty boundary, with two main guarded entries (one each for NIROP and UDLP). Accessis granted only with employee picture identification cards or by an appointment with picture identification card.
- The "North Forty" (property north of the main building), is where drum removal actionsoccurred. The area consists of a 40 acres weed-covered field with two of concrete pads,several scattered storage buildings, and some railroad tracks.
- A large portion of the NIROP/UDLP properties is covered with a 47-acre building. Thisbuilding houses both the Navy and UDLP operations. Most of the building consists of onefloor. This is a manufacturing area with large open spaces and approximately 50 footceilings. Office space in the plant has two floors.
- There were no standing pools of water or wetlands on the Site.
- On the east side of the Plant there is an air sparging system for pretreatment of groundwaterdischarge to the sanitary sewer that is no longer operating. The pipes are broken and arefilled with a reddish colored sediment appearing to contain iron. This system was in use for about three years from 1992-95 to lower contaminant levels to meetdischarge permit levels.
- We also walked past several monitoring wells and well 13 (City of Fridley municipalbackup well).
C. Demographics, Land Use, and Natural Resources Use
The nearest residential neighborhoods are located approximately 1200 feet east of the NIROP/UDLP site (Fridley, population 28,267 and Columbia Heights, population 18,683). The next nearest residential neighborhood (in Brooklyn Center, population 28,502) is approximately 1800 feet from NIROP/UDLP on the west side of the Mississippi River. The designated land use for the Site, land use to the south past the Minneapolis Water Works (MWW), and land use north to highway 694 is all industrial. The land to the east of the Site next to the Mississippi River is designated park land (Figure 17). Most of Anoka County Park was originally 20-30 ft. lower in elevation and has been back filled with NIROP/UDLP foundry sand and construction debris. Materials used for backfill have come under scrutiny because three buried drums have been discovered in the area. This discovery may lead to further investigation to determine if more drums are present and if they may be another source for groundwater contamination (see section A.1.a).UDLP has agreed to provide the EPA with historical information about this dump area in Anoka County Park.
The NIROP plant had two bedrock wells (Wells 2 and 3), and UDLP had one bedrock well (Well 1)that were constructed in the 1940's. These wells were used as a potable water source and for all ofthe industrial water needs. Currently, there are no ground water drinking wells on these twoSuperfund sites and municipal water is used for all industrial water needs (1). MDH has no recordsof these wells being sealed according to Minnesota Well Code. Across the street, in the northwestcorner of the Plant property, is the City of Fridley municipal well 13 (see Figure 17).
Directly west of the NIROP facility is the Mississippi River, and approximately one mile down riveris the Minneapolis Water Works (MWW). This is of special concern because MWW processes riverwater into drinking water. This water is the sole source of drinking water for much of theMinneapolis Metropolitan area, serving approximately 500,000 people. MWW has five waterintakes measuring approximately 5 feet by 5 feet which screen out large debris and allow an averageof approximately 70,000,000 gallons of river water to pass into the MWW treatment system perday. The system operates 24 hours/day. It is important to note that MWW has only one dayreservoir supply of treated water, with no other backup supply. Furthermore, the treatment system atthe MWW was not specifically designed to remove VOCs. However, there are several stages in thetreatment process where water is aerated, thereby causing VOCs to volatilize (See letter from MWWLaboratory Supervisor, Appendix B). In addition, VOCs are removed in the treatment process whena slurry of activated carbon is used to treat for color and taste. Both the NIROP and FMC/UDLPRODs acknowledged that site related contaminants were impacting the MWW's water supplyintakes. Data collected for the FMC Record of Decision dated from 1981 to 1983 listed 26 detects for TCE out of 40 samples (the highest TCE concentration = 3.1 µg/l) at the MWW raw water intake (7).
The MWW is required by the Federal Safe Drinking Water Act (FSDWA) to collect data forfinished water (treated). Quarterly Trihalomethane (i.e. trichloromethane, chloroform) analyses areperformed on distribution system water to meet some of the SDWA requirements. These tests alsoanalyze for approximately 62 other organic compounds including TCE. The water samples areanalyzed at the MDH laboratory and results are stored in MDH's County Well Index Data Base. Areview of this data is listed in Figure 18, which lists 27 detections of TCE a 16-year period, allbelow the MCL (Figure 19). Note that most of the detections occur during cold weather months when an ice cover may be present on the Mississippi River.
Figure 20 contains data from the annual monitoring of the MWW's intakes by UDLP. The samplesare collected every October or November. MDH observed a recent sampling event to determinewhere and how samples were collected. A sample was collected at a grate just inside of the waterintake building. Collecting the sample required removal of a grate (4ft.x2ft.) from the floor anddropping a bailer down approximately 15 ft. to reach the water. All the samples collected in thismanner by UDLP personnel, have had no detectable TCE at a detection limit ranging from 2.1 to 5µg/l. In other words, TCE could have been present at concentrations less than 2.1 µg/l. Forexample, a raw water sample could contain 1.5 µg/l TCE and it could be listed as nondetect. MDHand the MPCA have collected samples up stream from the MWW in the Mississippi Rivercontaining TCE below the 2.1 µg/l detection limits. Figure 21 lists the TCE levels found in theMississippi River with a detection limit of 0.1 µg/l.
D. General Regional Issues
The general area surrounding the NIROP Plant contains commercial/light industrial properties. To the north are several commercial and industrial businesses, including a print shop and other light industry. Kurt Manufacturing Company is responsible for a ground water plume northeast of NIROP. It manufactured precision computer components. COCs associated with the Kurt include solvents tetrachloroethylene (PERC), 1,1,1-trichloroethane (TCA), and 1,2-dichloroethane (DCE) (10). Kurt Manufacturing is on the federal National Priorities List (NPL). The City of Fridley has an auxiliary well (Well 13), used for high demand periods, that has been impacted with TCE and PERC (the City of Fridley well field has recently been added to the NPL and will be the subject of a separate Public Health Assessment).The source of these contaminants has not been ascertained; however, both of the contaminants have been identified in Kurt and NIROP plumes (9, 2). Fridley Well 13 is located across the street from the northwest corner of NIROP property and up gradient to known NIROP source areas. The east side of NIROP is flanked by a Burlington Northern Railroad Yard (BNR) that consists of numerous tracks laid in a north and south direction. There have been some releases of chemicals on the BNR property. However, there are no apparent impacts of these releases to the NIROP property.
NIROP is bordered on the west by the East River Road, Anoka County Riverfront Park, and theMississippi River. South of the facility on the Mississippi River is the MWW. Part of the MWW property is directly west of UDLP property. Figure 17 depicts the spacial relationship of these landmarks.
The MWW and NIROP are located along a section of the Mississippi River that is regionallyclassified as a Class 1 B (drinking water) Surface Water by Minnesota Rules Chapter 7050 (19). This classification stretches from Fort Ripley in the north to the upper lock of Saint Anthony Fallssouth of NIROP in Minneapolis (approximately 120 miles of river). As a result of this classification,and the close proximity of the MWW to NIROP, the MPCA has set the applicable water qualitystandard for TCE at 5 µg/l as specified in Minn. Rule parts 7050.0220, subpart 4; 7050.0221,subpart 4; and 7050.0222, subpart 3 (19). The 5 µg/l standard is applied at the wells nearest theMississippi River to protect the river as public water supply. The contaminated groundwater fromthe NIROP site flowing into the river exceeds the 5µg/l standard and must be reduced to 5µg/laccording to the MPCA staff. NIROP's nearest well to the river is 27S and UDLP's nearest wellsare FMC-39 and FMC-21. See figures 22 and 23 for TCE concentrations in these wells. In well27S, TCE concentrations fluctuate from 1000 to 16000 µg/l in 1993. From 1997-98, TCEconcentrations appear to have leveled off at 1000 µg/l in well 27S. TCE concentrations in FMCwell 39 were undetectable from 1993-96. In 1997, well FMC-39 had a TCE concentration of 15µg/l. FMC-21 had a TCE concentration of 3.4 µg/l in 1996 and a TCE concentration of 72 µg/l in1997. The MPCA is responsible for the interpretation and enforcement of Minn. Rule 7050 and7060 as they pertain to this section of the Mississippi River (see Appendix A).
E. Community Involvement
NIROP has an active Restoration Advisory Board (RAB) that meets quarterly. The RAB members consist of anyone who has an interest in the remediation activities occurring on NIROP. RAB members consist of concerned citizens, city, state, and federal representatives. The purpose of the RAB is to serve as a platform for voicing community concerns about the investigation and cleanup of NIROP. The RAB meetings are an important means of exchanging information among all parties involved. For example, state regulators and Navy representatives have learned of important plant operations and practices from RAB members. This information has aided in the identification and remediation of hazardous waste on site.
F. Agency For Toxic Substances and Disease Registry (ATSDR) Involvement
ATSDR is mandated by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 as amended by Superfund Amendments and Reauthorization Act (SARA 1986); to conduct a public health assessment at each site proposed for or listed on the National Priorities List (NPL). In cooperation with ATSDR, the Minnesota Department of Health (MDH) has evaluated the public health significance of NIROP/UDLP.