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The Wisconsin Department of Natural Resources (WDNR) asked the Wisconsin Bureau ofEnvironmental Health (BEH) to evaluate potential health effects associated with the plannedremediation of the Peach Avenue former manufactured gas plant (MGP) site in Marshfield,Wood County, Wisconsin. BEH concluded that potential effects on ambient and indoor air nearthe proposed MGP excavation were environmental health threats. BEH concluded that childrenat an adjacent day care center were the major receptors of contaminants in air, and recommendedtemporary relocation of the day care center, as well as public outreach by the responsible partyand proper site management during the remediation as needed to prevent unnecessary releases ofair contaminants. Further investigation was needed to determine the extent of groundwatercontamination and the potential for subsurface volatile organic vapors to affect air in nearbybuildings.


WDNR asked BEH to evaluate potential health effects associated with the planned remediationof the Peach Avenue former MGP site at Peach Avenue and Arnold Street in the city ofMarshfield, Wood County, Wisconsin. BEH provided numerous recommendations in letters andduring meetings. Those recommendations and how recommendations were implemented aredocumented in this health consultation. The surrounding area is a residential community bisectedby a wide industrial and railroad corridor (Figure 1). The former MGP lies within the corridor.An older, single-family residential neighborhood is north across Arnold Street. Pickle Pond Park,and a playground, is northeast of the site across Peach Avenue. A building supply company anda child care center are adjacent to and north of the former MGP site (Figure 1). Vacant lots andresidential neighborhoods lie farther west of the site. The residential and working population isestimated from maps as 100-150 people within a 100-yard radius and 400-550 people within a300-yard radius.

The Peach Avenue MGP, which operated from 1920 to 1959, is now the site of a propanedistributorship. No above-ground structures from the MGP remain. The Wisconsin Departmentof Transportation identified soil and groundwater contamination on the site in 1993. In 2001, theproperty, previously owned by Columbia Propane, was purchased by NiSource CorporateServices Company as part of the acquisition of Columbia Propane by NiSource. A businessentity, the Columbia Propane Remainder Company, was then created as the party responsible forthe remediation (see Appendix 1 for correspondence with NiSource). A Spill ResponseAgreement between WDNR and the Columbia Electric Remainder Company was signed onOctober 29, 2001. Under the terms of this agreement, Columbia Electric Remainder Companywould implement an interim remedy that was to include the partial removal of source materialfrom the site. The remedy, known as Operable Unit 1 (OU-1) (1), entailed removal of MGPwaste, buried structures, and contaminated soil.

Background: MGPs in Wisconsin. Beginning in the 1800s, towns and cities across the UnitedStates made their own fuel for heating and lighting at facilities known as MGPs. To manufacturethe fuel or gas, coal and other ingredients were heated in large brick ovens. As the coal washeated, it produced methane, hydrogen, and other gases that were filtered from the ovens andstored in tanks. The gas was then used throughout a community. By the early 1900s, Wisconsinhad at least 70 MGP sites in the state. By the 1950s, MGP production declined as a network ofnatural gas pipelines was built across the country. As inexpensive natural gas became widelyavailable, MGPs closed. Many MGPs were abandoned and eventually demolished. Coal tars,light oils, and inorganic wastes typically found in soil and groundwater around former MGPs arean environmental and public health concern.

This public health consultation contains discussions about several aspects of the Peach AvenueMGP remedy that were considered to be potential health issues as this work proceeded. Theseissues were as follows:

  1. Air effects during the remediation.
  2. Accumulation of polycyclic aromatic hydrocarbons (PAHs) on soils of nearby residences,playgrounds, and the day care yard.
  3. Effect of groundwater contaminants on the public drinking water supply.
  4. Precipitation runoff issues.
  5. Coordination of project with nearby road work.


The health evaluation of the Peach Avenue MGP site was based on site visits by BEH and WoodCounty health officials in August and December 2001 and on many discussions with WDNRofficials who have monitored the site since 1993. BEH reviewed site maps and environmentalassessment data. BEH also visited the ABC Child Care Center and informally discussed theproposed work with the Center's managers. BEH addressed the focal position of ABC ChildCare Center in a December 7, 2001, letter to the environmental project manager of theresponsible party (2). BEH also participated in a meeting of the Marshfield City Council onOctober 8, 2001, and a December 2001 Marshfield community meeting at which the PeachAvenue railroad underpass and Peach Avenue MGP projects were discussed. In the course of ourhealth evaluation, BEH identified several potential routes of exposure to MGP-associatedchemical wastes:

a) Ambient Air Releases. The excavation of MGP wastes exposes coal tar-related volatiles andPAHs to air release. The control of the these air releases is a technical issue at every MGPexcavation. Elsewhere in Wisconsin, acute health effects and complaints have come from peopleworking in buildings adjacent to MGP remediation sites. BEH documented two workplace casesin Wisconsin in the past several years (3). One case occurred in a bank adjacent to a thermaldesorption facility treating MGP wastes (Stevens Point, WI, April 1998). Employee complaintsincluded sore throats, coughing, body aches, and headaches; some employees reported that theylater had flu-like symptoms (fever and chills), and one employee later developed bronchitis. In aseparate case in April 2001, workers in the vehicle bay of the Wisconsin Electric Ft. AtkinsonService Center were exposed to dust and odors escaping from an adjacent thermal desorptionfacility that was treating MGP waste soils. Workers noticed tar odors and reported headachesand an unpleasant taste in their mouths. Indoor air tests revealed the presence of traces ofbenzene, toluene, and excessive workplace air concentrations of xylenes. The exposure wastraced to the soil staging area and was blamed partly on unseasonably warm and windyconditions. The exposure was halted by closing the garage doors and wetting the contaminatedsoils with surfactant (3).

The acute health complaints noted in these cases were consistent with exposure to the chemicalsreleased to ambient air. Respiratory effects, including asthma, would be expected in sensitivepersons. The compounds with potential for release to air consist of a variety of volatile organiccompounds (VOCs) and semivolatile organic compounds, as well as inorganic compounds ofsulfur and nitrogen. However, BEH focused on two key ambient air indicators having effects ofpublic health significance: (a) benzene and (b) total VOCs as a nonspecific indicator of benzene.Benzene, a by-product of coal coking or gas manufacturing processes, has both known humancarcinogenicity (U.S. Environmental Protection Agency class A) and high volatility (vaporpressure 75 millimeters of mercury (mm Hg), 20C). BEH recommended an action level at MGPsite perimeters of 0.05 parts per million (ppm) benzene or 0.1 ppm total VOCs (3). Theserecommendations were included in the remediation work plan (4). Nearby residents andbusinesses might have been exposed to contaminants released to ambient air. Those at risk forexposure included

  • Adjacent child care center. The nonindustrial business closest to the excavation was theABC Child Care Center, which was adjacent to the Columbia Propane Property. TheABC Child Care facilities consist of a playground and two buildings. Roughly80-100 students attend the day care; they range from infants to preschool age. Theplayground structures are approximately 50 feet from the MGP gas holder; one of thebuildings is approximately 100 feet from the holder. It was very likely that the planned excavation would have extended nearly to the ABC Child Care property. It was equallylikely that the ABC Child Care property would have been affected by any dust and VOCsreleased during the excavation and removal.

  • Nearby businesses. A number of small businesses and industries were within 300 yardsof the proposed excavation. Fewer than 200 workers were estimated to have been at thesebusinesses. The businesses less than 100 yards from the excavation were the day care anda small builder's supply company. The propane dealership on the MGP site was to beclosed during the excavation work.

  • Residential neighborhood and school. The Columbia Propane property lies on the edge ofan older (ca. 1920s-1940s) residential neighborhood. The nearest house is approximately340 feet from what was to be the center of the excavation, near monitoring well MW-302(Figure 1). Twenty-nine residences were within 200 yards of MW-302; the estimatedresidential population in the 200-yard radius was 30-120 people, excluding those at theday care center. The nearest school is 450 yards away, at the intersection of AppleAvenue and Doege Street.

b) Effects on Indoor Air Quality: VOC Intrusion From Groundwater Into Nearby Residences andBusinesses. A second potential source of air contamination related to this MGP site was fromvapor intrusion into the basements of buildings. Substances detected in groundwater samplesboth on-site and off-site (1) at levels that exceeded the Wisconsin Administrative Code ch. NR140 enforcement standards are shown in Table 1. Because all residents in the area were servedby municipal well water that was unaffected by these groundwater contaminants, exposurethrough direct ingestion was not expected. Exposure to these groundwater contaminants viainhalation of vapors diffusing into indoor spaces through basement structures was a possibilitythat had not been excluded. For example, 1,300 micrograms per liter benzene had been detectedin groundwater taken from piezometer P-319 [(1) in November 1999 samples (Figure 1) at adepth of about 14 feet below surface. This was about 600 feet from the concentratedcontamination around monitoring well MW-302 (Figure 1). Four residences are within 100 feetof P-319. A residence overlying this level of contamination might have some benzene vaporintrusion.

The extent of any intrusion was dependent upon the concentration of the contaminant at itssource near the affected building, the physical characteristics of the soil overlying the source ofcontamination, and the design and condition of the building in question. The Johnson andEttinger model for subsurface vapor intrusion into buildings (5), using silty clay loam as the soiltype and default assumptions for building condition, predicts a 1.8-6 increased lifetime cancerrisk from hypothetical benzene vapor intrusion into basements around the location of P-319.Although 1.8-6 cancer risk is not a significant health risk, inconsistencies in availablegroundwater monitoring data (1) lower the confidence in this prediction. Further monitoring ofthe degree and extent of groundwater contaminants was needed to determine whether anexposure posed a health threat via the vapor intrusion route.

c) Potential for Exposure to PAHs Deposited on Soils of Nearby Residences and Playgrounds.Soils at the Peach Avenue MGP were contaminated with coal tars that were at levels of healthconcern (Table 1). PAHs in these tars, when sorbed to fine soil particles could have beendispersed in air and deposited on surfaces encountered while playing or eating outdoors. Underthose conditions, exposure to PAHs would have been expected through incidental ingestion ofsoil, either directly or swallowed after inhaled. Children ingest more soil than adults do. Humansare able to metabolize small amounts of PAHs, although some PAH structures are carcinogenicafter excessive chronic exposure. Site management that included dust suppression and containment and air monitoring was recommended to be sufficient to prevent unsafeconcentrations of PAH dispersal and deposition. If air monitoring indicated that PAHs were notsufficiently contained, additional cleanup of nearby sensitive areas (e.g., playgrounds) mighthave been needed.

d) Effect of Groundwater Contaminant Plume on Public Drinking Water Supply. As previouslynoted, state and city officials had been monitoring the potential effect of groundwatercontaminants from MGP wastes on the municipal water supply that serves all nearby residents.Routine monitoring of municipal water supplies had not indicated that this was a problem. TheMarshfield drinking water engineer continues to monitor the water supply for contaminationfrom MGP wastes.

e) Precipitation Runoff Issues. Precipitation on staged MGP waste soils might have carriedcontaminated runoff off site to streets and storm drains. BEH recommended that waste soilsstaged or transported be covered to prevent runoff and suppress dust. Waste removal wascomplete in July 2002.

f) Coordination of Project With Nearby Road Work. The Peach Avenue railroad underpassproject, planned for spring 2003, is a separate project within the area affected by contaminantsfrom the Peach Avenue MGP. The railroad is approximately 150 feet from the central area of theproposed MGP excavation, and soils underlying the proposed underpass area contain coal tarwastes. Ideally, the excavation for the underpass would have been synchronized with the MGPexcavation to address all hydrogeologic and environmental issues associated with this site.However, the projects were planned as separate entities. Concerns have been raised that stormsewer runoff from the low-lying underpass will be contaminated with MGP wastes. No data areyet available to assess these health concerns. However, the engineers planning the underpasshave begun to design technical solutions to contain and monitor storm water runoff. The issuesconcerning the Peach Avenue railroad underpass will be addressed in a separate healthconsultation.


The day care center adjacent to the Columbia Propane property presented obvious concerns thatchildren and adults at this facility could have been affected by the remediation of the Marshfieldformer MGP. Hazards associated with the MGP remediation included the potential for inhalationexposure to VOCs and the associated possibility of respiratory distress, especially in childrenwho have asthma. PAHs sorbed to soil dust could have been released to air during soil removal,and might have been deposited on surfaces throughout the day care facility and surroundingplaygrounds. BEH recommended that the day care center be considered to lie within the airimpact zone and possibly the health and safety exclusion zone for this work. Therefore,temporary relocation of the day care center during the MGP remediation was recommended. Inaddition, efforts were made to avoid the deposition of PAH-containing particles on or around theday care center. Part of the MGP site remedy was to include monitoring for PAHs and planningto remove PAHs from indoor or outdoor surfaces if they had been detected at unsafeconcentrations.


  1. The close proximity of ABC Child Care to the proposed excavation area made thechildren likely receptors for any MGP-associated materials released to air.
  2. More information was needed to better predict indoor air contamination, via vaporintrusion, resulting from VOC-contaminated groundwater associated with the PeachAvenue MGP.
  3. More information was needed to determine the effects of both the removal ofcontaminated soil and the Peach Avenue railroad underpass on local hydrogeology andthe potential for contamination of local drinking water supplies.


  1. BEH recommended that ABC Child Care be relocated for the duration of the remediationactivity until the excavation has been closed and it has been determined that PAHdeposits around the day care center grounds are not a concern, as described in the letterpreviously sent to NiSource (2, Appendix 1).
  2. As of January 3, 2002, NiSource negotiated an agreement with ABC Child Care Centerto facilitate temporary relocation of the center during the soil removal project (6). The child care center began its temporary relocation on March 23, 2002.

  3. BEH recommended that plastic covers, or other protective measures, should be placedover the playground area to facilitate later cleanup.
  4. This recommendation was implemented by the remediation contractor.

  5. BEH recommended that the responsible party and its contractors notify area residentswho might have respiratory problems about the potential health effects from MGP-associated air releases to persons with respiratory sensitivity.
  6. All parties worked together to ensure the community was well informed about the issues.

  7. BEH recommended that guidelines issued in a previously prepared document (3)addressing public health air quality issues around MGP excavations be used. Specifically,

    • BEH recommended adequate public outreach before and during the MGP siteremediation.

    • To reduce the air volatility of soil contaminants and to limit the number of peopleoutdoors, excavation and thermal desorption at MGP should be conducted duringcold weather.

    • To minimize the emission of volatile organic wastes from the excavation andstaged soils, the use of applied foam or surfactants was recommended.

    • Soil handling, especially that involving loading trucks, should not be conductedduring dry windy conditions.

    • Air monitoring at the site perimeter, particularly for benzene, should be used tomonitor air quality to know if levels are protective of public health.

All of those recommendations were implemented when remediation was conducted.


  1. Dames & Moore Group Company. Final report, supplemental site investigation, andevaluation of remedial alternatives for the Peach Avenue former MGP site, Marshfield,Wisconsin. Los Angeles, CA: Dames & Moore Group Company; 2000 Jun 2. Proj. no.41384-019-133.

  2. Wisconsin Division of Public Health. Letter to Daniel Sullivan from Robert Thiboldeauxconcerning temporarily relocating the ABC Child Care Center. Madison, Wisconsin.December 7, 2001.

  3. Wisconsin Division of Public Health. Memorandum to Mark Giesfeldt from RobertThiboldeaux and Henry Nehls-Lowe concerning interim guidance on air management atformer manufactured gas plant sites. Madison, Wisconsin. January 25, 2002.

  4. Earth Tech, Inc. Remediation work plan, former Peach Avenue manufactured gas plant.Long Beach, CA: Earth Tech, Inc.; 2002 Jan. Project no. 51894.

  5. US Environmental Protection Agency. Johnson and Ettinger Model for subsurface vaporintrusion into buildings. Washington, DC: US Environmental Protection Agency; 2000.

  6. NiSource Inc. Letter to Tom Applegate from Daniel Sullivan concerning temporarilyrelocating the ABC Child Care Center. Merrillville, Indiana. January 3, 2001.


Robert Thiboldeaux, Ph.D.
Health Hazard Evaluation Unit
Bureau of Environmental Health
Division of Public Health
Wisconsin Department of Health and Family Services

Map of Marshfield former manufactured gas plant (MGP) site and surrounding neighborhood
Figure 1. Map of Marshfield former manufactured gas plant (MGP) site and surrounding neighborhood.

Table 1.

Hydrocarbons Detected in Groundwater at the former Peach Avenue Manufactured Gas Plant, November 1999 Survey*
Substance Mean concentration (µg/L±SE)† Maximum concentration (µg/L) Frequency of detection Comparison value‡ (µg/L)
Toluene8,103±7,916210,000§ 27/271000
Ethyl benzene115±731,800§ 27/27700

*Samples from 27 monitoring wells and piezometers located up to 800 feet from the former gas holder. Data from Dames & Moore Group Company (1).
†µg/L: micrograms per liter; SE: standard error.
‡Enforcement standard, Wisconsin administrative code, ch. NR 140.
§Sample location: monitoring well MW-302, between Peach Avenue and the former gas holder (Figure 1).
§ Sample location: piezometer P-331, across Peach Avenue from MW-302.


This public health consultation for the Columbia Propane Former Manufactured Gas Plantinvestigation was prepared by the Wisconsin Department of Health and Family Services under acooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR).The consultation is in accordance with approved methodology and procedures existing at thetime the Public Health Consultation was begun.

Gail D. Godfrey
Technical Project Officer, SPS, SAAB, DHAC

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

Roberta Erlwein
Chief, State Program Section, DHAC, ATSDR


Mr. Dan Sullivan
Program Leader,
Environmental Health and Safety
NiSource Inc.
801 E. 86th Street
Merrillville, IN 46410

December 7, 2001

Dear Mr. Sullivan,

In preliminary discussions with the Wisconsin Division of Public Health (DPH) and otheragencies regarding future work at the Peach Avenue former Manufactured Gas Plant (MGP) site,NiSource has proposed conducting the project within the confines of a tent enclosure. Thedescribed purpose of the tent is to limit fugitive air emissions resulting from the removal of soilcontaminants within the MGP site. An unresolved issue associated with the use of the tent iswhether to temporarily relocate the neighboring ABC Child Care.

DPH supports the use of the tent enclosure in this remedy, subject to technical review by theDepartment of Natural Resources. Based on the qualitative experience of site managers at otherlocations where tent enclosures have been used, we expect that the tent enclosure will limit dust,organic vapors, and odors, thereby aiding in protecting the public's health during the excavationof waste. Despite this expectation, DPH recommends that ABC Child Care relocate during theexcavation and removal of contaminated soils. In making this recommendation, DPH consideredboth the technical ability of the tent to limit air emissions and the effect of perceived health risksin conducting this project.

What we have seen in Wisconsin and other states during the excavation and disposal of MGPwastes is that even with environmental controls in place, air emissions from coal tar-contaminated soils can cause acute effects to nearby residents or workers. These effects includeheadache, dizziness, nausea, and tingling or numbness around the nose and mouth. It is alsoknown that constituents of coal tar at this site, for example benzene and benzo(a)pyrene, havechronic effects that include carcinogenicity.

What we don't know is whether the tent will limit unsafe air emissions entirely. We havechecked references offered by Earth Tech of similar work they have done elsewhere. Oneenvironmental regulator regularly working at a similar Earth Tech site reports that, despite hisenthusiasm for the tent technology, coal tar odors are evident from a block away.

The adjacent day care center represents a special case in risk management. Very young childrenrepresent unknowns in terms of their sensitivity and metabolic response to chemical exposure. Ingeneral, children can be expected to be more sensitive than adults to the acute effects of aircontaminants. In addition, perceived health risks from environmental contamination are oftendifferent from actual risk. Our experience is that the tolerance for risk by parents, for their veryyoung children, is zero. We believe that the perception of risk by clients of the daycare has thepotential to cause economic harm to this valuable community asset. The potential for harm,whether real or perceived, carries its own implications to the community acceptance of yourproject. It is with the best interests of ABC Child Care, the community of Marshfield, andNiSource in mind that DPH will recommend that the wordplay for the Peach Avenue MGPremoval include a plan to temporarily relocate ABC Child Care. This will remove from the tableboth actual and perceived risks, and will ensure that the work is completed smoothly and withouthealth ramifications. I will entertain additional discussion on this topic; however in the interestof moving the project along I feel it is important to let you know a change in this position isunlikely. Please contact me (608/267-6844) if you would like to discuss this further.

Overall, I am encouraged by the initiative of NiSource and their consultants in addressingcommunity health concerns. I am eager to support your continued efforts to that end, as theimportance of community involvement in cases of this nature cannot be overstated.


Robert Thiboldeaux, Ph.D.
Bureau of Environmental Heath
Wisconsin Division of Public Health

Cc: Krisann Mauritz, ABC Child Care Center; Bill Evans, WDNR; Tom Applegate, WDNR;Nancy Eggelston, Wood County Heath; Don Shosky, Earth Tech

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