Last updated: 05.07.04 Nadav_Carmel@Brown.edu

DISCUSSION

The following cumulative hazard ranking map shows the relative likelihood of a parcel presently containing contaminated soil based on the methodology.

(Click to enlarge).

The properties that the methodology predicted would have a heightened risk of contamination included:

• the American Woolen Company’s Valley Mills (a bleachery, the L-shaped parcel below the River, just north-northwest of Point Two)
• Asa Peck and Company, Incorporated (manufacturing jewelry, the rectangular parcel touching Point Two to the southwest)
• the Brown and Sharpe Manufacturing Company (the parcels above Point One)
• a Brown University Engineering Laboratory (the only parcel west of point Three)
• the City Machinery Textile Finishing Machinery Company (the small, lightly-shaded rectangular parcels east of Point Two)
• the Hingeco Manufacturing Company (the topmost lightly-shaded parcel directly southwest from Point Two, across the River)
• Merchants’ Cold Storage (the thin, vertical strip of parcels east-southeast of Point One)
• Monohasset Mills (metalworking, the smaller L-shaped parcel just northeast of Point Two)
• the Nicholson File Company (the two darkly-shaded, medium-shaded parcels directly between Points One and Two)
• the Providence Base Works of the General Electric (GE) Company (the large parcel just southwest of Point Two)
• the Providence Steel and Iron Company (the larger L-shaped parcel just northeast of Point Two)
• the Uncas Manufacturing Company (manufacturing jewelry, the dark parcel directly west of Point Two)
• the United States Rubber Company (the long complex of parcels above the River North of Point Two)
• the Westcott, Slade and Balcom Company Paint and Chemical Store House (the small parcel northwest of Point One)

None of these sites are still in operation. Many have been redeveloped, are currently being redeveloped or are being considered for redevelopment, though, so documentation of the presence or absence of soil contamination exists in the form of Environmental Site Assessments available at the Rhode Island Department of Environmental Management (RIDEM). Since the methodology was only intended to predict the presence or absence of soil contamination, and roughly its type according to three broad categories- not its quantity- only the names and types of compounds found were noted from the RIDEM records, and in most cases not their quantity.

RIDEM records indicate that the soil at the following sites contained the following contaminants in above RIDEM criteria (both the residential and industrial standards). Most of the sites also contained soil contamination in addition to what is listed here, but below RIDEM criteria.

Records were unavailable for the following sites:

• the American Woolen Company’s Valley Mills
• Asa Peck and Company, Incorporated
• the Brown University Engineering Laboratory
• the City Machinery Textile Finishing Machinery Company
• the Hingeco Manufacturing Company
• Monohasset Mills
• the Westcott, Slade and Balcom Company Paint and Chemical Store House

Most of the sites predicted by the methodology to be at risk for soil contamination were predicted to be at low to moderate risk. Of the two sites predicted to be at the highest potential risk (the Uncas Manufacturing Company and the United States Rubber Company), only the United States Rubber Company had heavy metals in its soil. Many of the sites had VOC's in their soils, which could mean either that commerce taking place at these sites after 1956 (the latest date for which this project had data) left behind VOC's in the soil, or that the methodology underestimates the amount of time that VOC's may persist in the soil. However, textiles manufacturers were categorized by the databases used in the methodology to leave behind mostly VOC's, and very few textiles manufacturers were predicted to have a lasting risk of soil contamination.

Further, the arsenic, lead and petroleum oil in the soils of these sites may or may not be connected to the industrial processes that have historically taken place at these sites. Lead and arsenic are known to exist at significant background levels in soils all over Providence (see here and here), and it is possible that it is these background levels that are reported in the Environmental Site Assessments.

The amount of arsenic in the soil at the Merchants' Cold Storage site hovered around the RIDEM limit for residential properties in Rhode Island (1.7 parts per million [ppm]), and the levels at the Brown and Sharpe Manufacturing Company ranged from 1.8 ppm to 6.5 ppm. Most of the soil samples from this site, though, showed arsenic levels closer to the lower limit; the soil sample with 6.5 ppm of arsenic was actually taken from a parking lot, and was the only sample with more arsenic than the RIDEM industrial/commercial limit of 3.8 ppm. Arsenic levels in the soil samples from the Providence Steel and Iron Company ranged from 1.2 ppm to 12 ppm, and arsenic levels in soil samples from the Providence Base Works of the GE Company site ranged from 7.2 ppm to 16.4 ppm, well above the RIDEM industrial/commercial limit, but still potentially within background levels in Providence and not necessarily indicative of releases at these sites.

The amount of lead in soil samples from the Brown and Sharpe Manufacturing Company was on average 710 ppm, while the amount of lead in soil samples from the Providence Base Works of the GE Company ranged from 182 ppm to 488 ppm. Both of these ranges stay within the RI Department of Health "lead-safe standard". The level of lead in the soil at the Providence Steel and Iron Company, however, was almost uniformly above 10,000 ppm. Over 80% of the soil at this site exhibited this excessive level. In this amount, the US Environmental Protection Agency classifies it as a hazardous waste, and the only remediation option is complete removal, which is what was done. The amounts of lead in the soils of the first two sites could potentially fall within Providence's background levels, but the lead in the soil at the Providence Steel and Iron Company is certainly related to the foundry processes that occurred there in the past.

The methodology also cannot predict the likelihood of a site containing a leaking underground storage tank (the sources of most of the petroleum oil contamination at these sites). These three contaminants, then, are not necessarily linked to the industrial processes that occurred at these sites, and hence may not be predicted by the methodology employed in this project, although, as can be seen, they may be present anyway.

Another illustration of the inherent limitations of the methodology is the case of the Brown University Engineering Laboratory within the study area. The Standard Industrial Classification (SIC) code for a site such as this is, "8733 Noncommercial Research Organizations," which also includes archaeological, biological, economic, educational, medical and sociological research. Nonetheless, the Boston Industrial Archaeology Mapping Project lookup table still included a list of chemicals associated with SIC code 8733, despite the broad categorization that code entails.

However, based on the available records from RIDEM, the methodology does seem to be a relatively good predictor of soil contamination via hydrophobic organic and soluble metal compounds at the former industrial sites along the Woonasquatucket River in Providence. The limited number of available records, though, does restrict an assessment of the overall effectiveness of the methodology.