The maps below were created using industry and chemical data obtained from a variety of sources. During the construction of these maps, discretion and interpretation was used to condense the data into a usable format.

Sanborn Maps
Initial data on historic industries in the District was acquired by scrutinizing Sanborn Maps, which are insurance maps detailing everything from old industries to building materials. These maps were licensed for use by Brown University. Interested parties can access these maps through the Sanborn website at http://sanborn.umi.com/. Because of the size of the District, multiple Sanborn Maps were examined: For the 1889 period, maps 60-63 were used, for 1920, maps 3, 6, 7, 11-14, 30-34, 51-54, and 56 were used, and for the 1940-1950 period, maps 3, 6, 7, 11-14, and 32-34 were used.

Mapping Historical Use
By georeferencing these maps on a current layout of Providence streets, the locations of past industries were spatially arranged to fit to present-day Providence. The georeferenced Sanborn Maps were then aligned with a Providence Plan plot and parcel map of Jewelry District properties from 2005. This created a picture of specific historic industry activity within modern property boundaries. Because property lines have changed in the past 120 years, some properties have a varied industrial history. Some amount of discretion was used in determining the most environmentally relevant industries. Up to five land uses for each property in each period was recorded. These included everything from jewelry manufacturing and auto shops to laundromats and residential areas. For some of the maps, industrial uses were organized by property into much broader categories to identify industrial trends and evolution in the District.

Standardizing Industry
Identified industries were researched to determine which chemicals were used during their operation. This was accomplished by searching the OSHA SIC Manual Search Website to determine an industry’s Standard Industrial Classification number (http://www.osha.gov/pls/imis/sicsearch.html).  We searched for the SIC code by entering in a keyword related to the industry.  For example, for jewelry manufacturing, we searched for “jewelry” and several results were generated, including 3911: Jewelry and Precious Metals and and 5944: Jewelry Stores.  We then had to read through the descriptions for each code to determine the most appropriate classification number.  For some buildings, the Sanborn Maps did not provide enough detail to select between two classifications.  In those instances, we only filled in the SIC number to three digits, which corresponds to the Industry Group rather than a specific industry. 

Linking Industry to Contaminants
The SIC number was then compared to an excel file provided by Raul Lejano, who was part of a research team that mapped historical and cumulative contamination of the metro Boston area.  His look-up table was prepared by researching historical records on contamination and spills associated with specific industries.  Using this table, SIC numbers were connected to potential pollutants from each historic industry.  Some industries were not included in the look-up table, so we had to use the EPA’s sector notebook to link to likely contaminants.

Hazard Ranking
Each industry was then assigned a hazard rank of 1-3 based on chemical persistence in the soil.  Industries associated with volatile organics received a hazard ranking of 1, since those chemicals evaporate readily and are least likely to remain in the soil.  Industries using hydrophobic organics and soluble metal compounds received a rank of 2, while industries associated with heavy metals received a rank of 3, the highest rank, since metals are the least mobile and thus most likely to be bound to the soil for longer periods of time.  When chemicals with differing hazard ranks were associated with a single industry, we assigned the highest rank.

Limitations
The identified chemicals are by no means conclusive. They instead represent the potential for these chemicals to have been used at some point in the property’s history, which could be present on the site today.  Moreover, our estimates have several potential sources of error.  First, we relied on personal judgment during both historical mapping and industry classification.  Although we communicated during this process and had a table of common SIC-industry links to crosscheck our work, it is possible that there was some inconsistency in labeling.  Second, we were largely limited by the detail in the Sanborn Maps.  For example, several buildings were labeled as “AUTO”, which could serve many different functions, including auto repair, parking, body shop, or upholstery repair, all of which have different SIC codes and associated chemicals.  Also, the maps did not include specific information on the nature or scale of industries at each site.  Third, there may be errors in linking SIC with contaminants.  Although industries may have the same SIC code, they might not follow the same practices or use the same chemicals.  Detailed profiles of each business would be necessary to more accurately estimate the types of chemicals present at each site.

Below you will find thumbnails of the maps available. For a larger view, click on the headings below or in the menu.