The 1996 Record of Decision (ROD) for the Community Soils Operable Unit (CSOU) established removal and backfill standards for soils showing elevated arsenic concentrations in residential and commercial properties within the Anaconda Smelter NPL site.
Residential soils exceeding an arsenic concentration of 250 parts per million (ppm) and commercial soils exceeding 500 ppm were removed and replaced with clean soil. A protective cover; appropriate for the original use of the property (e.g. sod/seeding, concrete, gravel, etc.) was installed to prevent recontamination.
During the development of the work plan, priority was designated for yards or areas frequented by children. Between 2002 and 2010 roughly 1,740 properties were sampled, 350 of which required remedial action. During this time, 39 acres of commercial properties were also cleaned up. As part of the CSOU work plan, institutional controls were created to permit future development within CSOU and provide educational opportunities to the community.
Data collected in 2007 and 2008 identified lead concentrations that were not previously addressed during the arsenic soil remediation. A few years later, the Center for Disease Control and Prevention (CDC) lowered the “level of concern” for blood lead levels (BLL) from 10 micrograms (mg)/deciliter (dL) to 5mg/dL. This was done in response to overwhelming scientific evidence indicating the serious adverse health effects of blood lead levels greater than 5mg/dL, especially in children.
In response to this data, the EPA conducted a Focused Feasibility Study (FFS) in 2012 to develop and evaluate the changes necessary to ensure the health and safety of humans and wildlife living in the Anaconda Smelter NPL site in regards to lead concentrations in residential soils.
In 2013, the original 1996 ROD for CSOU was amended to include the removal of soils exceeding lead concentrations of 400 ppm for residential soils. The amendment also included the sampling and remediation of attic dust when an exposure pathway exists; an exposure pathway could be a utilized attic or ceiling cracks.
In November of 2015, a new CSOU work plan was approved. The new plan called for deeper depths of arsenic levels and resampling of previous tested residential soils for lead. Yards that showed a level of 400 ppm concertation o higher were identified as priority yards and were remediated first. Landowners received multiple mailing requests from ARCO, asking for permission to sample residents’ soils. Approximately 1,130 priority yards were identified.
Residences that previously didn’t meet criteria and residences that haven’t been tested may request to sample their soil within property within the ADLC Superfund Planning Area (a map outlining this area is available on the Arrowhead Website).
To date, Atlantic Richfield Company has performed soil sampling at approximately 1,200 residential properties under the new program (500 in 2016, 500 in 2017, and 200 so far in 2018). Another 100 properties will be sampled this year. Of these 1,200 properties sampled, approximately 860 are being targeted for remediation from the 2016 and 2017 sampling events. Of the 860 properties targeting for remediation, approximately 468 have been remediated to date (40 in 2016, 318 in 2017, and 110 thus far in 2018). Another approximate 200 properties will be remediated this year.
Under the CSOU work plan, remediation includes removing contaminated soil, replacing it with clean soil, and installing an appropriate cover material (i.e. sod/seeding, gravel, etc.). Assuming landowners complete and return construction access agreements in a timely manner, remediation typically lags one construction season behind the sampling (i.e. properties sampled in 2017 would typically receive remediation in 2018).
Atlantic Richfield Company will test residential yards located within the Superfund Planning Area by request of the property owner for the next several years.
Questions and comments regarding CSOU or other Superfund issues in the Anaconda Smelter NPL site are welcomed by the Arrowhead Foundation. Residents may also direct questions to the EPA Project Manager, Charlie Coleman, at (406) 457-5038 or Atlantic Richfield Project Manager, Luke Pokorny at (406) 723-1832