Washington State Department of Ecology

Publication Summary

Title

American Plating Post-Interim-Action Groundwater Monitoring Results, April and September, 2007

Month-Year Published

February 2008

Online Availability

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Short Description

Groundwater samples for dissolved metals and WAD cyanide were collected in April and September 2007 from the former American Plating site in Tacoma to provide post-interim action groundwater data.

Dissolved cadmium, copper, and nickel were detected at concentrations below cleanup levels. Dissolved chromium concentrations peaked at 28 to 750 µg/L in April, then decreased to 28 to 84 µg/L in September. Dissolved hexavalent chromium was not detected. WAD cyanide concentrations exceeded the cleanup level of 1 µg/L in three wells, ranging from 7 to 13 µg/L. Due to damage in 2006, well MW-10, which had the highest nickel concentrations (29 to 62 ug/L), needs to be decommissioned.

(Also see abstract below)

Publication Number

08-03-004

Author(s)

Marti, P. and T. Roberts

Print Availability

Request from the program.

Number of pages

Keywords

cadmium, groundwater, toxic, water, wells

Subject Waterbodies

Thea Foss

Related Publications

Title

Relationship

American Plating Post-Interim-Action Groundwater Monitoring Results, February and August 2004

part of a series

Quality Assurance Project Plan: American Plating Post-Interim Action Monitoring

part of a series

American Plating Post-Interim-Action Groundwater Monitoring Results, March and August 2005

part of a series

American Plating Post-Interim-Action Groundwater Monitoring Results, May and September, 2006

part of a series

Abstract

Long Description

This report is one in a series that describes groundwater monitoring results at the former American Plating site located on the Thea Foss Waterway in Tacoma, Washington. During April and September 2007, groundwater samples were collected from four site monitoring wells. The samples provided groundwater data on dissolved metals (cadmium, chromium, hexavalent chromium, copper, and nickel) and weak acid dissociable (WAD) cyanide. A volatile organic compounds (VOC) sample was also taken from one well.

Results confirmed the presence of dissolved chromium, nickel, cadmium, copper, and WAD cyanide in the groundwater.

All four wells contained dissolved chromium. April concentrations increased significantly over those seen in the past, ranging from 28 µg/L to a high of 750 µg/L. Concentrations in September ranged from 28 to 84 µg/L, falling within the historic range of non-detect, 2.5 to 104 µg/L. The cause of the April increase is undetermined.

Dissolved hexavalent chromium was not detected in any of the samples, indicating that the less toxic and less mobile trivalent chromium is present.

All four wells contained dissolved nickel at concentrations from 1 to 6.7 µg/L, below the groundwater cleanup level of 8.2 µg/L.

Cadmium and copper were detected in the sampled wells, but at concentrations below the cleanup levels.

With the exception of well MW-2, WAD cyanide was detected in all wells at concentrations of 7 to 13 µg/L, above the cleanup level of 1 µg/L. While detected in well MW-4 since 2006, this is the first occurrence of WAD cyanide in wells MW-3 and MW-5. Total cyanide has been detected in on-site wells in the past.

Well MW-10, sampled since February 2004, was damaged during 2006 and should be decommissioned. Past samples from MW-10 contained elevated dissolved nickel (29 to 62 µg/L) and low concentrations of some volatile organics. A replacement well is warranted if monitoring continues.

Link to EIM data for User Study ID AMERPLAT

This page last updated October 8, 2008