Corrosion Control Letter - 04/15/04
DEPARTMENT OF THE ARMY
U.S. ARMY CORPS OF ENGINEERS, BALTIMORE DISTRICT
5900 MACARTHUR BOULEVARD, N. W.
WASHINGTON, D.C. 20016-2514
April 15, 2004
Mr. Jon M. Capacasa, Director
Water Protection Division
U.S. Environmental Protection Agency, Region III
1650 Arch Street
Philadelphia, PA 19103-2029
Dear Mr. Capacasa:
The purposes of this letter are to submit to EPA our final Desktop Corrosion Control Study prepared by CH2MHi11 on behalf of the Washington Aqueduct as outlined in the Action Plan to Reduce the Occurrence of Lead Leaching from Service Lines, Solder or Fixtures into Tap Water in the District of Columbia, Arlington County and Falls Church, Virginia and to request EPA approval of re-optimized Optimal Corrosion Control Treatment (OCCT.) Proposed OCCT is described in section 5 and section 6 of the enclosed study to include:
- Implementation of a partial system application of zinc orthophosphate corrosion inhibitor on or about June 1, 2004.
- Implementation of a full system (including the District of Columbia Water and Sewer Authority, Arlington County, Virginia and Falls Church, Virginia distribution systems) application of zinc orthophosphate corrosion inhibitor on or about July 15, 2004 assuming that there are no irresolvable issues resulting from the partial system application and upon approval of the Technical Expert Advisory Group.
- Conducting pipe loop studies to further optimize application of a corrosion inhibitor chemical starting on or about September 1, 2004. We will submit a detailed plan of the studies for your review and approval.
Washington Aqueduct is a wholesaler of water. It has no distribution system of own. Thus, any treatment, including OCCT, applied by the Washington Aqueduct will affect its customer's water systems. The Public Water Systems (PWS's) affected are:
|PWS Identification Number||Public Water System|
|D00000001||Washington Aqueduct Division,
U.S. Army Corps of Engineers
District of Columbia Water
|VA6013010||Arlington County Public Works|
|VA6013080||Washington National Airport|
|VA6610100||City of Falls Church Public Utilities|
We propose that interim Optimum Water Quality Parameters (OWQPs) for entry points to the distribution system be set for two phases with final OWQP's being set upon completion of pipe loop studies, and within one year of interim approval of OCCT. We propose that interim OWQP's be set as the following:
- Phase I (Partial system application)
pH 7.8 to 7.9 +/- 0.3,
Corrosion Inhibitor, 1.0 mg/1 minimum measured as phosphate.
(Starting at 3 mg/L in the distribution system as described in Section 6 of the enclosed study.)
- Phase II (Full system application)
pH 7.7 +/-0.3,
Corrosion Inhibitor, 1.0 mg/1 minimum measured as phosphate. (Starting at 3 mg/L in the distribution system as described in Section 6 of the enclosed study.)
We intend to conduct a study to optimize pH control and suggest that the pH requirements be reviewed and tightened after the recommendations of the study are implemented.
Thank you for your work with us on the important issue of corrosion control. If your staff has questions or requires any further discussion regarding these issues, please have them contact Mr. Lloyd D. Stowe at (202) 764-2702.
Thomas P. Jacobus
Mr. Jerry N Johnson, D.C. WASA
Mr. Robert Etris, City of Falls Church, VA Mr. Dave Hundelt, Arlington County, VA