Remediating highway deicing salt contamination of public and private water supplies in Massachusetts

Abstract

During the winters of 1974 1975 through 1989/1990, the Massachusetts Department of Public Works (MDPW) applied an annual average of about 196,000 tonnes of sodium chloride on state highways for snow and ice control purposes. During the period 1983–1990, MDPW received complaints of salt contamination of public and private water supplies frofm about 100 of the 351 municipalities in Massachusetts. During this period, 103 private well complaints were resolved by a variety of remedial actions. These include: well replacement, public supply connection, water treatment and highway drainage modification. The average remedia cost per complaint was about 12,000. Two additional remedial actions used by MDPW to alleviate salt contamination of private water supplies are: 1. (a) reduced salting on state highways; 2. (b) use of salt substitute, calcium magnesium acetate. Examples of the effectiveness of each of these remedial actions are: 1. (a) reduced salting on Route 9, in Goshen, Massachusetts, during the period December 1983 to December 1988, reduced the sodium levels in nearby domestic wells from 79 mg/1 (milligrams per liter) to 36 mg/1; 2. (b) use of calcium magnesium acetate as a salt substitute on County Road, Freetown and Lakeville, Massachusetts, beginning with the winter of 1987/1988, reduced the sodium levels ion nearby domestic wells from 75 mg/1 in 1986 to 34 mg/l in 1990. Reduced salting is also used to aleviate highway deicing salt contamination of public water supplies. During the winter of 1990/1991, there were 14 specifically defined reduced salt areas on state highways for this purpose.