Observations on the Wear and Tear of PL-566 Dams

The Congress of the United States enacted Public Law 534 in 1944 for the USDA Soil Conservation Service (now the Natural Resources Conservation Service) to implement 11 pilot watershed projects in the US. In 1954 Public Law 566 was enacted for the Soil Conservation Service to provide assistance to local sponsors to plan and construct dams and other water control measures in small watershed projects in upstream tributaries. Each of the dams is part of a watershed plan that involves local sponsors including at least one soil and water conservation district.

After the dams are constructed they become the responsibility of the sponsors for maintenance and repairs. In Virginia, the soil and water conservation districts own 104 dams. All of these dams, except one, were installed under the PL534 and PL566 small watershed program. The exception is the Woodstock concrete gravity dam.

In 1997 the Virginia Department of Conservation and Recreation under-took a study of the 104 dams to develop long-range maintenance and replacement needs and costs. The study included detailed inspection and analysis of the dams and their appurtenances including all metal and concrete components, mechanical systems, and a review of their designed functions.

A detailed inspection of 22 of the oldest Class I and Class II dams was made in 1997. The study was continued in 1998. The 1998 detailed inspections included 16 Class I and Class II dams. Fifteen of the dams are earthfill embankments designed by the SCS for flood control and were constructed between 1971 and 1991. They are typical of the SCS dams designed and built during this period. The 16th dam was the Woodstock dam constructed in 1957 to provide water supply to the town of Woodstock.

This paper presents the results of the 1998 study which included; visual inspections, video/diver inspections, recommendations on concrete repair procedures, and recommendations and cost estimates for routine and periodic maintenance for the remaining service life of the structures. 12 pp.