ACID SPRING RUNOFF ETCHING CONCRETE

photo by Gerry Hawkes - May 2000

This is a photo of the basement floor of a house built in 1957 near Woodstock, Vermont. The floor is about 7 feet below ground level. Since 1957 water has run across this floor for one to three weeks each spring. Just in the last year etching of the concrete became very noticeable along with a white, foamy residue at each side of where the runoff crossed the concrete floor.

photo by Gerry Hawkes - May 2000

This is a photo of a basement floor that was constructed in 1992. The fiber reinforced concrete was coated with an epoxy paint. This floor, also in a house near Woodstock, Vermont, is about 6 feet below ground level. Shallow runoff water sits on small portions of this floor for one to two weeks each spring. In the spring of 1999 it was first noted that the pooled runoff water was pitting the floor and leaving behind a white, foamy residue. In the spring of 2000, the pitting and foaming were even more pronounced.

Both locations are very rural and about one mile apart with all runoff coming from either the house roofs or nearby wooded hillsides. There is no possibility of any local pollution source. No other houses have been investigated.

We would certainly be interested in hearing from anyone who has seen similar damage or who has more information.

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Contact Gerry Hawkes: ghawkes@eco-systems.org