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1 I 1 I I I I I I I I 1 I I I I I I I 1.2.2 Crest The crest of the dam is roughly 14 feet wide and the service and National Forest access road that runs along its length is well maintained, with only minor irregularities in elevation. 1.2.3 Upstream Face The upstream face of the dam is generally in good condition. The slope is uniform at 3.5H to lV and sparsely covered with hard, angular riprap derived from Precambri an crystal 1 i ne rock in a quarry wi thi n the reservoi r; The riprap was probably hand placed and is of a small diameter, nominally 12 inches, but considering the size of the reservoir is probably adequate; No si gn of erosion or sl oughi ng of ri prap was observed, although the top fi ve feet of the slope above the normal water surface have been covered wi th sand and grass. 1.2.4 Downstream Face The downstream face is variable in the maKimum section with alternating steeper and fl atter slopes rangi ng from 3H to 1 V near the top; to 1. 3H to 1 V at the toe. The steep slope at the toe is stabilized by a hand placed loose masonry rock wall about eight feet high. The downstream face is protected from erosion by a thick carpet of grass. 1. 2. 5 Seepage One of the concerns at Twi n Lakes Dam is uncontroll ed seepage. Seepage measurement weirs have been in place for years and the City inspects the dam on a daily basi s when the reservoi r is in operati on. Although the reservoi r was empty at the time of the i nspecti ons, seepage i nformati on was gathered from inspection reports on file at the State Engineer's Office and from a visit to the dam by MKE personnel when the reservoir was full in 1982. Consi derabl e seepage flow emerges at the toe of the dam renderi ng the area immedi ately downstream a bog as evi denced by the 1 ush growth of grass. A -43-