Mud from Edgewood Av reaches lake for 3rd time

On Saturday June 5, I inspected the site just before rain about 4:15 pm, then during moderate rain that lasted for more than an hour.  The pavement of the construction area had been swept, though with imperfect results.  I concentrated my observations on the pipe at the bottom of Edgewood Av, below Vilas Av, because this is "the last line of defense."  There was a large gravel dam on the W side of Edgewood here; on the E side, a silt sock directed runoff into the large pit.

Inside the pit was
  1. A newly laid storm sewer line (apparently not working yet)
  2. A blue pipe bringing stormwater from at least two inlets on Vilas just above the pit, and
  3. A large concrete pipe with a jagged end leading out and directly to Lake Wingra.

The pit, showing water level before rain starts of 6/5.  Pipe on right exits to lake.

When I noticed the pit before rain began, there was a puddle of water in the bottom, with the water's surface several inches below the outlet pipe 3. 

About an hour after it started raining, when I returned, water was cascading in several places into the pit along the sides, and a vigorous stream of muddy water was coming in via blue pipe 2.  The water's surface in the pit was now substantially above the opening to exit pipe 3, and water was flowing towards the lake.  There was now a large plume of muddy water in Lake Wingra, with a vigorous outflow of muddy water from the exit pipe, confirming that this was the destination of the water from the pit.

During the rain, the water in the pit comes up, and exits to the left towards the lake.

I called foreman Todd Timmerman and informed him of the situation about 5:30 pm.  He said that he and Tim Troester had gone over the site on Friday, and that Tim had said that everything was OK.

To me, it appears that the pit was intended to be the last line of defense against runoff, but that the exit pipe had been overlooked.  The pit was taking runoff from the entire E side of the two-block-long slope towards the lake, plus a bit of the W end of Vilas Av.  It was very muddy, because water cascading into the pit was eroding its sides.

Below: Mud in the lake for the third time.

See a slide show of all 6/5 photos here.

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