Update #2 Flash flooding at building M

Testing has been successful in characterizing the drainage problems at building M.

There are design issues (the building sits in a valley), problems with the primary drainage (which has been blocked with a stone garden), and problems with the subsurface drains (occluded).

See photos and maps of the flooding (click here). 

 The drainage problems are:
  1. Underground drains at 5118, 5120, 5122 filled with dirt and building material.
  2. Gutters at 5120 blocked and dumping water into the flooding area.
  3. Surface flume running alongside of 5120 is blocked with stone and dirt. The photo(see first photo) compares the primary drainage at 5108 (left) which is fully functioning and 5120 (right) which is blocked.
  4. The sump pump that was added years ago to compensate for the loss of drainage works but only provides a small percentage of the needed drainage.
  5. A french drain added few years ago has filled with dirt. 
  6. A tree at 5130 has raised the terrain and the terrain blocks the runoff of water in that area.
  7. Landscape edging directs water to the flooded areas and away from the runoff path and in some cases traps and holds water.
  8. The northeast side of building M sits in a valley below the base of the parameter fence and below 7 neighboring homes to the northeast and southwest. 
The initial testing effort focused on items 1 and 2 and employed utility construction equipment to see if drains could be opened, to map the underground system, and to identify line breaks. Photo #2 is one of the tools (hydro-jetting machine) utilized. There were also robotic cameras and large auger.

The exploratory was successful in opening five drains that were heavily packed with dirt, rocks, roots, bottles, tile grout, and duck tape. A line break was identified and repaired. Photo number 3 shows the line repair which was on broken the outside parameter of the community fence and near Knoll Trail Road where it empties. Th etotal cost of the effort was $3,500.

At this point, we will wait for the next rain to see how well the drains perform before proceeding onto the other issues.


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