Flash flooding problems at building M

In heavy or prolonged rains the surface water rises to 6 inches in areas near building M (5120-34) and encroaches into the patios.

Starting in February, exploratory testing will be conducted in search of possible solutions. The exploratory testing will be done in stages and the effectiveness observed afterward during the spring rain storms.

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 - rainwater from that large area runs downhill and collects at the lowest point (northeast side of building M). The primary path for the water to exit the area is a concrete flume located alongside 5120. There are large supplemental box drains behind building M that empty into Knoll Trail.

Primary drains: At this time, the primary path for water to exit is barely functional. It has been filled in with dirt and stone. See photo 2 comparing the blocked drain (right) to a functional one (left).

Secondary drains: Collectively, the secondary drains (below ground drains) are not functioning sufficiently to remove water during flash flooding. See photo 3.  It is anticipated that some are occluded or broken.

The past attempts to remedy the situation including the installation of a sump pump in the flume and a parallel french drain. The sump pump works but only at about 4%- 10% of the intended capacity of the flume. The french drain appears non-functional. The top photo shows the area being overwhelmed and water backing up. There was an attempt to auger a secondary drain in recent years and that effort failed.

The exploratory testing will be done in stages and the effectiveness observed afterward during the spring rain storms. The exploratory testing will look at unblocking the flume and doing a laser study to see if it can be repaired or if needs to be replaced, and scoping and seeing if it is possible to fix open the underground drain with utility contractor machinery. Updates will be reported here.