Water Watchdog Report

What: Sediment
Where: Bennington Tributary of Sligo Creek
When: 2014-06-12
Reported By: Anne Vorce
Additional Details:

Chelsea Construction Site Sediments Bennington Tributary and Sligo Creek Today after Heavy Rainfall
The storm water management practices in place at the Chelsea construction site near downtown Silver Spring had been successfully protecting Sligo Creek from sedimentation as large amounts of earth are moved – until today. In fact, the practices had reflected a successful partnership between the Seven Oaks-Evanswood community, the developer and the Department of Permitting Services (who manage the sediment control and storm water management permit). Stormwater management expert Richard Klein had been hired to provide advice to the community on protecting Sligo Creek.

However, we have been having a series of storms which the storm water management system in place has not kept up with. The silt fences and mound stabilization efforts at the corner of Ellsworth Drive and Springvale, to which the entire site drains, have not been able to hold back the muddy runoff leaking under the fences, following several days of a lot of intense rain. More rain is expected.

One photo shows Bennington trib 8:30am, June 12
Another photo shows Bennington trib 5:15pm, June 12

The muddy water is going into the storm drain at the construction site corner, where it is conveyed fairly quickly into Sligo Creek via the buried watercourse under Ellsworth. The first daylighting occurs at the Bennington Outfalls.

The last photo shows the muddy runoff which has leaked under the silt fence
heading into the storm drain at Ellsworth Drive and Springvale.

I was in immediate contact with DPS and the developer. Bales of straw were to be added today to try to slow the leakage. The silt fence clearly needs repair when the water has receded. The sediment pond trap may be clogged, and other steps to protect Sligo Creek may be needed.

Are storm water management practices up to the volume and intensity of storms we are now typically experiencing ?

Richard Klein will be at the site Friday morning around 10 to assess the situation.