Investigating Sligo Creek for Illicit Discharges
January 2011
July 2011
March 2012
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Investigating Sligo Creek for Illicit Discharges |
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Photos and text by Mike Smith January 2011 |
Update by Mike Smith July 2011 |
Update by Mike Smith March 2012 |
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Preliminary findings include locating likely sewer and water main breaks in the upper watershed. The Center is expecting to release a complete report later this year of their findings and recommendations.
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Lori Lilly (in white) of the Center for Watershed Protection and Sue Allen (in green) from the Montgomery County Department of Environmental Protection monitor outfall below the Dennis Avenue ponds. |
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Sadie Drescher and Lori Lilly, both of the Center for Watershed Protection, do tests for ammonia and potassium levels on collected water samples from Sligo Creek back in the lab. |
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The Center for Watershed Protection, in its Illicit Discharge Detection and Elimination: A Guidance Manual, has produced a listing of common discharge types with their associated water quality characteristics or "fingerprints." This is very useful in helping to interpret findings from water quality monitoring and is reproduced here below, from page 8.
| Flow Type | Hardness(mg/L as CaCO3) | NH3(mg/L) | Potassium(mg/L) | Conductivity(µS/L) | Fluoride(mg/L) | Detergents(mg/L) |
| Sewage | 50 (0.26) | 25 (0.53) | 12(0.21) | 1215 (0.45) | 0.7 (0.1) | 9.7 (0.17) |
| Septage | 57 (0.36) | 87 (0.4) | 19(0.42) | 502 (0.42) | 0.93 (0.39) | 3.3 (0.33) |
| Laundry Washwater | 45 (0.33) | 3.2 (0.89) | 6.5 (0.78) | 463.5 (0.88) | 0.85 (0.4) | 758(0.27) |
| Car Washwater | 71 (0.27) | 0.9 (1.4) | 3.6 (0.67) | 274 (0.45) | 1.2 (1.56) | 140(0.2) |
| Plating Bath (Liquid Industrial Waste) | 1430 (0.32) | 66(0.66) | 1009 (1.24) | 10325 (0.45) | 5.1 (0.47) | 6.8 (0.68) |
| Radiator Flushing (Liquid Industrial Waste) | 5.6 (1.88) | 26 (0.89) | 2801 (0.13) | 3280 (0.21) | 149(0.16) | 15 (0.11) |
| Tap Water | 52 (0.27) | <0.06(0.55) | 1.3 (0.37) | 140 (0.07) | 0.94 (0.07) | 0 (NA) |
| Groundwater | 38 (0.19) | 0.06 (1.35) | 3.1 (0.55) | 149 (0.24) | 0.13 (0.93) | 0 (NA) |
| Landscape Irrigation | 53 (0.13) | 1.3 (1.12) | 5.6 (0.5) | 180 (0.1) | 0.61 (0.35) | 0 (NA) |
| The number in parentheses after each concentration is the Coefficient of Variation; NA =Not Applicable | ||||||
At the July 20th Friends of Sligo Creek program meeting Lori Lilly of the Center for Watershed Protection described findings from the monitoring and investigation. Outfalls (pipes near the creek) are examined for flows during dry weather when they presumably should be dry as well. Flows were tested for ammonia, fluoride, bacteria and other measures, and where possible tracked to possible sources. 58 of the 213 outfalls checked were found to have dry weather flow. Causes of the flows are often improper sewer and water line connections to the storm drain system. Here are presentations made at the meeting.
The CWP has a number of recommendations for Montgomery County. These include: improve mapping of the outfalls; changing some of the water quality parameters measured; training; and increasing dedicated staff time. Friends of Sligo Creek will likely attempt to schedule a public program meeting with County staff to see how these recommendations are being addressed.
We all have a role in seeing that these discharges are reduced. Be alert for discharges in pipes during dry weather, or with suspicious odors or colors, and contact the County at 240-777-DUMP when you think there is a discharge. Consider "adopting" an outfall near your house to check consistently and report regularly when there are problems
Four of the worst outfalls for illicit (dry weather) discharges in Sligo as identified by the Center for Watershed Protection in 2011.
Place your mouse over the photo to see a photo of this outfall.
