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Leaky Sewer Pipes

Leaks

Sewer pipes break in limestone ground & put raw sewage into ground (followup messages & news articles)

8% of sewage in sewer pipes escapes untreated (EPA report on CSO, SSO: 853 to 860 billion gallons escaped, out of 11 trillion gallons processed, p.ES-5. 3-10 billion gallons of this was from separate sanitary sewer systems, p.4-26)
Guidance on operation, maintenance, and rehabilitation of sewer pipes (New England 12/03)

Sewer leaks reported in Maryland

Sewer leaks need to be included in daily load of Potomac (TMDL)

Leak Detection, Which Is Often Similar to Oil Pipelines

Tracer gases to detect leaks http://www.bnl.gov/bnlweb/pubaf/pr/1999/bnlpr012199.html

Water audit, acoustic leak detection http://irc.nrc-cnrc.gc.ca/irc/fulltext/nrcc42802/nrcc42802.pdf

Continuous flow comparisons between 2 points 30 CFR 250.1004(b)(5) "metering system to provide a continuous volumetric comparison between the input to the line at the structure(s) and the deliveries"

3rd party inspections "External and internal inspections of all oil and gas pipelines by a third party are also required in alternating years." "Oil and Gas Operations Offshore California: Status, Risks, And Safety" by McCrary et al. in Marine Ornithology 31: 43-49 (2003) http://www.marineornithology.org/PDF/31_1/31_1_6_mccrary.pdf

Office of Pipeline Safety http://ops.dot.gov/

Comment on difficulties in monitoring oil pipelines http://www.pipelinesafetyfoundation.org/docs/CommunitiesAgainst.doc

Leaks in Jefferson County, WV

Leaking pipes were found in the Charles Town, Ranson & County PSD in 1997, "Sewer System Evaluation Survey, October 1997, City of Charles Town, City of Ranson, Jefferson County Public Service District" by Chester Engineers [now View Engineering].

The systems have not fixed all those leaks, and have not done full scale evaluations since then.

They reported rain leaking into the pipes at the numerous cracks, so sewage flows increased on rainy days. The same cracks let raw sewage leak out.

The systems still have high correlation of metered flows with rain, showing continuing leaks. In July to October 2004, rainfall added 223,000 gallons of flow per inch of rain. Flows were particularly high on 9/17 and 9/28, which were the days of heaviest rain during those months.

The 1997 study found many leaks, of several types. These are natural in old systems, and still happen.

The 1997 leaks were estimated to average 200 to 7,500 gallons, from each leak each day, and over 50 separate leaks were listed.

"break-in service leaking"

"joint leak"

"cracked pipe"

"broken pipe"

"open joint"

"service lateral leaking"

"leaking joint"

"frame offset"

"leak at outgoing pipe connection"

"heavy roots from apron, incoming line, & barrel se"

"heavy roots over outgoing pipe"

"heavy roots from walls"

Even in well-built new pipes, WV expects infiltration: 2,400 gallons per day per mile in 12" pipes:

47CSR31 App.B part A 2.2. "An infiltration allowance of two hundred (200) gallons per inch diameter per mile per day and a reasonable allowance for future industries may be added to the per capita design flows to arrive at the average daily flow."

It has been suggested that sewage leaks will be visible on the surface. Occasionally they are, but often they go subsurface in this karst geology. None of the leaks found in the 1997 study was visible on the surface. It has also been suggested that sewer pipes below the water table are subject to constant inward pressure, so cannot leak out. This could be true elsewhere, but is not applicable in these systems, where groundwater is far below the sewer pipes (WV Geological and Economic Survey, "Ground-Water Hydrology of Jefferson County" 1978).