8-inch VCP gravity sewer exfiltration rate? No Groundwater.

[Pipeexpert]

We are searching for the source of the below formula, alleged to be a pipe leakage rate for small diameter 8" VCP gravity sanitary sewer pipe by an "expert", with no citation/source given. The leakage is expressed in Liters per meter of pipe length, and it has been used to estimate the leakage rate of a "newly installed" 8-inch VCP gravity sewer pipe flowing at about one-half inch depth, serving three homes, on a steep .094 slope:

Leakage rate = 0.37 to 0.92 Liters/hour/meter of pipe; or 0.1 to 0.25 gallons/hour/39 inches of pipe.

Note there is no pipe size, slope/velocity, flow quantity, or pressure head, only x Liters per hour per length of pipe?? This may have come from an urban drainage or flood flow source??
We have searched everywhere including the EPA/CDM 2000 "Exfiltration in Sewer Systems"

http://www.epa.gov/nrmrl/pubs/600r01034/600r01034.pdf

and the EPA/CDM Project Summary 2003 at

http://www.epa.gov/nrmrl/pubs/600r01034/600sr01034.pdf

"Exfiltration in Sewer Systems Project Summary" March 2003
and numerous other sources, WEF,Civil Engineering Database, and others to no avail. Where does this formula come from or is it completely bogus???

Your opinion/assistance will be greatly appreciated.

 

[dicksewerrat]

Sounds like BS to me. In the first place the VCP pipe with Neo gaskets should not leak. There ae vacuum and /or pressure tests done to verify this. Most new installations are tested to5 psi before sign off for payment. This pipe will have a total Q flowing .5 inches of 18,000 GPD. I don't think you will get that much flow for 3 houses on an average day. His max leakage for a 250 ft line is 450 gal. per day. Not a very good installation.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[bimr]

You seem to have the units incorrect. It should actually read "Exfiltration leakage shall not exceed 240 gallons per inch of pipe diameter per mile per day (22.2 liters per millimeter of pipe diameter per kilometer per day) of sewer pipe including manholes in the test section.

Note that Liters/hour/meter of pipe is not the same units as liters per millimeter of pipe diameter per kilometer per day.

I don't know where the number originates, but it is a valid number and is listed in the Standard Specifications.

The leakage for a 250 ft sewer actually calculates to 91 gal. per day

You also need to have the testing procedure spelled out.

Attached is the Standard Specification for leakage testing.

 

[rconner]

If one were to get perhaps overly picky I’m not even really sure that what the “expert” provided (if what you have written is verbatim/quote) is really a “formula”. I believe that is usually defined in a sort of Math. unabridged context as something to the effect “”Any general fact, rule, or principle expressed with algebraic symbols…” What is instead provided though does however appear to be at least some vague sort of expression of an allowable leakage range.

Now, with regard to same and not knowing any more of the specific case nor time period when the specific pipeline was designed/installed, the expressions “completely bogus” or “BS” could be a little too strong characterizations in some circumstances, as who knows what leakage rates may have been locally accepted by inspectors (or even specified by whatever authorities) over many decades? In this regard, the spokesfolks for the major clay pipe industry in the USA in effect even contemporarily claim that a significant leak path “was” [see e.g.

http://www.terrehautecleanwater.com... Vitrified Clay Pipe Coupling and Repair.pdf,

“of benefit”, “expected”, as well as being (they say) the ”standard of the day”, as it allowed(s) dilution by groundwater when same was at a level above the pipeline].

Everyone have a good weekend.

 

[bimr]

Since you are being picky, the leakage rate is actually the coefficient in the formula:

240 gallons per inch of pipe diameter per mile per day *(Y)*(X) = Total Gallons of Leakage per day

where X is the miles of pipe
and Y is the diameter in inches

 

[Pipeexpert]

Here is the "expert's testimony, under oath; after being asked about his "leakage assesment":

BASED ON PUBLISHED LITERATURE FROM VARIOUS
SOURCES FROM E.P.A. TO LOS ANGELES COUNTY TO ORANGE COUNTY
SANITATION DISTRICT, THERE HAVE BEEN STUDIES THAT IDENTIFY
SEWER LINE LEAKAGE AND THE RATES OF SEWER LINE LEAKAGE PER

FOOT OR PER METER. THOSE PUBLISHED RATES EQUATE TO 0.37 TO
0.92 LITERS PER HOUR PER METER OF CLAY SEWER LINE.
Q DO YOU HAVE ANY OF THOSE REFERENCES IN YOUR
NOTEBOOK?
A NO, I DON'T.
I HAVE THE SOURCES GENERALLY CITED BEING BROWN
& CALDWELL, 2005; ORANGE COUNTY SANITATION DISTRICT, 2005;
CONFERENCE OF URBAN DRAINAGE MODELING, 2004;
CITY OF LOS ANGELES BUREAU OF SANITATION, 2006; E.P.A., 2003;
AND CAMP, DRESSER & MCKEE, 2000.

There you have it. I have been an expert witness in about 30 pipe cases from FL,OH,NJ,WA,CA,AZ,AL,etc., including the USA v. Miami Dade Metro and the State of Florida for the US DOJ, and I have never seen this formula. Black Magic, I guess. I just want to know wher it came from, if not just smoke, probably mis-used.

 

[bimr]

One would not think the "published rates" are not worth anything without a testing procedure. Refer to the test procedure above in the standard conditions.

I would go back and question the fellow on how to conduct the leakage test. If he can not come up with a testing procedure, it will weaken his testimony.

 

[dicksewerrat]

I thought that was for a pressurized water main. I still wouldn't pay for a line that leaked that much. Make up your own testing and leakage spec.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[rconner]

After seeing all this, I wonder if there is any chance what is being referred to is not allowable leakage for hydrostatic testing of new sewer pipelines, but instead talking about some sort of rates of leakage or infiltration in(to) sewer systems already "out there"? [If so, I guess that incidentally might include all sources of infiltration (manholes, penetrations, service connections etc.), and not just the clay pipeline).]