Environment, Coasts, Oceans, & Infrastructure

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Syed Alvi M.ASCE
Junior engineer
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In Corpus Christi, Texas we tend to use a lot of PVC to replace failing VC pipe or for new installations.  Sanitary sewer mains and laterals tend to be SDR 26 PVC.

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John McMullan P.E., P.Eng, M.ASCE
Corpus Christi TX
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You have just opened Pandora's box. There is no simple answer. First some considerations should be acknowledged. Industrial wastes typically have a potential for expensive remediation if any leakage occurs (ex-filtration, spills, etc.). So a sound long life joint system is critical. Additionally the life of such utility products often exceeds anyone's expectation. That being said I suggest that you start with any local/state/federal permit requirements. Second you need to identify the anticipated characteristics and strength of the discharge stream. It may be so string that even various plastic formulations are not appropriate. You may be looking at a more exotic material such as stainless steel in some cases up to any industrial pretreatment system, with a more affordable pipe material to the discharge point. 

There are many fine text books and manuals of practice (WEF, USEPA, etc.) available to cover the basics of design. They may not provide the level of guidance you desire to select the best or an appropriate product. I don't know what a Junior Engineer is but I assume you are a student or graduate engineer gaining experience. There are no short cuts. You need to invest time to become familiar with strengths and weaknesses of various pipe products. That kind of foundation work is essential. After 50+ years in the trades and 40 in engineering I still find that some unique applications require my additional research to arrive at an appropriate solution. Add in the Owner's expectations, value engineering and sustainability complicates your work, but if it was easy they wouldn't need an engineer.   You have selected an good career and I wish you great success.

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James Rabine P.E., F.ASCE
Consulting Engineer
Grand Blanc Township MI
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You need to first identify the type of sewage flow, especially w/ industrial wastewater. Most newly installed municipal gravity lines are themoplastics, usually a type of PVC b/c of the economics. PVC is cheap, light and easy to install. That being said, they are not resistant to chemical attacks and solvents. Ductile iron (DIP), concrete and vitrified clay pipes (VCP) are good options too, and all have their own strengths and weaknesses. They all have good corrosion resistance. DIP and concrete are heavy and probably cost a bit more to install. Concrete pipes are susceptible to H2S attacks, which is common near lift stations for sanitary sewer flow. VCP can be costly too because there are a lot of joint sections, and the clay pipe is brittle. I have noticed that a lot of infiltration and inflow leaks come from the VCP joints, but that's typically due to poor installation and/or chemical attacks on the seals. Also, due to the brittleness, VCP can cause more long term maintenance issues. I found a reference from the EPA called "Wastewater Technology Fact Sheet Pipe Construction Materials and Costs." You can also find more references through AWWA and NASSCO. Although NASSCO will be more focused on repairs and defect identification. I recall a project that involved metering the effluent industrial wastes, it was a type of soap manufacturing. Within one month, the plastic probe from the meter dissolved. We found out it was acid wastes from the processing.

To wrap this all up, I recommend you identify the type of effluent wastes you are dealing first. Then take the economics and long term maintenance into account.

Here's the link to the EPA paper... 

https://nepis.epa.gov/Exe/ZyNET.exe/P1000W83.txt?ZyActionD=ZyDocument&Client=EPA&Index=2000%20Thru%202005&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5CZYFILES%5CINDEX%20DATA%5C00THRU05%5CTXT%5C00000015%5CP1000W83.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&slide

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Frederic Brown P.E., M.ASCE
Project Engineer
Seattle WA
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The oil refineries in my area are still specifying the use of ductile iron pipe for their gravity sewers. The sewer company that treats the sewer specifies the use of PVC pipe type SDR 35 for sewers 12 inches and smaller and reinforced concrete pipe for larger than 12 inches. So at the property line of the refinery there is a material change.

We do see a lot of HDPE used in the repair of older sewer service lines when using pipe bursting as a method of trenchless repair/replacement.

Cure In Place Pipe lining (CIPP) is the preference of the local sewer company for both service line and main line pipe rehabilitation.

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Jacob Scott Aff.M.ASCE
EIT
South Davis Sewer District
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We need to know more information about your site before recommending HDPE. 

Normally you would want to use PVC pipe for sewer. It's resistant to hydrogen sulfide gas from the sewer flow. PVC is fairly tough and stiff so it can be installed easily on the grade/design slope. 

HDPE is tougher than PVC. It's also not as stiff, it bends easily, therefore installing without creating low spots is a problem. And HDPE has to fused together to joint two pipes. Fusing takes about 20 minutes per joint and is typically done to the entire pipeline next to the trench. So you need a lot of area for the fused pipe storage. 

In a normal situation I wouldn't use HDPE pipe for sewer. I used HDPE for sewer once, it is the first horizontal directional drilled HDPE gravity sewer line installed in Arizona.

But your site specific issues may require HDPE.

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Ricky Holston P.E., M.ASCE
CE
Sunrise Engineering, Inc.
Mesa AZ
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I use HDPE on all underground applications - drain or pressure lines.  You may get reminded that there are lower cost alternatives, but none that will last as long as HDPE and the value is in the fact that you will not have to replace it in your career.  Check the temperature of the drain effluents and HDPE maximum.

My last application was a sewer drain line for a remote recreation area draining to a small WWTP.  The original sewer was improperly back filled resulting in < 30 year life.  We replaced one section with 1 mile of welded HDPE.  

My favorite application was replacing over 2 miles of underground PVC pressurized water line that failed prematurely from improper back fill.  The water line supplied a remote power station with boiler water from a water well field.  We used welded HDPE and proper backfill and I am confident that it will outlast the power station.  

My engineering rule of thumb is - use welded HDPE for longer life.  Engineering economic evaluations must take into account shorter project life with other lower cost materials. Always backfill to specification and watch the contractor for short cuts.

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Eric Fridley P.E., P.L.S., PH, M.ASCE
Power Station Director
Frankford WV
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