pipe through unstable soil

[tjmh]

I'm looking for information (design aids) related to the design of ductile iron pipe with restrained joints through areas of unstable (organic)soil. Pipe is 8" to 12" water main, 5' of cover required and length of organic soil to cross is 300' to 600'. Organic deposit is approx. 13' deep. Organic content is presently unknow. Desire is to install pipe by horizontal directional drilling due to several factors. HD Polyethylene pipe has been eliminated from consideration by owner.

 

[KRSServices]

May I enquire the rationale at to the Owners objection to HDPE? Is this area susceptible to frost? What type of cathodic protection is being considered, if at all?

HDPE is inherently resistant to corrosion and highly tolerant to movement due to unstable ground. DI is very rigid and brittle which therefore begs the thought as to the OWners considerations in the matter.



KRS Services

http://www.krs-services.com

 

[tjmh]

Owner's Objection: unknown but firm. Frost depth: 42". Cath. Prot.: still considering alternatives, feel free to offer ideas. Is HDPE resistant to hydrocarbons? DIP allowed to deflect at joints.

 

[KRSServices]

Hydrocarbons?? Your post refers to water.

What is the application? The Owner should really reconsider. I can take him/her on a few guided tours of DI and AC pipe placed in weaker soils...and show him all the repair locations over the years, both due to frost and swelling due to groundwater and other factors. I'm currently involved in a small job replacing DI pipe in medium soils due to movement and corrosion. I strongly suggest an alternative, or get him/her to call me as one Owner to one experienced P.Works Manager.

KRS Services

http://www.krs-services.com

 

[dicksewerrat]

The organic soils will give you an acidic soil condition. you will have to protect this DI pipe. HDPE can go in at 5 feet, 6 feet or any other depth. Even down in the stable soil. Is there a good reason to change pipe sizes in the weakened soil? HDPE moves well and can be designed for almost any condition. If you suspect VOC's in the water table maybe a double line? one inside the other. Owner should come out of the Dark Ages. Attend a few trade shows and see what's being done these days.