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| | | Forum Newbie
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Last Login: 10/10/2008 3:17:31 PM
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| | I am reviewing a watermain construction plan showing a 12" casing for proposed water-main crossing under four segments of storm and sanitary sewers. What are the trade-offs (cost and difficulty) between a 12" casing (50' long) and a replacement for four sewer segments? I have no information regarding what the service areas are of existing sewers. |
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| | | Supreme Being
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Last Login: 11/19/2008 10:41:32 PM
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| I am reviewing a watermain construction plan showing a 12" casing for proposed water-main crossing under four segments of storm and sanitary sewers. What are the trade-offs (cost and difficulty) between a 12" casing (50' long) and a replacement for four sewer segments? I have no information regarding what the service areas are of existing sewers.
Do you mean that the water main is to be "encased?" If so, it's probably "encased" in concrete, which is used to protect the water main from damage that might incur from a break in the piping that would be above it. Normally, you don't want to install a water service pipe "below" a potential contaminating source, such as a sewer line. Plus, a failure of one of the sewers could cause erosion of the soil around those pipes, which could cause stress to the water main. In other words, it would be considered good engineering practice to encase the water main located below a sewer line (or, several sewer lines). If concrete encasement is not to be used, I would guess that other material, such as an outer pipe casement could be used.
I can't imagine that replacing four other pipes would be cheaper than just installing the encasement around the water main. Also, why would the sewer pipes be "replaced?" I am assuming that they are gravity lines, so that routing them other than where they are would be needlessly complicating the issue.
Jeff Naumann
(310) 540-0045
FAX (310) 540-0337
http://www.jeffnaumannassociates.com/ |
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| | | Supreme Being
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Last Login: 11/7/2008 4:48:41 PM
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| | If it meets your requirements, sleeving the water line with SDR 35 would be cheap. Mark |
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| | That's an interesting alternative to concrete encasement; how do you seal the ends? |
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| | | Supreme Being
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| | We always filled the ends with non-shrink grout. Plus the ends were extended 10' beyond the area in question. If it was a new gravity sewer we would transition from SDR 35 to C-900 through the area and then back to SDR 35. Mark |
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Last Login: 9/9/2008 1:41:16 PM
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| hdpe pipe should meet all the requirements, to install under other utilities it can be directionally drilled. It is a great alternative in soils that normally corrode watermains. no casing would be need unless required, which then you could drill a larger hdpe and pull the smaller sized hdpe watermain through it. i have done this several times. fusion joints make this pipe virutally seamless.
ajj |
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