At an industrial complex in the San Francisco Bay Area, we have a buried water supply pipeline. This pipeline serves several low-consumption applications: an equipment pressure washer, some irrigation, etc. But it also supplies the home of a caretaker's residence which is located on-site.
Recently, we've been having a lot of problems with breaks and leaks in this pipeline. The pipeline was built in stages by various previous owners/operators over many years. As a result, it is a hodgepodge of PVC and galvanized of various diameters (3/4" up to 1-1/2"), but not of reducing diameter over its length (e.g., there is a section of 3/4" pipe at the supply end, and larger pipe downstream). It is not a straight run and there are sections of the line where we do not know exactly where the pipe is buried. Based on the projected path in one section, it appears to have been built over by a 150' wide concrete slab. Perhaps the biggest problem is that it's not buried deep enough: it's depth ranges from less than 18" to no more than 2", and there is one 60' section where the pipe (PVC) is literally laying on the surface of the ground. To further complicate matters, the ground is not stable (it's "bay mud" -- similar in properties to land fill) and the ground water table is very high. Lastly, this pipeline runs along a gravel access road that is traveled by heavy trucks. Currently, there is a small leak that we have isolated to an 800' section of this pipeline, but we have not yet located the break.
We are discussing options for replacing this problematic pipeline. One idea is to mount it along the back of the steel industrial buildings that run the length of the access road. The access road is a straight line, and the backs of the buildings are mostly straight and aligned with only occasional offsets in depth, so it would be fairly simple to mount a pipeline to the backs of the buildings using unistrut and clamps. This would be considerably less-expensive than properly trenching and back-filling a buried pipeline, and it would make it infinitely easier for us to locate and repair any problems in the future (although, hopefully, that should be very rare with the new installation). If we do this, we would probably opt for 1-1/4" or 1-1/2" schedule 80 PVC.
Questions:
1. Any objections or major problems with this plan?
2. We are in a very temperate climate: the average lows are in the 40's to 50's, and the average highs are in the 70's to 80's. But historical metrological data for the past 117 years shows the temperature can get as low as 20 deg F and as high as 110 deg F. So we probably should be concerned about the possibility of freezing. We could use pre-formed fiberglass insulation sleeves. But insulation on it's own will not prevent freezing, only delay it. Heat tape would be impractical for such a long run. Would 1-1/4" sch80 PVC, combined with insulation, combined with normal usage from the residence be enough to prevent freezing? (Of course, if the house were to be vacant during a rare freezing spell, we would have to shut-down and drain the line.) How about the installation of a pressure relief valve (to vent excess water pressure in the event of a freeze)? Any other ideas on this topic?
3. Any other issues, concerns, or recommendations?
Recently, we've been having a lot of problems with breaks and leaks in this pipeline. The pipeline was built in stages by various previous owners/operators over many years. As a result, it is a hodgepodge of PVC and galvanized of various diameters (3/4" up to 1-1/2"), but not of reducing diameter over its length (e.g., there is a section of 3/4" pipe at the supply end, and larger pipe downstream). It is not a straight run and there are sections of the line where we do not know exactly where the pipe is buried. Based on the projected path in one section, it appears to have been built over by a 150' wide concrete slab. Perhaps the biggest problem is that it's not buried deep enough: it's depth ranges from less than 18" to no more than 2", and there is one 60' section where the pipe (PVC) is literally laying on the surface of the ground. To further complicate matters, the ground is not stable (it's "bay mud" -- similar in properties to land fill) and the ground water table is very high. Lastly, this pipeline runs along a gravel access road that is traveled by heavy trucks. Currently, there is a small leak that we have isolated to an 800' section of this pipeline, but we have not yet located the break.
We are discussing options for replacing this problematic pipeline. One idea is to mount it along the back of the steel industrial buildings that run the length of the access road. The access road is a straight line, and the backs of the buildings are mostly straight and aligned with only occasional offsets in depth, so it would be fairly simple to mount a pipeline to the backs of the buildings using unistrut and clamps. This would be considerably less-expensive than properly trenching and back-filling a buried pipeline, and it would make it infinitely easier for us to locate and repair any problems in the future (although, hopefully, that should be very rare with the new installation). If we do this, we would probably opt for 1-1/4" or 1-1/2" schedule 80 PVC.
Questions:
1. Any objections or major problems with this plan?
2. We are in a very temperate climate: the average lows are in the 40's to 50's, and the average highs are in the 70's to 80's. But historical metrological data for the past 117 years shows the temperature can get as low as 20 deg F and as high as 110 deg F. So we probably should be concerned about the possibility of freezing. We could use pre-formed fiberglass insulation sleeves. But insulation on it's own will not prevent freezing, only delay it. Heat tape would be impractical for such a long run. Would 1-1/4" sch80 PVC, combined with insulation, combined with normal usage from the residence be enough to prevent freezing? (Of course, if the house were to be vacant during a rare freezing spell, we would have to shut-down and drain the line.) How about the installation of a pressure relief valve (to vent excess water pressure in the event of a freeze)? Any other ideas on this topic?
3. Any other issues, concerns, or recommendations?