Protecting system from Entergy trucks

cougiecat(8b)April 26, 2010

I'm planning on installing an irrigation system in an electrical servitude. I'm pretty sure that a power pole near the area will have to be replaced within the next 5 years (completely rotted through), which means a large truck will drive over (and probably park on)the pipe.

Will 1" S40 PVC pipe burried 18 inches be sturdy enough to handle this? Should I look into flexible tubing? My neighbor's water line (PVC) was broken last time they drove through, but that was at the point where it meets the meter.

I'd hate to install this system and then have to dig it all up again in a few years.


I plan on hooking the irrigation to an outside spigot. What kind of backflow preventor do I need? (I was told a simple check valve would be fine.)

I'm planning on using an air compressor to winterize the system every year. Do I need a pressure relief valve in addition to this?

How necessary are pressure regulators? (I'm using city water.)

I havn't actually done calculations for water availabilty/capacity- would it be a safe assumption that I don't have to worry about it as long as I am just doing 200 ft of shurbs and veggies?

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Hi Cougar,

I am going to go out on a limb here and answer some of your questions. Others on the forum can correct me if I go astray.

1. At 18" deep you would be safe if you do two things. Make the trench as narrow as possible and still get the pipe in and compact the trench material as hard as you possible can. Oh, yeah make sure the are no rocks, stones in the backfill material.

2. Schedule 40 is fine but schedule 80 is better. It is like insurance but will cost you more.

3. A regular irrigation main valve and vacuum breaker installed at least 6-8" higher than your highest irrigation head will do fine. Check your local regulations. Backflow devices should be inspected every year to make sure they are operating properly.

4. No. Your last irrigation head is your air relief valve when you fill your system with water in the Spring. In late Fall you are actually trying to get air into you lines and water out through the last sprinkler head.

5. In-line pressure regulators are only needed for drip systems which use supply tubes that are only rated for low pressure to operate properly. Do you have your house pressure regulated? To what psi pressure?

6. You don't have to worry. If you would like to know what flow you are getting and what pressure. Fill a five gallon bucket up and time how long it takes. Let us know here what you get. Then buy a 15$ hose faucet pressure gauge and put it on the faucet, turn the water on and read the pressure. With that info forum members can give you more specific details about the system you need.

JMHO Aloha

    Bookmark   April 27, 2010 at 12:20AM
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Thank you very much for the quick reply lehua.

I was thinking about using S80 PVC, but was worried about the friction loss. Hopefully that won't be a big issue with a city water/low demand situation. Maybe I'll use S80 for the main line and S40 (or CL 315) for the laterals I think are 'safe'. Any expense now is cheap compared to having to dig this up and do it again.
Thanks for the advice about a narrow trench and making sure the soil is compacted after trenching.

Awesome about the vacuum breaker. I installed one last year when I put in a simple irrigation system. (Just a hose connected to a soaker hose.) The breaker's gone now... I think my husband took it off. I'll have to make sure he knows not to take off this one. Who inspects them? The water company? A plumber? Me?

Static Water Pressure for my neighborhood is 40-60 PSI (just called)... don't know if it's that at the hose bibb, but from what I read 60 PSI shouldn't be too high for valves/irrigation equipment to handle, and my water demands will be low enough that I shouldn't have to worry about pressure being too low. (I'll just be careful about what I buy.)

Thanks again!

    Bookmark   April 27, 2010 at 6:43PM
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No one really checks but if you have bad tasting or cloudy water and you have contaminated the City's water system. They check homes for the source of the problem and can charge you for re-chlorinating their mainlines and other costs. It would have to be a code requirement for your City for them to charge you. The friction loss would not differ for the Sch 80 versus 40. Your run is too short to worry about friction loss. Use schedule 80 where ever you have a tee or 90 degree elbow or taking off a metal fitting in the area where the trucks may drive over.

40-60 psi is ideal pressure and you don't need a pressure regulator. If you use drip you may need a in-line pressure regulator(not expensive)to reduce to 25-30 psi. Higher pressures can shorten the life of the water using fittings in your house like the washer, faucet seals, etc.

If you want to be sure you know how much water you are using. Fill a 5-gallon bucket up and time it. That flow rate (gallons per minute or hour) is your maximum flow rate for the pressure in your house. Design your irrigation to use only 80% of that rate per zone. Add all the flow rates from the heads in each zone and it should not be more than 80% of what you get out of your faucet. JMHO Aloha

    Bookmark   April 27, 2010 at 7:30PM
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Quick question: Is this going to be a drip, spray head or rotary gear head system? You said 40-60 psi is the range in your area. Check your actual pressure before you do anything. It is also advisable to design around the lowest expected pressure.

    Bookmark   April 27, 2010 at 10:22PM
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