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Thread: Need design advice - 75' well servicing two residences

  1. #1
    DIY Junior Member robyn's Avatar
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    Default Need design advice - 75' well servicing two residences

    Hello all, I've been browsing the forum for quite awhile and am now making my first post. I'm looking for some advice on how to design and implement our new water well system to two residences on my property.

    We just had a new well drilled, and I don't yet have the full Driller's Report but want to start getting input. It's about 75' deep, with water sitting at about 35', mostly sand I understand. 5.5" PVC casing, with two 8' sand screen sections put in (since we wanted a little better production for two houses). Again, I don't have the final report, but they've estimated about 10gpm production from the well.

    I will try to attach a map of our acreage showing the well, our main house, and the second residence (mobile trailer). There will be a total of 4 adults, 3 children, 4 bathrooms, etc. The well is about 350' from the house, and about another 300' to the trailer. We will be doing our own trenching (I have access to a smaller backhoe with 24" bucket) at approximately 8' depth from ground level.
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    Here's my questions:

    1) Should we use 1 submersible pump in the well, pump to the house with pressure tank there, and then another line from house to trailer? What size/type of pump and pressure tank(s)?

    2) What type of line should be laid in the trench, 1-1/4" poly rated at about 100 psi? Does the trench have to be prepared at all, bed of sand etc, to protect the line?

    3) At one point, our planned trench for the water line will be in the near vicinity of the existing septic/sewer pump-out line, is this an issue? Is there a minimum distance to keep these separate for sanitary reasons?

    4) Someone had mentioned instead of one submersible pump in the well, using two 2-line jet pumps, one at each residence. This would mean way more pipe used (2000' instead of about 650') for the 2 lines from each pump. Is this reasonable? Why would I use this over one submersible?

    Thanks, hope I'm asking the right questions and showing at least some sign of trying to do my own research first!

    Robyn

    PS: I will complete the template as per rules also...

    Type of pump?
    Submersible___please recommend_____
    Two wire (no control)________
    Three wire (control box)______
    Wire Size_________ Wire Length________
    or
    Jet Pump (above ground)_________
    One or two pipes down the well____

    Size of Pump?
    Motor Horsepower?____please recommend______
    Pump Model #______________
    Date Pump Installed__________

    Pumping from?
    Cistern tank___________
    Pond, lake, river________
    Water Well____yes________
    Depth of well____75'______
    Depth to water____35'_____
    Pump Setting__________
    Pipe Size_________"
    Drop Pipe Material
    PVC________
    Steel_______
    Poly________

    Well Recovery Rate___~10____gpm
    Well Casing Diameter___5.5____
    Rock Well__________ Sand Well____yes, 2 screens______ Other______________
    Date Well Drilled_____Sep. 2011_______

    Well Casing Material
    PVC____yes____ Steel_________ Other_________


    Pressure Tank?
    Bladder or diaphragm tank (one pipe to tank)___please recommend_______
    Size or model of tank____________
    Air charge in top of tank, with pump off and water drained____________PSI
    (check with car tire gauge)
    or
    Plain Hydro Pneumatic tank (two pipes to tank, one in and one out)_________
    Size of tank________________

    Pressure Switch Setting?
    On 30, off 50 ____please recommend____
    On 40, off 60_________
    Other_______________

    Pump Control Method?
    Cycle Stop Valve model #____please recommend_____
    Variable speed control #__________
    Pump Start Relay (sprinkler timer, no tank)__________
    Manually turned on and off____________

    Pump Protection
    Cycle Sensor____please recommend_____
    Pumptec_____________
    Low pressure cutoff switch (lever on side)__________
    Other_______________

    Filters or Softeners_____probably_________
    Before or after pressure tank__please recommend_____
    Type of filter_________iron and hardness__________
    Bypass available________________

    Water Used For?
    House Use___yes____ Number of baths___4____ Number of People____7____
    High Flow Showers____3?___gpm?
    Plus/Or
    Irrigation with timers___n/a_____
    Irrigation with hoses________
    Heat Pump______gpm?


    Problems Experienced
    No Water_______n/a__________
    Water only part time________
    Water at all times but weak_____
    Air in water_______________
    Pressure surging___________
    Water Hammer (noise)______
    Too Much pressure_________
    Other____________________


    Pump makes clicking or buzzing sounds___n/a_____
    No Sounds______________
    Pressure gauge reading________psi
    Other____________________________________

    Do you have, and know how to use
    an Ampmeter and Voltmeter________yes, very well__________

    Describe Problem__________n/a________________.....

  2. #2
    In the Trades Texas Wellman's Avatar
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    Definitely use one pump, don't even consider a jet pump. Submersible all the way.

    I prefer PVC over poly, but that's an opinion. PVC is much stronger than 100 psi poly. If you do use poly, get the 160 psi stuff, stay away from the cheap stuff.

    If you want to keep it simple go with one pump/tank at the well site. Get a big tank for storage/surge purposes, and dig the trenches right and make sure you get them deep enough.

  3. #3
    DIY Junior Member robyn's Avatar
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    Okay, so another vote for submersible, which makes a lot more sense to me anyways.

    With PVC, would that be a Schedule 40 then? Do I need to look for a particular type that can be used for potable cold supply, or is it all pretty standard? With the poly I realized that there's different grades (standard and CSA-approved) depending on use. What diameter do you think I would need for this size of a system? How is PVC connected, looks like the stuff I can source from Home Depot or Home Hardware is only plain-end, so I'd need several dozen couplers also? And do I need to use a special glue for potable supply, or is regular PVC primer and glue sufficient and sanitary?

    In Saskatchewan here, we've been told to trench all the way down to 8 feet deep, does that make sense? Certainly wouldn't need to be more than that, correct?

    Thanks!

    Robyn

  4. #4
    Moderator valveman's Avatar
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    I would use about a 10 GPM, 3/4 HP submersible in the well, and 1 1/4" sch 40 PVC all the way to the trailer. Turn the pressure switch up to about 50/70 PSI because of the long distances. Your water is stored in the well, not a tank. You have 14,000 gallons a day you can use from the well, so an 80 gallon pressure tank that only holds 25 gallons of water is not going to help. The main purpose of a pressure tank is to limit the number of times the pump cycles on and off. When controlled with a Cycle Stop Valve the pump will not cycle, so a 4.4 gallon pressure tank, like the picture to the left is all you really need.

  5. #5
    In the Trades Texas Wellman's Avatar
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    With the well only making ~10 gpm (probably less, drillers lie), wouldn't you want to use a slightly larger tank for peak demand? I understand what you're saying about the 4.4 gal tank and CSV, but what if they over-run the well (easy with a 3/4 HP pump and 75' well)?

  6. #6
    DIYer, not in the trades LLigetfa's Avatar
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    An 80 gallon tank would provide less than 20 gallons of drawdown at 50/70, so if storage is what you need, you won't get it from a bladder tank. What you need for storage is a large non-pressurized vessel and two pumps. A 3/4 HP pump in such a shallow well could draw down the small amount of storage in 30 feet of casing when it fills such a large tank. A CSV would choke back the GPM to match demand.

  7. #7
    Moderator valveman's Avatar
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    You can’t count on a large pressure tank for peak demand. You have no way of being sure the tank is full when you need peak flow. With a 50/70 pressure switch. Murphy says the system will be at 51 PSI, and the tank will be empty, when you start using water. So all you can count on is the amount of water delivered from the pump and well.

    Even if you are lucky enough to have an 80 gallon tank full with 20 gallons of water when you turn on the faucets, it will only give you a little over a minute extra peak demand on top of the 10 minutes the well can produce. Then the tank is empty before the pump starts, and the well and pump see that tank as an additional demand for 20 gallons of water. So the pump is trying to refill the big pressure tank at the same time the houses are using water, which increases the demand on the limited amount in the well, making you run out of water sooner.

    With 40’ of water, you have an extra 60 gallons stored in the well above the 10 GPM recovery rate. And a 10 GPM pump can produce 14 to 16 GPM for peak demands. So you can run 16 GPM for 10 minutes peak, or 14 GPM for 15 minutes peak before your well draws down to producing only 10 GPM. A CSV will deliver 16 or 14 GPM for peak demands, then it will draw only 9 or 3 GPM directly from the well when that is all the water you are using. A 4.4 gallon pressure tank only holds 1 gallon of water, so the well won’t be pumped dry while trying to refill the pressure tank.

    If you use more GPM than this you will “over run” the well, and a large pressure tank will just make the well be “over run” that much sooner. You should have plenty of flow for what you are doing, but if you need more GPM, a storage tank with a booster pump is the way to get it like LL says.

    The Water Systems Council and several pressure tank manufacturers have written that if you reduce the air charge in the pressure tank, you can use even more than 16 GPM for a short period of time. This is true, but the tank has to be refilled before the pump will shut off, and the extra water needed to fill the tank has to come from the well that is already depleted. Large pressure tanks are just an additional load on low producing wells.

  8. #8
    General Engineering Contractor ballvalve's Avatar
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    Quote Originally Posted by robyn View Post
    Okay, so another vote for submersible, which makes a lot more sense to me anyways.

    With PVC, would that be a Schedule 40 then? Do I need to look for a particular type that can be used for potable cold supply, or is it all pretty standard? With the poly I realized that there's different grades (standard and CSA-approved) depending on use. What diameter do you think I would need for this size of a system? How is PVC connected, looks like the stuff I can source from Home Depot or Home Hardware is only plain-end, so I'd need several dozen couplers also? And do I need to use a special glue for potable supply, or is regular PVC primer and glue sufficient and sanitary?

    In Saskatchewan here, we've been told to trench all the way down to 8 feet deep, does that make sense? Certainly wouldn't need to be more than that, correct?

    Thanks!

    Robyn
    First off, DO NOT go into a 2' wide 8' deep hole unless its half hard shale or you have a trench shield handy, OSHA stamped... Keep the kids far away, and have the pipe string ready made, glued up on the surface. If you choose PVC, [WHITE -for water] which is cheap, do not use the Home depression stores, go to your mechanical supplier and get 20' sticks with bell ends, schedule 40. Use tons of primer and heavy grey glue, and pressure test the line to at least 100 PSI before, during and after backfilling. I would pressurize it on the surface for a day or 2 before putting it in the hole.

    To sand or not to sand the trench, a big question. A big headache, expensive, and maybe a headline death because you'll have to get in the hole. If you are good on a hoe and can dig a flat bottom hole in reasonably rock free soil, then you can drop the pipe and work it from the surface and backfill with carefully chosen and "sorted dirt" for 6 or more inches over the pipe. I have installed one larger and longer tooth on the center of a bucket in some cases to give a 'line' to be the pipe bed.

    Personally, I would pump to a static 2500 gallon tank, about 600 bucks here, and spring for another submersible pump to service the homes via a pressure tank. If you have a hillside, or a high point, you will have water when the power is out for a week - but if you have an 8' frostline, you would have large issues with freezing.

    At the mech. supplier you can get a quote for 160 PSI or 200 PSI Poly on a huge spool and have few or no hidden joints
    Just be sure you get the manufacturers directions on making splices, not from billy bob on aisle 9, and not even from the mech. supply house.

    Unless you are in sand [in which case your trench should have a 2/1 or more side slope] you might be in over your head. [pun intended] I would'nt dig an 8' hole without an excavator and stepped or sloped sidewalls. A chain saw type trencher might be the best solution if they work in your area.

    And if you do dig it, be ready for some unpleasant surprises if its a built up area.

    And finally, 1" specs out with your quite small water production, especially if you go to a large static tank.

    Dont worry about the septic, except for digging it up acidentally.
    Last edited by ballvalve; 09-21-2011 at 10:22 PM.

  9. #9
    DIY Junior Member robyn's Avatar
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    Hey, thank you all for the replies so far! And a big yes to ballvalve's comment about the trench shield, my uncle has one and has explained the use of it for us already. It's his backhoe that we are using, so he's got the stuff to go with it.

    So I definitely understand the suggestion about 160 psi or 200 psi pipe, but I find it very interesting that *all* the local plumbers and well-service businesses that I've talked to (4 so far) have all said "Yeah, we never actually use 100+ psi, everything we install is 75 psi Poly only" for this type of a length on an acreage. Different codes in Canada, or just being cheap?

    I'd love to be able to install the constant-pressure / variable-amperage pump control system, but it's a luxury I can't afford at the moment. I believe as far as trenching lines goes there wouldn't be any difference for the pipe or wiring, correct?

    From the information I've collected so far, I'm planning to go with a 3/4hp 230v submersible pump, likely 10ga/4conductor pump wire to the primary house, Maass pitless adapter (1-1/4"), and 1-1/4" poly. Still a few questions remain...

    1) What is the preferred wiring for a submersible pump, 2-wire or 3-wire? Around my area, the 2-wire models are a fair bit more common and cheaper, but the 3-wire is apparently cheaper to repair if the control box gets blown (due to surge etc) since it's separate from the submersible. Do those 2-wire pumps actually blow control boxes that easily, etc? Wiring would be the same 10ga for either (10/3 or 10/4 obviously)?

    2) For a storage tank like ballvalve suggested, I really like that idea and would try to get one... Our yard is quite flat, so no hills to put it on, could I build a stage of some sort to get it higher up? Basically just needs to be higher than highest fixture in house (likely the shower head)? Power in our neck of the woods is spotty sometimes and can go out for 2-3hrs at a time every couple months, kind of annoying but not deadly.

    3) ... more questions to come as I ponder the responses again!


    Thanks, this is such a huge help!!!

    Robyn

  10. #10
    DIYer, not in the trades LLigetfa's Avatar
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    Quote Originally Posted by robyn View Post
    So I definitely understand the suggestion about 160 psi or 200 psi pipe, but I find it very interesting that *all* the local plumbers and well-service businesses that I've talked to (4 so far) have all said "Yeah, we never actually use 100+ psi, everything we install is 75 psi Poly only" for this type of a length on an acreage. Different codes in Canada, or just being cheap?
    They are being cheap. Don't use anything less than 160 PSI poly.

    Quote Originally Posted by robyn View Post
    I'd love to be able to install the constant-pressure / variable-amperage pump control system, but it's a luxury I can't afford at the moment. I believe as far as trenching lines goes there wouldn't be any difference for the pipe or wiring, correct?
    You don't need a fancy VFD to get constant pressure. A Cycle Stop Valve will give you constant pressure with a standard pump. A CSV does require a higher PSI rated pipe than the cheap stuff they are trying to sell you. The wire is the same.

    Quote Originally Posted by robyn View Post
    For a storage tank like ballvalve suggested, I really like that idea and would try to get one...
    I would consider that as a last resort. The cost of the tank is just part of it. You would also need a second pump and a Cycle Sensor to protect it.

  11. #11
    General Engineering Contractor ballvalve's Avatar
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    75 PSI pipe is for above ground drip irrigation feeds on pot farms. At 8' deep it would likely become a very small oval.

    20' sticks of PVC is the best, likely, and if no one uses 160 poly in the area, its likely very expensive.

  12. #12
    DIY Junior Member robyn's Avatar
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    Quote Originally Posted by ballvalve View Post
    20' sticks of PVC is the best, likely, and if no one uses 160 poly in the area, its likely very expensive.
    What would be a decent price (USD$ or CAD$) for the 20' pvc sticks? I'm assuming bell-end is the way to go, and Schedule 40, correct?

    Robyn

  13. #13
    General Engineering Contractor ballvalve's Avatar
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    Guessing, but 1" is around 22 cents US and 1.25" maybe 35 or 40 cents per foot. 160 poly is @.65 per foot in 1"

    bell-40 yes
    Last edited by ballvalve; 09-24-2011 at 01:00 PM.

  14. #14
    DIYer, not in the trades LLigetfa's Avatar
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    A 1000 foot coil of 160 PSI poly at Manerds is $450 and doesn't need gluing every 20 feet.

  15. #15
    General Engineering Contractor ballvalve's Avatar
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    Wish we had a *******. Is that US$ ? 1"?

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