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Septic tank riser

Megunticook | Posted in Construction Techniques on June 8, 2007 05:42am

I want to install a cylindrical riser above my septic tank lid to provide quick easy access. It was simply buried when installed with lawn atop (I need to get in there twice a year to clean the outlet screen).

I was thinking a round plastic pipe with some sort of lid, painted green, would be an unobtrusive and fully functional solution. Ideally, it would be nice to have the lid right at grade, so the mower could pass right over it.

But anybody with experience and knowledge in this realm, please advise me.

I had my local yard drop what I thought might work based on a quick phone chat with one of their sales guys, but I’m not sure it’s quite right. It’s basically a 24 inch high x 20 inch diameter piece of corrugated HDPE, but there’s a special flange on the bottom with some sort of foam around the perimeter, as if it’s supposed to mate with another piece of plastic and form a seal (my tank is concrete).

I can cut this down (my lid is only about 16 inches below grade) and make it work, but I’m wondering if it’s the right product. On the label it says “riser extension.” Hmmmmm.

Thanks for tips.

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Replies

  1. RedfordHenry | Jun 08, 2007 06:04am | #1

    You can also get these precast in concrete in various lengths and diameters from any concrete yard, including a lid.  Think they call them extension rings.  Just get something larger than the diameter of the existing opening and bed it in mortar.  I've seen an HDPE one that was stove in when it got whacked by a lawn tractor.  Go with concrete and you'll only have to dig the hole once.

  2. Piffin | Jun 08, 2007 01:01pm | #2

    The tank suppliers have just such an animal in concrete or in fibreglass with a nice green lid.

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
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  3. DanH | Jun 08, 2007 01:51pm | #3

    Yeah, you need something for a concrete, flat-top tank. It can be either pre-cast concrete or plastic/fiberglass, depending. The simplest solution is pre-cast extension rings, stacking several to reach lawn level.

    Whatever you get may come with a hatch, you can use a simple precast concrete lid, or buy reenforced plastic hatch. Be sure whatever it is is "man rated" -- you don't want it to cave in when some stupid kid is jumping up and down on it.

    So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
    1. tuolumne | Jun 08, 2007 03:51pm | #4

      With my kids, and knowing their curiousity levels, I would want something that locked or was too heavy for them to lift.  It could make for a bad day if someone went missing...

  4. User avater
    hammer1 | Jun 08, 2007 04:32pm | #5

    Sounds like something is wrong with your septic system if you have to get into it twice a year. They should be maintenence free except for an occasional pumping.

    Beat it to fit / Paint it to match

    1. User avater
      Megunticook | Jun 08, 2007 04:43pm | #6

      Pif, can you give me the name of a local supplier? That sounds like the right tack--deal with somebody who specializes in septics. I suppose I could call Reggie down at Interstate in Rockland...Yes, a strong lid would be key. You see any issues with putting the lid right at grade so the mower can pass over?Also, how important is it really to seal the riser to the tank? I realize you don't want tons of water getting into your tank through the seams on the lid, but it seems like it's been fine just buried.By the way, the reason for the frequent access (every 6 months) is because my outlet has a special screen thingy that needs to be pulled out and hosed off. The first year I made the mistake of waiting a full year, and the tank was overflowing through the lid. So now I clean out the screen every October and April.The tank has only been pumped once (that year I waited too long and I didn't dare pull the screen out with the tank overfull, as it would've sent gobs of solids down into my drainfield), back in 2004. I know a lot of people pump every 3 years or so--I'm inclined to go longer, though. How long do you all go between pumps?

      View Image

      Creative Communications | Logos | Business Cards | Websites | http://www.hwaters.com

      1. DanH | Jun 08, 2007 05:46pm | #7

        Sounds like you don't have a double chamber tank, with the filter serving to separate the solids vs the chamber partition.Pumping frequency depends on the system and the occupants. Generally you pump after 3 years and base subsequent pumpings on how full it was then.
        So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin

        1. brownbagg | Jun 08, 2007 07:09pm | #8

          MOM house was built in 1972 and nevered been pump. nothing wrong with it.Most hated person on the net

          1. JimB | Jun 08, 2007 11:59pm | #11

            Over the last 20+ years I've looked at failing drainfields with a lot of owners who said "I don't understand why it's failing now.  We've used it for 20 (or 25 or 30) years and never even had to pump the tank."  And I've seen septic systems that were still function just fine after more than 50 years--perhaps without the tank ever being pumped.

            But no septic system keeps all solids out the drainfield, and enough solids will at some point cause the field to clog.  Occassional pumping of the tank is really a low-cost way to prevent or postpone the cost fixing a failing system.  How often a tank needs to be pumped depends on the size of the tank and the amount of waste generated. 

            Here's a table with typically recommended pumping frequency.

            Tank Size

            Household Size (No. of People)

            (gal.)

            1

            2

            3

            4

            5

            6

            7

            8

            500

            5.8

            2.6

            1.5

            1.0

            0.7

            0.4

            0.3

            0.2

            750

            9.1

            4.2

            2.6

            1.8

            1.3

            1.0

            0.7

            0.6

            1000

            12.4

            5.9

            3.7

            2.6

            2.0

            1.5

            1.2

            1.0

            1250

            15.6

            7.5

            4.8

            3.4

            2.6

            2.0

            1.7

            1.4

            1500

            18.9

            9.1

            5.9

            4.2

            3.3

            2.6

            2.1

            1.8

            1750

            22.1

            10.7

            6.9

            5.0

            3.9

            3.1

            2.6

            2.2

            2000

            25.4

            12.4

            8.0

            5.9

            4.5

            3.7

            3.1

            2.6

            2250

            28.6

            14.0

            9.1

            6.7

            5.2

            4.2

            3.5

            3.0

            2500

            31.9

            15.6

            10.2

            7.5

            5.9

            4.8

            4.0

            4.0

          2. Piffin | Jun 11, 2007 05:27am | #14

            yeah, but Mom lives alone and only takes a dump once every three days, right? 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          3. DanH | Jun 16, 2007 03:46pm | #20

            Yeah, right. Nothing wrong with it.
            So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin

      2. Piffin | Jun 11, 2007 05:25am | #13

        Sounds like you have an interior grease catch to me. Six months is the recommended cleaning interval, but they are usually a separate box out here.my dirt guys provide everything when they do a waste water system. They do get their concrete stuff from Interstate tho. They have manholes with crete caps too 

         

        Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

        1. User avater
          Megunticook | Jun 11, 2007 06:36am | #15

          It's one of Dennis Small's systems, I believe an Elgin Drain or some such name (one of those proprietary drainfield systems, requires smaller footprint--although we had plenty of space and a good site, I just took what Dennis recommended).The tank outlet screen is a plastic cylinder with a series of screens that slides into the T-fitting on the outlet. It does clog up--but it may be that I have a little extra water coming in from the tank lid seam. Reggie at Interstate, when he pumped it, figured on once-a-year check as being advisable.We don't have a disposal in the sink and we're pretty careful what goes down there.

          View Image

          Creative Communications | Logos | Business Cards | Websites | http://www.hwaters.com

          1. Piffin | Jun 11, 2007 06:49am | #16

            There is getting to be a lot of Elgin systems out here, because it uses so much less gravel, which is expensive to haul.I can understand it requiring a strainer/filter on the output side of the tank because of the reduced size. Cheap insurance! 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

  5. JohnD1 | Jun 08, 2007 09:21pm | #9

    If I am reading you correctly, you want to be able to GO INTO the area.  Does this mean PUT YOUR HEAD INTO the opening?

    DON'T DO IT!!!

    This is what they in OSHA call a "confined space".  Considering what goes on in a septic field, at the least you could have the area full of carbon dioxide and you could pass out without any fuss.  Then you die without a fuss.

    If on the other hand you have a tool for reaching in, and no body parts go beyond the plane of the opening, to borrow from Lily Tomlin: Never mind.



    Edited 6/8/2007 2:21 pm by JohnD1

    1. User avater
      Megunticook | Jun 11, 2007 04:33am | #12

      Don't worry, I'm not about to crawl in there! Just reach down with my arm to open the lid to the tank. Only about 16 inches or so.I spoke with the fella owns a local septic pumping outfit. He said concrete or plastic would be fine, and unless the soil above the tank is especially wet no need to worry about sealing the riser. I gather some of you don't agree with that. I'm leaning toward plastic--I can cut it exactly to the height I want. Can I seal the plastic to concrete with some sort of goop?As far as the frequency of cleaning the outlet filter, I gathered from the contractor who installed the system (and the guy who designed it) that this is normally an annual task. But after my experience the first year, I figure twice a year is a better bet.

      View Image

      Creative Communications | Logos | Business Cards | Websites | http://www.hwaters.com

      1. fingersandtoes | Jun 12, 2007 05:47am | #19

        "I'm leaning toward plastic--I can cut it exactly to the height I want. Can I seal the plastic to concrete with some sort of goop"

        On new installs they are usually attached with epoxy. I have also put them on with the thick tarry rope-like seal they use for joining a two piece septic tank together.

        1. Snort | Jun 16, 2007 04:07pm | #21

          Our health dept requires the riser to be sealed to the tank, normally with mortar, but also with the black tarry rope stuff someone mentioned...the plastic riser/lid is much more complicated to get into than the concrete ones, but they're much lighter than the concrete jobs. Here, any alternative system has to be inspected at least every five years, no way a health inspector is digging around to find lids...LOLI've got a pump to an infiltration system, definitely keep up with the filter or the riser will also be another holding tank<G> Someone's got it in for me, they're planting stories in the press

          Whoever it is I wish they'd cut it out but when they will I can only guess.

          They say I shot a man named Gray and took his wife to Italy,

          She inherited a million bucks and when she died it came to me.

          I can't help it if I'm lucky.

    2. MGMaxwell | Jun 11, 2007 06:56pm | #17

      IIRC It was Gilda Radnar that said "never mind", not Lilly Tomlin.

      1. JohnD1 | Jun 11, 2007 09:15pm | #18

        Never Mind

  6. JimB | Jun 08, 2007 11:43pm | #10

    Several companies make risers for septic tanks, including at least some of the manufacturers of outlet filters (Zoeller, for example).  In this area it's typical to see a section of concrete well casing with a shoebox lid.  That may be difficult to find if you don't have bored wells in your area, but I think you are in Maine and a quick google search turned up this http://www.americanconcrete.com/catalog_pdf/residential/risers/Round%20Risers-Catalog%20Vertical.pdf  Whatever you use needs to be water-tight to keep rain water and groundwater from seeping into the tank.  Some of the plastic risers are made to take a gasket betwen the tank and the riser.

    As a regulator and designer of septic systems, I like outlet filters, and I assume that you are using one manufactured specifically for the purpose.  But it is really unusual for a filter on a home system to need cleaning every year--most get hosed off when the tank is pumped every three to five years.  It sounds like the solids may not be settling out properly.  That could be from too much water getting into the tank (overuse, plumbing leaks, a tank that is not water-tight), the tank is way too small, or too many solids going into the tank (e.g., over use of garbage disposal).  That's the easy guess and it's not possible to really diagnose a septic system problem without being on the site. 

    And it may simply be that the filter you are using filters finer particals than most and is therefore more prone to clogging. If so, everytime you have to wash it, be thankful those solids aren't going into the drainfield and contributing to future failure.

     

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