Sandy Well

[Travis Slagle]

Hi guys-

We bought a one acre property with a known sand problem, and have city water to connect to as a backup measure.

300' well
Pump at 180'
Water level at 120'
New Grundfos pump
7.5gpm Dole flow restrictor at pump inlet
Lakos TwistIIClean filter installed

Problem statement:
The well is producing enough sand that we have to purge the Lakos filter multiple times per day. Sometimes it makes it through an entire shower without a drop in pressure at the showerhead, sometimes not. We have to purge it before almost every load of laundry or dishwasher load. In addition, 7.5GPM is insufficient flow for our home (2 adults, 4 kids). I have tried turning on the sprinkler system once, and don't even have enough flow to find out what the issues are with it. The pump company installed the flow restrictor in an attempt to suck up less sand.

The pump company is coming out today to put a camera down the well and see if the casing has failed. I am also going to have them remove or increase the size of the flow restrictor and possibly change the pump level.

The neighbors in this area all have similar issues, but usually call the well company to come out and 'tweak' the setup when it gets worse. They change pump level or flow and get it to settle down.

I have been considering installing a Lakos Sandmaster or similar centrifugal filter with an auto-purge valve. One concern about that solution is that the sand we are getting is a wide range of sizes. Some of it is beach sand sized. I am confident the Sandmaster would take care of that sand. But there is also a MUCH finer sediment that doesn't settle out for multiple hours. When it does it creates a sticky paste. I don't know if the Sandmaster would deal with this particle size. If not, and I have the TwistIIClean or similar filter after the Sandmaster, I might spend thousands and not have an improvement! Some of this fine sediment does get through the TwistIIClean because we have a Berkey filter in the kitchen for drinking water. The fine sediment is getting trapped in the 'dirty' portion of the Berkey filter.

Does a centrifugal filter such as a Sandmaster make sense?
Are there other solutions out there that I should research?
Does anyone make an auto purge valve that is based on pressure drop across the filter rather than time?

 

[LLigetfa]

Describe the well in detail. How far down is the casing? Is it slotted (screened) in some portion? What size casing? Putting an extra long flow inducer sleeve on the pump may help if it is top fed meaning there is no casing or screened casing above the pump.

Also describe the pump cycling in detail as cycling can exacerbate the motivation of sand. In such cases, using a CSV may help.

 

[Sponsor]

 

[Valveman]

I hope the well guys can figure out where the sand is coming from and fix the problem. Your pump will not last long pumping that much sand. Like LL says a long flow inducer may help, or you can get a Lakos SubK, that will keep the heavy stuff from getting into the pump. In our area we gravel pack the well with stuff that looks like it comes from a sand media filter. This really small gravel will keep the sand from getting into the well in the first place. My rule of thumb is if the pump will last 5 year, filter the water. If the pump will not last 5 years, drill a well that doesn't make sand.

 

[Boycedrilling]

I’m installing a Lakos sub K on a well right now. Pump is set at 900 ft.

A Lakos sub K will centifuge 95% of sand down to 100 mesh. Their above ground centrifugal filter will do 95% of sand to 200 mesh. As I remember right they say if it will settle out in less than 30 seconds, their centrifugal filter will work.

If you have turbidity that won’t settle for hours, thats a whole ‘nother beast. Your now talking flocculation and coagulation.

 

[Travis Slagle]

LLigetfa-

The original well (1992?) was 95' or 100' with a 6 inch diameter casing. Shortly after the original well was drilled it was deepened to 295'. The deepened portion of the well is a 5" casing from 95' to 295'. There are a quantity of four 3/32" perforations (or slots) at 100', 180', and 240'. There is no gravel filter pack around the 5" casing, which the well guys today are pointing at as the source of the problem. The bottom of the well is not open as they knocked an old pump to the bottom.

I'm not sure how often the pump cycles. We have a 22 gallon pressure tank. What is a CSV?

The pump company came out yesterday and today. They removed the pump yesterday and then came back today after the well was clearer. The video inspection of the well showed no holes in the casing. They ran the pump at a variety of flows. Their recommendation was to leave it as is. I pushed back and had them install a 12gpm Dole flow restrictor. I figured if I was going to pay them $1500 I should at least try to change something!

One thought I had:

The current TwistIIClean filter I am using is a T2C-100 with a 150 micron filter element. According to Lakos they also offer a T2C-200 that would increase the filter area from 12 sq in to 55 sq in. In theory that should cut down on my filter purges by a factor of four, right?

 

[LLigetfa]

There are a quantity of four 3/32" perforations (or slots) at 100', 180', and 240'.

With the pump hanging at 180 feet, some of the sand silt could be coming in from above but a flow inducing sleeve would be a tight fit in a 5 inch casing.

A CSV is a Cycle Stop Valve. It reduces the flow rate close to the actual amount you are drawing and stops the pump from cycling. Pump cycling can sometimes "surge develop" the well which can motivate silt/sand.

 

[Reach4]

http://www.lakos.com/_literature_178295/LS-304_SUB-K_Brochure describes the Lakos sub K.

A flow inducer sleeve is often constructed of solvent weld D2729 sewer pipe: OD 4.215 ID 4.056. It is much cheaper than the Lakos Sub-K.