Borehole Pump Installation

The water rest level is 140m.

the voltage either 415v 3 phase or 240v single phase

Okayy.... That answers one question among several.

Do keep British Standard 7671 handy. It will be needed....

For what kind of duty do you require the pump?. Is it for short time to fill a tank(s) or bowsers or to continuously operate 24/7 for sprinkler irrigation called centre pivot system?. You must pump water out till level goes very low and measure well production(how long it takes for the water to comeback to -or near- the original level). Based on that you should decide Q.His known to you,so write to manufacturer.

What size motor were these disparate quotations offering?

Did the vendor who quoted a smaller size cable also offer a smaller motor?

Did the vendors offer any calculations with their proposals?

Make the vendors work harder for their money.

If you can calculate what is needed independently than you can vet the proposals confidently.

Pumping volume rate and head will determine your pump size. The pump size, operating voltage and cable length will determine the conductor size.

1. Do a prolonged and reliable pumping test.
2. Determine water level at various flow rate.
3. Get pump's mfg performance charts.
4. From the charts determine number of stages required.
5. Calculate power required based on your water level and flow rate and number of stages
6. Get submersible pump cable specs.find Ampacity, take a good safety margin.

Your pump is relatively small. 4" multistage. if you have 3φ system USE it. Get the best pump you can afford and design it WELL. getting a pump from 150 meter deep is a pain in the butt...Hope it helps.Wangito.

Don't forget to take water sample,measure its temperature at starting and after pumping for long time and get sample tested in a lab for anions,cations,pH,sand content,TDS, etc

and send to manufacturer with your quote request. For the pump installation there should be low level alarm,dry running protection,voltage monitor relay,thermistor relay etc

Here is a very good Link that you and every layman can follow regarding the development (design of pumps, yield testing, etc.) of your water well:

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/wwg408

Note: In order to obtain consistent quotations from the Contractors you will need to prepare some sort a Contract Documents and Bidding Forms (both of which are legally binding documents) that effectively (and exactly) spell out what is required from them regarding their price quotes. Make sure there is language within these documents that pints out that any bidding deviations from them could result in their bids being rejected by you, the Owner.

Honestly, I think you need to hire a local Licensed Civil Engineer to oversee this process, as well as to properly design and size the well pump, it's controls, etc., plus provide Construction Administration to verify conditions and to assure you that everything has been installed properly pursuant to the Contract Documents.

Water well construction is extremely expensive and you may want to hire a design professional to prevent undersizing/oversizing of the well pump. To do otherwise could potentially cost you a lot of money to rectify errors and omissions regarding the installation work. Also, it is extremely important that water well Yield Tests be performed. I can't stress that requirement enough!

Why did you recommend to hire a civil engineer for this?. An experienced(pumps/water supply) mechanical engineer should be considered.