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Syria - Well Yield Test - Adapted step test

Looking for criticism of this dumbed-down test to be conducted by non-technical crew in Syria. If test is passed the source (well/borehole) will be deemed candidate for install of low discharge pump (upto 6gpm).

Current Well Statistics

“Depth” being measured form top of well casing

Current demand on well – Cubic meters per day. During test phase this is termed Base Demand. Based on... Number and size of vessel, Pumping, if any – duration and discharge of pump(s)

Depth of well (meters) (meters)

Depth of pump intake (meters) (p)

Depth of surface of water in morning before water drawn (meters) (s). Static head is to be taken as (p-s)

Depth of water in evening (meters) (e). Daily drawdown is taken as (s)-(e)=(d)

Confirmation of Yield of Source – Adapted Step Test

Once the current yield has been established the following tests should be run. Note – it is assumed that water continues to be drawn at previous rate during the test. Thanks!

  1. Test A. Pump water at same rate as Base Demand. Record water level every 15 minutes until Static Head(s) is 10m and then every 5 minutes. Stop pumping if less than 5m. Stop pumping after one hour = “success” or when level 2d (twice the daily drawdown) is reached. Measure level in 15min intervals till level d (daily drawdown is reached). If “success” proceed to Test B

  2. Test B. Pump water at twice Base Demand. Record water level every 15 minutes until (s) is 10m and then stop. Stop pumping after one hour = “success” or when level 2d (twice the daily drawdown) is reached. Measure level of rising water in 15m intervals till level d (daily drawdown is reached). If “success” proceed to Test c

  3. Test C. Pump water at three times Base Demand. Record water level every 15 minutes until (s) is 10m then stop. Stop pumping after one hour = “success” or when level 2d (twice the daily drawdown) is reached. Measure level of rising water in 15min intervals till level d (daily drawdown is reached). If “success” proceed to Test D

If 3x Base rate is less than 25 liter/min then…

  1. Test D. Pump water at rate of 25 liters/min record level every 15 minutes until Static head is 10m and then every 5 minutes. Stop pumping if less than 5m. Stop pumping after one hour or when level 2d (twice the daily drawdown) is reached. Measure level of rising water in 15min intervals till level d (daily drawdown is reached).
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I suggest you add to the process (I agree with the previous comment by Richard) a description of what and how you are trying to measure and/or the rationale to the measurement scheme. If people understand the rationale you are less likely to induce errors.

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Dear Nigel, I see you've had no responses to this. Possibly that's because what you propose and describe is a little bit involved. I've looked at it a few times and postponed replying until I had time to get my head around what you propose to do.
Frankly the question in my mind is "why re-invent the step-test, when there are well established ways of conducting them?" The usual way of conducting a well test or step-test would be to pump at a series of different discharges (your 'base rate', 'base rate times two' etc) while recording water levels frequently at first (when drawdown is happening quickly) and less frequently as time goes on. You can either allow full recovery between steps, or pump for a fixed duration per step, opening the outlet valve between steps to increase the discharge, without recovery. You may also want to carry out a longer constant discharge or aquifer test, as this would enable you (a) to estimate aquifer transmissivity, and (b) perhaps pick up any nearby aquifer boundaries which ultimately might limit planned abstraction rates. Standard methods for test pumping are described in the British Standard Code of Practice, the ILRI publication by Krusemann and de Ridder, and in all standard hydrogeology text books. Anyway, good wishes with whatever you decide to do. Richard Carter.

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Asked:
2016-06-19 06:25:03 -0500
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Last updated:
Jun 30 '16