Water Stewardship

Guidelines for Minimum Standards in Water Well Construction, Province of British Columbia — June 1982

Part 2 — Technical Information Appendices

APPENDIX 5: COMMUNITY WATER SUPPLY WELLS, GROUND WATER REPORTS AND WELL TESTS IN SUPPORT OF A CERTIFICATE OF PUBLIC CONVENIENCE AND NECESSITY

1. General Information

Well performance and aquifer capabilities must be adequately assessed where a ground water supply is to be developed for community use. Certain procedures must, therefore, be followed in well testing and the presentation of ground water information by the applicant to the Comptroller of Water Rights for a Certificate of Public Convenience and Necessity under the Water Utility and Utilities Commission Acts. The intent of these requirements is not to lay down rigid rules but to avoid unnecessary delays or retests at the applicant's expense due to inadequate test procedures or report presentations. The Comptroller, with the assistance of the Ground Water Section, Water Management Branch, is prepared on request to review the requirements for any particular case with the applicant or the applicant's engineer prior to the well test.

The applicant is advised to retain the services of a consulting ground water geologist or a professional engineer whose field of competence lies within the ground water field. The final ground water report presented should where possible discuss such points as the geologic setting, aquifer boundaries, recharge conditions, water quality, possibility of pollution, contamination, including salt water and other unpotable water, recommendations, if any, on a future monitoring program, observation well(s), operation of the well, e.g., overpumping, backwashing, rawhiding, etc. The report is to include a site plan showing locations of the well sites, locations of any unsuccessful test well sites, and any neighbouring wells. The sites are to be shown in relation to existing gazetted roadways, streams and lakes, sanitary land fills, septic field disposal, and the boundaries of any municipalities, improvement districts, etc., in the vicinity. The site plan should show the locations of water sources of other water works within one half mile of the boundaries of the proposed utility, also the location of any wells that may be affected through interference by pumping of the applicants well. A legal description of the proposed well site areas must be provided including where possible registered plan and lot numbers as assigned by the Local Land Registry Office. Approximate elevations should be given on each well assembly, and if possible elevations on important adjacent features such as lake levels, river levels, etc. The report should contain a copy of the well driller's original log for every hole drilled under the program, and also a sketch showing well design specifications for each completed well. Details should be given of the pumping equipment used, and the method of measurement for water well readings and for flow.

At least one sample of the pumped well water must be taken near the end of the pump test and sent for chemical analyses. The analyses should include all major ions, iron and manganese, and tests for other metals if known to be present in the ground water of the area. A list of recommended parameters is given in Section 3 of Appendix 7. Preferably two water samples should be taken, one near the end of the pumping test and one near the beginning of pumping, e.g., almost one hour after start of pumping. The applicant is expected to make his own arrangements with a commercial laboratory for this service. The laboratory's requirements for sample collection and transmission should be adhered to. Samples for bacteriological analyses should also be taken according to the requirements specified by the Ministry of Health (see Section 4 of Appendix 7).

Pumping tests, recording of data and report preparation should follow standard procedures. For example with field measurements the drawdown and recovery measurements in the pumped well and in the observation wells should be measured in feet to the nearest one hundredth of a foot. The time intervals for both drawdown and recovery readings should be short enough to adequately record any rapid drawdown during start of pumping and any rapid recovery immediately after pump shut down. The time interval after these initial periods can of course then be lengthened between the readings. The pumping rate Q of the water well is to be expressed in U.S. or Imperial gallons per minute or metric equivalents. The pumping rate Q is to remain constant throughout the period of pumping, in the final "constant rate" test. This test will involve continuous pumping at a constant rate for 24 hours or longer (see special conditions). Step drawdown tests or "maximum drawdown" tests can be used initially to determine the Q rate but these tests are not mandatory. Well water must not be allowed to return to the aquifer during the pumping test period. Sufficient discharge pipe must be laid away from the test well to prevent this possibility arising. The reader is referred to the tables on the next page for the type of information to be recorded in pumping and recovery tests. A record of any rainfall immediately before, during and after the well test should be reported. Certain conditions may be attached to the certificate with regard to the well source, for example the further collection of data during subsequent well operations and in certain cases a hydrogeological report may be mandatory. These special requirements have to be met where legal problems arise in the development of ground water supplies such as ground water withdrawals affecting stream and spring flows which may be under license, where supplies of water to adjacent well, may be affected by pumping or where a producing aquifer is suspected of being limited in extent or capacity.

2. Special Conditions

A. Boundary Conditions

If recharge or discharge boundaries are detected, then more frequent measurements are also recommended. This can best be done by returning to the time interval set out for the commencement of the test, i.e., "every minute from 1 to 10 minutes," etc.

B. Induced Infiltration

This condition could apply in well sites located adjacent to a surface water body, river, lake, etc.

If equilibrium test conditions are clearly shown, that is, a stable water level in the well in conjunction with a uniform rate of pumping, the test may be terminated prior to the recommended standard 24 hour pumping period.

C. Fractured Bedrock

For wells located in fractured bedrock the pumping rate should be at or in excess of the requirements of the application. The pumping rate must be held constant throughout the testing period which should last for a minimum of 72 hours. In the Gulf Islands and in coastal areas, wells are only to be tested in the middle and late summer and early fall periods. Developers and engineering consultants should coordinate their activities to provide for the testing of wells during the above stipulated periods. Such a procedure would avoid unnecessary delays and will enable a more accurate estimate of well performance to be made.

D. Flowing Artesian Condition

In this special case, it is essential to note the artesian pressure head prior to and after a pumping test.

E. Developed Springs and Seepage Sites

In the case of springs and seepage areas developed by excavation into ponds and "holding reservoirs" the following procedures are recommended. The excavation dimensions must be noted. The reservoir must be (if practical) pumped dry and recovery measurements taken as specified above under general comments. The full recovery should be obtained. Notes regarding entry of water into the excavation should be made where possible.

F. Coastal Aquifers

The need for carrying out the recommended procedures for taking samples of the pumped well water for full chemical analyses is emphasized. It is also strongly recommended that a field test kit be available for testing the chloride content of the pumped water during the pumping test. The purpose of the recommendation is to try to determine possible sea water encroachment. If encroachment is evident the pump test may have to be terminated. In coastal aquifers the consultant must include data on local tidal fluctuations where these are affecting the apparent drawdown in the test well.

PUMPING TEST

Depth to water in well from top of casing before test _______________ ft.

For the above table, readings should be taken every minute from 1 to 10 minutes and then every 10 minutes from 10 to 120 minutes (2 hours), then readings every 11/2 hours thereafter.

A preferred method for ease in plotting the data, but one that is harder to comply with is as follows:

Readings every 30 seconds from 1 to 5 minutes

Readings every minute from 5 to 10 minutes

Readings every 2 minutes from 10 to 20 minutes

Readings every 5 minutes from 20 to 50 minutes

Readings every 10 minutes from 50 to 100 minutes

Readings every 100 minutes thereafter

RECOVERY TEST

For the above table, readings should be taken every minute from 1 to 10 minutes and then every 10 minutes from 10 to 120 minutes (2 hours), then readings every 11/2, hours thereafter. Slow recovery may require that the last readings be spaced as much as 8 to 12 hours apart.

A preferred method for ease in plotting the data, but one that is harder to comply with is as follows:

Readings every 30 seconds from 1 to 5 minutes

Readings every minute from 5 to 10 minutes

Readings every 2 minutes from 10 to 20 minutes

Readings every 5 minutes from 20 to 50 minutes

Readings every 10 minutes from 50 to 100 minutes

Readings every 50 minutes from 100 to 500 minutes

Readings every 100 minutes from 500 to 1,000 minutes

Readings every 500 minutes from 1,000 to 5,000 minutes

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