Guidelines for Data Collected from Monitored Neighboring Wells Associated with Well Pumping Tests for MPWMD Water Distribution System Permits

Prepared by Joe Oliver, Water Resources Division Manager, and

Henrietta Stern, Project Manager

June 27, 2012

As part of the Monterey Peninsula Water Management District (MPWMD or District) Implementation Guidelines associated with Ordinance No. 150 (Noticing) for Water Distribution System (WDS) Permits, this memorandum is intended as a guide for successful data collection from Neighboring Wells, when feasible, in association with Well pumping tests that are completed to meet the MPWMD Well Source and Pumping Impact Assessment report (Well Assessment) requirements. It responds to questions about what Neighboring Well owners should expect regarding data requests by the Applicant’s consultant (who must be a qualified professional as defined in Rule 21-A-9), and the length of time their well must be turned off. Notably, there is no single definitive “standards of practice” manual for Well monitoring. This guidance by MPWMD hydrogeologists as to what is acceptable is gleaned from textbook protocols and professional judgment based on many years of experience in the field. The terms “Applicant,” “Neighboring Well” and “Well” are defined in MPWMD Rule 11. The term “subject Well” means the proposed Well for which the Applicant seeks a WDS Permit. The most recent version of the MPWMD Rules & Regulations may be found at:

http://www.mpwmd.dst.ca.us/ (click on “Rules and Regulations).

Minimum Data Needed from Neighboring Well

The following information is the minimum that should be requested from a Neighboring Well owner in order to assess the feasibility of monitoring the Well in association with the subject Well pumping test:

· Well depth

· Well diameter

· Well completion (e.g., well construction log)

· Type and size of Well access for water level measurement (e.g., sounding tube, Well plate entry).

Suggested Additional Data for Improved Accuracy and Reliability

The following additional information is desirable to help confirm that a Neighboring Well can successfully be used as a monitor Well in association with the subject Well pumping test, and to enhance the reliability of the Well-yield and pumping-impacts analyses in the Well Assessment:

· Type of well pump (e.g., submersible, vertical turbine)

· Depth of pump-intake setting

· Static water-level depth

· Pumping water-level depth

· Occurrence of cascading water in the well

· Operating frequency and rate

· Column-pipe centralizers

· Potential obstructions in the well that could impair water-level device placement or use.

Minimum “Down Time” for Neighboring Well

The Neighboring Well should be idle for 24 hours in advance of the start of pumping of the subject Well, during which time water-level monitoring should be collected to establish an antecedent trend. The Neighboring Well should remain idle during the entire pumping phase of the subject Well pumping test (up to 72 hours, depending on the geologic setting), and for 24 hours after pumping ceases, to assist in verifying hydraulic connectivity, aquifer characteristics and boundary conditions. To enhance the understanding of water-level dynamics that may be influencing a Neighboring Well (such as other active wells in the vicinity), it is recommended that background water-level measurements begin 1-2 weeks prior to the initiation of the pumping phase of the subject Well pumping test. The Neighboring Wells may be operating during this 1-2 week pre-test period.

Reciprocal Well Effects

A Well can potentially influence any other Well in the vicinity, depending on the hydrogeology. Thus, the subject Well might influence Neighboring Well(s) or the Neighboring well(s) might influence the subject Well. Whether or not Neighboring Wells are monitored in association with the subject Well pumping test, the District encourages the Applicant’s consultant to collect, analyze and document water-level data from the subject Well while it is idle (e.g., during a 1-2 week period prior to the Well pumping test) to determine if there are any observable drawdown effects from Neighboring Wells. This information could assist in the assessment of the subject Well impacts to Neighboring Wells, especially if the Neighboring Wells are not monitored.

Infeasible Monitoring due to Technical Factors

In some cases, a Neighboring Well owner may agree to have his/her Well monitored and provides the requested information, but the Well cannot be successfully monitored due to technical reasons. These might include: no water-level device access, inadequately-sized access, and questionable reliability of water-level data collection due to Well design, construction or condition. If a Neighboring Well cannot successfully be monitored for technical reasons, the reasons should be clearly documented in the Well Assessment, based on the professional judgment of the Applicant’s consultant.

MPMWD Not Responsible for Well Damage

If a Neighboring Well owner agrees to have his/her Well monitored, and damage to the Well is alleged to occur as a result of such monitoring, the MPWMD shall bear no responsibility or obligation with regard to any alleged damage to a Neighboring Well or to monitoring devices used for the subject Well pumping test. The monitoring arrangement is solely between the Applicant’s consultant and the Neighboring Well owner(s).

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Revised 6/27/2012