BLM Buffalo Field Office Grant: Deep Groundwater Monitoring in the Powder River Basin

B. Project Objective: The WSGS will prepare a deep groundwater monitoring report which will present the following: baseline water levels within the PRB coal zones based on collected data; summarize groundwater level and wellhead pressure changes; identify potential hydraulic connectivity with overlying and underlying sandstone beds and estimate magnitude; correlate results with surrounding CBNG production; and compare to the impacts predicted in the PRB FEIS groundwater model. Some specific objectives are as follows:

1. Quantify drawdown in the production zone, and leakage between the coal production zone and overlying or underlying aquifers. These data are critical for both groundwater model and impact analysis verification.

2. Present well head pressure build-up data in production zone monitoring wells which can indicate the in-situ desorption pressure of methane gas.

3. Measure potential changes in methane gas concentrations in monitoring well bores to detect gas migration from the production zone to other formations.

4. Quantify groundwater recovery and recharge rates following the cessation of CBNG production. Little is known about recharge mechanisms in the PRB, rates of water level recovery following the cessation of CBNG production may be used to estimate recharge rates and duration of potential impac