EPHRATA - The state accepted a plan to monitor the septic systems at the Grant County Fairgrounds for the next two years.

Richard Benson, with the state Department of Health's large on-site septic system program, approved a plan for the county to build three monitoring wells focused on the largest of the fairgrounds septic systems.

GSI Water Solutions' Hydrogeologist Kevin Lindsey prepared the plan after the Department of Health required the county to get a permit for the large on-site septic systems.

The potential number of large on-site septic systems, the fairground's size and the complexity of the hydrogeology makes monitoring the entire fairgrounds a problem, according to the plan.

"One site will be monitored and evaluated, and this site will be used as a surrogate for evaluating the potential impact to groundwater of the fairgrounds as a whole," according to the plan.

The site, located near the rodeo arena, receives waste from four of the most commonly used restrooms, according to the plan. Other drain fields receive waste from a single, generally lower use restroom.

The plan calls for the county to drill three monitoring wells. One will be placed "upstream" of the system, and two will be placed "downstream," according to the plan. County staff will monitor the amount of waste going into the system. GSI will oversee the testing at the monitoring wells.

The samples are going to be tested for nitrogen, nitrate, ammonia and orthophosphate, according to the plan. Testing is expected to start by mid-April 2012, and a second test in July 2012.

Following the fair, the plan calls for three more tests at two weeks, four weeks and eight weeks after the fair. Three additional samples are expected to be taken in November 2012, February and April 2013.

"Fairgrounds use currently is episodic, with peak uses associated with specific events.  The largest of these events is by far the annual county fair," according to the plan. "It is the intent of this plan in the first year of monitoring to schedule specific groundwater sampling events before and after the county fair in an effort to build a picture of groundwater impacts, if any, from these peak use events."

The plan calls for quarterly samples for the second year, with samples taken in July and October 2013 and January and April 2014, according to the plan.

Once all the data is received, a final report will be prepared. The report will analyze whether the septic systems affect Moses Lake, and suggest whether monitoring should continue.

Commissioner Cindy Carter said the county plans to contract with GSI Water Solutions to continue the work.