Federal Way

General Information:

In operation since 1991, Federal Way has 1 ASR well accessing the Mirror Lake aquifer. The Lakehaven Utility District developed ASR as part of their “OASIS” project, which stands for Optimization of Aquifer Storage for Increased Supply. Hydrogeologists, with Robertson Noble, estimated the Mirror Lake aquifer has a storage capacity of up to 9.5 million gallons of water. The current ASR well (well # 25) injects and recovers up to 3000 gallons per minute. Additionally, up to 27 future ASR projects have been proposed.

Additional Information:

Lakehaven Utility District's OASIS Project: ASR in Progress 
Abstract from: National Groundwater Association: Stormwater Management (April 12, 2010, Denver, CO)

F. Michael Krautkramer, Robinson, Noble & Saltbush Inc. Tacoma, WA
Joseph E. Becker, Robinson Noble &Saltbush Inc., Tacoma, WA

In the early 1980s, Lakehaven Utility District began producing water from the highly transmissive Mirror Lake Aquifer. Incomplete recovery from that production led to the idea of using the aquifer for Aquifer Storage and Recovery (ASR). Following initial testing of an ASR well, the District began to investigate the possibility of large-scale ASR. The concept was titled “Optimization of Aquifer Storage for Increased Supply” or OASIS. A 1994 feasibility study concluded that 29,000 acre-feet of water could be artificially recharged, stored, and later recovered during annual production/recharge cycles using 27 ASR wells. The study estimated the project could be operational by 2000 and fully built out by 2040.

Though the District wished to pursue the project, a required Reservoir Permit was not issued by Washington State until September 2006. The permit is phased, with two 6-year pilot phases and eight 6-year operational phases, making the project operational at the earliest in 2018 and not fully operational until 2066. The maximum annual ASR quantity (Qa) during the pilot phases is 5,000 acre-feet. The Qa increases with successive phases, so that under the final phase, the permit allows the fully projected storage of 29,000 acre-feet. Injected water must come from existing water rights and can occur from November to May. Recovery is allowed from June through October. Prior to becoming operational, the District must address the State’s concerns about induced leakage from surface water bodies and overlying aquifers, slope stability, potential land-surface subsidence/uplift, and water quality changes. Extensive monitoring is required during both pilot and operational stages.

The District has begun Phase 1. Work to date includes monitoring springs and local streams, constructing monitor wells, and installing a new ASR well. Near-term future work includes ASR testing using groundwater as a source and constructing a new numerical model of the aquifer.