By Sue Danver
Even before COVID-19, warehouses and applications for mega-warehouses along I-5 were creeping into Lacey, Tumwater, and Thurston County. Since the COVID-19 pandemic the plans for warehouses have accelerated. With limited large tracts of land close to Seattle and delivery services popular, warehouse developers find Thurston County’s relatively inexpensive lands extremely attractive. Unfortunately, warehouses and their huge impervious footprints, many over a million square feet, could seriously threaten Thurston County’s aquifer and extensive wetlands, streams and prairies. Thurston County and its jurisdictions, some more than others, are unprepared for this invasion.
When the Thurston County Water Recharge section of the Comprehensive Plan was last completed about a decade ago, no one anticipated increased infiltration or injection of storm water runoff to our drinking water aquifer, in some cases by penetrating through the protective till layer. It would be wise for Thurston County to immediately address this issue and update its water recharge ordinances to stop and/or at least modify and monitor the engineering practices being employed currently by warehouse developers.
For the past two years, BHAS dedicated funds to hydrogeologist Jim Mathieu to investigate the engineering plans for Puget Western’s Distribution Center at the southeast corner of I-5 and 93rdAve. The warehouse will be 1.1 million square feet and located in the Salmon Creek Basin watershed, famous for its flooding during winter rains.
After the participation of four hydrogeologists, including Jim Mathieu, and several comment exchanges, the hydrogeology consultant for the City of Tumwater rejected BHAS’s concern and concluded that the engineering designs by Puget Western would meet Tumwater’s storm water code.
This decision is troublesome. We believe the developer’s model is insufficient and cannot determine whether the proposed storm water mitigations will work. In defeat, our final request of Tumwater was to minimally install monitoring to collect data from fall 2020 through summer 2021, thus improving the data and analysis used to design the building’s storm water infrastructure. Monitoring would also demonstrate post-construction effectiveness at properly managing storm water quantity and quality. This type of monitoring is a reasonable standard of care which would inform necessary modifications, if needed, to Puget Western’s warehouse site storm water management. Such monitoring would also provide helpful information to water managers engaged in future warehouse proposals in areas of high groundwater tables, and where local citizens withdrawal their drinking water.
Tumwater staff chose not to monitor the approved warehouse site.
