The Administration is requesting $226,220 for groundwater monitoring engineering services at their 10/20/09 City Council Meeting.
UPDATED 10/21, City Council approved the funding for this project. We (Administration) propose installing twelve additional groundwater monitoring wells and three "high pressure water monitors" at selected sites for use in conjunction with surveying and monitoring. The proposed monitoring facilities are designed to track the recharge of groundwater and the potential influx of contaminants into the Redmond alluvial aquifer. We propose contracting for professional engineering services in an amount of $226,220 for the Groundwater Monitoring Network Project.
The objective is to obtain additional monitoring data that will lead to a better understanding of movement of groundwater and contaminants within the Critical Aquifer Recharge Area (CARA) and understand the primary mechanisms by which groundwater in the City’s alluvial aquifer is recharged. Three principal recharge processes are recognized, as follows:
Direct infiltration of surface water flows into Bear Creek, Evans Creek, Sammamish River.
Stormwater infiltration from retention ponds, vaults, storm drains and other infiltration facilities throughout the City; and infiltration through previous surfaces (dirt, sand, beddings, grass, etc.)
Upland runoff that percolates into the margins of the alluvial aquifer at the valley floor.
Documents and Maps of the critical recharge areas, proposed groundwater monitoring wells and pressure monitors and streams :
http://redmond.gov/insidecityhall/citycouncil/20091020pdfs/AM09225.pdf
BACKGROUND
The City of Redmond operates five shallow groundwater supply wells that deliver between 3.5 and 5 million gallons of water per day, supplying approximately 40 percent of Redmond’s drinking water. These five wells, which draw from the shallow alluvial aquifer, are located in the heart of Redmond’s downtown and industrial areas, and are highly susceptible to contamination due to the local geology and proximity to potential pollution sources. In October 2003, the City Council adopted a wellhead protection ordinance to meet federal, state, and regional requirements for the protection of the Critical Aquifer Recharge Area (CARA) and the City’s drinking water supply. An important requirement of the ordinance is the establishment of a city-wide groundwater monitoring program to detect the presence of contaminants and declines in water levels before they impact a water supply well.
Hazardous Materials Questionnaire and Aquifer Map.
Source: Redmond City Council Consent Agenda, 10/20/09
posted by Bob Yoder