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of the US Geological Survey |
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Groundwater is water found beneath the surface of the land. Here in
Redmond, and in most of the Puget Sound Lowlands, groundwater is often
found in sand and gravel deposits. Precipitation percolates through the
ground in the spaces between the grains of sand and gravel until it
reaches an impermeable layer or layer saturated with water (aquifer).
The City of Redmond sits atop a large aquifer, called the Alluvial
Aquifer, which was formed by ancient river and glacial deposits over
10,000 years ago.
Redmond operates five shallow production wells that draw groundwater
from the Alluvial Aquifer beneath the downtown and industrial core of
the City. Clean drinking water from these wells is delivered to homes,
businesses and industries to the area east of the Sammamish River. The
City produces this water at about half the cost of water purchased from
the Seattle regional water system. Because nearly 40% of Redmond's water
supply comes from groundwater, our water rates are among the lowest on
the Eastside.
Just like many of our other natural resources, groundwater can be
threatened by improper use, storage or disposal of harmful chemicals and
substances (hazardous materials). Some examples of potential threats to
groundwater supplies include underground storage tanks, septic systems,
cleaning solvents, automotive fluids, pesticides, and even contaminated
stormwater. If hazardous materials enter the groundwater the aquifer can
become indefinitely unusable.
Our groundwater is very shallow, only 5-20 feet below the ground, and is
highly susceptible to contamination by improper hazardous chemical use
and disposal. We use our groundwater for drinking water; if it becomes
contaminated we would have to replace it with alternate supplies until
it could be cleaned up, which could take years. Cleaning up the
groundwater is extremely expensive and inefficient, often costing 100
times more than preventing the pollution in the first place; in some
cases it can't be cleaned up at all!
The area surrounding the City's drinking water wells is called a
wellhead (the "head waters" of the well). The Federal Clean Water Act
mandates that the City develop and implement a program to ensure that
the source area of our drinking water is protected. The City's Wellhead
Protection Ordinance (RMC 13.07) meets the federal requirements in the
protection of your drinking water resource. The City's Wellhead
Protection Program puts the Ordinance requirements into practice. To
review the Ordinance click on the following link
Wellhead Protection
Ordinance (This pdf file is 350 kbs. and may take a while to download
with a dial up modem).
The Wellhead Protection Program's central theme is focused on
preventing pollution. We protect the general public health and prevent
contamination of groundwater by educating people about our water supply,
helping them to understand how to properly manage their hazardous
materials, preventing new activities that pose a hazard and enforcing
the requirements of the ordinance.
The City is taking the following actions to help protect our
groundwater:
- The City is implementing its Wellhead Protection Program in
compliance with State and Federal requirements;
- Wellhead Protection Zones have been established around the City's
water supply wells;
- Performance Standards have been developed to encourage groundwater
protection;
- New facilities or activities that may pose a significant hazard to
the groundwater are prohibited;
- Inspections and technical assistance visits are conducted to help
businesses and facilities comply with environmental regulations that
help to protect our groundwater;
- Groundwater monitoring activities are being conducted to detect
and monitor the presence of contaminants in groundwater;
- Environmental investigations, cleanups and construction activities
are monitored to ensure that impacts to our drinking water supply are
minimized, and,
- Developing and building capital improvement projects that will
further help to protect the groundwater.
All residents, businesses and facility operators
within the City of Redmond can help to protect our groundwater by
properly managing their hazardous materials in order to prevent soil and
groundwater contamination.
Businesses and facilities in closes proximity to
the drinking water wells (Wellhead
Protection Zone Map) will be asked to provide information and
implement practices to help protect the groundwater. Implementation of
these requirements and protective measures began phasing in with
Ordinance adoption in 2003. The measures include:
- Annual Reporting of Hazardous Materials Use to the City
- New Development, Construction, and Tenant Improvement Performance
Standards and Prohibitions
- Stormwater Infiltration Standards and Prohibitions
- Secondary Containment Requirements
- Clean Fill Material Source Statement
- Installation, Protection and Data Submittal Requirements for
Groundwater Wells and Borings
- Hazardous Material Spills and Releases Reporting
- Reporting of Site Closures and Remedial Activities
- Elevator and Hydraulic Lifts Inspection
- Best Management Practices Requirements
For a full listing of measures and more
information on these requirements and how they may affect your business
please click on the following links:
What you need to know about
Wellhead Protection.
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