City staff reviewed record drawing across the City and notified owner/operators of stormwater infiltration systems of the requirements. If you were not contacted by the City, but suspect you have an infiltration system review construction drawings or contact Kevin Murphy at 425-556-2756.
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What types of stormwater infiltration systems are regulated and by whom?
Owners or operators of any facility within the City of Redmond's Wellhead Protection Zones 1 and 2
are required by the City of Redmond’s 2003 Wellhead Protection Ordinance to evaluate and upgrade their stormwater infiltration systems to ensure protection of the drinking water resource. Stormwater systems that infiltrate stormwater into drywells, perforated pipes or trenches, bottomless vaults or infiltration ponds (Typical Stormwater Infiltration Systems
) are regulated by this ordinance.
The Washington State Department of Ecology (Ecology) and U.S. Environmental Protection Agency also require registration, assessment and modification of many of these same infiltration systems. The City is coordinating with Ecology so that owners who meet Redmond's requirements will also be in compliance with the Ecology's rules on infiltration.
Stormwater infiltration systems outside of Wellhead Protection Zones 1 and 2 are regulated by Ecology and not the City. Ecology refers to perforated pipes or drywells used to infiltrate stormwater below the ground surface as Underground Injection Control Wells, or UICs. Ecology regulates all UIC wells in the state This link will take you directly to the Department of Ecology website where you can register your UIC-type stormwater infiltration system
. Ecology also requires an assessment of these stormwater infiltration systems.
Owners of the known stormwater infiltration systems located within wellhead protection zones 1 and 2 have registered their systems with the City of Redmond and Ecology.
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Owners are now required to complete an assessment of their stormwater systems to ensure protection of the groundwater resource by February 3, 2011. City and state codes require that the assessment be complete by February 3, 2011, but encourages completion of the assessment well in advance of this date.
The assessment criteria along with a schedule for completing assessments and modifications to existing stormwater infiltration systems was adopted by the City Council as Ordinance 2521
on February 2, 2010. Resolution 1321
was also adopted to provide incentives to owners to complete their assessments and modifications before the deadline which will provide for earlier implementation of groundwater protection measures.
Assessments, for systems located in Wellhead Protection Zone 1 and 2, submitted to the City by February 2, 2011 will be eligible for up to $4,000.00 in 50% matching funds. Please read the instructions for complete details on the incentive program (Resolution 1321) and elimination of permit fees for required modifications.
The City of Redmond Existing Stormwater Infiltration Assessment Criteria was developed to help owners and the City assess the specific risks presented by individual facility uses to the groundwater. Owners/Operators will provide information by answering 12 questions in four categories to evaluate risk: Assessment Form
and Instructions for Completing the Assessment
- Land Use - information on specific actions, materials, and products being used within areas that drain to the infiltration system.
- Location - proximity to public or private drinking water wells.
- Infiltration system description - size and treatment capacity of the system and depth to groundwater.
- Risk Reduction - list pollution prevention measures already in place at the facility.
Points are assigned for items in each category, and at the end of the form the points are tallied. Sites with scores less than seven (7) are identified as low risk sites. Low risk sites must implement Best Management Practices
(BMPs) applicable to their site as currently required by the Wellhead Protection code.
Sites with scores higher than seven (7) are identified as potential significant groundwater hazard sites. Those sites must implement required BMPs
as well as site specific BMPs that are applicable to their operations as well as modifications to their systems. The Assessment is written in such a way that it can be used as a guide for determining which types of modifications that can be applied to a site to reduce its risk score.
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The goal of the assessment process is to determine the risks to groundwater at a facility and determine what modifications can be made to operations, physical structures or to the stormwater system itself is to reduce each site's risk level to less than eight (8) points. Implementing permanent measures to protect groundwater quality will be required at all facilities.
City staff will review the Assessment for completeness and accuracy; all questions must be answered on the assessment for the City to accept it and issue a Voucher letter. The Voucher letter is important because it documents that a facility has complied with the City and State requirement to complete an assessment of the stormwater system. It is also important to the facility owner because it documents the date the City has accepted the Assessment and the owner's eligibility for the Groundwater Protection Incentives
The Flow Chart
graphically describes the process and approximate schedule for completing the assessment, review, work authorization, design, permitting and incentive process.
Schedule and Process for Review and Modification:
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- Implement appropriate BMPs to protect groundwater immediately.
- Submit assessment before February 3, 2011 for a $4,000 voucher and reduced permit fees.
- Submissions after February 3, 2011 will be in violation of State and City codes and may be subject to penalties and will not be eligible for a voucher.
- The City will schedule assessment reviews within 60 days of receipt of the assessment form.
- A facility specific modification schedule will be developed during the review; emphasis will be placed on the highest risk systems.
- After the City has reviewed the assessment, they will issue an Authorized Work letter and schedule detailing the work that must be done to reduce the risk to groundwater at the facility.
- The modifications approved by the City will also satisfy Ecology's requirements for infiltration systems.
- The owner will design the system modifications, seek the appropriate permits from the City Permit Center and begin work upon issuance of the permits.
- Each facility will produce a Stormwater Pollution Prevention Plan or equivalent plan for approval by the City within 60 days of completion of BMPs and or modifications.
- Facilities requiring modifications are to be modified or replaced within 2.5 years of assessment approval or as scheduled by the City of Redmond to coordinate with stormwater infrastructure modifications. Waivers from this timeframe may be developed on a site-by-site basis in consultation with the City.
- All modifications are to be completed no later than February 3, 2016.
What is stormwater infiltration?
When precipitation falls to the ground it generally does one of three things: it evaporates, it percolates, or it becomes stormwater. Evaporated water forms clouds. Percolation is when precipitation soaks into the soil filling the spaces between grains of sand and gravel saturating the ground.
is the portion of precipitation that does not naturally evaporate or percolate into the soil. This stormwater can flow over land, in channels or pipes into a surface water channel, or to a facility designed to place the stormwater into the ground. Stormwater that is filtered into the ground is called stormwater infiltration.
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How does infiltration affect Redmond's groundwater?
Precipitation and stormwater infiltration sustain the groundwater aquifer that Redmond uses to supply 40% of its drinking water. Percolation in natural, undisturbed areas provides clean water to the groundwater aquifer. Stormwater collected from man-made areas such as clean roof run-off can also beneficially recharge the aquifer.
Stormwater from roads, parking lots, and industrial areas however, may pick up oils, metals, and other contaminants not beneficial to the aquifer. The shallow groundwater aquifer in the valley areas of Redmond is only a few feet below the surface and is highly susceptible to contamination, so infiltration of contaminated stormwater is a potential problem.
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The City of Redmond's Natural Resources staff collaborated with businesses and the Chamber of Commerce through a series of meetings in 2009 to create a risk assessment tool that can be uniformly applied, and owner completed, to evaluate the risk to groundwater from existing stormwater infiltration systems. The assessment has been endorsed by Ecology as meeting their assessment requirements and is supported by the businesses that participated in its development.
You can ensure that activities at your facility are not creating a stormwater or groundwater hazard by ensuring chemicals are handled and stored safely, spills are avoided, and that chemical use is minimized where possible to help protect our drinking water resource.
All facilities are required to implement the Required Operational and Structural BMPs
to protect groundwater from stormwater contamination. These BMPs include, but are not limited to, basic practices like:
- forming a spill prevention team
- good housekeeping
- preventative maintenance
- spill cleanup
- regular inspections, and
- record keeping
These measures are required by the City of Redmond Wellhead Protection Code.
Click here for the complete version of Section IV of the Stormwater Manual
that describes BMPs for specific business types such as:
- fueling facilities
- materials handling
- vehicle maintenance
- outside manufacturing activities
- landscape maintenance
- dust and sediment control
- storage of equipment and materials
- storage in tanks
- spill response
- many other best management practices
The complete Stormwater Management Manual for Western Washington Volume IV
can help to provide information on design, operation and maintenance of all stormwater systems. City of Redmond code requires that "any facility, activity, or residence in the City in which hazardous materials or other deleterious substances are present shall be operated in a manner that prevents their release to the environment" and ensures that they do not "pose a significant groundwater hazard."
Please use your chemicals and equipment carefully. If you would like to request a technical assistance visit from a City staff member or King County's Local Hazardous Waste Management Program
to help you find different ways to reduce the risk of pollution you may contact us at email@example.com
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You may download a shallowest depth to groundwater map
that shows the approximate depth to groundwater in many areas of the City. You will need this information when completing your Assessment.
If you need other information related to your site you may contact the City. We will need your parcel number to quickly help find information for your location. You may contact us at firstname.lastname@example.org
In addition, the following links will help you complete your registration and assessment:
WASHINGTON STATE DEPARTMENT OF ECOLOGY
United States Environmental Protection Agency
The U.S. Geological Survey
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