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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.
Stormwater 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.
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.
The City of Redmond's 2003 Wellhead Protection Ordinance established
the requirement for owners or operators of any facility within the City
of Redmond's
Wellhead Protection Zones 1 and 2 to evaluate and upgrade their
stormwater infiltration systems to ensure protection of the drinking
water resource.
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.
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.
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.
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. 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.
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.
Owners that complete and submit the assessment to the City early,
before August 3, 2010, will be eligible for up to $6,000.00 in 50%
matching funds for pollution prevention changes that may be required at
the facility (spend $12,000 and get $6,000 back). Assessments 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.
Although Redmond does not regulate these systems under this code,
Ecology does regulate these systems and 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.
An assessment of each stormwater infiltration system located in
Wellhead Protection Zones 1 and 2 will be required to ensure that it
is not a hazard to the groundwater. The assessment will need to be
completed by the owner and submitted to the City of Redmond no later
than February 3, 2011.
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
Instructions for
Completing the Assessment
1. Land Use - information on specific actions,
materials, and products being used within areas that drain to the
infiltration system.
2. Location - proximity to public or private drinking water wells.
3. Infiltration system description - size and treatment capacity
of the system and depth to groundwater.
4. 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.
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:
- Implement appropriate BMPs to protect groundwater immediately
.
- Submit assessment before August 3, 2010 for a $6,000 voucher and reduced
permit fees
.
- 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.
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
- training
- 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
-
parking
-
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
groundwater@redmond.gov.
If you are considering a new construction or redevelopment project
with stormwater infiltration you should coordinate with the City's
Development Services staff to determine what the current code requires
and ensure that you have the proper permits. The City encourages
infiltration of clean stormwater to recharge the aquifer and may allow
infiltration of stormwater that has been treated depending on the
location of the facility.
The City requires registration of stormwater infiltration systems in
Wellhead Protection Zones 1 and 2. The State of Washington requires
registration of new infiltration pipes and catch basins; they refer to
them as 'wells' or underground injection control (UIC) wells. The state
Guidance for UIC Wells that Manage Stormwater is an excellent
resource for designing a new system in combination with the
Stormwater Management Manual for Western Washington.
If you have an existing stormwater infiltration system that is failing
and needs to be rebuilt, it will need to meet the
Guidance for UIC Wells that Manage Stormwater.
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
groundwater@redmond.gov.
In addition, the following links will help you complete your
registration and assessment:
WASHINGTON STATE DEPARTMENT OF ECOLOGY
KING COUNTY
GEOMAP NORTHWEST
(information and data on groundwater depth and geology maintained at the
University of Washington)
UNITED STATES ENVIRONMENTAL PROTECTION
AGENCY
The Office of Ground
Water and Drinking Water
THE U.S. GEOLOGICAL SURVEY
Ground Water Information Pages
(You will need Adobe Acrobat Reader to view most of the links on this
page. If you do not have Acrobat
Reader you may download it here for free.)
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