Contaminated Water on Construction Sites
These are resources to aid contractors in handling contaminated water on construction sites.
Please contact us with any questions regarding contamination on your construction site.
Documents and helpful links
Treatment Systems for Contaminated Construction Runoff (TSCCR)
Provides guidance for filling out a Notice of Intent (NOI) Application Form, section VI; and/or those filling out
a SWPPP in conjunction with the General Construction Stormwater Permit, S9, Part 9. The table shows treatment systems (listed
across the top) that may be effective in treating various specific contaminants (listed down the side). Users should evaluate
the effectiveness of any treatment system they plan to implement and confirm that the chosen treatment system does not cause or
contribute to a violation of the Water Quality Standards. View the table | Download the data
EPA's Drinking Water Treatability
Database of treatment processes. This database provides definitions and detailed information on Treatment Processes currently available. The EPA provides this information as a courtesy; Ecology does not guarantee or endorse any of the listed treatment systems.
Technology Assessment Protocol - Ecology (TAPE) database
The TAPE program provides a peer-reviewed regulatory certification process for emerging stormwater treatment technologies.
Hazardous Substance Information and Educational Office (HSIEO)
HSIEO is an information
resource for workers, schools, and communities.
Effluent Calculation Tools: Effluent Characterization for Permit Application (Attachment A) | Permit Calculator Workbook
Effluent Limitations Guidelines from EPA
Effluent guidelines are national standards based on the performance of treatment and control technologies for wastewater
discharges to surface waters and municipal sewage treatment plants. Your local jurisdiction may have different guidelines for discharge. Check with your local jurisdiction before discharging from your site.
Definitions from the Washington
State legislature regarding Dangerous Wastes and Toxic Substances
Construction Stormwater General Permit
Frequently Asked Questions
What do I report to Ecology if I answered yes on the Notice of Intent (NOI) that contaminated soils will be disturbed or contaminated groundwater will be discharged because of the proposed construction activity?
- Provide the location(s), contaminant(s), and contaminant concentration(s) of the soil or groundwater.
- Provide the pollution prevention and/or Best Management Practices (BMPs) proposed to control the
discharge of soil/groundwater contaminants (example: treatment method).
Is there a database of contaminated sites so I can see if my site has already been reported to have contaminants?
Do I have to conduct further testing for contaminants on my construction site to receive a permit?
- No. Report known or suspected contaminants that you are already aware of on the NOI.
If my soil is contaminated, do I have to control my stormwater runoff?
- Yes. The construction stormwater discharge must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), groundwater quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health criteria in National Toxics Rule (40 CFR Part 131.36). Discharges that cause or contribute to a violation of these standards cannot be covered by the Construction Stormwater General Permit.
If my site meets MTCA is it clean?
- No. Meeting MTCA cleanup criteria for soil and/or groundwater does not automatically mean the stormwater discharge from your site will meet Water Quality standards (Chapter 173-201A WAC). MTCA Cleanup standards may leave residual contaminants in soil or groundwater that construction or Engineering may expose, and could cause or contribute to a standards violation.
If my site has a No Further Action (NFA) letter, is it automatically considered clean?
- No. NFA letters are issued for several reasons (i.e. meets MTCA, an engineered barrier has been installed, or a deed restriction is in place). Construction activities may breach engineered barriers or suspend residual contamination in construction stormwater and/or groundwater that may cause or contribute to a standards violation.
Do my WQWebDMR reports have to include my contaminant concentrations found in the construction stormwater?
- Yes, any additional sampling or monitoring that is required by Ecology will be issued in an Administrative Order that includes reporting sampling results on the Discharge Monitoring Report (DMR).
- The DMR will list the parameters that must be recorded.
Where do I find BMPs for managing and containing contaminants?
- The Western Washington and Eastern Washington Stormwater Management Manuals both contain guidance for assistance in selecting appropriate BMPs to manage contaminated runoff. Your Local jurisdiction’s manual may also contain BMP information. Treatment systems can be complicated and you may want to seek professionals with expertise in this area.
- See the Treatment Systems for Contaminated Construction Runoff spread sheet for a list of common Treatment Systems that may be applicable to treat your contaminants.
Can treatment systems can be grouped together?
- Treatment systems may be linked in series to allow you to remove all contaminants to discharge levels (example: pH treatment, oil and water separators). Talk with your vendor about what treatment options may be available.
Where do I find the contaminant concentration levels I need to treat to?
- Site specific Indicator Levels will be established by Ecology if treated construction stormwater or dewatering water will be discharged.
- Stormwater discharges should meet the Water Quality Standards for surface waters of the State of Washington. Specifically, WAC section 173-201A-240 contains information on Toxic substances.
Can I discharge my treated runoff into waters of the State?
- Discharges must be in compliance with the Construction Stormwater General Permit (CSWGP). See S1.C. (Authorized Discharges) & S1.D. (Prohibited Discharges).
- Written approval from Ecology is required prior to using chemical treatment.
- pH adjustment using CO2 or dry ice does not require written approval. If you plan to discharge to 303(D) or TMDL waterbodies; See S8. in the CSWGP for information on the limits on coverage for discharges.
Can I infiltrate contaminated dewatering water back into contaminated soil?
- The answer is site specific. Infiltration of dewatering water must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), groundwater quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health criteria in National Toxics Rule (40 CFR Part 131.36).
- Also see G18 in the CSWGP and RCW 90.48.080 regarding compliance with the Clean Water Act and Water Pollution Control.
If I have a flow through treatment system, do I need to have secondary containment for 110% containment of the total volume?
- No; however, we recommend you develop a contingency plan for water storage if the treatment system does not perform as anticipated. This will help reduce setbacks due to ineffective treatment methods.
Where do I dispose of my pollutant refuse?
- Thirty companies and agencies in Washington can treat, store, dispose or recycle hazardous waste (TSDR) or process used oil. Seventeen facilities accept wastes from other businesses on a commercial basis. List of waste disposal facilities
How should I contact Ecology if I have a breach in my contaminant containment system?
- If the event may cause a threat to human health or the environment, you must immediately notify Ecology by calling the applicable regional office
Environmental Report Tracking System (ERTS) phone number.
- Immediately take action to cease the discharge or pollution.
- You must also contact Ecology if there is a high turbidity (250+ NTUs or transparency 6cm or less) discharge on your site.
When can I expect to hear back from Ecology regarding my Notice of Intent (NOI) Form?
- Ecology will respond to your NOI within 2 weeks indicating 1) receipt of the NOI and 2) request for additional information if applicable.
- Upon receipt, expect a two-week turnaround time for Ecology to review the additional information.
Return to Construction Stormwater Page
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