Presentation Overview

Transcription

1 Stormwater Underground Injection Control (UIC) - An Alternative to NPDES Discharge Rod Struck, RG GSI Water Solutions, Inc. & Barbara Adkins, UIC Program Manager City of Portland, Oregon Bureau of Environmental Services.. Presentation Overview Portland s stormwater challenges Stormwater management using UICs Overview of City of Portland s UIC permit What we ve learned from 9 years of stormwater monitoring Challenges of implementing a new program Using science to demonstrate UIC discharges are protective of groundwater Portland Stormwater Challenges Multiple regulatory programs Perception of stormwater as toxic Implementation of UIC program 1

2 Stormwater Regulations Federal Regulatory Driver Safe Drinking Water Act (SDWA) Clean Water Act (CWA) State Regulations OAR OAR WQ Criteria Permit UIC WPCF MS4 NPDES Compliance Numeric Limits Maximum Extent Practicable Limits MADL Acute Chronic Portland Stormwater Management Standard City UIC System Catch Basin Point of Compliance Sedimentation Manhole Standard Stormwater UIC System Definition: Structures used to dispose of fluids in the subsurface 2

3 Portland UICs Collect stormwater from public rights-of-way and infiltrate into subsurface soils Promote use of stormwater as a resource Keeps water in the watershed Recharges local aquifers Provides cool base flow to surface water Supports Portland s watershed strategy Benefits of Stormwater Injection Keeps pollutants out of surface water and sediments Restores natural hydrologic cycle Provides an alternative to traditional pipes and reduces the need to increase or install new infrastructure Reduces MS4 discharges and in-stream peak flows City of Portland s UIC Permit First regional municipal permit in the nation for stormwater discharges to UICs 10-year permit issued on June 1, 2005 Covers stormwater discharges to ~9,000 City owned UICs 3

4 City of Portland s UIC Permit Protects groundwater as drinking water resource Permit is prescriptive Defines noncompliant UICs Requires Corrective Actions for noncompliant UICs Development of UIC Permit Little known about stormwater quality from municipal rights-ofway when permit issued Assumed UICs impact groundwater quality Conservative permit conditions Infiltration provides pollutant attenuation (i.e., treatment) UIC Management Plan System Management System Monitoring Evaluation and Response Corrective Action 4

5 Portland s UIC Monitoring Program Statistically robust monitoring design Over 1,400 UIC stormwater samples collected over 9 years Stormwater analyzed for over 120 potential pollutants UIC Monitoring Structure 30 UICs: randomly, spatially distributed One fixed panel Five rotating panels Sample locations divided equally between two traffic categories: < 1,000 and >1,000 TPD Five events per year Compliance based on annual geometric mean 5

6 Stormwater Analyses Over 120 pollutants analyzed and reported for each sampling event Volatile Organic Compounds (VOCs) Polycyclic Aromatic Hydrocarbons (PAHs) Semivolatile Organic Compounds Herbicides/Pesticides Metals (total and dissolved) Nitrate/Nitrogen Total Suspended Solids (TSS) UIC Monitoring - what we learned Stormwater in Portland rights-ofway generally meets levels protective of drinking water at the point of discharge into the UIC Arsenic, lead, B(a)P, DEHP, and PCP only pollutants to exceed permit limits Other pollutants detected at low concentrations below permit limits Pollutants exhibit narrow concentration ranges Pollutant concentrations consistent over 9 years Permit Limit Exceedances Resulted in non-compliant UICs requiring corrective action Lead to development of groundwater protectiveness demonstration 6

7 Groundwater Protectiveness Demonstration Model GWPD - What We Learned Pollutant concentrations attenuate quickly with depth Pollutant concentrations reduced to levels protective of drinking water GWPD Outcomes Supported DEQ determination that GWPD is an acceptable corrective action Supported City permit modifications and provided foundation for DEQ s UIC municipal permit template Informed City Policies UICs included in Portland s Stormwater Management Manual Incorporated into green street design to manage overflow Will inform DEQ revisions to UIC Statutes and Rules 7

8 UIC Program Challenges 1 st area wide permit in the nation Overcoming perceptions Stormwater as toxic UICs cause significant groundwater degradation Large number of noncompliant UICs identified in initial systemwide assessment Implementation of monitoring program Estimated corrective action costs Using Science to Address UIC Program Challenges Developed robust statistically valid monitoring program Comprehensive analyses of stormwater quality Partnered with USGS to define regional groundwater depths Developed defensible Evaluation and Response protocols to address anticipated program challenges Developed site specific fate and transport model UICs - An Alternative to NPDES Discharge Benefits of Portland s UIC Program Keeps pollutants out of surface waters /sediments Reduces MS4 discharges and in-stream peak flows Protective of groundwater Stormwater used as a resource Groundwater recharge Cool base flows for surface water (TMDLs, etc.) Cost Effective Manages stormwater near the source (less infrastructure) Low installation costs Low maintenance costs (line cleaning, street sweeping, line repair) 8

9 Questions? Rod Struck, RG GSI Water Solutions, Inc. & Barbara Adkins, UIC Program Manager Bureau of Environmental Services UIC Compliance Monitoring Permit Defined Common Pollutants (All samples in all years) Benzene Ethylbenzene Pentachlorophenol Benzo(a)pyrene Total Chromium Total Lead Total Nitrogen Toluene Xylenes Di(2-ethylhexyl)phthalate Total Arsenic Total Cadmium Total Copper Total Zinc UIC Compliance Monitoring Permit Defined Priority Pollutants (Sampled in Years 1, 4, and 9) Total Antimony Total Beryllium Inorganic Mercury Total Thallium Atrazine Carbon Tetrachloride Chlorobenzene Dalapon p-dichlorobenzene Bis(2- chloroisopropyl)ether Dinoseb Glyphosate Pichloram Total Barium Total Cyanide Total Selenium Alachlor Carbofuran Chlordane 2,4-D o-dichlorobenzene 1,3-Dichlorobenzene Bis(2-chloroethyl)ether Diquat Lindane 1,2,4-trichlorobenzene 9

10 Stormwater Underground Injection Control (UIC) Systems Definition: Structures used to dispose of fluids in the subsurface Portland s UIC Monitoring Program Objectives Characterize stormwater quality Conduct pollutant trend analyses Demonstrate compliance with permit limits Demonstrate groundwater protection Groundwater Protectiveness Demonstration Model Uses a one-dimensional mathematical equation for fate & transport through the vadose zone Utilizes conservative assumptions Incorporates attenuating mechanisms (sorption, degradation, and dispersion) to estimate pollutant concentrations Evaluates pollutant concentration reductions & potential impacts to groundwater Results used to support risk-based decisions Developed by GSI, independently reviewed by Papadopoulos, and approved by DEQ 10

11 SOURCE: BES, Annual Stormwater Discharge Monitoring Report Year 5 11