Potential Impact of TMDLs on Industrial Dischargers: From Regulatory Background to Strategic Planning for Compliance

Date / Time:
Tuesday, Sep 26 10:55am to 11:25am
Convention Center Hall D
Track / Session:
Industrial Track / Planning for Industrial Stormwater Compliance

With thousands of sites moving to ERA Level 2 and the incorporation of more stringent TMDL related requirements on the horizon, industrial dischargers are facing significant capital investment to manage storm water. Selecting the correct long term strategy is critical and should include evaluation of a variety of options, such as infiltration, to capture, use and infiltrate storm water. This presentation will introduce the environmental setting for established TMDLs for specific watersheds and how draft TMDL implementation language potentially affects industrial dischargers compliance with Water Quality-Based Effluent Limitations and implementation of their monitoring program. The advantages, disadvantages, and design considerations for dischargers when selecting whether capture and use for infiltration or treatment and infiltrate will also be presented.

Many industrial sites have historically avoided infiltration because of potential risks of the fate and transport of storm water pollutants. The advantages of discharge avoidance have become more attractive than the inherent uncertainty associated with discharge of storm water. The recent extended drought in California has also highlighted the additional benefits associated with capture and recharge of storm water to augment groundwater supplies.

While the Industrial General Permit does not currently promote or provide credit/incentive for infiltration and pollutant mass reduction, TMDL specific requirements that will be brought into the IGP in early 2018 are likely to provide additional incentive that make infiltration an attractive compliance option. This presentation will provide analysis from continuous hydraulic simulation modeling performed to evaluate the pollutant removal efficiency associated with use of the 85th percentile, 24-hour storm event for infiltration system sizing to evaluate the feasibility of capture/ infiltration to meet waste load allocations for several TMDLs, as well as the overall pollutant mass reduction over time.

The objective of this presentation will be to provide an overview/ evaluation of the feasibility and the benefits of potential compliance strategies, including infiltration, and the potential risks associated with these strategies.

Primary Speaker:
Chris (Meng-Horng) Hsu, GSI Environmental, Inc.
Supporting Speaker 1:
Matthew Lentz, GSI Environmental
Supporting Speaker 2:
Timothy Simpson, GSI Environmental
Primary Speaker Biography: 

Dr. Hsu is an environmental engineer with 7 years of professional experience in consulting and research associated with water quality treatment and chemistry. He also has over 4 years of compliance experience in stormwater NPDES permitting and regulatory analysis, including Total Maximum Daily Load (TMDL). He gained extensive knowledge of NPDES permit compliance while completing his doctoral project “Feasibility Study for the Dry Weather Flow Diversion of Storm Drain Outfalls to Sanitary Treatment System”. He is a licensed Professional Engineer in the State of California and holds numerous stormwater-related professional certifications issued through the California Water Resources Control Boards.

Supporting Speakers Biographies: 

Mr. Lentz is a board certified environmental scientist in surface water resources and has over 18 years of experience providing stormwater and multi-media compliance support to industry, the public sector, and the legal community.

Mr. Simpson has been extensively involved in the evolving NPDES stormwater regulations and has assisted hundreds of industrial facilities and numerous municipal dischargers with all aspects of compliance. He has served as a technical advisor on stormwater to many groups including the Institute of Scrap Recycling.