Is your facility located in the Los Angeles, Santa Ana, San Diego or San Francisco regions? Those are the four regions in California that have adopted TMDLs. Do you know the water body receiving the stormwater running off your facility? Well, now you really need to know.
Stormwater is regulated even though it is simply the rain that falls on our roofs, our property and roads, because it picks up trash, chemicals, oils and other substances as it flows into rivers and streams. Now if that stormwater will reach a waterbody that has an established TMDL (total maximum daily load), new requirements will apply.
A TMDL is a regulatorily-set maximum amount of a pollutant an impaired water body can receive from all its surrounding sources and still attain water quality standards. The establishment of a TMDL under the Clean Water Act is a time-consuming planning and study process, and so only four regions in California have had the time and capacity to adopt them, Los Angeles (25 TMDLs), San Diego (7 TMDLs), Santa Ana (1 TMDL) and San Francisco (2 TMDLs). If you are unlucky to be a facility located in one of these regions, the new stormwater requirements may apply to you.
There are approximately 10,000 industrial facilities that allow stormwater runoff on their buildings and property to run off into water bodies in California into waterways, including oil refineries, landfills, waste haulers, livestock operations, manufacturing plants, auto yards, and scrap metal recyclers.
For the first time, exceeding a numeric effluent limitation (NEL) will be an automatic violation of the permit, subject to enforcement and plaintiff’s citizen suits. In the prior stormwater permit, exceedances of the numeric action levels (NALs) were not a violation of the permit, just an indication that your facility’s BMPs (best management practices) were ineffective. And quite frankly, when the rain starts falling, it may be very difficult for a facility to control whether an NEL is violated.
Hence, the new stormwater permit also provides incentives to capture the stormwater, rather than let it runoff. Those facilities that choose to invest and construct stormwater capture will be shielded from enforcement if their stormwater exceeds the permitted levels. The two stormwater capture options are: 1) capture and on-site reuse, infiltration or evapotranspiration; or 2) capture and diversion to a POTW (publicly-owned treatment works). The amount of stormwater runoff that must be captured is that produced during the 85th percentile 24-hour storm event and recover this capacity within 24 hours, so that in the event of back-to-back storm events, the discharger has the ability to retain the required storm volume.
For dischargers to utilize the capture and diversion approach, they must first obtain POTW approval, including a new or revised POTW permit. Given the uncertainty of how much capacity POTWs may have in the event of large storms, it behooves facilities to apply as soon as possible since the door to this option may shut once capacity is met.
So lots to consider now in order to be in compliance by July 1, 2020.