Tip #1
How Important is the Sampling Technique?
I receive a lot of questions about sampling techniques and I would love to discuss something truly important.
People ask me if they should hire someone to take a sample for them. If you are on a budgetand don’t mind standing in the rain for a bit then the answer is “No”. Stormwater sampling is tricky but it is not rocket science and you can get the best result when you know exactly where and how you sample. First get some basic training like contacting your lab and ask them about storm water sampling and sometime they might even come out and train you on the sampling. A few rules of sampling 1) Do not force a sample if there is no discharge. I see it too many times where staff were asked to take a sample when it rain, but in reality water is in puddle and it wasn’t even discharging out of the facility so the sampler forced a sample by either scraping the bottom of a small puddle (where all the sediment settle). So the best way when it is raining, but not discharging is to do documentation. Take a picture of the discharge point and note that it is not discharging. Also don’t think you can fool the Water Boards by always showing a photo that it is not discharging. Water Boards can look into rain data and your surrounding facility data to see if you are telling the truth.
OK. So what are some tips on sampling? 1) Make sure your BMPs are maintained (Ex: dirt and sediment build up needs to be clean up) 2) Field sampler should choose the best sampling point based on field condition and not blindly following the SWPPP. If there is a better alternate sampling point that can avoid cross contaminant from landscape area or run-on then change the spot and revise your SWPPP and site map to show the alternative sampling spot. 3) Take your sample after any BMPs 4) Sample are required to be taken within the first 4 hours of the first discharge. Stick your head out of the window and see how heavy the rain is. If it looks like there will be enough rain for a while then wait a bit before you take a sample because the first rain (especially first of the season) will have the most concentrated discharge due to accumulation (so CLEAN before the first rain of the season). 5) Make sure you are taking flowing water and an easy way is to create a dam with gravel bag and add a PVC pipe in the middle for your sampling collection point.
Tip #2
EZ BMPs!
There are a lot of fancy and expensive BMPs products out there to help reduce storm water pollutant discharge, but you should evaluate your situation before making a big purchase. The #1 way to control pollutants is source control which means controlling at where the pollutant came from, for example, metals foundry uses sand in their production process and the sand is stored outdoor and sign of sand track out are observed at the yard, therefore the most effective way is to change the process by storing the sand indoor or within a non-leaking covered container and do a weekly vacuuming at the yard, but sometimes changing the process is not that easy and requires time for the worker to adapt.
Another way is to take a look at your sample result and if your Total Suspended Solid (TSS) levels are high that means you might have a fighting chance before consider higher level BMPs such as metals filter socks, clarifier, retention basin and treatment system. Install BMPs such as gravel bags, straw-wattles, filter fabric with aggregate to help filter out some of the sediment. This works because metals and other contaminant tends to easily attach to dirt and if you can filter some of the dirt then you can reduce your total level of metals.
There are many cheap and creative ways to filter water. Here is a video example created by the Sacramento Student.
Here is another drain inlet protection sample created by HI DOT SC-2 using center block, filter fabric, and aggregate rocks.
Tips #3
Where am I?
OK. It rains so water flows to the drain and/ or to the street, but have you ever wondered where the storm water actually goes? There are many websites out there to show you where is your nearest channel, creek, and lakes. Here are a few examples of sites that are really helpful. The information you gather here can also help you fill out the question “Nearest Water Bodies?” on your Notice of Intent (NOI) and writing your SWPPP.
Here are a few links you can use to help you locate your nearest water bodies.
· EPA: https://watersgeo.epa.gov/mywaterway/
· LA DPW Storm Drain System: http://dpw.lacounty.gov/fcd/stormdrain/index.cfm
· USGS: http://historicalmaps.arcgis.com/usgs/
· CA State Water Boards: HUC 10 Watershed Map download from https://ftp.waterboards.ca.gov/WebInterface/login.html
Use the following userID and password to log on and access the GIS files:
- UserID: GIS_Shared
- Password: GIS_Download
Google earth layer is titled impaired5132015_MapToKML.kmz. Click on the file name to download. Use Google earth and import the kmz file.
