Run Off Water Measurement and Sampling Equipment

[candu6]

I need to upgrade our rainwater run-off flow measurement and sampling equipment, at a fuel storage site. We currently use an ultrasonic flow measurement device with a Parshall flume and added a sample pump to take samples every 1000 gallons. Its a homemade arrangement that never worked very well.
Does anyone have experience with run-off water sampling? Any recommended products, which could meet my needs.

Thanks.

 

[BobPE]

check out a company called ISCO...they make automated samplers that may be what you are looking for....If this isn't what you are looking for, give us a bit more info..

BobPE

 

[HB2U]

I don't know Bob, last time I used an ISCO sampler the basis of sampling was time. It did not have the capability of flow paced sampling. Have they added that capability to
those units? (It's been about 5 years since I used one)

Candu6 what was the problem you were having with the original setup cause it seems like the way to go.

 

[candu6]

The existing controller is old and no longer available, so if we get a failure then we will be scrambling to get a replacement. Our Parshall fume is sized for a very large storm and the resolution of the ultrasonic flow measurement is poor for low volumes of water.
The largest problem with our existing setup is: If we get a large amount of rain, when the 1000 gallon mark is reached the sample pump is started to circulate and flush the lines and then take a sample. However, if a second 1000 gallon mark is reached before the sample is taken, then the sample pump cycle is reset and it starts the line flush again and the sample is missed. So, we may only get a sample of the last 1000 gallons.
We can build a new, and improved, homemade system but I would like to find one commercially available the is proven and has technical support.

 

[DMcGrath]

ISCO makes a variety of automatic samplers that can be configured to sample based on a variety of "events" (flow rate, liquid level, rainfall rate, time, etc.) Sample volumes can be programmed from 200 ml to 5 gal (I think). I have one installed now that is programmed to pull a 1 liter sample every 15 minutes as long as the flow in the flume is deeper than 0.15 feet (about 120 GPM). The key to accurate flow-weighted sampling is an accurate flume and locating the sensor within that flume. ISCO samplers aren't cheap and there is a learning curve for programming them to do exactly what you want. I believe the website is

http://www.isco.com