Jim Moore

 
A Mayfly sensor station was installed at Marsh creek on May 21, 2018 following the procedure given in the EnviroDIY installation manual. This involves inserting a clip (basically an oversized safety pin) thru holes in the sensor bundle’s PVC pipe and the predrilled holes in the anchor pin. Fairly straight forward on dry land but try doing this in winter with the water temps a few degrees above 0ºC. I did this once to clean a sensor bundle in winter – never again! 

I understand the issue of keeping the sensor bundle oriented if a turbidity sensor is installed so that it doesn’t rotate. Without a turbidity sensor this is not an issue and simply putting a cap on the sensor bundle PVC pipe with a ¼ “ hole drilled in it to let the air escape and drop it over the anchor pin. The pin will support the sensor bundle and the depth will be consistent between servicing of the sensor bundle. Another advantage of this support method is cost of a pre drilled pin vs. the cost of standard ½ “ rebar. Less than $4 vs. about $10 for the predrilled pin.

If the sensor station has a turbidity sensor this method becomes even more desirable since the turbidity sensor will require much more service even in winter to clean the sensor window. For this I would recommend beaver proofing the station which should be done anyway if any beaver are around. The ¾ “ flex conduit attached to the sensor bundle will keep it in a fixed orientation. See my note on Beaver proofing in the EnviroDIY forum. 

I have a similar issue with the need to collect a water sample. We have an array of LEC water monitors in the various UNT’s into Great Marsh. One is downstream of the Turnpike service plaza and we are seeing the usual EC spikes correlated with the winter weather. However, a few are very large and don’t seem to be weather correlated hence the nee to get water sample since they are relatively short duration of a few hours or less.
I came across a low cost 12 Volt fountaintain pump that is perfect for pumping a water sample into a collection bottle. I built a 4 channel sampling system based on this pump with a Mayfly controlling four pumps. When the EC gets above a prescribed level the pump is activated for about 12 seconds, enough time to fill a 500cc sample bottle. The software in the mayfly resets when the EC drops below the set threshold and advances to the next port and runs on the next EC spike.

I attached a few pictures of the system I built. However I may have missed the weather events causing EC spikes.

If there is interest I can write up a blog with Mayfly code and construction details.

Adam did you see my blog on “low cost EC sensor” ? I was using the Atlas sci probes but switched to the Sensorex probes which are cheaper. A more expensive version is available with an intergrel 10K RTD for temperature measurement. It comes with a 3m cable and pigtails – no BNC!