Stormwater sampling presents a number of challenges to the municipality, researcher, consultant, or industrial user whether the sampling is required by permit or if the sampling is part of a research project. Many times the sampling location is remote, or, even if it is close, it may not be visited on a daily basis to ensure that the system is in working order. In addition, you are relying on meeting a set of established criteria to consider a rain event “qualifying”. For example, a site with a qualifying rain event defined by a 0.1” rain event AND a 3” rise in water level is now relying on two factors to occur at the same time in order to collect samples. Improper maintenance of a rain gauge can easily lead to a clogging (bird droppings) and in turn result in a missed storm event even with a 3” rise in water level. It is essential to have the right equipment, maintenance schedule, and location for a successful stormwater sampling program.
We find customers, particularly those without stormwater sampling experience, sometimes struggle with selecting or budgeting for equipment that offers the most flexibility and control over their sampling system so their stormwater sampling program can be a success. One such item is a cellular modem. Recent changes to Teledyne Isco’s cellular modems have resulted in the ability to use low cost data plans ($8-$10/month) with a CDMA cell phone provider as opposed to more costly voice plans in the past which ranged between $20-$40/month. These newer modems are also IP addressable so remote connection is possible from anywhere with an internet connection. Gone are the days of the dial up modem! These cellular modems can be used to send text message alarms when sampling starts or completes, text messages to initiate sampling on other remote samplers, download flow meter, automatic sampler, and battery voltage data, or perform any programming changes.
Since the idea behind stormwater sampling is to collect samples when it rains it’s easy to overlook considering times when you may not want to collect samples. With short hold times for bacteria samples, sample collection times may be severely restricted to times when the laboratory is open. Having a cellular modem installed allows the end user to remotely connect to the site and disable the sampler for storms that may occur outside of the laboratory’s normal hours. Eliminating the need to drive to the site to simply replace bottles for storm events you couldn’t sample can quickly offset the cost of a modem.
Another important consideration is protecting your equipment from vandalism. When you’re investing money in equipment the last thing you want to deal with is broken or stolen equipment or even equipment that has simply been tampered with enough to cause you to miss a storm event. While somewhat counterintuitive, we have found that equipment that is installed in a more visible location is less likely to be tampered with than equipment installed in an area that is somewhat hidden. A proper instrument shelter and sometimes even a chain link cage may need to be considered.
In addition to basic equipment needs there are a host of site considerations that need to be taken into account when looking for a location to install your stormwater sampling system. We are happy to meet with you on-site to help you find the most suitable location. We recognize that each project and site has its own unique set of considerations and there is not a “one shoe fits all” solution to stormwater sampling systems. We are happy to guide you in selecting the proper equipment for your project. To view an example of a stormwater sampling system click on the video below. Additional guidance on stormwater sampling can be found on our Resource Center.