Storm Water

Collection

All samples were analyzed for coliform bacteria and the indicator organism E. coli using the Coli-lert tray system (IDEXX Laboratories Inc.), and for total suspended solids, water hardness, and total nitrogen and total phosphorus concentrations in the water using standard methods (APHA 1989).  Water samples were also analyzed for priority pollutant metals when the suspended solids content appeared high during a visual examination; for chloride when samples were collected during snow melt events; and periodically for toxicity or growth stimulation using a common green alga (Selenastrum capricornutum) (USEPA 1989).

Storm Event Monitoring by Autosampler:  Because of the construction of the new science center and lake aquarium next door (ECHO at the Leahy Center for Lake Champlain) and damage to the autosampler line during this period, the sampler was inactive during much of the summer.  Lake levels of 97 feet and above during the early part of the summer caused lake water to push back up into the College Street drain, all the way up to and beyond the intake of the automated sampler.  Data collected at this time do not represent pure stormwater, but a constantly varying mix of lake and stormwater.

Figure 1 provides an example of the type of temporal information that can be obtained using the automated sampler.  Total phosphorus was determined for samples collected during a 24-hour rainy period in July 2002.  Phosphorus concentrations were at least 100 times higher than the average concentrations in Lake Champlain throughout the storm, and during a period of heavy rain, reached to almost 1000 micrograms per L.  This type of temporal data would be difficult to obtain when samples are collected by hand.

Volunteer Storm Water Monitors

The volunteer monitoring program was a success, as measured by volunteer support and the results gained from the collections.  Volunteers were enthusiastic and committed to the program.  Sixteen volunteers signed up, and all but one continued with the program throughout the entire season.  The volunteers persisted in the face of fickle weather patterns that made it difficult to predict when sampling would occur, poor weather conditions during sampling, and a changing construction site that made sample delivery to the lab a challenge.  Many of these volunteers have also indicated a willingness to continue with the monitoring project in 2003.

Six storm events were sampled by the volunteers from May to October.  A Burlington Eco Info intern, a UVM graduate student working with Mary Watzin, was responsible for notifying and coordinating the volunteers during storm events.  This intern conferred with Burlington Bay personnel to identify appropriate storms.  Because of safety concerns regarding lightning and the difficulty in accessing many of the drain sites in the dark, sampling was limited to daylight hours and did not occur during electrical storms.  Volunteers received an initial contact via email or telephone that alerted them to the possibility of sampling in the next 24-48 hours.  Pairs of volunteers monitored each site to increase the likelihood that at least one person would be available to sample during any given event.  A second contact was made with the designated sampler during the actual event, giving the authorization to sample the drain.

Volunteers were provided with clean bottles for each collection and a field sheet for pertinent information.  All samples represented random grab samples, collected when the volunteer could reach the site during the event.  Samples were analyzed for the same parameters as measured at the College Street drain, following similar guidelines.  Because no winter events were sampled, there are no chloride data for these drains.  Data from several of these collections are discussed on the results page (Figure 2 and Figure 3).  Additional data can be found on the Burlington Eco Info web page and samples collected late in the season are under analysis.
 

Toxicity Testing Utilizing Selenastrum

Flasks containing mixtures of stormwater and culture media ranging from 0 to 50% stormwater were inoculated with a known concentration of Selenastrum.  Flasks were placed under lights at constant temperature and mixed twice daily to keep the cells suspended.  Three replicates were run for each concentration.  Aliquots were withdrawn from each flask at the onset of the experiment and 96 hours later, at the conclusion of the test.  Cells counts were made using a microscope at 200x.  Cell densities in flasks containing stormwater were compared to growth in flasks containing 100% culture medium.  Tests were conducted primarily with effluent collected from the College Street drain.

APHA. 1989.  Standard Methods for the Analysis of Water and Wastewater.  17th edition.  American Public Health Association.  Washington DC.

US Environmental Protection Agency. 1989. Short-term methods for estimating the chronic toxicity of effluents and receiving waters to freshwater organisms.  EPA/600/4-89/001, second edition. Environmental Monitoring Systems Laboratory, U.S. Environmental Protection Agency. Cincinnati OH.