Research Monitoring Equipment

Research monitoring consisted of stormwater flow measurements, stormwater bacteria testing, groundwater bacteria testing, water table elevation recording, and rainfall recording. All recorded data was performed using loggers set on a specific logging interval. Rainfall was recorded by event. The data were downloaded semi-monthly, transferred to a computer via the logger's accompanying software, then archieved and analyzed in Microsoft Excel. Water samples were delivered to TriTest Laboratory in Wilmington, NC with the EPA holding time and analyzed via the Enterolert method.

Rainfall

Rainfall was measured via several 0.25 in tipping bucket raingauges attached to HOBO Event Loggers, as shown below.

Figure: Tipping Bucket Rain Gauge and Event Logger.

Stormwater

Stormwater flowrates and volumes were recorded via ISCO Bubbler 730 Modules attached to ISCO 6712 Automated Samplers. Both Sites L and M had one set of ISCO equipment to monitoring the single storm pipe, while Site K had two sets to monitoring two of the three diverted pipes. The third pipe at Site K was not monitored due to site constraints and its small contribution.

The ISCO equipment was attached to solar panel-charge controller complexes for power and were placed within secure, metal boxes. The boxes at Sites L and M were installed on top of the diversion vaults (below, left), while the boxes at Site K were installed within the road/sidewalk adjacent to the drop inlets (below, left).

Figure: Site L Stormwater Monitoring Station. The Site M Station was similar.	Figure: Site K Stormwater Monitoring Stations.

The vaults at L and M were fitted with four pieces of monitoring equipment: bubbler tubing/tubing mount within the storm pipe to determine the depth of water in the pipe, sampler tubing/strainer, 4 ft long sharp-edged metal weir plates, and vault water level loggers (below, left). These devices were used to calculate storm inflow into the vault, collect stormwater samples from the vault, and the calculated overflow over the weir. The modified drop inlets were fitted with the bubbler tubing and mount and sampler tubing and strainer. The bubblers were used to determine the depth of flow in the distribution pipe for DIS inflow and stage within the drop inlets to determine overflow over the weir (below, right).

Figure: Interior View of Site M Vault. The Site L vault was similar.	Figure: Interior View of a Site K Modified Drop Inlet.

Groundwater

Groundwater sampling was accomplished via 2 in diameter PVC wells installed to near elevation zero (below). A new, sterile bailer was used to purge each well before a sample was collected. Samples were collected monthly and following several storm events with at least 0.25 in of rainfall. The samples were delivered to TriTest Laboratory in Wilmington, NC for Enterolert analysis. Each study site contained several wells surrounding the systems, as shown in the second set of figures below.

Figure: Groundwater Sampling Wells.

Figure: Site L Monitoring Schematic.	Figure: Site M Monitoring Schematic.

Figure: Site K Monitoring Schematic.	Figure: Control Site Monitoring Schematic.

Dune Hydrology

Dune hydrology was monitored via continous water table elevation recording. Infinity Water Level Loggers (below, left), manufactured by Infinities USA, were installed throughout the dunes, both upslope and downslope of the DISs, as shown in the three figures above. The loggers were installed on top of 4 in diameter PVC pipes that were connected to 2 in diameter PVC pipe wells that extended down into the dunes to near elevation zero (below, right). Elevations were recorded every 20 minutes.

Figure: Infinity Water Level Logger.

Figure: Water Table Monitoring Well.