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The purpose of this project was to characterize runoff and pollutant export from three commercial sites: one with no storm water control measures (NoTreat), one with a wet detention basin (WetBasin), and one with low impact development (LID) measures. The sites were located in the Piedmont and Coastal Plain physiographic regions of central North Carolina. Rainfall, runoff, and pollutant concentrations were monitored at each site for more than one year by using automated rain gauges and samplers. The storm event mean concentrations (EMCs) of total kjeldahl nitrogen (TKN), nitrate+nitrite nitrogen (NOx-N), and total phosphorus (TP) in runoff were generally less than corresponding EMCs for many other urban areas in the United States. Also, EMCs were similar to those found for eight parking lots in North Carolina. Storm runoff to rainfall ratio was greatest for the NoTreat site and least for the WetBasin site, which was anticipated because the NoTreat site had no detention/storage and the WetBasin site had the greatest detention/storage. Export of TKN, ammonia nitrogen (NH3-N), TP, and total suspended solids (TSS) was lowest for the LID site, whereas export of NOx-N and TN was lowest for the WetBasin site. Although by no means definitive, the monitoring data indicated that the LID site with its multiple LID measures was more effective at reducing export for most pollutants than the WetBasin site with its wet detention basin. [ABSTRACT FROM AUTHOR]

A study was conducted in Louisburg, North Carolina, to determine the effect of level spreader-vegetative filter strip (LS-VFS) storm-water control measures (SCMs) on runoff temperature and thermal loading. Two LS-VFS systems draining an urban catchment were monitored during the summers of 2008 and 2009. The first VFS was 7.6 m wide and entirely grassed. The second was 15.2 m wide, with the first-half grassed and the second-half wooded. Runoff temperatures and thermal loads from the urban catchment tended to peak toward the beginning of a storm event. Median and maximum storm temperatures were significantly reduced across both the 7.6-m and 15.2-m LS-VFSs. However, median and maximum effluent temperatures for both filter strip lengths were significantly greater than the 21°C trout threshold. Mean and median effluent temperatures from the 15.2-m LS-VFS were slightly lower (<1°C) than those from the 7.6-m LS-VFS, which may show the impact of increased filter strip width and/or the shading from wooded vegetation on effluent temperatures. Expected differences between influent and effluent temperatures (both median and maximum) were greater as the influent temperature increased. Substantial and statistically significant (α=0.05) thermal load reductions were observed in both LS-VFSs because of measured reductions in both temperature and flow volume. Thermal load was eliminated in seven of 38 storm events because of infiltration of the entire runoff volume in the filter strips. The ability of LS-VFS systems to reduce storm-water temperatures and thermal loads supports their use in thermally sensitive watersheds. [ABSTRACT FROM AUTHOR]

The article presents a forum that documents how poor design and inadequate management of two constructed storm-water wetlands (CSWs) caused each to become wet ponds. Information is presented on the use of CSWs in eastern regions of the state of North Carolina where high water tables are common. The problems associated with a storm-water wetland constructed in Brisbane, Queensland are discussed.

An assessment of the performance of four level spreader-vegetative filter strip (LS-VFS) systems designed to treat urban storm-water runoff was undertaken at two sites in the Piedmont of North Carolina. At each site, a 7.6-m grassed filter strip and a 15.2-m half-grassed, half-forested filter strip were examined. Monitored parameters included rainfall, inflow to, and outflow from each LS-VFS system. A total of 21 and 22 flow-proportional water quality samples were collected and analyzed for the Apex and Louisburg sites, respectively. All studied LS-VFS systems significantly reduced mean total suspended solids (TSS) concentrations (p<0.05), with the 7.6 and 15.2-m buffers reducing TSS by at least 51 and 67%, respectively. Both 15.2-m VFSs significantly reduced the concentrations of total Kjeldahl nitrogen (TKN), total nitrogen (TN), organic nitrogen (Org-N), and NH4-N (p<0.05), whereas results were mixed for the 7.6-m VFSs. Significant pollutant mass reduction was observed (p<0.05) for all nine pollutant forms analyzed in Louisburg, which was caused by infiltration in the VFSs. The effects of VFS length and/or vegetation type are very important for pollutant removal, as effluent pollutant concentrations were lower (with one exception) for the 15.2-m VFSs. The median effluent concentrations for TN and total phosphorus (TP) for the four LS-VFSs were nearly always better than fair water quality benchmarks for the Piedmont of North Carolina, but only met good water quality metrics in one-half of the studied storm events. [ABSTRACT FROM AUTHOR]

Throughout the 2004 mosquito season, 52 stormwater retention facilities were sampled to characterize the seasonal occurrence and relative abundance of mosquito species in relation to the structural complexity and biological diversity of the facilities. The three different types of facilities included standard wet ponds (n = 20), innovative ponds (n = 14), and wetland ponds (n = 18). All retention structures were sampled at the beginning, middle and end of the mosquito season so that seasonal changes in mosquito production could be characterized. Overall samplings, mosquitoes were collected from 34% of the retention structures. Fourteen species representing 7 genera were collected, but only 5 species (Culex erraticus, Cx. territans, Anopheles quadrimaculatus, An. punctipennis and Uranotaenia sapphirina) were commonly collected in all three types of stormwater management facilities. In general, the seasonal prevalence and relative abundance of mosquito species did not vary among three types of retention structures. A significant association (P < 0.01) between the presence of mosquito larvae or pupae and the absence of mosquitofish was found for innovative and wetland stormwater retention facilities but not for standard retention facilities (P > 0.05). [ABSTRACT FROM AUTHOR]