37 research outputs found
Assessment of the physical characteristics and stormwater effluent quality of permeable pavement systems containing recycled materials
This paper evaluates the physical characteristics of two recycled materials and the pollutant removal efficiencies of four 0.2 m2 tanked permeable pavement rigs in the laboratory, that contained either natural aggregates or these recycled materials in the sub-base. The selected recycled materials were Crushed Concrete Aggregates (CCA) and Cement-bounded Expanded Polystyrene beads (C-EPS) whilst the natural aggregates were basalt and quartzite. Natural stormwater runoff was used as influent. Effluent was collected for analysis after 7–10 mins of discharge. Influent and effluent were analysed for pH, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), Electroconductivity (EC), turbidity, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Nitrate-Nitrogen (NO3-N), reactive phosphorous (PO43-) and sulphates (SO42-). Both CCA and C-EPS had suitable physical properties for use as sub-base materials in PPS. However, C-EPS is recommended for use in pavements with light to no traffic because of its relatively low compressive strength. In terms of pollutant removal efficiencies, significant differences (p 0.05) were found with respect to TSS, turbidity, COD and NO3-N. Effluent from rigs containing CCA and C-EPS saw significant increases in pH, EC and TDS measurements whilst improvements in DO, TSS, turbidity, COD, PO43- and SO42- were observed. All mean values except pH were, however, within the Maximum Permissible Levels (MPLs) of water pollutants discharged into the environment according to the Trinidad and Tobago Environmental Management Authority (EMA) or the United States Environmental Protection Agency (US EPA). In this regard, the CCA and C-EPS performed satisfactorily as sub-base materials in the permeable pavement rigs. It is noted, however, that further analysis is recommended through leaching tests on the recycled materials
TMDL WATERBODY ASSESMENT USING LANDSAT 7 EMT+ AND IKONOS IMAGERY
ABSTRACT The use of remote sensing imagery to assess 303(d) listed water bodies and for use in tracking progress in TMDL implementation was tested on 14 waterbodies in the summer of 2001. Water bodies on the south shore of Massachusetts were surveyed to evaluate water quality and identify the presence of noxious aquatic plants. Four different overpasses of Landsat 7 ETM+ and one IKONOS 4-meter multispectral image were acquired through a data purchase grant offered by the NASA Affiliated Research Center Program at Brown University. A field crew consisting of remote sensing specialists and field geologists collected ground truth data concurrently with the image capture in a roughly 100-km 2 area equivalent to the IKONOS data set footprint. Field parameters collected during a four-hour window included water and plant visible and near-IR spectra as well as in situ water quality measurements such as turbidity, Secchi disk depth, and pH. Laboratory analysis of water samples yielded chlorophyll-a and phosphorous content. Vegetation mapping was typically performed in the afternoon or within two days of a flyover. As a result of the field data collected, a predictive relationship between Secchi disk transparency and chlorophyll-a concentrations was established and could be used as a cost effective solution for future water quality assessments. A process was developed to detect the trophic state of the lakes and ponds in a subset of the study area. Remote sensing imagery analysis holds promise as a low cost technique in the monitoring the implementation of TMDLs. This methodology may also be applied in the future to tracking stormwater management control effectiveness