View the Whole Report - Center for Research in Water Resources ...

nature of construction activities resulted in removal of silt fences from operation, changes
in configuration, or flow diversions resulting from the progression of construction.
Samples were collected from six specific constructions sites using silt fences. The
approximate locations of the sampling sites are detailed in Figure A2 in Appendix A.
Schematic representations of the installation configurations and collection locations are
presented in Figures A3 through A17 in Appendix A. Two installations incorporated
non-woven fabric and four employed woven fabric.
4.2.1 Sample Collection
Manual grab sampling with 1-L plastic containers was selected as the most
appropriate method of sample collection. This method of sampling requires the presence
of the researcher and allows the opportunity to make operational observations during
runoff events. A basic plan of action was formulated; however, variations in the
procedure were necessary since individual rainfall events and site conditions dictated
specific collection methodologies. Depth requirements for sampling could be satisfied
only through runoff created from rainfall events of moderate to heavy intensity and/or
duration. The adequacy of an event was determined on site to fully exploit the limited
sampling period. Regardless of difficulties in access, every possible precaution and
consideration were exercised to secure the most representative sample in all cases.
Uncontrolled discharges caused by tears, over-topping, end-runs, and under-flow failures
were excluded from sampling.
Each specific sample was assigned an alphanumeric designation for identification
and was catalogued according to relative position in regard to silt fence, the site, date, and
time of collection. For the sampling period, February 1 to June 14, 1993, 108 individual
samples were obtained for seven rainfall events. Additionally, 14 field composited
samples were collected from three events. This information is compiled and presented in
Tables A1 and A2 in Appendix A. Specific information regarding the intensity, duration,
or quantity of each rainfall event was not obtained because of limited equipment on site.
26