Evaluation of Septic Tank and Subsurface Wetland for

Chapter 4 - Methodology
Field Data Collection
Site evaluation began on August 17, 2004 prior to the beginning of the school term to
gather background data that would reveal the status of the systems under no loading. The
field visits continued over a seventeen-week period ending on December 14, 2004 as the
school term finished. Both sites were visited a total of sixteen times to collect water
quality samples and record operational data.
Water quality samples included one set of background, five sets of in-service samples and
one duplicate set for inter-laboratory comparison. Water quality grab samples were
collected from three points along the treatment process to measure the progress through
each unit operation. Sample point locations are indicated in Figure 3-3 and Figure 3-6.
The first sample at each site was drawn from the top of the first septic tank (first
chamber) to represent the raw sewage influent. The second sample was drawn from the
wetland inlet distribution manhole or inlet distribution pipe. The third sample was to
represent the effluent. At Retrieve, this sample was collected at the wetland outlet.
Because there was never effluent at Pisgah, a surrogate sample was collected near the
middle of the wetland at the edge of the flourishing, tall wild cane. This mid-wetland
sample point was a slotted 4-inch PVC pipe reaching the bottom of the bed. Water from
this point should have passed through the most significant portion of the treatment
process. All samples with the exception of the effluent at Retrieve were collecting using
a basting syringe (see Figure 4-1).
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