SU0014580 - Laserfiche WebLink

Home Browse Search

3 3 Auparl 1979 I Table 2. Parameters measured and Application Rate•0.55 m3/hr frequency of analysis. I I e I Vorameter Analyses/wk' I BOD 3 E z I TSS 5 -- I TKN 1 E I NH,-N 5 I NO,-N 5 Ranoti Rale•0.45-3/hr TotalP 1 _ PO„ 1 E I I Turbidity 5 u 4 pH 5 Specific conductivity 1 1 I Chloride 1 I— —Steady Stole Period—� Fecal coliforms 1 I I Fecal streptococci 1 1 I I *Based on five application periods 0 2 4 6 B per week. ON Time(Ilya) OFF Figure 3. Typlcolrunoffhydrograph. m' hr t. Altogether,50 detention times were measured at the CRREL site during this study (see 160 APP•A)• Flow-proportioned composite samples were taken Section B 3 of the applied primary effluent and runoff during Application Rote=0.6 m/hr. each application period. Primary effluent samples were taken at fixed time intervals with an automatic 120 composite sampler. Runoff samples were taken by small peristaltic pumps which were activated by relay switches during each operating cycle of the catch Ei basin's sump pump. The water quality parameters measured and the frequency of analysis are shown 80 i in Table 2. Analtyical techniques are discussed in a ' Appendix B. I I o I U I V 1 ao , HYDRAULIC DETENTION TIME The hydraulic detention time on an overland flow terrace is dependent on many factors including appli- cation rate,slope, length of terrace, surface micro- 01 1 topography,soil infiltration rate,evapotranspiration 0 loo zoo 300 Time (min.) and vegetation density. Of all these factors, only application rate is controllable by the operator. Figure 4. Typical chloride response curve for meas- Slope and length of terrace are largely dependent on uring detention time. site characteristics. Surface microtopography is con- trollable to some extent by careful site preparation, but each terrace will develop different hydraulic path- in the constant head weirbox. Composite samples ways. Infiltration rate and evapotranspiration will were taken of the runoff at various intervals and vary from site to site depending on soil characteristics analyzed for chloride. Chloride concentrations were and climate conditions. Vegetation density, or surface then plotted vs time, and the peak of the response roughness,varies with the type of vegetation and the curve was chosen to represent detention time. The maturity of the terrace. A mature terrace usually has center of mass was not chosen to represent detention a higher vegetation density and will normally have an time because 36%of the tracer was lost in the perco- organic mat near the soil surface caused by a buildup late and plants. An example of a typical chloride re- of grass clippings from previous harvests. This sponse curve is shown in Figure 4. The detention time organic mat increases the resistance to flow which, in this case was 40 min for an application rate of 0.6 in turn, increases detention time. 4