Peristaltic Pump Autosamplers for Solids Measurement in Stormwater Runoff

Abstract

Regulatory agencies approve automatic samplers containing peristaltic pumps as a sample collection method for stormwater characterization and for treatment-device evaluation. Autosampler performance, as discussed in the limited available literature, can vary across the entire particle size range typically found in stormwater from different source areas and outfalls-reasonably consistent performance for particle sizes ,250 lm, but much less consistency for particles .250 lm. Therefore, a series of experiments was undertaken to quantify the upper range of consistent particle capture that may occur with sampling stormwater suspended sediment and particulate-bound pollutants. These experiments, based on triplicate sampling at each experimental condition, found that peristaltic pump autosamplers commonly used in stormwater monitoring could not repeatedly and effectively capture particles .250 lm from a simulated stormwater whose particles have a specific gravity of 2.65. It was expected that the effective size for autosamplers would be correspondingly larger for particles having smaller specific gravities. The height of the sampler had no influence on particle recovery up to a height of 2.5 m, with slightly decreasing recoveries of large particles occurring at greater heights, as a result of reduced sampler intake velocity. Therefore, to characterize the solids across the entire size range and specific gravities that may occur in stormwater runoff, autosamplers should be deployed in conjunction with bedload and floatables sampling. Water Environ. Res., 80 (2008).

Using high-resolution phosphorus data to investigate mitigation measures in headwater river catchments

“…The same Phosphax measure- ments compared with samples taken adjacent to the Sigmatax intake show a small deviation (b = 88; R 2 = 0.97) from unity. This deviation may be due to either each method not directly sampling the same parcel of moving water and/or due to loss of material in the transfer of water from the Sigmatax intake to the Sigmatax jar -a horizontal length of 10 m and a vertical height of 2 m -as noted in other automatic sampling methods (Clarke et al, 2009). …”

Sediment yields from small, steep coastal watersheds of California

“…Warrick and Mertes, 2009), (ii) the dominance of fine-grained sediment (silt and clay) in the suspended-sediment loads owing to the marine sedimentary parent material, which combined with the high stream velocities, was hypothesized to result in well-mixed profiles of suspended-sediment in these streams (cf. Warrick, 2002;Clark et al, 2009;, and (iii) the rapidity of variations in flow and suspended-sediment conditions during precipitation events that made it impossible to manually sample these unsteady conditions across several watersheds. (2012); sum of land cover may not equal 100% owing to rounding.…”

Comparison of two stream gauging systems for measuring runoff and sediment yield for a semi‐arid watershed

“…It has been hypothesized (Clark et al, 2009) that automatic pump samplers are not effective at sampling across a wide range of particle sizes especially >0.25 mm even if the flow is well-mixed. Our results suggest that this range of useful application could be extended up to 0.5 mm particles for channels of comparable size.…”