5. Dissolved P is about 90 percent bioavailable, compared to about 20% for particulate P
Approximately 3 - 0.30 mg/L compared to 0.10 mg/L, though concentrations and standards vary
False - particulate P is about 60 percent of TP across all land uses, with the percent being higher in industrial/transportation settings and lower in residential settings.
Organic material, including plant material and animal waste
A high canopy area in St. Paul, due to the importance of organic material as a source of dissolved P
Ponds that turn over infrequently, that are poorly maintained, that have high organic inputs, and that are shaded and therefore not mixed have a greater tendency to export P
False. Biochar does not appear to leach P, but it has not been show to absorb P.
We aren't sure what the cutoff is yet, but research suggests compost concentrations of greater than 5% in bioretention media will leach P.
True. P is attenuated in the unsaturated zone and in groundwater
True. Runoff from frozen soils and overirrigated lawns are considered important sources of dissolved P, though more research is needed to quantify these sources.
This page provides guidance related to assessing the total suspended sediment (TSS) and total phosphorus (TP) removal efficiency of permittee owned/operated ponds constructed and used for the collection and treatment of stormwater. Four (4) evaluation strategies are discussed.
The TSS and TP removal efficiency of constructed stormwater ponds degrades over time due to the loss of storage volume to sedimentation and/or sediment phosphorus release. For this reason, it is critical that stormwater ponds be sized correctly for their contributing drainage area and that pond inspection and assessments be performed routinely to monitor sedimentation and identify potential maintenance needs. In addition to evaluating pollutant removal efficiency through comparison to design standards and evaluation of sedimentation, the water quality performance of stormwater ponds can be evaluated using various water quality modeling programs or measured directly through water quality monitoring.
Guidance presented will assist MS4s (Municipal Separate Storm Sewer System) evaluate the TSS and TP treatment effectiveness of ponds post-construction and over their design life. The adjacent table provides a summary of the four (4) TSS and TP removal efficiency evaluation strategies discussed within this memorandum.
TSS and TP Removal Efficiency Evaluation Strategies
A tour of the Minnesota Stormwater Manual content