Difference between revisions of "Phosphorus credits for bioretention systems with an underdrain"
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<td>Is Media Mix C or D being used or, if using a mix other than C or D, is the media phosphorus content 30 mg/kg or less per the Mehlich 3 (or [[Design criteria for bioretention#Notes about soil phosphorus testing: applicability and interpretation|equivalent]]) test<sup>1</sup>? | <td>Is Media Mix C or D being used or, if using a mix other than C or D, is the media phosphorus content 30 mg/kg or less per the Mehlich 3 (or [[Design criteria for bioretention#Notes about soil phosphorus testing: applicability and interpretation|equivalent]]) test<sup>1</sup>? | ||
| − | *If yes, credit = | + | *If yes, credit = 80% |
*If no or unknown, credit = 0% | *If no or unknown, credit = 0% | ||
| + | |||
| + | *TP removal if credit is 80% = Particulate fraction (55% of TP) * removal rate for that fraction (80%) = 0.55 * 0.80 = 0.44 or 44% | ||
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<td>1. Is Media Mix C or D being used or, if using a mix other than C or D, is the media phosphorus content 30 mg/kg or less per the Mehlich 3 (or [[Design criteria for bioretention#Notes about soil phosphorus testing: applicability and interpretation|equivalent]]) test? | <td>1. Is Media Mix C or D being used or, if using a mix other than C or D, is the media phosphorus content 30 mg/kg or less per the Mehlich 3 (or [[Design criteria for bioretention#Notes about soil phosphorus testing: applicability and interpretation|equivalent]]) test? | ||
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*If yes, additional 40% credit | *If yes, additional 40% credit | ||
| + | *TP removal if credit is 20% = Dissolved fraction (45%) * removal rate for that fraction (20%) = 0.09 or 9 percent | ||
| + | *Adjust TP removal if credit is higher due to use of P-sorbing soil amendments | ||
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Revision as of 20:40, 31 March 2014
Phosphorus credits for bioretention systems with an underdrain.
Link to this table
| Particulate phosphorus | Dissolved phosphorus |
|---|---|
Is Media Mix C or D being used or, if using a mix other than C or D, is the media phosphorus content 30 mg/kg or less per the Mehlich 3 (or equivalent) test1?
|
1. Is Media Mix C or D being used or, if using a mix other than C or D, is the media phosphorus content 30 mg/kg or less per the Mehlich 3 (or equivalent) test?
2. Does the system include approved P-sorbing soil amendments2?
|
1Other widely accepted soil P tests may be used.
2Acceptable P sorption amendments include
- 5% by volume elemental iron filings above IWS or elevated underdrain
- minimum 5% by volume sorptive media above IWS or elevated underdrain
- minimum 5% by weight water treatment residuals (WTR) to a depth of at least 10 cm
- other P sorptive amendments with supporting third party research results showing P reduction for at least 20 year lifespan, P credit commensurate with research results