Difference between revisions of "Phosphorus credits for bioretention systems with an underdrain"
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<td>1. Is Media Mix C or D being used or is the media phosphorus content 30 mg/kg or less per the Mehlich 3 test? | <td>1. Is Media Mix C or D being used or is the media phosphorus content 30 mg/kg or less per the Mehlich 3 test? | ||
| − | *If yes, credit as a % = 20 * (depth of media above underdrain/2) | + | *If yes, credit as a % (up to a maximum of 20%) = 20 * (depth of media above underdrain, in feet/2) |
*If no or unknown, credit = 0% | *If no or unknown, credit = 0% | ||
2. Does the system include approved P-sorbing soil amendments<sup>2</sup>? | 2. Does the system include approved P-sorbing soil amendments<sup>2</sup>? | ||
Revision as of 20:07, 16 January 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 is the media phosphorus content 30 mg/kg or less per the Mehlich 3 test1?
|
1. Is Media Mix C or D being used or is the media phosphorus content 30 mg/kg or less per the Mehlich 3 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