Percent P Removed Via Non-Volume Reduction Treatment.

Caution: NOTE: These percentages apply to the non-volume reduction portion of stormwater runoff. The volume reduction portion of stormwater runoff receives 100 percent credit for particulate and dissolved phosphorus.

Link to this table

Particulate P Dissolved P
Current in MIDS calculator Proposed Current in MIDS calculator Proposed
No underdrain 0% 0% 0% 0%
Elevated underdrain 45% Is soil P content tested to be < 30 mg/kg per Mehlich III (or equivalent) test?
  • If yes, 40%
  • If no, 0%
0% Is soil P content tested to be < 30 mg/kg per Mehlich III (or equivalent) test?
  • If no, 0%
  • If yes, is there at least 2 feet of soil above the elevated underdrain? If yes, 20% credit,
  • If no, credit = 0.2*x
Where x = (soil depth above elevated underdrain) /2 feet
  • Additional credit for approved P-sorbing soil amendments = 40 percent if one of the following conditions aapplies.
    • 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 (1/3 foot)
    • 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
Underdrain at the bottom 45% Is soil P content tested to be < 30 mg/kg per Mehlich III (or equivalent) test?
  • If yes, 40%
  • If no, 0%
0% Is soil P content tested to be < 30 mg/kg per Mehlich III (or equivalent) test?
  • If yes, 20%
  • If no, 0%

Additional credit for approved P-sorbing soil amendments = 40 percent if one of the following conditions applies.

  • 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 (1/3 foot)
  • 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
Internal Water Storage (IWS) Not in calculator Is soil P content tested to be < 30 mg/kg per Mehlich III (or equivalent) test?
  • If yes, 40%
  • If no, 0%
Not in calculator Is soil P content tested to be < 30 mg/kg per Mehlich III (or equivalent) test?
  • If yes, 20%
  • If no, 0%

Additional credit for approved P-sorbing soil amendments = 40 percent if one of the following conditions applies.

  • 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 (1/3 foot)
  • 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

This page was last modified on 26 March 2014, at 10:35.

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