Ill. Admin. Code tit. 35, § 616.207 - Determining Background Values and Maximum Allowable Results ("MARs")

Current through Vol. 46, No. 16, April 15, 2022

a) The owner or operator shall, beginning no later than the beginning of operation of the unit and continuing for a period of at least one year, sample each monitoring well at least every two months and analyze each such sample according to the following program:
1) For a unit subject to Subpart E (land treatment units), Subpart F (surface impoundments), Subpart K (road oil storage and handling units) or Subpart L (de-icing agent storage and handling units), analysis shall be for pH, specific conductance, total organic carbon, total organic halogen, and any other parameter that meets the following criteria:
A) Material containing such parameter is stored, treated or disposed of at the unit; and
B) There is a groundwater standard for such parameter.
2) For a unit subject to Subpart I for the storage and handling of pesticides, analysis shall be for each pesticide stored or handled at the unit.
3) For a unit subject to Subpart J for the storage and handling of fertilizer, analysis shall be for pH, specific conductance, total organic carbon, nitrates as nitrogen, ammonia nitrogen and for any other parameter that meets the following criteria:
A) Material containing such parameter is stored or handled at the unit; and
B) There is a groundwater standard for such parameter.
b) The results obtained under subsection (a) shall be used to calculate the background mean, background standard deviation and the Maximum Allowable Result (hereinafter referred to as "MAR") for each parameter using the following procedures:
1) Results from all samples collected during the year must be used in the calculations unless the owner or operator demonstrates to the Agency that one or more of the results was due to error in sampling, analysis or evaluation.
2) All calculations must be based on a minimum of at least six sample measurements per parameter per well.
3) If any measured value is equal to or greater than its PQL, or if any measured value is greater than its corresponding groundwater standard, the actual measured value must be used calculating the mean and standard deviation.
4) If any measured value is less than its PQL and less than its corresponding groundwater standard, the PQL rather than the measured value is to be used in calculating the mean and standard deviation.
5) Except for pH, the MAR is the quantity equal to the measured mean value of the contaminant plus the product of the contaminant's standard deviation times the following constant:

Sample Size

Constant

6

2.10

7

2.03

8

1.97

9

1.93

10

1.90

11

1.88

12

1.85

13

1.84

14

1.82

6) For pH, the upper limit for the MAR is the quantity equal to the measured background mean pH plus the product of the calculated background standard deviation of the samples times the constant tabulated in subsection (a)(5).
7) For pH, the lower limit of the MAR is the quantity equal to the measured background mean pH minus the product of the calculated background standard deviation of the samples times the constant tabulated in subsection (a)(5).

Notes

Ill. Admin. Code tit. 35, § 616.207

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