Section R. 299.10 - Generic cleanup criteria for groundwater in aquifer based on ingestion of groundwater for drinking waterRule 10.
(1) Exposure to groundwater by ingestion shall be considered a relevant pathway for groundwater that satisfies either of the following conditions: (a) The groundwater is in an aquifer.(b) The groundwater is not in an aquifer, but can reasonably be expected to transport a hazardous substance into an aquifer in a concentration that exceeds the generic residential criteria developed under subrule (2) of this rule.(2) The criteria developed pursuant to R 299. 9 and R 299. 10 are not applicable if ingestion of the groundwater is, or as part of the response activity will be, reliably restricted by a restrictive covenant, a notice of approved environmental remediation, or an institutional control that is allowed for under these rules and approved by the department, if approval is required.(3) Cleanup criteria for groundwater based on ingestion of groundwater for drinking water shall be calculated according to the following algorithms, except as provided for in R 299.34. Criteria calculated under this subrule shall be the generic cleanup criterion, unless a state drinking water standard is available or, if a criterion protective of adverse aesthetic characteristics is more restrictive, as provided for in section 20120a(5) of the act.EQUATION FOR CARCINOGENIC EFFECTS:
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| where, |
| DWC | (Drinking water criterion) | = chemical-specific (ug/L or ppb) |
| TR | (Target risk level) | = 10-5 |
| BW | (Body weight) | = 70 kg |
| AT | (Averaging time in days) | = 25,550 days (70 years x 365 days/year) |
| CF | (Conversion factor) | = 1000 ug/mg |
| SF | (Oral cancer slope factor) | = chemical-specific (mg/kg-day)-1 |
| EF | (Exposure frequency) | = 350 days/year (residential) |
| = 245 days/year (nonresidential) |
| ED | (Exposure duration) | = 30 years (residential) |
| = 21 years (nonresidential) |
| IRdw | (Drinking water ingestion rate) | = 2 liters/day (residential) |
| = 1 liter/day (nonresidential) |
EQUATION FOR NONCARCINOGENS:
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| where, |
| DWC | (Drinking water criterion) | = chemical-specific (ug/L or ppb) |
| THQ | (Target hazard quotient) | = 1 |
| RfD | (Oral reference dose) | = chemical-specific (mg/kg-day) |
| BW | (Body weight) | = 70 kg |
| = 10,950 days (30 years x 365 |
| AT | (Averaging time) | days/year - residential) 7,665 days (21 years x 365 days/year - nonresidential) |
| RSC | (Relative source contribution) | = chemical-specific or 0.2 if chemical-specific data are not available |
| CF | (Conversion factor) | = 1000 ug/mg |
| EF | (Exposure frequency) | = 350 days/year (residential) 245 days/year (nonresidential) |
| ED | (Exposure duration) | = 30 years (residential) 21 years (nonresidential) |
| IRdw | (Drinking water ingestion rate) | = 2 liters/day (residential) 1 liter/day (nonresidential) |
(4) For the purposes of this rule, the point of exposure shall be presumed to be any point in the affected aquifer.Mich. Admin. Code R. 299.10