890 F.3d 304
D.C. Cir.2018Background
- EPA used the Hazard Ranking System (HRS) to score the West Vermont Drinking Water Contamination Site in Indianapolis and listed it on the National Priorities List (NPL) after a 2015 HRS analysis produced a site score above the 28.50 threshold.
- EPA treated a shallow Glacial Outwash Aquifer and a deeper Limestone Bedrock Aquifer as a single hydrologic unit because it concluded they are hydraulically interconnected within two miles of contamination sources (Genuine Parts and Michigan Plaza).
- EPA relied on several studies (including well logs, an Indiana University survey, and Indianapolis Water Company cross sections) to support interconnection and combined the aquifers in the HRS scoring, producing a maximum ground water migration pathway score and a final site score of 50.
- Petitioners (Genuine Parts and Aimco) submitted comments pointing to cross-section diagrams and survey language in the record showing a continuous clay/till (nonaquifer) layer separating the aquifers within the two-mile radius, and argued EPA therefore lacked substantial evidence of interconnection.
- Petitioners also argued EPA improperly counted nearby municipal wellfields in the HRS "targets" calculation without accounting for groundwater flow direction that indicates flow away from those wells.
- EPA’s final rule response did not address the cross-section diagrams directly and explained it lacked sufficient data to assess regional groundwater flow direction; EPA affirmed its interconnection finding and its distance-weighted targets calculation.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Whether EPA had substantial evidence to treat the upper and lower aquifers as interconnected and thus combine them in the HRS scoring | Cross-section diagrams and survey text in the administrative record show a continuous clay/till confining layer separating the aquifers; EPA ignored this contrary evidence so its interconnection finding lacks substantial evidence | EPA relied on well logs and other studies it says show no consistently present separating clay layer and argues cross sections can be unreliable extrapolations; post-hoc counsel explanations support interconnection | Court: EPA acted arbitrarily and capriciously and lacked substantial evidence because it failed to address record evidence (cross sections) that contradicted its conclusion; listing vacated and remanded on this ground |
| Whether EPA properly included nearby wellfields in the HRS "targets" score without accounting for groundwater flow direction | EPA should have excluded or down-weighted wells upgradient of contamination because evidence shows groundwater flows away from those wells | HRS methodology requires distance-weighting of wells within four miles and does not mandate considering flow direction at the listing/screening stage; EPA lacked sufficient data to determine flow direction across full area | Court: EPA reasonably applied the HRS distance-weighting rules and did not act arbitrarily; this claim rejected |
Key Cases Cited
- Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29 (1983) (agency action arbitrary and capricious when it fails to consider important aspects or relies on explanations counter to record)
- Universal Camera Corp. v. NLRB, 340 U.S. 474 (1951) (substantial evidence review considers record as a whole, including contradictory evidence)
- Butte County v. Hogen, 613 F.3d 190 (D.C. Cir. 2010) (agency may not ignore evidence contradicting its position)
- Carus Chemical Co. v. EPA, 395 F.3d 434 (D.C. Cir. 2005) (describing HRS and NPL consequences)
- US Magnesium, LLC v. EPA, 630 F.3d 188 (D.C. Cir. 2011) (permitting challenges to an agency's application of HRS despite timing rules)