1. I RIS E NVIRONMENTAL Independent Review of Documents Pertaining to the Lehigh Southwest Cement Permanente Facility Rob Balas & John McLaughlin February 6, 2012 I RIS E NVIRONMENTAL 1438 Webster St, Suite 302, Oakland CA 94612 (510) 834-4747 www.irisenv.com

2. I RIS E NVIRONMENTAL Limit of Review Human Health Risk Assessment (HHRA) for Cement Plant Documents Pertaining to Discharges of Water From Quarry and Cement Facilities Additionally, at the direction of the Town of Los Altos Hills, one sediment and one surface water sample were collected in Permanente Creek

3. I RIS E NVIRONMENTAL Human Health Risk Assessment (HHRA) AB 2588 Air Toxics “Hot Spots” Program Review focused on –Estimated Emissions –Air Dispersion Modeling Assumptions and Inputs –Toxicity Assessment and Risk Evaluation Objective: evaluate adequacy of the methods used in HHRA to estimate emissions and associated potential impacts to human health

4. I RIS E NVIRONMENTAL Human Health Risk Assessment (HHRA) HHRA concluded health risks were below agency- specified thresholds Review determined HHRA was adequately and sufficiently conducted Summary of significant comments: –Current scenario assumes production at levels below permitted maximum –Future scenario assumes implementation of emission reduction technologies

5. I RIS E NVIRONMENTAL Review of Historical Discharges Discharges of sediment-laden water in violation of Storm Water Permit Of concern is that the Facility is potentially increasing discharges of naturally occurring metals (e.g., selenium, mercury, chromium) present in soil to Permanente Creek Water Board is in the process of bringing the Facility into compliance under a different discharge permit Water Board also requiring additional characterization of discharges

6. I RIS E NVIRONMENTAL Permanente Creek Sampling One sediment, one surface water sample were collected (i.e., snapshot of conditions) Analyzed for metals Hexavalent chromium, mercury, and selenium not detected in the surface water sampling Detections of molybdenum in surface water and arsenic and vanadium in sediment soil exceeded conservative screening levels A detailed analysis to determine the source of these metals was not within the scope of this sampling effort, though they may be background related Based on this single data point, there does not appear to be excessively high levels of contaminants in the creek at the sampling location

7. I RIS E NVIRONMENTAL Next Steps It may be useful to evaluate ongoing compliance with emission and discharge standards It may also be useful to monitor Facility response to these requirements on an ongoing basis to ensure the adequate and timely compliance of the Facility with proposed actions