UAR/PROP 65 FILE 3 - Laserfiche WebLink

Home Browse Search

i CONESTOGA-ROVERS Mr. Michael Infuma & ASSOCIATES November 26, 2008 Monitored natural attenuation requires adequate site assessment and monitoring to confirm potential sensitive receptors are not adversely affected and to confirm the compounds are attenuating at an acceptable rate. Natural attenuation has been selected at Superfund and other sites where removal of hydrocarbons is not technically possible and where it has been determined active remedial measures would be unable to significantly speed remediation time frames compared to natural attenuation. ASTM guidance indicates "the primary line of evidence for remediation by natural attenuation is provided by observed reductions in plume geometry and observed reductions in concentrations of constituents of concern at the site' ." Additional evidence can be gained by measuring dissolved oxygen, oxidation reduction potential, nitrate, sulfate, ferrous iron, and alkalinity. The only aspect of natural attenuation requiring implementation is a monitoring program, which is already ongoing. When a clear attenuation trend is demonstrated and a reasonable time period ' to reach WQOs is established, monitoring should cease and No Further Action status should be granted. Monitored natural attenuation is recommended to achieve the remediation goals subsequent to implementation of Persulfate injection. SCHEDULE CRA will initiate work described above following written agency approval. Upon receipt of the necessary permits and scheduling with subcontractors, a start date will be provided. If this plan is approved by the end of 2008, then the schedule below presents the approximate timeline for completion of this work and submittal of a report. 1) Permitting/scheduling January 2009 2) Sample collection and one injection well installation February 2009 3) Bench-test treatability study and report February - April 2009 4) Eleven injection well installation June 2009 5) Submit notice of intent to discharge waste June 2009 6) ISCO injection events August 2009 — May 2011 7) Quarterly discharge and monitoring reports October 2009 — July 2011 8) Monitor natural attenuation August 2011 ' American Society for Testing and Materials (ASTM) Designation: E 1943-98. Standard Guide for Remediation of Ground Water by Natural Attenuation at Petroleum Release Sites. - 240783 8 Worldwide Engineering, Environmental, Construction, and IT services