New Closure, 2007

***Q.  I found the MSW and the occurrence and movement of groundwater very interesting.  I had little previous knowledge of both.  I particularly found it interesting how ground water moves underground.  One question I had was based on the MSW.  I can see that it is inevitable that hazardous waste will end up at a dump from households, however what is done to ensure the regulations are met?  Are all of the chemicals listed on the webpage provided in module 11 https://classes.uaf.edu/webapps/portal/frameset.jsp?tab=courses&url=/bin/common/course.pl?course_id=_39753_1 analyzed?  Also if you have a hazardous waste such as old rat poisoning, which presents an arsenic hazard, what is the most appropriate way for a household to dispose of it?
A. Household wastes are exempt from RCRA for political reasons, not logic-based risk assessment.  Having said that, the hazardous waste in household refuse is a very small percentage and probably not that big a deal today.  Also, today, landfills are lined and groundwater is monitored.  If there are no drinking water wells close by – the risk may be very small. 

** Q. One thing I found foggy was if there was typically an official risk assessment (with all receptors and pathways identified) performed when siting a municipal solid waste landfill.
A.  Oh yes.  Lots of them.  Landfill and incinerator siting are some of the most controversial public actions and are subject to long and acrimonious political action at the local level followed by court actions.  Most of the objections are based upon risk assessments done by various parties.

**Q One thing I found a little foggy is the concept of natural attenuation.
It seems that with the plethora of treatment technologies available, this
would be a last resort.  How often is this strategy employed today?
A. It is the preferred choice by all PRPs, because it is cheapest.  The question depends on the agency that is overseeing the cleanup - will they allow it?

*Q. I found it interesting that underground injection sites were required to be just 1/4 mile from drinking water aquifers.  I imagine that injection
was limited to certain types of HW, depending on toxicity.
A. No new wells of that type have been allowed in many years. Yes it is horrifying.  But indeed there are locations where it does not matter.