Leachate detection

[Okeydokey]

We are installing a well located somewhat near a old town dump. While groundwater flow has been proven (prior hydrogeo investigation) to flow away from the well, we need to confirm there is no contamination at the new well. What type of water quality test would be a good indicator there is no leachate in the well water?

Thanks

 

[dicksewerrat]

TCLP. Test for everything, especially if this water will be used as drinking water.

 

[KRSServices]

is the dump still in use? If not, how long was it in operation, how much refuse is in it, what type of waste (municipal/industrial) and how long ago was it capped (closed).

Leachate contains some of the nastiest compounds known to mankind. If the landfill was recently closed and was in use for about 30 years, leachate will be a problem for about the next 50 years. If the landfill is not lined properly then the problem has exponentially accelerated. Proximity to the landfill, the surrounding soils, the landfill management policies, post closure policies, etc. will all play a role in the leachate migration and possible contamination into the aquifer.

Be very careful with this one, and do your homework first. Otherwise carry some big insurance.

KRS Services

http://www.krs-services.com

 

[kenvlach]

If there is a leachate collection system and/or monitoring wells downstream of the dump, this should be public access data, so you can get a list of compounds to look for (and add any likely degradation products).

Agree strongly with KRS: “Be very careful with this one, and do your homework first.” You need to do a 24 hour continuous maximum pumping, with sampling before and after, as you may cause localized drawdown and backflow of the aquifer. Also, you may be liable for effects upon neighboring wells. Check for historical watertable records from any nearby municipal or irrigation wells (both heavy users). Effect of drought years?

 

[mmenarry]

Common approach in addition to the above suggestions would be to put sample wells in between the two, to track any possible migrations in the hydro-geo.
Very common practise here in Ireland.
Michael

 

[elcid77]

All posters have made good points (check with local environmental regulators for available data, be careful of drawdown effects, put in well between your well and those at the landfill, etc.) Something to consider is that deep (or confined aquifer) flow can sometimes be contradictory to shallow (or unconfined aquifer) flow. Presumably, the well you are putting in is a domestic well and will therefore be in the deep or confined aquifer. In some cases the fissures groundwater travels in can be equivalent to pipe flow so that while a contaminant plume in the shallow aquifer may appear to dissipate laterally to non detectable concentrations a “safe” distance from your well site, it may be slipping into your drawdown zone via the deep aquifer. Hopefully, available data includes an examination of the deep aquifer as well.

As to your original question, if budget was a concern and I could just run one test I would analyze the groundwater in your well for EPA Method 8260 volatile organics. This method targets common volatile organics in fuel, solvents, household products, etc and can detect very low concentrations of these compounds. Also, some of these common volatile compounds such as acetone are very soluble and therefore more mobile.