GW investigation - how to interpret these results? 1

[murdock]

I am performing a subsurface investigation for a client whose property (which historically has been dry) has saturated soils. We suspect the upgradient (ground topo) mobile home park, which had a history of bad infrastructure (example- neighbor to our client had the same problem and found that a trailer's water service had leak which produced 6000 gpd). The septic mounds are uniformly old (25+ years), and installed before our state (VT) instituted sepic system rules.

Wells were installed near the property line between the park and the client's property. We tested chloride (for potable water), TKN, ammonia and coliform/e coli (for a failed wastewater system). The well closest to the PL had a total coliform count of >24192 coliform/100mL, 435.2 coliform/100mL for E Coli.

Are these results indicative of a failed WW system? What would be the potential sources of cross-contamination from a GW well that would give such a result to the sample? Thanks for the help.

 

[4tuna]

Murdock: to be frank, your questions are basic/fundamental -- you don't have a complicated situation. Your inability to interpret your own analytical results raises questions as to whether you should be performing this type of investigation for your client.

I am not trying to be rude, but I would ask the following: What do YOU think these results mean? Have you called the lab and asked what typical coliform levels are? Have you done a simple web search on coliform? Checked a local or state website for information? You would be surprised how much you will learn. Remember, we are here to help, but not here to do your work for you. Apologies in advance if I have misinterpreted your question, but as written the answers are self evident to anyone experienced in this field.

As Focht3 would say:
"Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora"

 

[Focht3]

Thanks, [blue]4tuna[/blue] - but I didn't originate the tag line - I borrowed it (with permission) from another member of "the Round Table" whose handle is [blue]VPL[/blue]. I had no idea how much of an impact it was making until now. (Round Table members offer suggestions and otherwise consult with [red]Eng-Tips[/red] management.) I'm flattered you thought it was my work. It's an excellent FAQ.

Thanks for the feedback. And feel free to add it to your own 'signature.' We want the site to be as useful as possible for everyone. And I'm sending [blue]VPL[/blue] a message to read this thread.

[blue]murdock[/blue]:
It is important to do your own homework before coming to the [red]Eng-Tips[/red] fora for help. If you have exhausted your resources, I apologize - but your original posting doesn't reflect that.



Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[KRSServices]

Murdocck,

I am not going to repeat the previous posts, but I agree with them totally. I suggest you engage the services of a hydrogeologist. I sympathize with your situation, and can relate to it somewhat. I too had to evaluate the possible migration of effluent into the surrounding groundwater system. In my case, it was with a wastewater treatment plant discharging through rapid infiltration basins. This mechanism was complicated by the fact that these basins were situated in a flood plain which was very ecologically sensitive (natural wetlands). I have a good understanding as to how coliforms can or cannot migrate through the strata, but there are also many other sources for contamination. Have you heard of the Walkerton (Ontario) contamination, where the groundwater was contaminated by surface runoff? I pose this scenario to illustrate that hasty conclusions can be the result of inexperience or lack of fundamental knowledge of the topic. Your post suggested contamination. While that may indeed be the case, it may be as well.

Further, have you considered testing for trace amounts of caffine in the water? If the trailer park is served by a well system, they may not be treating with chlorine. I have seen some tests (contamination of lakes) wherein caffine was present, but chlorides were not. Since coffee is north america's favorite beverage, the caffine in wastewater makes for an excellent identifying marker.

KRS Services

http://www.krs-services.com

 

[agsgeophysics]

Just wanted to add:
Another good way to determine if "city water" could be mounding - test for flouride. Flouridated water supplies will come up positive. Natural groundwater will be ND. (Obviously in this case the trailer park may be served by a well and not flouridated.)

 

[hotgas]

KRS Services

Caffine as a marker of groundwater contamination? Have you actually done this? Where can I find out more?

 

[cvg]

I believe caffiene would indicate contamination due to wastewater