Basically we're working on expanding a loading dock outward and digging down 6 feet underneath it to turn the old crawlspace into usable space.

The pain in the ass is that we just pulled out a 70 year old oil tank that has completely saturated the soil around where we want to do this. Any ideas on how to seal up brick against petroleum soaked dirt?

10/12/2009 8:43:08 PM

This sounds like an environmental issue.

10/12/2009 8:46:51 PM

The EPA supervised removal.

The sweet part is that the surface above the tank was covered in concrete and there was no permeable surface nearby, so no rainwater touched the dirt since the tank was buried and the amount in the soil has hardly been diluted.

10/12/2009 8:51:21 PM

you shouldn't have any petroleum left in the ground. did they excavate and remove the contaminated soil when they got the tank?

10/12/2009 10:27:46 PM

if you have remediated the site, then this stuff should work for waterproofing the crawl space -> http://www.wrmeadows.com/wrm00063.htm. you can get the membrane from Guaranteed Supply. It is a stock item at their Greensboro store. This is BY FAR the easiest to use, most effective waterproofing membrane I have ever used.

I would recommend using washed stone right up next to the wall for compaction issues. Therefore, you should use a drainage mat to keep the membrane from being punctured by the backfill and a french drain to daylight or a nearby storm structure to alleviate water pressure against the wall.


[Edited on October 12, 2009 at 11:22 PM. Reason : .]

10/12/2009 11:20:11 PM

^^ They dug down 22 feet within a roughly 10' x 10' square and the soil was very well saturated. 28 tons of contaminated dirt was removed and replaced with sand. The only part that concerns me was that due to existing structure as well as a city sidewalk existing on three sides of the pit meant that a large amount of contaminated dirt was left in situ.

^ I've used something similar in the past, but worry that the large amount of petroleum in the ground will eat through parts of any conventional PVC based liner. I imagine that backfilling around the wall would keep the soil from contacting it, but everytime it rained some contaminates would rise in the water and contact the membrane. Damn, I guess we could repour the concrete around the new structure and make the soil impermeable again, though I'm not sure the EPA would let us, of course I have no idea if they would even catch wind of it from the permitting office.

Hopefully now that the concrete above it has been removed it will start to dilute at least a bit. The EPA guy said that the acceptable level of contamination was 10 (not sure what scale he was using) and that ours started at 700 and climbed over 900 as we dug.

10/13/2009 1:06:48 AM

If the AHJ didn't make you remediate further than you needed to, the I would say you are in the "clear" as far as contamination goes.

Most, if not all, of the waterproofing materials out there are bituminous, therefore petroleum distillates shouldn't affect their performance.

10/13/2009 8:52:57 AM