There needs to be a standard to compare it with. What would a soil sample from a narmal garden show from those same materials. Without that no one can say whether these results are good, bad, or indifferent.

The shaded areas in bold print indicate the metals are above the safe clean fill standards. For gardening, I wouldn't want to try it.

The problem with ponds/lakes, etc. is everything is concentrated. Both the good and the bad.

A lot would depend on where the water from the pond came from. If it's draining from farmland that uses chemicals, or there is a factory upstream emitting pollutants, or a sub-division, I wouldn't touch it.

I do a lot of cutting of weeds for composting material. It takes about an acre to fill a bin just 3 feet around and 3 feet tall. When I see these big piles of commercial compost, I wonder where they are getting their materials.

In our city they do some collecting of plant matter. They also mix the street sweepings in with it on the theory the bad stuff is diluted enough. This is probably fine for flowers, but I wouldn't want to eat it.

My general theory is the further one gets away from using hand tools, the more likely it is pollutants will be introduced. And the more one uses materials collected by others, the more pollutants will be introduced.

As I've been gardening, I've become more aware the land in America has become a chemical wasteland.

Jake,

Glad you posted this question here. I deal with these numbers all day although for a different state. I will try to give you some perspective.

Regulatory standards - such as PADEP's 'clean fill' numbers - vary quite a bit and do not always tell the whole story. I am not sure what the system is in PA but these numbers look to be at or close to naturally occurring background. These standards seem very conservative and a lot of native soil in my state would fail! Of course soils vary by region as well, I'm just mentioning this for perspective. Exceeding PADEP's numbers may only mean that additional evaluation is suggested before using the stuff. It does not necessarily mean there is a significant health risk.

There are a lot of numbers out there - my state has conservative clean fill standards, plus residential use (in some cases higher than the clean fill numbers), and non-residental. These are calculated using pretty much the same toxicity and exposure parameters nationwide, based on EPA models. I'll list below some of our residential numbers and a few comments about the metals that were flagged:

Arsenic: low 6.5 hi 11.9 This is likely natural background, we often see it this high in MO or even higher. Note, our health-based number for residential use is about 4, and PA's is probably in that range, we all use the same models. No way to clean up below natural background.

Beryllium lo 1.1 hi 1.7 Our residential number is 0.7 and background in MO soils is typically in the 1 - 1.5 range. Again, background higher than calculated health-based standards. Also they noted that the analysis had interference.

Lead lo 15 hi 67 MO residential 260 EPA/HUD residential 400. Again, background, no problems here.

Manganese lo 438 hi 930 MO residential 2720 this is a plant nutrient, not sure what natural background typically is but I would bet what's in my pocket...

Nickel lo 20 hi 27 MO residential 505. Ditto.

Zinc lo 52 hi 162 MO residential 7220 Another plant nutrient and low toxicity.

Frankly I am surprised PADEP is giving the impression this stuff is not safe. I don't see anything here suggesting it is not safe to use. You may want to contact PADEP and ask them what these numbers mean to them. Are they close to natural background and does PADEP take that into account in their standards?

The PCB/petroleum etc. numbers look fine too. Bottom line, this does not look like screaming contamination to me, and I would not hesitate to use this in my yard.

Hope this helps!

Tox

Tox!

Thank you so much for that info!! I'm happy to find someone who knows what all those numbers mean :). Both tributaries for this particular lake come through mostly residential areas not industrial. My intent (as mentioned above) is to mix in a lot of horse manure and plant a cover crop of clover or rye or something like that for the winter. Then plant my garden in there next year. I'll definitely send the soil out for analysis in the spring before planting anything. I have one garden already that's about 3000 square feet and I'm trying to make another one about 2500 square feet just for garlic/onions/leeks /etc...(things that deer won't eat) with this sediment.

I saw a topic here where someone had mixed their soil with some water in a mason jar then measured the different amounts of sand, clay, and organic material after it had all settled. I tried this over the weekend but my results were not nearly as dramatic. As everything settled there was no distinction at all between the different layers if indeed there are different layers.

Here is a lot more information about the project and soil analysis etc...Much more than I care to copy and paste ;)

http://www.lrp.usace.army.mil/pm/Final_detailed_project_report.htm#sediment

Thanks again for the input!

~Jake

Jake, that test, the so called jar test, shows what your soil is and not every soil will settle out as is described because that information is about loam. A test I did on a soil in Ohio showed three types of clay and no sand or silt. One I did in Indiana showed clay and silt with no sand. What you are most interested in is the amount of organic matter on the top. If there was no apparent different layers of stuff after everything settles out your soil is similar to many others, including mine, just one type of mineral particle, but if there was no organic matter on the top you need to add a lot. I have seldom seen that test done where there was no OM.

Glad to be of some help. I read those kinds of reports all day, so forgive me if I step away from the keyboard and pick one up off my desk that's actually billable. :-D

toxcrusadr, your analysis is fascinating. One thing I don't understand: in your breakdown, HUD puts safe lead levels at 400 ppm, and so does the EPA. So figuring that a cubic foot of soil weighs, say, 100 pounds, this means that a typical 8' Ã 20' garden bed can safely contain more than 6 pounds of lead. I mean, I'd be concerned if I lost a couple of lead fishing weights in the garden!

I checked the math and that looks correct, assuming the soil is 1 ft. deep. 6 lb lead dispersed in 16,000 lb of soil, of course. Freaky isn't it. The thing about these numbers is, if you believe in the process, you have to accept the result, even if it seems weird.

Lead is actually one of the most studied contaminants because of the lead paint issue, and, in MO, lead mining, which has made entire counties into Superfund sites. There is more direct data on human toxicity than for most contaminants because lead is so widespread. For example, you can measure lead in the blood of a population and correlate it to toxic effects such as nervous system development and intelligence in children. That's where the numbers come from. And I believe the residential risk assessment does include exposure from gardening.

Having said that, if I lived on 400 ppm lead I would think about raised beds with imported soil, or at least washing the heck out of my root crops (adhered soil is probably a larger dose factor than uptake). Especially if I had kids. Our state uses 260 as a residential standard (the feds are still cleaning up sites to 400 here though - go figure).

We don't know everything, the science isn't perfect, but anything below 100 seems very unlikely to be a problem.

By the way, one more thing on the 6 lb of lead...the standards, as well as the lab analysis, are all based on dry weight. So if the soil is 25% moisture by weight, for example, there is 12,000 lb of dry matter there instead of 16,000, and only 4.8 lb of lead instead of 6.4. I'm sure you feel so much better now.