The California Department of Toxic Substances Control has some helpful background information about different kinds of historical pesticide applications in their soil sampling guidance.

http://www.dtsc.ca.gov/Schools/upload/Ag-Guidance-Rev-3-August-7-2008-2.pdf

We don't call pesticides RECs, but we do recommend sampling. 

Patrick

I agree with Goldbarfellow - Lead a_rsenate was applied as a pesticide at orchards before the use of DDT became prevalent.  We have seen very high concentrations of lead and a_rsenic (and dieldrin....) in shallow soils at former orchard properties.  Although typically just shallow soils are impacted - it can be over such a large area that it can pose a pretty substantial cost if the property is to undergo development as a residential use (either as a remedy to address risks posed by the levels present; or just for special management considerations of soils requiring removal as a result of routine site grading).

With regard to DDT - I have seen in the literature where application rates for DDT for row crops would be anywhere from 1 to 30 lbs/year per acre - potentially accumulating to levels ranging from 20 to 100 pounds per acre.  I have not seen many agricultural sites where the remaining concentrations would be of concern - primarily due to the 1/2-life as noted by Tom above; and perhaps as a function of the limited number of investigations of this type I have been involved with.   I haven't evaluated crop dust application vs. other forms of application though.

Sampling of former Orchards that may convert to residential use seems a must - primarily due to the potential for lead arsenate and dieldrin impacts.  Land that was formerly used for row crops is perhaps less of concern - but I would still consider it prudent to sample.  At least a few States have guidance to this effect (California, Oregon).

Check out the attached to see how perceptions change over time with regard to what is considered acceptable and perfectly safe! 

In California, pretty much SOP to sample shallow soils at planned residential developments when there is former ag use.  Of course that was back in the day when we were actually building new homes in California :)

Matt

I would classify early to mid-20th century (the "better life through chemistry" age) agricultural application of pesticides/herbicides a REC in the absence of additional information regarding past pesticide types, crop types, application, common historical practices for the area, or other information.

I would virtually guarantee that you'll find some trace concentrations of DDT and its breakdown products (DDE, etc.) on just about any piece of land used for agricultural purposes during the mid-20th century.  It's unbelievably persistant and ubiquitous.  If you look for it, you'll find it.

Be wary of small air strips in agricultural areas, especially reviewing historical aerial photographs.  These are the places where the pesticides were stored, mixed, rinsed, and loaded on to the crop dusters.  I can think of at least one location in the Phoenix area where this was a problem.  Any place where pesticides were stored, mixed, rinsed, and loaded is a big red flag.

Lead arsenate applied to the orchards of central Washington is a huge issue.

Yakima schoolyard cleanups

Oregon, among other states, has been proactive and has published a guidance on residual pesticides.

Guidance for Evaluation Residual Pesticides on Lands Formerly Used for Agricultural Production

The Oregon guidance posted by Stones has been incredibly helpful!!  Anyone who comes across the agricultural land use issue on a large acreage multi-use development project should have a copy of the Oregon guidance.  It is has been a valuable document to present to clients who initially tought I was being too conservative.   The approach and rationale now sit a bit better with the naysayers after seeing the Oregon guidance.  Yes, this can be a real problem and some State governments have spent valuable resources to get a handle on it.  Thx again

I used to work in research and development in the pesticide industry.  I have actually collected crops and soil for residiue analysis.  You have little fear from the currently registered  pesticides, as you can't get a label if the product is persistent.   That doesn't mean someone can't create a problem by being stupid.    I don't get too worried about row crop frarms that haven't been farmed for a while.  An orchard or fields intensively used for agriculture are different.  I have sampled a few orchards that were in production the year before we did our assessment and found little to nothing.   I have heard of groundwater issues in areas (mid west) that use a lot of atrazine and lasso (alachlor, I think).    

You will rarely get to interview a farmer that was around when DDT and aldrin, etc was sprayed.  And he probably wouldn't say he did if he did.  Another problem is in the old days, chemicals were known by their trade name.  DDT- Toxaphene could be called Atomic Six or anything.  Small companies could buy tank truck loads of peticides and reformul and repacakge it in 5 to 55 gallon container under their own name.       

You seem to focus on "crop dusting" (aerial application).   Around here much more is put out with ground rigs.  There is not real diference except ground rigs may actually get more on the target.  However, airstrips that had an aerial applicator operating from it are prime problem sites.   I know of one personally.  The pilot used to do our test plots and he had a "dump pond" at hsi parking pad.   It's now a state superfund site.    

The real problems with farms are the storage, mixing and disposal areas.  I've never been on a farm that was inoperation before the 70s that did not have a dump somewhere.  Its usually as far as it can be from the house, in an area that can't be used for anything else (ie wetland or swamp)  Also look for gullies.  They are great places to throw stuff. 

In short, I don't get too worked up over row cropped fields where I am.   An orchard that is going to be used as a subdivision might  warrant furher investigation.   Look for dump sites on all farms.   

In response to Dr. DDD, I'm not sure I agree that an REC can be determined based on the proposed land use.  I agree that the cleanup of an REC is based on the proposed land use, such as a residential development versus continued agriculture. However, identifying the RECs should be independent of the proposed land use.

Technical side note brought up in other discussion threads - the application of pesticides in accordance with labels is not an REC based on CERCLA regulations, even if it was the historical application of inorganic pesticides, chlorinated herbicides, or organochlorine pesticides. I'd recommend either bringing it to the attention of the client as a BER or "other environmental condition". 

Patrick

We found another problem at orchards.....Pentachlorophenol. The PCP was applied to "prop poles" - sticks that hold up fruit laden branches. The farmers would make dip tanks to treat the poles. The dip tank and pole storage areas were impacted. 

Farms also treat livestock with bio-cides. Like a "hog-dip" operation, whereby the animal is walked through a trough containing chemicals.