Jb, welcome to the forums!
As your crawl is connected to the basement, the walls should be insulated (as existing) AND a house-air supply should be installed. This will move warm air currents around in the area to remove moisture so it won't condense on the cold plastic/earth. OR--- close it off from the basement air, and ventilate it per minimum code requirements. Once moisture condenses on plastic- you have a moisture problem there, that will only get worse as the temps get colder. Expect condensation on the wood joist framing/wood deck sheathing boards/ply/OSB and mildew (mold). Crawlspace air RH tracks outside RH- this is where your water is from- not a leak; http://www.smartvent.net/docs/crawlspacestudy.pdf
Condition the basement /crawl with house air supply and numerous choices of exhaust; http://www.buildingscience.com/docum...ance-and-codes
If the basement is unfinished, you could insulate the crawl/basement floor/water supply lines; http://www.google.com/url?sa=t&rct=j...,d.cGE&cad=rja
Though for a premium install, add foil-faced foam board (PIC) - air sealed and leave a gap at fibrous insulation/floor sheathing; http://www.buildingscience.com/docum...n-crawlspaces/
Check with local AHJ per code left uncovered.
Fibrous insulation is rated for R-value in a six-sided chamber, leaving a side off (attic/crawlspace application) takes a hit in the R-value, exposed to air movement; pp.12;http://www.energystar.gov/ia/partner...ide_062507.pdf
In a heating climate, the pressure drive (air/moisture) is usually upwards, any crawlspace air leaks find their way to the attic (stack effect) due to pressure/temperature differences (natural/mechanical); http://www.wag-aic.org/1999/WAG_99_baker.pdf
First; insulate/air seal the rim joists, a major contributor of air infiltration/exfiltration due to the seasonal shrinkage/expansion of older solid wood rim joists (R-1.25 per inch); http://www.buildingscience.com/docum...d-but-strange/