for drainage purposes and helping to lessen lateral and hydrostatic pressure you should--contractor--builder... backfill with....peastone---gravel-

http://www.yodergroup.com/concrete.asp

They state as i have " even more important to keeping a basement dry is the foundation backfill process. We firmly believe a foundation should be backfilled with washed gravel(not dirt)from the basement florr level all the way up to within 2-3" of the finished ground level outside the home.This type of drainage prevents trapped water and saturated soil next to the foundation from building up horizontal hydrostatic pressure against the wall. This pressure will crack walls,cause leaks, and in a worse case collapse the wall inward.Despite these Facts, most local building codes require only 18" of coverage from the bottom up.The additional cost for full height backfill is approx. $3,000. For this reason, most builders provide the minimum coverage required by codes."