Permaculture in New Zealand

kia ora tatou, 

 wondering if anyone has had any experience  / heard tell of  approaches to sites contaminated with the ddt family? i am in process of designing/building  a permaculture food forest/garden  and some of our site was a commercial grape and tomato-growing glasshouse in the 50s thru to 70s..i

hill laboratories has just given us the fab news of ddt contamination of just over .2mg per kilo of soil as well as " insignificant" levels of lindane.

removal will now be heinously expensive and i 'm hoping there's a body of knowledge out there to deal with rendering it inert/locked in/stabilised onsite. prefer not to go the way of phyto-mediation ( ie removal by sacrificial plant, have come up with pumpkin growing !) as it would also involve the removal of much nutrient/soil life/structure  as well.  in the mean time, any leads/suggestions/experience /referrrals?

thanks in advance, 

alice