18. The method according to claim 1, wherein step (c) further comprises applying a surfactant to the soil.
19. The method according to claim 18, wherein the surfactant is a non-ionic surfactant selected from the group consisting of ethoxylates, alkyl phenol ethoxylates, and lauryl alcohols.
20. The method according to claim 1, wherein step (d) further comprises adding an activation agent with the reducing agent to adjust a pH of the soil.
21. The method according to claim 20, wherein the activation agent is one of a solution, a powder, or a fine granulate.
22. The method according to claim 20, wherein the activation agent is an acid selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, and acetic acid.
23. The method according to claim 20, wherein the activation agent is a base selected from the group consisting of calcium oxide, calcium hydroxide, sodium hydroxide, sodium carbonate, and sodium bicarbonate.
24. The method according to claim 1, wherein the reducing agent is a biological agent.
25. The method according to claim 24, wherein the biological agent is sludge from wastewater.
26. The method according to claim 24, wherein the biological agent is return activated sludge.
27. The method according to claim 24, wherein the biological agent is leachate from landfill or from composting operations. 28. The method according to claim 24, wherein the biological agent is waste activated sludge. 29. The method according to claim 24, wherein the biological agent is compost material from municipal wastewater, industrial wastewater, or solid waste operations. 30. The method according to claim 1, wherein the soil treated by the method has an amount of hexavalent chromium no greater than 5 mg/L.
31. A method for the in-situ reduction of hexavalent chromium to trivalent chromium in soil comprising hexavalent chromium in a hydraulically isolated area comprising:
(a) sampling soil comprising hexavalent chromium to determine a reaction amount of a reducing agent;
(b) providing a frame on a top surface of the soil;
(c) wetting the soil in the frame;
(d) spreading a reducing agent on the top surface of the soil in the frame;
(e) flushing the soil in the frame with water to dissolve the reducing agent;
(f) pumping water comprising the reducing agent from an aquifer below the soil and applying the pumped water to the soil in the frame.
32. A method for the in-situ reduction of hexavalent chromium to trivalent chromium in soil comprising hexavalent chromium in a hydraulically isolated area, wherein the area comprises a contaminated waste product selected from the group consisting of return activated sludge and waste activated sludge, comprising:
(a) sampling soil comprising hexavalent chromium to determine a reaction amount of a reducing agent;
(b) calculating a reduction power of the contaminated waste product;
(c) providing a frame on a top surface of the soil;
(d) wetting the soil in the frame;
(e) pumping water comprising the contaminated waste product from an aquifer below the soil and applying the pumped water to the soil in the frame.