Reclamation On Brine Spills In Upland Boreal-forested Areas

Abstract

Introduction Large volumes of brine are produced in the oil fields of Alberta each year and disposal lines carrying salt water to the disposal wells occasionally rupture. Much of the oil and gas exploration is centred in the forested portion of the province, yet there is little information on the reclamation of salt spills in the boreal forests. Two spill sites were established in 1977 and four main treatments and three sub-treatments were applied in 1978. Flushing the brine-treated plots with water rapidly lowered the salt content of the soil compared to brine-treated plots. That is, flushing reduced the length of time the soil colloids and flora were exposed to high salt concentrations. The addition of gypsum in combination with flushing lowered the sodium adsorption ratio of soil in the 0 – 30 cm depth and prevented dispersion (liquefaction), thereby substantially reducing the erosion hazard. In contrast, soil/or the 0–30 cm depth in the brine-treated plot that was left to natural forces became a jelly-like mass (liquefaction). Four vascular species were monitored during this study and their response indicated that a combination of flushing, gypsum, fertilizer and a cover crop was superior. The calcium in the gypsum probably had a beneficial physiological effect on the flora. By the fall of 1981, all treatment plots had a complete cover but the brine-treated plots with no flushing had mainly salt-tolerant invader species. Flushing should be undertaken promptly following a spill together with containment plus a follow-up application of gypsum, moderate fertilization and establishment of a cover crop. Introduction Abundant information is available regarding the reclamation of agricultural land affected by waters high in sodium. The Dutch were pioneers in this work because food production in Holland depended on their ability to reclaim land that had been inundated by sea water. Closer to home, White and de Jong(1) conducted a literature review of potential methods for reclamation of salt-damaged soils in Saskatchewan. de Jong(2) then prepared a field manual for the Canadian Petroleum Association outlining actions that should be undertaken to reclaim nonforested lands affected by salt spills in the oil fields of Saskatchewan. However, apart from monitoring studies (Edwards and Blauel(3); Rowell and Crepin(4)), there is little information in the literature regarding the reclamation of forested lands that have been contaminated with brine. The reclamation techniques used for agricultural and nonforested areas may not be applicable to forested areas. In farm lands, amendments normally can be tilled into the soil and there is a good choice of salt-tolerant crops. In forested areas, however, amendments normally should not be tilled into the soil because understory flora (shrubs and mosses) should not be disturbed. To further complicate matters little is known about the effects of concentrated brines on the survival of many of the forest species. Yet, a major portion of oil-related salt spills occur in forested regions of Alberta. Brine production in Alberta over the seven-year period; 1971 to 1978 increase from 16 million m3 to 63 million m3 (100 million to 400 million barrels).