Department of Environmental Science, Faculty of Science and Technology, Mount Royal University, Canada

Speech Title:Effect of a water-based drilling waste on receiving soil properties and plants growth
Abstract
One of the primary concerns of the rising growth of the petroleum industry in Alberta, Canada is on the proper management of drilling streams generated during drilling operations. Land spreading represents an attractive option for managing water-based drilling waste, however, the impact on soil properties and phytotoxicity remains largely unknown. This study was carried out to assess the relative effects of recommended guideline for land spraying loading rate application on soil properties and plants growth. The source of the drilling waste material was from an active well site drilling program. Composite representative samples of the drilling waste streams which also included the flocculated finer solids from the collection bins were transferred into a clean 20 L high density polyethylene pail. The pail was then homogenized and stored at 8 _₀C in a refrigerator prior to initiate the analyses. Soil sample used in this study was retrieved to a depth of 10 cm from a cultivated land located in Southern Alberta and represents soil type with physicochemical properties generally found in the area. The drilling waste was analyzed for dry Bulk Density, pH, EC, TDS, chloride, sodium, calcium, magnesium, SAR and COD. Maximum application rate for a regulated parameter was calculated according to the following equation: MAR (m3ha-1) = Pmax (kgha-1) {[1 x 106 (mgkg-1) / Pw (mgkg-1) x DBD (kgm-3). The drilling waste loading rates were investigated for their phytotoxicity on Alfalfa (Medicago sativa), Oat (Avena sativa), Barley (Hordeum vulgare) Corn (Zea mays), and Radish (Raphanus sativus). Drilling was applied at 0 x, 10 x, 40x, and 50 x in excess of the recommended loading rate. Following weighing, 500 g of the treated soil samples were transferred into respective germination pots (15 cm ID x 12 cm), covered and appropriately labeled. Each pot was seeded with a bio-indicator and spatially optimized as recommended by the seed company. The experiment was carried out in triplicate. Plants growth was monitored for a period of ten days. Drilling waste applied at 10 times above recommended loading rate improved the growth and germination rate of all plants excluding radish. Loading rates in excess of 40 and 50 times had a deleterious effect on radish, corn and oat but not on alfalfa and barley. Germination rate decreased as waste loading rate increased. Effects on soil physical and chemical properties were more pronounced at the 40 and 50 times exceeding recommended loading rate. Significant changes in soil parameters occurred at the higher rates in terms of increase in soil porosity, pH, EC, hydraulic conductivity, SAR and textural classification. This study indicates that the applications of this type of water based drill cutting if executed at an optimal loading rate, may improve soil quality and results in better plant growth.