ASSESSMENT OF AN INNOVATIVE TECHNOLOGY TO REDUCE SEDIMENT AND IMPROVE WATER QUALITY IN A STORMWATER POND Laursen, A. 1 , Ulhaq, S. 2 , Bostan, V. 1 and Mar9n. D 2 . 1 Ryerson University. Department of Chemistry and Biology. Toronto, Ontario 2 WCI Environmental Solu9ons Inc. OJawa, Ontario. ABSTRACT WCI Environmental Solu9ons Inc., Toronto Water and Ryerson University partnered to complete a 12-week pilot project to assess changes in sediment and water quality using WCI’s EOS-2000 at the Lower Duck stormwater (SWMP) reten9on pond in High Park, Toronto. The EOS-2000 operated from September 11, 2015 to December 3, 2015. The EOS-2000 is solar-powered, mobile and requires no infrastructure. Ryerson monitored for one month pre-installa9on and throughout the project. Dissolved oxygen (DO) increased rapidly at installa9on and stayed above historical values over the treatment period. Oxygen satura9on surpassed 100%. The oxida9on reduc9on poten9al (ORP) increased sharply at start and remained high and stable thereaZer. Aerobic bacteria counts increased 1000 fold. Water clarity improved by 68 cm (218%) and chlorophyll a reduced by 87%. Between 14 – 23 cm (7.9% – 12.6%) of sediment was digested in only 3 months. Using the EOS-2000 within a SWMP could be an innova9ve and cost-effec9ve alterna9ve that is capable of rejuvena9ng/ extending the life of a SWMP by 8-12 months and in this project demonstrated dredging cost savings of $55,000 to $360,000 (depending on classifica9on of bio-solids removed). INTRODUCTION Redox poten9al (ORP) is an important determinant of biological process - High redox poten9al increases efficiency of carbon metabolism Dissolved oxygen (DO) is an important contributor to redox poten9al (ORP) - Aerobic respira9on is the most efficient pathway of carbon metabolism Relevance à a pond that supports high rates of carbon metabolism in sediment will accumulate sediment more slowly as the organic carbon is mineralized to CO 2 Technology that increases redox, par9cularly DO, can enhance net respira9on in a pond and slow or reverse the accumula9on of sediments Goal à reduce the frequency of dredging thereby reducing maintenance costs OBJECTIVES 1. Determine the effect of treatment by the EOS-2000 on DO and DO satura9on 2. Determine response to increased DO and redox poten9al by aerobic bacteria in sediments Ø Using # of ac9ve heterotrophic bacteria as proxy 3. Quan9fy sediment depth over 9me to determine if there is a response to treatment i.e. diges9on due to increased aerobic bacteria 4. Assess esthe9c water quality through clarity improvement using chlorophyll a and secchi disc Pre-installa9on Week 1 Week 2 Week 3 Week 4 Week 6 Week 8 Week 12 Sept 1 Sept 10 Sept 17 Sept 24 Oct 1 Oct 8 Oct 22 Nov 5 Dec 3 O2, Temp X Con9nuous from Sept 14 ORP, pH, cond X X X X X X X X X Secchi depth X X X X X X X X X Chlorophyll X X X X X X X X Bacterial plate counts X X X X X X X X Nutrients (w & s) X X X X X X X X Sediment mapping X X X X Contaminants (sed) X X RESULTS • EOS-2000 rapidly increased DO (2 à 8 mg/L) and ORP aZer installa9on; s9mulated aerobic respira9on in sediments • 14-23 cm of sludge reduc9on Ø Ini9al depth 183 cm (es9mated vol 14,823 m 3 ) Ø Es9mated sediment loss 1,175 m 3 – 1,863 m 3 (7.9% to 12.6%) in only 3 months • Aerobic bacteria count increased by 2-3 orders of magnitude • Water clarity greatly improved (218%) • Result of enhanced respira9on is reduc9on of sediment organic maJer – rolling back pond maintenance Table 1: Data collec.on schedule Objec.ve 4: Water Clarity Objec.ve 3: Sediment reduc.on Objec.ve 1: DO Satura.on Objec.ve 2: Redox poten.al and Aerobic bacterial counts