1 1 Water Plant Optimization Study GRIMSBY WATER TREATMENT PLANT June 1991 Environment Environnement 1 arytado Copyright Provisions and Restrictions on Copying: This Ontario Ministry of the Environment work is protected by Crown copyright (unless otherwise indicated), which is held by the Queen's Printer for Ontario. It may be reproduced for non-commercial purposes if credit is given and Crown copyright is acknowledged. It may not be reproduced, in all or in part, for any commercial purpose except under a licence from the Queen's Printer for Ontario. For information on reproducing Government of Ontario works, please contact ServiceOntario Publications at co ri ht ontario.ca f ISBN 0-7729-3293-X WATER PLANT OPTIMIZATION STUDY J 1 J Grimsby Water Treatment Plant Project No. 7-2012 June 1991 e Cette publication technique n'est disponible qu'en anglais. Copyright: Queen's Printer for Ontario, 1991 This publication may be reproduced for non-commercial purposes r with appropriate attribution PIBS 1557 log 89-2302-134 r 9 1 1 I 1 1 r 1 G7 mo 1 1 1 Study conducted by: R. Kargel of 1 MacLaren Engineers Inc. 1 J 1 Under the direction of the t Grimsby Project Committee: Ron Hunsinger - MOE Water Resources Branch Al Smith - Regional Municipality of Niagara 1 Grant Bagshaw - Regional Municipality of Niagara Andrew Forbes - Regional Municipality of Niagara Nick Ehlert - MOE West Central Region 1 Bill Gregson - MOE Project Engineering Branch Janusz Budziakowski - MOE Environmental Approvals Branch Gerry Sigal - R.V. Anderson Associates Limited 1 1 -------------------------------------------------------------------------------------------------------- I Address all correspondence to: 1 Ministry of the Environment Water Resources Branch St. Clair Ave. W., 4th Floor 1 Toronto, Ontario 1 M4V 1K6 Please note that some of the recommendations contained in this report may have already been I completed at time of publication. For more information, please contact the local municipality, I or the Water Resources Branch of the Ministry of the Environment. 1 r 1 1 1 1 1 TABLE OF CONTENTS 1 1 e 1 1 S-1 1 SUMMARY OF FINDINGS AND RECOMMENDATIONS 1 1.0 INTRODUCTION 1 This report on the Grimsby Water Treatment Plant Optimization Study was prepared by MacLaren Engineers Inc. on behalf of the Ontario Ministry 1 of the Environment under Agreement dated April 24, 1987. 1 The project is a result of the Drinking Water Surveillance Program (DWSP) being carried out by the Ministry of the Environment on muni- 1 cipal water supplies. Under this program, which began on April 1, 1986, a continuously updated base of information is being established 1 on Ontario water plants and water quality. The Water Plant Optimiza- tion Study (WPOS) program was initiated for each plant entering the program in order to complement the data gathered from the Drinking I Water Surveillance Program. The study approach and detailed Terms of Reference for the Water plant Optimization Study were prepared by the Ministry of the Environment. The purpose of the study is to document and review present conditions and determine an optimum treatment strategy for contaminant removal at the plant, with emphasis on the removal of particulate materials and disinfection processes. To maintain a current database of information, it is envisaged that the WPOS report will be updated on an annual basis. As a supplement to the Water Plant Optimization Study for the Grimsby Water Treatment Plant, a separate report was prepared on the existing waste management practices at the plant. The report includes recommen- dations for the optimization handling and disposal of wastes generated at the plant and provides first-order cost estimates for the recom- mended option. The report was prepared by MacLaren Engineers Inc. for f the Ministry of the Environment under the title: Wastewater Disposal Study, Grimsby Water Treatment Plant, August, 1988. 1 S-2 1 2.0 HIGHLIGHTS OF STUDY 2.1 Raw Water Quality 1 The raw water source for the Grimsby plant is Lake Ontario. Water is drawn from a depth of 3 to 4 m through the main gravity flow intake which extends about 230 m into the lake. A submersible pump, -installed 1 in about 2 m of water at the end of an existing pier about 50 m off- shore, serves to supply additional water to the plant during the summer period. Raw water is subject to wide variations in turbidity and bacteriologi- cal quality. The water quality at the main intake is influenced by runoff from the nearby Forty Mile Greek and the re-suspension of lake It bottom sediments during storm events. Similarly, the water quality at I. the pier intake is influenced by the turbulence in the lake. Monthly average raw water turbidities at the main intake for 1984 to 1986 varied from 1.7 to 35.8 NTU; whereas daily average values varied from 0.8 to 144.8 NTU. The pH of the raw water varied from 7.9 to 8.6 units and was found to be at its highest during the algae growing season. Although no data for algae content were available, test results for chlorophyll a revealed that algae are present in the raw 1 water at low to moderate levels. t 2.2 Flow Measurement i Flow is measured for the following process streams: raw water from the pier pump to the pressure filter - by orifice plate flow meter; I treated plant output water - by venturi flow meter; t backwash water used in cleaning of the pressure filters - by orifice plate flow meter. 1 S-3 r The raw water flow from the low lift pumps is not metered. Orifice plate flow meters are equipped with flow totalizers and the venturi meter includes low and high flow differential pressure trans- mitters, totalizer and circular chart recorder. 2.3 Plant Capacity and Process Design r The Grimsby W.T.P. has two treatment trains consisting of a conven- 1 tional gravity flow filtration section and a pressure filtration section. 1 The rated capacity of the gravity filtration plant is 13,600 m3/d. 1 The plant includes chemical coagulation, two-stage flocculation, sedi- mentation and dual media filtration. 1 The pressure filter plant comprises chemical coagulation and single i medium sand filters. The pressure filters have a rated capacity of 5,700 m3/d, and are only operated during the summer during periods of peak demand, since the pier pump intake is not frost protected. Alum was used as the coagulant in 1984 and 1985, while polyaluminum chloride was used in 1986. Gaseous chlorine, applied in solution form in pre- and postchlorination modes, is used for disinfection. Taste 1 and odour control is achieved by the addition of powdered activated carbon, as necessary. 1 Sedimentation tank sludges and filter backwash water are discharged r directly to the lake through individual drain pipes. Capacity limitations exist in both sections of the plant. Pressure filters operate on the principle of direct filtration. This process is affected by raw water quality, and when the raw water turbidity exceeds 1 about 15 NTU the rated capacity of 5,700 m3/d cannot be sustained on a continuous basis. In the gravity filtration plant, the pretreatment 1 1 S-4 1 units are severely overloaded at the rated capacity of 13,600 m3/d resulting in poor performance of the sedimentation units. Also, since there are only two gravity flow filters, it is necessary to reduce raw water flow with one filter out of service in order to prevent over- loading of the in-service filter. 1 During the winter the plant intake is subject to partial blockage by 1 frazil ice which greatly affects plant capacity. At times, during very cold winter nights, ice blockage has been so severe that several back- flushes were required resulting in the depletion of the stored water in 1 the distribution system. 1 2.4 Process Automation No process automation equipment has been provided at the Grimsby W.T.P. Pumps and all motorized equipment are started and stopped manually. Chemical feed pumps operate at preset constant speed and constant .stroke and require manual adjustment for quantitative control of the dosage with varying flow. Only the chlorinators are equipped with flow proportional controllers. The discharge from the gravity flow filters is controlled by a self- powered mechanical rate control valve. 2.5 Plant Operations 1 The plant operating staff consists of one senior plant operator and three plant operators. The area superintendent of the Region of Niagara is responsible for the treatment process and all activities at the plant. Plant maintenance is the responsibility of the Region's t area foreman. Plant operators are responsible for the day-to-day running of the plant, which is staffed on the basis of two 12-hour shifts per day 1 seven days per week. 2.6 Process and Quality Control 1 The operator on duty maintains the daily log sheet and, at various t timp-, dijrina the shift- rprords information on flows- filter operation.