COUGAR CREEK RELOCATION PROJECT
Project Description
In the early nineteen hundreds, coal mining was flourishing in the rocky mountains of southwestern Alberta. At that time it was normal to place coal waste in piles wherever it was convenient. This resulted in large coal waste piles being situated throughout the mining area. These coal waste sites were/are a nuisance because when the wind blows, particles of coal dust are scattered over large settled (homes and business) areas. The coal waste site of concern for this project was located in the settlement of Blairmore. The residents of Blairmore wanted the waste site removed from within the settlement. Alberta Environment solution was to haul/place the coal waste in the Cougar Creek Valley located 7 km north of Blairmore. Sameng Inc. (formally Samide Engineering Ltd.) was retained to design a system to convey Cougar Creek’s water around the coal waste fill site.
The coal waste filled up a 600 m reach of Cougar Creek. The height of the fill at the downstream end was 40 m while the height at the upstream end was 3 m. Sameng Inc. design and construction managed a system that diverted the flows from Cougar Creek, around the coal waste site and then back into Cougar Creek downstream of the coal waste fill site. The diversion system consisted of:
1. A diversion channel constructed into the mountain side (till material) around the north side of the coal waste site. The channel intercepted the flows in Cougar Creek upstream of the waste site.
2. At the downstream end of the diversion channel the water flows through a culvert into a rock filled seepage channel. The rock filled seepage channel was designed to lower the water from the culvert outlet 40 m down to the original bed of Cougar Creek. The rock filled seepage channel was constructed 3 m wide at the bottom, sideslopes of 2.5H to 1V with a minimum rock fill depth of 2.5 m. In order to confirm that the channel was operating according to design, crest stage gages were installed. One was placed in at the upstream end of the culvert to determine maximum flows entering the rock filled channel and three were installed in the rock filled channel at regular intervals down the rock slope to measure water depths in the rock filled channel. Measurements obtained after runoff events from the crest gages indicated that the rock filled seepage channel functioned as designed.
Water flows throughout the year in Cougar Creek. The system was designed to handle freezing conditions throughout the winter.
The decision to use a rock filled seepage channel as opposed to other conventional methods was based on economics. The rock filled channel was estimated to cost half as much as other conventional drop structures.
G. Samide presented a paper in 1990 at the International Erosion Control Conference in Washington D.C. entitled Reallocation of Cougar Creek.
In 1995 a very large rainstorm flood occurred in south-western Alberta. G. W. Samide inspected the diversion system following this flood and no damages were apparent. The rock filled channel and outflow system had handled the flood without damage.
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STUDY DONE FOR THE CITY OF EDMONTON TO DETERMINE THE AMOUNT OF FLOATABLES/SOLIDS BEING DISCHARGED INTO THE NORTH SASKATCHEWAN RIVER BY THE SANITARY SEWERS THAT ALSO CARRY STORMWATER
In 1998 and 1999 the City of Edmonton Drainage Services was in the process of developing a comprehensive Combined Sewer Overflow (CSO) Control Strategy to mitigate the impact of CSO discharges to the North Saskatchewan River (NSR). In order to develop this strategy they needed an accurate assessment of the amount of floatables and solids being discharged into the NSR. The City commissioned Sameng Inc. to gather data on floatables/solids and then determine the amount of floatables and solids being discharged from the CSOs into the NSR. A secondary portion of the study was to identify potential mitigative measures to reduce or eliminate CSOs. Sameng Inc. devised a unique steel mesh net bagging system for capturing floatables/solids at the CSO monitoring sites. These systems were placed in front of the CSO outlets and consisted of a steel mesh cage with a cloth mesh liner inside. The cloth mesh and the steel mesh screened out the floatables/solids. In addition to the bagging system, for one of the CSO o utlets, a floating boom with a net system hanging down from the boom was placed around the outlet within the river. Monitoring of floatables/solids began in June and ended in the middle of September. On average, floatables/solids for five rainstorm events were collected for each of the monitoring sites.
Edmonton’s wastewater treatment plant has screens that remove the floatables and solids from sanitary sewer water. The wastewater treatment plant recorded the weights of the screenings/floatables/solids collected. Based on these recorded weights, the floatable/solids data collected at the storm sewer outlets and discharges at CSOs and into the treatment plant, a method was developed to predict concentrations of floatables/solids at the main CSO site where approximately 90% of all CSO’s occur. With this method, all that is required to predict floatables/solids at the main CSO site are the volumes of overflow discharges at the main CSO site for each rainfall event. To determine the total volume of floatables/solids discharged to the NSR, Sameng Inc. recommended adding an additional 10% to the floatables/solids to the volume calculated at the main CSO site. Using the method developed, Sameng Inc. calculated that in 1999, the maximum to minimum range of floatables/solids being released from CSOs to the NSR was 28000 kg to 22,000 kg. In terms of volume of floatables/solids being released to the NSR in 1999 would range from 12 to 8 m3.
Sameng Inc. performed a literature search on how other cities were handling their CSO floatables and solids.
Sameng Inc. also did an extensive literature search to obtain information on available floatable control technologies. A summary was completed of the control technology that may work for the CSO conditions in Edmonton. A critical evaluation of the advantages and disadvantages along with associated cost of each of these alternative designs was also performed.
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La Glace – Bear Lake Flood Reduction Study
Project Description
Flooding problems are occurring on parts of the Bear Creek Drainage Basin located just north of the City of Grande Prairie. Bear Creek, which is the main stream of the basin, has several smaller tributaries and flows through two large lakes, La Glace Lake and Bear Lake. Grande Prairie Creek enters Bear Creek downstream of Bear Lake. Downstream of Bear Lake in Bear Creek the flow can reverse directions and flow upstream. This only occurs when Bear Lake is low and flood levels at the confluence with Grande Prairie Creek are high. This reverse flow situation made modeling the basin a challenge and to handle the complex flow situations within the basin a one –dimensional zero-inertia model was developed and applied to the Bear Creek drainage network to simulate the effect on flood levels and discharges of various trial solutions.
In recent years, flooding problems have become more severe in the Bear Creek Basin, particularly, around La Glace Lake and on the northwest side of Bear Lake. Spring flooding lasts for long periods of time even after the peak runoff flows have subsided. This flooding has resulted in significant agricultural losses. The project area was severely affected by the 1997 spring flood, which has been estimated to be a 1:25 year event.
Sameng Inc. conducted an engineering study that investigated various methods of alleviating/reducing the flooding problems in the project area. As these flood reduction methods could not result in increased flooding problems elsewhere in the basin, each flood reduction method was modeled to determine its effect through out the basin on flood levels. Numerous methods/solutions were modeled. The recommended solution that significantly reduced flooding in areas that were previously flood prone and did not result in an increase in flooding in other parts of the basin consisted of:
clearing and improving Bear Creek downstream of La Glace Lake (La Glace Lake outlet channel);
moderate improvement works done on Bear Creek downstream of Bear Lake (Bear Lake outlet channel); and
improvements to the existing outlet control structure so that in the fall of every year Bear Lake Water levels could be lowered to similar levels that the lake has experienced in the past.
The estimated cost for the recommended design solution was $408,500.00.
This report was submitted to Alberta Environment and from an engineering standpoint it was approved. However concern was raised regarding the fish resource in Bear Lake. Bear Lake is a shallow lake with an average depth normally about 1 m. Bathometric surveys reveal no deep pockets of water in the lake (areas that would normally be required to over winter fish). However there are reports of fish in the lake. The fish must be indigenous to the lakes/creeks in the area since the existing dam in the City of Grande Prairie prevents fish from moving upstream into Bear Creek. Thus somehow the fish are surviving in the lake and the concern is that if the lake is lowered (even slightly) every fall it may be harmful to the fish. Thus the project has not proceeded as of yet to construction.
1. Shome, M & G.W. Samide, 2001, Application of One-dimensional Modeling Technique to Bear Creek Network, Presented at CSCE conference held in Victoria, B.C. May/June 2001.
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Oil / Grit Separator for the City of St. Albert
Location - Project is located on St. Anne Street in City of St. Albert.
Project Description
The City of St. Albert is located along the Sturgeon River. The storm sewer system drains into the river through a number of outfalls. At several of these outfalls, particularly those larger ones serving older areas, there has been at deposition of silt at the outlets. These silt deposits present a number of concerns including blockages to fish passage; loss of flow capacity resulting in higher flood levels; water quality impacts; and aesthetic degradation. In order to reduce sediments and hydrocarbons entering the river Sameng was commissioned to design a separation facility upstream of the St. Anne St. outfall. Although a number of proprietary products where considered, a custom designed separator was found to provide the best solution. The separator designed by Sameng had a much smaller construction footprint than could be achieved with any other product and in a busy downtown location this was very important. Further extremely poor foundation soil conditions found during the site investigation would have required considerable special measures to utilize any of the commercial products. The Sameng Separator is constructed within a sheet pile framework with steel and cast-in-place concrete fittings. With this design there was no excavation required beyond the interior of the chamber. The Sameng Separator utilizes a unique flow control system that prevents re-suspension of sediments during large flow events. Sameng is currently applying for a patent for this design. The project was successfully constructed in the late fall of 2002 with minimum impacts on traffic and parking.
Services Provided by Sameng Inc. :
Conceptual design review of available products.
Custom Separator Design (patent pending) including hydraulic analysis of storm sewer and chamber, sediment removal analysis, structural design, geotechnical design.
Preparation of Construction Drawings, Specifications and Tender Documents.
Assisted in Tendering and Award.
Construction management and inspection.
Preparation and Approval Payment Requisitions.
Preparation of As built Drawings.
Key Consultant Staff
Gerald Samide, P. Eng
David Martz. P.Eng.
Company Technician.
Company’s survey crew.
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St. Albert Stormwater Management Regional Master Plan
Location - City of St. Albert
Project Description
Sameng Inc. is currently part of the team developing a Stormwater Management Regional Master Plan for the City of St. Albert. The Plan will address a number of issues in both the existing developed area of the City as well as in future expansion areas. These include analysis of the existing systems capacity and condition; potential impacts on the Sturgeon River of increasing flows and sedimentation; water quality issues; servicing requirements for new development; impacts of changes in the Big Lake basin; and integration of stormwater system with parks and open spaces.
Previous floodplain studies conducted by Alberta Environment in 1975 and 1989 have provided a baseline for assessment of changes that may me impacting flood levels. The river will be resurveyed and the impacts of sedimentation will be analyzed. Based on our findings, recommendations will be made regarding the updating of flood hazard mapping; flood hazard management strategies; sedimentation control in existing storm sewers; and sedimentation control standards for new developments.
Sameng has undertaken an inventory and inspection of all the existing storm sewer outfalls and assessed their condition and made recommendations their maintenance.
Services Provided by Sameng Inc. :
Surveyed Sturgeon River through St. Albert.
Site Inspection of sedimentation sites.
Review of previous floodplain studies.
Inspection of all Storm Sewer Outfalls.
Analysis of sedimentation in Sturgeon River.
Services to be Provided by Sameng Inc. :
Estimate of future sedimentation in Sturgeon River.
Modelling of impacts of sedimentation and infilling of floodplain on peak flood levels.
Recommendation for managing flood risk which may include remedial measures (dyking, dredging) as well as non-structural approaches (zoning, setbacks).
Recommendations for control of sediments from existing outfalls (grit separators, source control, wetlands).
Recommendations for Best Management Practices to control sediments form new developments.
Provide input on the Master Drainage Plan
Provide input on effect of sedimentation on hydraulic function of storm sewer outlet system.
Key Consultant Staff
Gerald Samide, P. Eng
David Martz. P.Eng.
Company Technician.
Company’s survey crew.
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