Category: Published Articles

As published in the Ontario Concrete Pipe Association’s Concrete Pipe Journal Spring 2018 Issue.

Written By:

Frank Vuk, Project Coordinator, City of Burlington

Phil Campbell, P.Eng., Project Manager, CIMA+

Sammy Wong, P.Eng., VP Engineering & Quality Con Cast Pipe

 

Con Cast Pipe manufactured and supplied a precast, three-sided box and wingwall units for a rapid bridge replacement project in the fall of 2017. The original bridge, a 1.5m (rise) x 7.3m (span) x 6.7m (platform width) concrete rigid frame bridge structure on spread footings with concrete wingwalls and precast concrete block retaining walls, was constructed in the 1950s over Grindstone Creek on Hidden Valley Road in Burlington, Ontario, immediately north of the tunnel underpass of Highway 403. Hidden Valley Road is a rural two-lane, dead-end roadway with approximately 25 residential properties beyond the bridge structure. A January 2014 inspection report provided a recommendation to replace the existing Hidden Valley Road bridge structure within one to three years. This recommendation was based on the consideration of the structure’s age, concrete condition, undermining of the abutments, unstable retaining walls, inadequate railing systems and poor orientation of the structure abutments with the watercourse.

In October 2015, the City of Burlington retained the engineering services of CIMA Canada Inc. to commence a Schedule ‘B’ Municipal Class Environmental Assessment (EA). The options included: a) a two-phase replacement, b) new alignment of the road/bridge, c) rapid bridge replacement or d) replacement with temporary road/bridge access. Upon consideration of public comments and the specific criteria, option “d” was selected as preferred and progressed to detailed design.

Subsequent to the completion of the EA, CIMA commenced a detailed design of the bridgere placement with a temporary diversion road/bridge. Tendering included the details of a new 2.0m (rise) x 9.1m (span) x 8.0m (platform width) concrete bridge structure, with consideration for many temporary/working constraints associated with the site’s unique location and physical properties, natural environment, roadside environment and adjacent properties. Maintaining continuous access for residents, emergency services and other services (i.e. waste collection, mail services etc.) during construction was paramount, understanding that even short duration road closures were not viable. This involved establishing a temporary road alignment and temporary bridge criteria. A 5.0m wide single lane temporary gravel roadway was designed immediately east of the existing bridge and an approved area for the temporary bridge was established to provide suitable separation from the new bridge construction. In consultation with pre-fabricated, modular steel structure suppliers, the criteria for the temporary bridge was established. The temporary roadway and bridge were designed to accommodate fire pumper truck and garbage collection trucks. The temporary single lane width was designed to be controlled by temporary traffic signals at each end of the project site for the duration of construction.

The design process saw a collaboration of many aspects of the engineering and construction community, including a precast concrete and modular bridge supplier to ensure the design was constructible and that scheduling was respectful of the limitations of manufacturing. Coordination with the precast manufacturer was particularly sensitive given the project’s expectations for success within the timing window provided. By allowing Lancoa Contracting Inc., the contractor, to develop their own temporary/working schemes, a cost-effective project was delivered on time and on budget.

The manufacturing of the new three-sided box units took place during the summer of 2017 in a certified precast plant at Con Cast Pipe. Unlike typical three-sided boxes, the combination of a skewed end face, special joint details, post tension hardware, and the limitations of lifting and handling points created a uniquely complex situation. The fabrication of these precast units was controlled under CSA A23.4 requirements and successfully carried out by Con Cast Pipe. A tight quality control and assurance process was put in place to ensure the required precision was achieved during the installation.

In conclusion, the completion of the project ensures the City of Burlington and the residents on Hidden Valley Road will have a reliable bridge structure in this access-constrained location. With the city’s proactive replacement of the existing structure before the end of its useful life, the threat of requiring emergency work has been avoided. This project also showcased the use of precast concrete bridge elements in accelerated bridge construction to minimize the social impact and to provide high quality, sustainable, resilient infrastructure to the public. This project has received the 2018 civil engineering project of the year award from the Hamilton-Halton Engineering Week committee, which is a subcommittee of the Ontario Society of Professional Engineers.

As published in the Ontario Concrete Pipe Association’s Concrete Pipe Journal Fall 2017 Issue.

The Scottish Heather Development Inc. Subdivision Ph 3 in Brampton, Ontario is the latest project to benefit from the long-term performance of concrete pipe that arrives on site with a high density polyethylene (HDPE) liner. The concrete pipe provides the strength to carry heavy loads from overburden and traffic, and hydraulic design to collect and drain sewage from the site and upstream communities. The liner protects the interior concrete surface from the damaging effects associated with corrosive gases and liquids that can form in a sanitary sewer system, including Microbial Induced Corrosion (MIC).

The PERFECT PIPE system was included in the construction of Rivermont Road, the north-south collector connecting Steeles Avenue and Heritage Road. Rivermont Road is 30m in width, providing two traffic lanes in each direction, and accommodating storm and sanitary sewers (among other services and utilities). Installation of the sanitary sewer pipeline system included 206m of 600mm diameter PERFECT PIPE installed at a depth of 9.5m at a rate of 30m per day. Installation took place between April 26 and May 10, 2017.

The average trench width near the bottom of the pipe was measured as 1.8m. The trench wall was found to be rough and not maintained vertically due to the pre-installation blasting of the bedrock. The width of the trench tapered from the top of the pipe at an approximate 1:1 ratio. The trench was sandwiched with 50mm thick flexible panels, and HL6 bedding material placed to a minimum thickness of 150mm, continuing to the crown of the pipe. Compaction of the HL6 is considered as a C 1 bedding in accordance with CSA S6-14 Table 7.9. Sand fill was used to backfill over the pipe with compaction of at least five passes using a plate tamper. The installation is considered an equivalent to Type l installation in accordance with Canadian Highway Bridge Design Code.

About PERFECT PIPE

PERFECT PIPE is manufactured to CSA A257.2 and OPSS1820 specifications. It is manufactured in various diameters that are 100% protected by the HDPE liner. PERFECT PIPE has a lay length of 3m, 560mm longer than traditional pipe. Con Cast Pipe utilizes its self-consolidating concrete mix design which provides exceptional protection against the shifting or separation of the concrete pipe from the HDPE liner. Every liner is anchored to the concrete pipe by 900 homogeneously extruded anchors per square meter. Each anchor provides 56lbs (250N) of pull-out strength, ensuring that the liner stays in its intended position. The joint system can withstand a constant internal pressure of 36 psi through the combination of a dual jointing system that seals the liner inside the joint of the concrete pipe. The PERFECT PIPE is supplied with two Swift Lift lifting anchors located at the crown of the pipe, which are used for the safe handling and installation of the pipe.

PERFECT PIPE is suited for deep sanitary sewer gravity applications. Through the collaborative efforts of Con Cast Pipe, Con Drain Group, R. J. Burnside & Associates Limited, and the approval of the Region of Peel, the Scottish Heather Phase 3 project was an ideal project to demonstrate the features, functions and benefits that PERFECT PIPE offers as an infrastructure product.

As published in the Ontario Concrete Pipe Association’s Concrete Pipe Journal Spring 2017 Issue.

Written by: Christopher Pfohl, C.E.T., EP, Can-CISEC – Sr. Aquatic Ecologist is the Aquatic Group Team Lead at RJ Burnside and Associates Limited, a company that provides Innovative Engineering and Environmental consulting services for private and public sectors across Canada

RJ Burnside & Associates Ltd. and Con Cast Pipe

Introduction

Degraded cast-in-place structures eventually need to be replaced but the costs associated with clear-span structures may not be affordable to all clients. Innovation in the precast industry may be at a new level for ecological consideration with the new Barefoot Box Culvert™ designed by R.J. Burnside & Associates Limited. The Barefoot Box Culvert™ was designed to promote groundwater upwelling while maintaining thermal conditions – an acceptable precast replacement for watercourse crossings.

Background

The Township of Melancthon is responsible for numerous concrete structures that convey headwaters, which support sensitive cold-water species such as Brook Trout that are protected and regulated under the Fisheries Act, governed by the Department of Fisheries and Oceans (DFO).

A structure replacement was required on a headwater stream of the Pine River that supports all life stages of Brook Trout, with numerous areas of groundwater input (critical habitat). The existing degraded structure was a “cast-in-place open-bottom culvert.” The old structure was experiencing severe deterioration and had a 10 tonne load limit posting which prevented local agricultural equipment and machinery from travelling over the structure. The Township requested Burnside to design a replacement for Structure 2027, located on Sideroad 15, approximately 0.2 km west of CR124, north of Shelburne.

Burnside worked with Con Cast Pipe to ensure that the Barefoot Box Culvert™ design integrated all of the required specifications relating to structural integrity of the precast concrete box units and cut-off walls. Each box unit was 2.0m in length and designed according to OPSS 1821 and CSA S6 (CHBDC). The five pieces of 3658mm x 1829mm box units and two precast concrete cut-off walls were manufactured to CSA A23.4. The installation contractor, Drexler Construction Limited, was responsible for the removal of the existing structure, the installation of the new precast concrete culvert and the construction of the cast-in-place distribution slab that was required due to the very low cover over the culvert.

Solution

Based on the sensitivity of the site and headwater system that supports Brook Trout, it was important to replicate the form and function of the watercourse as well as the existing conditions. Burnside proposed the 3658mm x 1829mm precast concrete box culvert that was designed to promote groundwater input through strategically placed perforations in the bottom slab of the box units. The Barefoot Box Culvert™ incorporates unique design characteristics such as the preformed holes in the bottom slab of the box units for groundwater upwelling and discharge as well as suitably sized river stone simulating natural substrate, accommodating a meandering low flow channel within the structure. The plan view in the next column illustrates the strategic placement of preformed holes to promote groundwater upwelling.

The profile below illustrates the comparison between the Barefoot Box Culvert™ and a typical open bottom culvert with footings. Based on the design comparison we note the following observations:

• No footing that forms a barrier blocking lateral ground water input
• Cut-off wall promotes ground water upwelling into perforations
• Cut-off wall creates the required hydrostatic pressure to promote groundwater upwelling
• Speed of construction between a precast box culvert and a clear span requiring cast-in-place footing (substantial cost savings and ease of construction)

Supply and Construction

A budget estimate of $300,000 (plus HST) was allocated to complete the engineering and construction of the new structure. Burnside was required to identify a suitable design option that addressed the safety and environmental concerns at the site and fit within the Township’s budgetary constraints. The contract included demolition and removal of the existing 3.0m span concrete open bottom structure, which was determined to be in poor condition and recommended for replacement.

Burnside successfully managed the culvert replacement by providing engineering services and contract administration for the Township. Con Cast Pipe delivered the client a precast box unit structure that addressed the environmental, safety and budgetary conditions associated with the project.

The 3658mm x 1829mm box units were manufactured at Con Cast Pipe’s Guelph, Ontario manufacturing facility. The units were cast in advance of the project installation date and were delivered to site in a “just-in-time” delivery scenario to eliminate wait times on site and expedite the installation of the precast box units. The openings cast into the bottom slab of the box units were placed in accordance with the details provided by Burnside to ensure that the Barefoot Box Culvert™ units would perform as designed and would function properly to improve the manmade environment within the invert of the box units.

Results

To monitor the success of the Barefoot Box Culvert™ and this new approach, a number of metrics needed to be determined prior to actual construction and placement of the structure. To determine if the design (base slab perforations, cut-off walls, bedding) worked, Burnside installed shallow stream bed piezometers at various depths to measure groundwater upwelling and hydraulic gradient. Each piezometer was outfitted with an Automatic Water Level Recorder to determine water levels within the piezometer compared to the natural stream conditions.

Based on the results of the surface and groundwater data collected, all piezometers located within the Barefoot Box Culvert™ show an upward hydraulic gradient (increased water levels) that promote groundwater discharge and upwelling within the culvert (See graph below). Piezometers revealed a 2-4cm increase in groundwater level above existing base flow conditions which could significantly increase groundwater contribution.

Additional monitoring is still being conducted with regards to groundwater levels and temperature Brook Trout use and underwater footage of spawning activity downstream of the culvert (<5m downstream) has been captured using under water cameras by Burnside. As-built conditions have also been reviewed by DFO and the Conservation Authority to ensure all mitigation measures and approved detailed design was completed as proposed.><5m downstream) has been captured using under water cameras by Burnside. As-built conditions have also been reviewed by DFO and the Conservation Authority to ensure all mitigation measures and approved detailed design was completed as proposed.

Closing

The new structure brought the site to current standards in all respects, including safety, geometry, road grades and load capacity. It is Burnside’s understanding that the Barefoot Box Culvert™ is the first of its kind approved by the Nottawasaga Valley Conservation Authority and DFO in Ontario. Collaboration between Burnside’s aquatic ecologists, hydrogeologists, structural engineers and Con Cast Pipe’s precision manufacturing has taken pre-cast innovation to a new level in watercourse crossing design with the Barefoot Box Culvert™.

As published in the Ontario Concrete Pipe Association’s Concrete Pipe Journal Winter 2017 Issue.

Municipal inflow and infiltration reduction programs across the country have changed long-term expectations regarding the sustainability and resilience of sanitary sewers.

For example, York Region and its area municipalities have committed to implementing specifications and standards for inflow and infiltration in their existing and future sanitary sewer systems. Reducing inflow and infiltration is a high priority initiative with a budget of $100 million over a 20-year period.

Inflow and infiltration reduce the capacity of the sewage systems leaving less for existing residents and future growth. When sewage is diluted by water, treatment becomes less efficient. The cost of water to residents increases because plants are required to treat a higher volume of low.

Another challenge within municipal sewage systems is microbial induced corrosion (MIC). A sanitary sewer that has a shallow gradient, with low flow velocity is an ideal environment for a slime layer to develop on the surface of the pipe below the water level. Anaerobic bacteria reduce sulphate to sulphide. Above the sewage level, the hydrogen sulphide gas is consumed by Thiobacillus, a sulfur oxidizing bacteria (SOB), which produces sulphuric acid that reacts with the exposed concrete surface causing corrosion.

To mitigate MIC and improve concrete durability, engineers reference CAN/CSA A23.1 and specify a C-XL exposure class in combination with other commercially-available admixtures and additives which may be unsubstantiated in their performance while adding cost to the production process.

A third challenge designers often face in Ontario, due to our increasingly built infrastructure resulting from continued population growth, is the need to it sanitary sewer extensions into an already crowded underground space. Subsequently, sanitary sewers often need to be installed deeper with increased joint capacity. Open cut construction is disruptive to municipalities, businesses and the public, thereby opening opportunity for microtunnelling, which has seen continuous growth as a preferred construction option.

Con Cast Pipe worked with Schlusselbauer Technology GmbH & CoKG Austria to introduce PERFECT Pipe into the Ontario market to address the inflow and infiltration, microbial induced corrosion and microtunnelling challenges.

PERFECT Pipe combines the strength and structure of reinforced concrete pipe with the chemical resistance of high density polyethylene (HDPE), and a water-tight jointing system. PERFECT Pipe is manufactured in diameters up to 1200mm. The pipe is fully-protected with an HDPE liner that demonstrates superior abrasion resistance when compared to competitive products.

The HDPE liner protects the interior concrete surface from the damaging effects associated with corrosive gases and liquids that form in the sanitary sewer system by mitigating MIC and improving the durability and life cycle resilience of the pipeline.

PERFECT Pipe has a dual jointing system that seals the liner using a thermoplastic internal connector with dual elastomeric rubber gaskets joining pipe sections. No field welding is required. PERFECT Pipe is designed as a gravity pipe for use in open cut and microtunneling applications. The 1.65mm thick liner has 900 homogenously extruded anchors per square metre. The pattern increases in density toward the thermoplastic coupler to ensure that the liner is firmly anchored at the joint. Each anchor has a pull-out strength of 250 N (56 lbs) while providing an overall pull-out strength of 0.255 N/mm^2. Self-consolidating concrete is used in the production of PERFECT Pipe because of its wetcast properties that make it highly flowable, yet stable enough to spread easily into the formwork, thereby covering the anchors and reinforcement without any mechanical consolidation.

Con Cast Pipe is manufacturing PERFECT Pipe in 600mm, 900mm and 1200mm diameters with pipe classes of 65-D, 100-D and 140-D and a standard lay length of 3.0m. This lay length is 23% longer than typical reinforced concrete pipe which in turn reduces the number of joints and opportunities for infiltration. This difference is also important for microtunneling, since the jointing process is the only time when pipe jacking is stopped. Aside from the chemical and abrasion resistance, the PERFECT Pipe also has an improved joint performance compared to traditional concrete pipe systems. PERFECT Pipe is especially suitable for specification where designers need to mitigate infiltration, exfiltration, corrosion or require deep bury sanitary sewers or micro tunneling.

Con Cast Pipe has commissioned the PERFECT Pipe manufacturing equipment at its Oakville, Ontario production facility and has added the PERFECT Pipe to its Plant Prequalification Certificate. Municipal wastewater infrastructure faces many challenges. PERFECT Pipe can be the first step in mitigating these sanitary sewer challenges by protecting pipeline assets, public health and the natural environment.