Technical Memorandum. Trenchless Technology Options for Rehabilitation of the Yambury Road Drainage Culvert

Transcription

1 Technical Memorandum Trenchless Technology Options for Rehabilitation of the Yambury Road Drainage Culvert Prepared for: Bob Weir P.Eng. Town of Qualicum Beach Engineering Department Primrose Street. Qualicum Beach, B.C V9K 1S7 Prepared by: M.J. Pawlowski & Associates Infrastructure Management Consultants Suite 739, No. 2 Rd, Richmond, BC, V7C 5J8 Phone: July 4, 2013

2 CONTENTS 1.0 INTRODUCTION CONDITION ASSESSMENT OF THE YAMBURY RD. CULVERT PHYSICAL INSPECTION AND ULTRASOUND MEASUREMENTS CCTV INSPECTION TRENCHLESS REHABILITATION TECHNOLOGIES BENEFITS OF TRENCHLESS TECHNOLOGIES EVALUATION OF TRENCHLESS REHABILITATION METHODS SEGMENTAL SLIPLINERS CONTINUOUS SLIPLINING CURED-IN-PLACE-PIPE SPIRAL WOUND PIPELINE REHABILITATION JOINT REHABILITATION (WRAPPING) ABRASION RESISTANCE OF LINING MATERIALS FLOW CAPACITY REHABILITATION COSTS (APEGBC CLASS C ESTIMATE) CONCLUSIONS M.J. Pawlowski & Associates Page 2 of 18 Town of Qualicum Beach

3 1.0 Introduction The Yambury Road drainage culvert is a 1371mm (54 ) diameter corrugated metal pipe (CMP) located on the west side of Yambury Road allowance and crosses Butterball Drive and terminates at a small slough entering the Georgia Straight. The culvert consists of 2.8mm (12 gauge) thick galvanized corrugated steel and is approximately 43m long (see sketched attached). Record drawings indicate that the culvert was installed in 1979 and laid to a grade of approximately 31%. In 2012 one of the mechanical couplings over the joint located at the lower mitered bend (near beach access) appears to have failed which in turn allowed water to travel outside the culvert and to erode the bedding material. The process caused significant undermining of the embankment. M.J. Pawlowski and Associates (MJP) were retained by the Town of Qualicum Beach to access the current condition of the metal culvert and to recommend options for rehabilitation using trenchless technology methods. 2.0 Condition Assessment of the Yambury Rd. Culvert 2.1 Physical Inspection and Ultrasound Measurements Inspections were conducted in three phases. MJP & Associates conducted a preliminary site visit on July 18, 2012 to evaluate (1) accessibility for additional inspection work and (2) the potential working footprint for rehabilitation equipment. In addition we performed a limited inspection through the open manhole at the top end and a cursory inspection from the outfall end to view damaged sections of culvert at previous repair sites. Pipe Eye Video Inspection Services of Nanaimo conducted a CCTV inspection of the culvert on October 1 st, Details of the CCTV inspection are listed below. On October 11 th, 2012 MJP & Associates performed a limited number of measurements of the culvert invert using an ultra sound instrument to establish the current culvert wall thickness. Thickness measurements were taken at the transition from concrete to steel and the first metre from the access manhole. Additional measurements were taken on the culvert surface (outfall end) at the beginning of the change in grade (past the mitred bend). The instrument used was a Panametrics 37DL Plus ultrasonic thickness gauge. The steel surface was cleaned with a wire brush prior to taking measurements. M.J. Pawlowski & Associates Page 3 of 18 Town of Qualicum Beach

4 The thickness of 12 gauge steel has the following dimensions: Material Dimensions (mm) Dimensions (inches) Metal Gauge Galvanized steel Standard steel Tests on an area of unblemished steel at around 09 o clock of the culvert equaled 2.69mm which demonstrates a good correlation with the published thickness for 12 gauge galvanized steel. At some locations it proved difficult to obtain readings. This is attributed to slime and/or corrosion deposits remaining on the surface even after treatment with a wire brush. Upstream end 07 o clock 06 o clock 05 o clock Series mm 2.64mm 3.08mm Series mm 2.21mm 2.71mm Series 3 No reading 2.93mm No reading Downstream end 07 o clock 06 o clock 05 o clock Series 1 No reading 2.27mm 2.87mm Series 2 No reading 2.52mm No reading Series 3 No reading No reading 2.90mm In general, the thickness measurements indicate slight deterioration of the metal culvert surface at the 06 o clock position with a maximum of 20% reduction based on theoretical published thickness values for galvanized steel pipe. 2.2 CCTV Inspection Distance (m) Joint No. Comments 0.0 Manhole some signs of slight surface corrosion Slight bending (lifting) of joint at from 05 o clock to 06 o clock. External coupling visible from 10 o clock to 03 o clock. 8.6 Some light surface corrosion observed 13.0 Slight surface corrosion at invert No observed problems Joint appears to be open at invert from 05 o clock to 07 o clock. Debris and roots trapped at the joint gap. Possible location of perforation at invert 21.9 Junction of 600mm diameter storm main at 09 o clock Open joint impeding flow at invert. Some debris / corrosion at invert 29.9 Slight corrosion at invert possible perforations 33.1 Possible perforation at 06 o clock Separation of joint from 05 o clock to 07 o clock. Debris trapped in joint (rocks) 36.3 Corrosion at invert 40 6 Joint tight good Open joint 05 o clock to 07 o clock at miter bend transition? Survey Abandoned at transition to mitred bend at damaged section of culvert M.J. Pawlowski & Associates Page 4 of 18 Town of Qualicum Beach

5 The lower section of the drainage culvert was not CCTV inspected from the outfall end. However, physical inspection and observations note the damage section of CMP at the downstream mitered bend and joint. This is the location of the original damage and embankment erosion. View from outfall end, first mitre joint Joint No. 3 at 20m from upstream manhole M.J. Pawlowski & Associates Page 5 of 18 Town of Qualicum Beach

6 Joint No. 4 at 27.5m from upstream manhole; note lifting of water at joint Joint No. 5 at 34m downstream of manhole; arrows indicate separated joint M.J. Pawlowski & Associates Page 6 of 18 Town of Qualicum Beach

7 Joint No. 7 at 41.5m (zoomed image) downstream of manhole; arrow indicates major separation 3.0 Trenchless Rehabilitation Technologies 3.1 Benefits of trenchless technologies The use of trenchless technologies is recognized by many communities as a method of reducing social disruption and minimizing the impact of construction activities on adjacent underground utilities, pavement surfaces, and environmentally sensitive areas. Some technologies provide the ability to overcome complex and challenging construction issues such as depth and high water table. Studies by the University of Waterloo 1 also imply a considerable reduction in carbon emissions when comparing traditional cut and cover utility construction projects with trenchless technology rehabilitation methods. A significant quantity of carbon emissions are generated during open cut activities such as emissions from backhoes, idling dump trucks, and emissions incurred on route to dump sites and when transporting imported backfill materials. 1 Do Trenchless Pipeline Construction Methods Reduce Greenhouse Gas Emissions?, Knight M. et al, Centre for Advancement of Trenchless Technology, University of Waterloo, 2007 M.J. Pawlowski & Associates Page 7 of 18 Town of Qualicum Beach

8 4.0 Evaluation of Trenchless Rehabilitation Methods We have conducted an evaluation of the following five (5) trenchless technology methods deemed suitable for the rehabilitation of the culverts. Segmental Sliplining Continuous Sliplining Cured-in-Place-Pipe Spiral Wound Linings Joint Rehabilitation (Wrapping) 4.1 Segmental Slipliners Sliplining technology entails inserting a new pipe of smaller diameter into the host pipe and filling the resulting annulus space with grout. There are a number of PVC and High Density Polyethylene (HDPE) segmental lining products available to slipline the Yambury Road culvert including short length segmental liners. Of note are the following products: A2 PVC liner by Contech (PVC) Lampson Vylon (PVC) Snap-Tite (HDPE) Weholite (HDPE) Installation of HDPE segmental liners Image courtesy of Snap-Tite M.J. Pawlowski & Associates Page 8 of 18 Town of Qualicum Beach

9 Installation of HDPE segmental liners Easy handling of segmental liners HDPE: Ability to fabricate mitred bends and joints M.J. Pawlowski & Associates Page 9 of 18 Town of Qualicum Beach

10 A crucial component of the sliplining process is filling the annulus void with grout which will provide additional strength to the finished product, and prevent further deterioration of the host pipe and erosion of the surrounding bedding material and soil. Thus, the superimposed loads are transferred through the grout eliminating any point loading. The design of the grout mix must include considerations for density requirements and the ability to flow freely. Thus, to achieve optimum requirements, an additive is used to incorporate air into the mix. The grouting process requires careful monitoring of pressures to ensure the ring compression values of the slipliner are not exceeded which could result in a collapsed liner. The Yambury culvert is constructed at a 30 degree angle and therefore the introduction of the annulus grout must be completed using a process termed stage grouting, where grout is introduced in a controlled manner ( lifts ). Segmental Sliplining Limitations PVC products are difficult to use at mitred bends and changes in direction. Need for annulus space grouting (added expense). Need to provide blocking to prevent flotation of product during annulus grouting. Attributes HDPE has custom fittings available from manufacturer or may be constructed in the field. HDPE offers a variety of products up to 1524mm (60 in.) in diameter. Segmental slipliners allow for more compact construction footprints. Low profile joints available for both PVC and HDPE. The need for bypass pumping can be reduced or eliminated. Good abrasion resistance. 4.2 Continuous Sliplining Continuous sliplining is a similar process to segmental sliplining in that a smaller diameter pipe is inserted into the host pipe and the annulus space is filled with grout. The continuous sliplining method typically utilizes butt-fused joints, polyethylene pipe sections forming one long, continuous length. Continuous Sliplining Limitations Time consuming to fuse joints together (up to 1 hr per joint). Requires unobstructed layout area for fusing and installation. Access pits need to be designed to accommodate allowable bending radius of HDPE pipe. Need for annulus space grouting (added expense). Need to provide blocking to prevent flotation of product during annulus grouting. Attributes HDPE s joint fusion process guarantees joint integrity (high strength, no leaks). The need for bypass pumping can be reduced or eliminated. Good abrasion resistance. M.J. Pawlowski & Associates Page 10 of 18 Town of Qualicum Beach

11 4.3 Cured-In-Place-Pipe The Cured-In-Place-Pipe (CIPP) method was developed by Insituform Technologies, UK in the early 1970 s. The technology utilizes a felt tube impregnated with resin and catalyst which is inserted into the host pipe by means of an inversion process. The resin is then catalyzed by the introduction of heat. The procedure for the installation process and design guidelines was formally adopted in North America as ASTM F1216 in the early 1990 s. Over the past decade, since the expiration of the Insituform original patent for this process, the trenchless rehabilitation industry has developed a number of variations of this procedure using a variety of materials, resins and curing procedures. These include both inversion processes and pull-in-place methods. This type of technology is commonly used in Canada for the rehabilitation of deteriorated sanitary sewer mains. Recent developments in the industry have introduced composite" liners consisting of traditional needle felt liner material in combination with fiber glass or carbon fiber reinforcement. These types of liners become economically feasible for pipe diameters greater than 900mm in diameter. The technology permits for thinner wall liners with superior physical properties. One of the major concerns of using CIPP liners for drainage culvert rehabilitation is the potential for environmental contamination of the surface water downstream of the culvert. The majority of resins used in the CIPP lining process are comprised of approximately 40% by volume of styrene monomer. Styrene is classified as toxic or highly toxic to aquatic life. Styrene has the potential to be released during the installation and curing process and is reported by several studies to continue to leach from the surface of the liner for several weeks after installation at levels that exceed the Canadian Council of Ministers of Environment (CCME) guidelines for the protection of aquatic life. The CIPP resin industry has responded to the environmental concerns and has developed resins that are styrene free. Cured-In-Place-Pipe Limitations Environmental contamination of the surface water downstream of the culvert. Styrene free resins are approximately 3 times more expensive than standard polyester resins. Requires bypass pumping and a dry host pipe. Level of quality control greater than other products. Long cure time (up to 36 hrs) to ensure proper cross-linking of polymer. Poorer abrasion resistance than PVC or HDPE. Attributes Relatively small footprint compared with other lining procedures. No requirement for annulus space grouting. Smaller cross-sectional area loss, low Mannings co-efficient resulting in increased flow capacity. M.J. Pawlowski & Associates Page 11 of 18 Town of Qualicum Beach

12 4.4 Spiral Wound Pipeline Rehabilitation There are several technologies available in North America using this method. Essentially, the PVC or HDPE spiral wound liners are custom fitted with automatic winding machines producing a formwork behind which cement grout is pumped to produce an interactive design with the host pipe. Photo courtesy of RibLoc Photo 2 This method can be used in a variety of geometric configurations including egg-shape, arch and rectangular drainage culverts and sewers. This technology offers the advantage of a minimal reduction in pipe diameter resulting in equal or greater flow capacity than the existing host pipe due to the lower Manning s roughness coefficient of HDPE and PVC material. There are also few environmental concerns compared to Cured-in-Place- Pipe lining systems. 2 Overview of spiral wound pipe lining technologies, Paper 2B-4, International No-Dig Conference 2011, Berlin M.J. Pawlowski & Associates Page 12 of 18 Town of Qualicum Beach

13 Spiral Wound Pipeline Rehabilitation Limitations Limited number of contractors available (all currently US based). Need for annulus space grouting (added expense). Pit access requirements for winding equipment and product installation. Attributes Need for bypass pumping minimized or eliminated. Able to line around bends and variations in pipe geometry. Both PVC and HDPE products have good abrasion resistance. Minimal loss in pipe diameter. 4.5 Joint Rehabilitation (Wrapping) Image courtesy of RibLoc From the CCTV inspection, we note signs of failure at some joints. Joint wrapping would address defects within ~250 mm of each side of each joint (total of 0.5m wide). This procedure addresses localized defects at joints and will not correct any corrosion or invert deterioration at other locations along the length of the culvert. Joint wrapping is an alternative to the technologies described in the preceding sections. The area to be treated is cleaned using sand blasting. A primer coat is then applied and voids are filled with a resin-based putty. Typically, a fibreglass chopped strand matting consisting of three layers will be applied to the joint and anchored with stainless steel screws drilled through the mat and into the culvert. A fourth layer of fibreglass roving is applied over the top of the anchored mat. A wax coat is applied to seal the fibreglass layers. Finally, an epoxy sealer will be used to seal the edges of the fibreglass on the edges of the joint. MJP & Associates solicited quotes from two local suppliers: Chemstar Industries Ltd. (based in Parksville) and Fibrwrap (based in Coquitlam). Chemstar provided pricing (see Rehabilitation Costs section.) Fibrwrap did not reply. M.J. Pawlowski & Associates Page 13 of 18 Town of Qualicum Beach

14 5.0 Abrasion Resistance of Lining Materials The majority of PVC and HDPE lining manufactures reference abrasion resistance tests original developed at the University of Darmstadt, Germany in the 1970 s. These tests are still commonly performed in Europe today on a variety of materials to demonstrate the degree of abrasion resistance and material loss over extended periods of time. Typical Abrasion Resistance Test Values (Darmstadt method) (diagram courtesy of KWH Pipe, The Basics of Weholite Lightweight Pipe System ) The graph above developed under the Darmstadt test procedure indicates that both High Density Polyethylene (HDPE) and PVC pipe material demonstrate high abrasion resistance compared to other materials such as vitrified clay pipe, concrete, fiber glass reinforced pipe (CIPP) and asbestos cement pipe. M.J. Pawlowski & Associates Page 14 of 18 Town of Qualicum Beach

15 6.0 Flow Capacity We have conducted an analysis based on the Manning s equation for open channel flow substituting a variety of coefficients of friction for a variety of trenchless rehabilitation options. The calculations are all based on full-flow (100%) conditions for comparative purposes. Summary of Flow Capacity Location Pipe (mm) Pipe (in.) Flow ft 3 /s Flow m 3 /s Manning coefficient Pipe type % capacity Q Yambury Rd Design Q 31.0% grade Original installation 100% Mature CMP 92% HDPE Snap Tite 102% HDPE Snap Tite 147% CIPP 165% The calculations are sensitive to the Manning s coefficient selected for the various pipe materials and rehabilitation options. Regardless, our computations demonstrate that relining a pipe even with a smaller diameter, smooth surface product will increase the flow capacity of the existing corrugated metal pipe. M.J. Pawlowski & Associates Page 15 of 18 Town of Qualicum Beach

16 7.0 Rehabilitation Costs (APEGBC Class C estimate) Yambury Rd. Drainage Culvert Rehabilitation (54 inch culvert) Segmental - Continuous Sliplining Unit Qty Rate Costs 1.1 Partial By pass pumping / flow diversion Lump sum 1 $ 5, $ 5, Modify manhole entry (temporary) Lump sum 1 $ 5, $ 5, Repair damaged sections of culvert Lump sum 1 $ 5, $ 5, Install 1200mm liner Metres 50 $ 1, $ 80, Annulus space grouting Lump sum 1 $ 22, $ 22, Service connection reinstatement Each 1 $ 1, $ 1, Field construction of HDPE mitred bends Each 2 $ 5, $ 10, Post installation CCTV inspection Metres 50 $ $ 1, Section Total $ 129, Cured-In-Place-Pipe (CIPP) 2.1 Full By pass pumping / flow diversion Lump sum 1 $ 20, $ 20, Modify manhole entry (temporary) Lump sum 1 $ 5, $ 5, Repair damaged sections of culvert Lump sum 1 $ 5, $ 5, Install 1351mm CIPP liner Metres 50 $ 2, $ 125, Service connection reinstatement Each 1 $ 1, $ 1, Construct bulkhead at outlet end Each 1 $ 3, $ 3, Post installation CCTV inspection Each 50 $ $ 1, Section Total $ 160, Spiral Wound Lining (SWL) 3.1 Partial By pass pumping / flow diversion Lump sum 1 $ 5, $ 5, Modify manhole entry (temporary) Lump sum 1 $ 5, $ 5, Repair damaged sections of culvert Lump sum 1 $ 5, $ 5, Install 1350mm HDPE SWL liner Metres 50 $ 2, $ 110, Annulus space grouting Lump sum 1 $ 22, $ 22, Service connection reinstatement Each 1 $ 1, $ 1, Post installation CCTV inspection Metres 50 $ $ 1, Section Total $ 149, M.J. Pawlowski & Associates Page 16 of 18 Town of Qualicum Beach

17 Yambury Rd. Drainage Culvert Rehabilitation (54 inch culvert) Joint Rehabilitation / Wrapping Unit Qty Rate Costs 4.1 Full By pass pumping / flow diversion Lump sum 1 $ 20, $ 20, Modify manhole entry (temporary) Lump sum 1 $ 5, $ 5, Repair damaged sections of culvert Lump sum 1 $ 5, $ 5, Install 1350mm diam. fibre-wrap joints Each 8 $ 14, $ 115, Construct bulkhead at outlet end Each 1 $ 3, $ 3, Post installation CCTV inspection Metres 50 $ $ 1, Section Total $ 150, Class C estimate (±25-40%): An estimate prepared with limited site information and based on probable conditions affecting the project. It represents the summation of all identifiable project elemental costs and is used for program planning, to establish a more specific definition of client needs and to obtain preliminary project approval Conclusions Our field inspections of the Yambury Rd. Culvert together with the analysis of the CCTV inspection survey conclude that the invert of the 54 in. corrugated metal pipe is at a moderate stage of deterioration as observed by the surface corrosion. However, of the eight joints in the corrugated metal pipe, seven exhibited signs of joint separation varying from slight misalignment and bent edges to wide gaps large enough to trap debris and allow root incursion. The original point of failure/washout is believed to have been caused by large joint separation as indicated in the photographic records. Current joint condition is not as advanced; nonetheless, it would be prudent to plan for rehabilitation to avoid a similar mode of failure. We recommend that the Town of Qualicum Beach consider full-length lining over joint wrapping as this will address long term corrosion issues that will inevitably affect the functionality of the invert of the pipe. We have provided preliminary estimates of each trenchless technology that is feasible for this culvert. Current pricing can vary depending on the economic climate, availability of contractors, and costs of mobilization of equipment and crews to Vancouver Island. We recommend that the Town solicit bids on all three full-length lining options and allow the market to offer the best value. 3 APEGBC M.J. Pawlowski & Associates Page 17 of 18 Town of Qualicum Beach

18 This Technical Memorandum entitled Trenchless Technology Options for Rehabilitation of the Yambury Road Drainage Culvert is respectfully submitted by, M.J. Pawlowski & Associates Marek Pawlowski, A.Sc.T. The use of this Report is subject to following Statement of General Conditions. The reader s attention is specifically drawn to these conditions as it is considered essential that they be followed for the proper use and interpretation of this report. Statement of General Conditions: This report was prepared by M.J. Pawlowski and Associates for the Town of Qualicum Beach. The material contained herein, and the recommendations and conclusions reached, reflect M.J. Pawlowski and Associates opinions based upon the information provided to us by the Town of Qualicum Beach and their consultants at the time of report preparation. Any use which a third party makes of this report, or any reliance on or decisions based upon it, are the responsibility of such third parties. M.J. Pawlowski and Associates accepts no responsibility for damages of any kind suffered by any third party as a result of decisions made or actions based on this report. M.J. Pawlowski & Associates Page 18 of 18 Town of Qualicum Beach

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