Contents

Restricted to FERIC Members and Partners Vol. 6 No. 26 September 2005

1 Introduction

1 Objectives

1 Backgroundand sitedescription

2 Planning anddesign

3 Materialsand equip-ment

4 Site prepara-tion

5 Installation

9 Project costs

11 Conclusionsand imple-mentation

12 References

12 Acknowledge-ments

IntroductionCrossing fish-bearing streams along

forest roads in Alberta has typically beenaccomplished with clear-span (bridge) struc-tures, partly because of the regulatory andapplication processes associated with alterna-tive structures such as culverts and arches.Because these alternatives require workwithin the watercourse during installation,the level of protection given to aquatic eco-systems—including fish habitat, fish passage,water quality, and continued navigability—isimportant. This protection is governed byprovincial and federal legislation. Although thepreservation of aquatic resources is paramountwhen working in or near streams, installinga closed-bottom stream-crossing structurewhile maintaining and protecting the waterquality and riparian resources is feasible.

Alberta-Pacific Forest Industries Inc.installed a closed-bottom structural-platecorrugated-steel round culvert along a fish-bearing stream in its Forest ManagementAgreement (FMA) area following bestmanagement practices while working in andnear the stream. FERIC was on-site at thebeginning and end of the construction phase

of this project. Lengthy delays due to wetweather postponed the completion of thisproject more than once and for up to twoweeks at a time.

ObjectiveThe purpose of this study was to provide

FERIC’s members with information aboutthe procedures and costs of installing culvertsalong fish-bearing streams.

Background and sitedescription

Piche Road was built during the summerand fall of 2004 and leads into the easternportion of Alberta-Pacific’s FMA area. Theroad location was planned and preliminarilymapped in advance of ground-truthing andlay-out in the field. The road was built to aClass 3 standard: a permanent road for useup to 20 years, built with an 8-m-widerunning surface, with a cleared right-of-wayfrom 25 to 30 m (Alberta-Pacific 2003).Large amounts of fill were required toaccommodate the vertical alignment of theroad through the depression at the watercrossing (Figure 1).

Installation of a structural-platecorrugated-steel round culvert along afish-bearing stream in Alberta

Abstract

The Forest Engineering Research Institute of Canada (FERIC) monitored and docu-mented the installation of a culvert along a fish-bearing stream in Alberta. Detailed in-stallation procedures and cost information are presented, as well as suggestions for imple-mentation of future culvert projects.

Keywords

Stream crossing, Water crossing, Culvert, Fish habitat.

AuthorClayton T. Gillies,Western Division

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Forest Engineering Research Institute of Canada (FERIC)

Eastern Division and Head Office Western Division580 boul. St-Jean 2601 East MallPointe-Claire, QC, H9R 3J9 Vancouver, BC, V6T 1Z4

(514) 694-1140(514) 694-4351admin@mtl.feric.ca

(604) 228-1555(604) 228-0999admin@vcr.feric.ca

DisclaimerAdvantage is published solely to disseminate information to FERIC’s mem-bers and partners. It is not intended as an endorsement or approval of anyproduct or service to the exclusion of others that may be suitable.

Copyright 2005. Printed in Canada on recycled paper.

ISSN 1493-3381

The road was built across an unnamedfish-bearing stream containing brook stick-leback, with a meandering channel througha muskeg/grassy wetland containing wateryear-round. The main stream channel wasbraided through much of the wetland areanear the crossing. Numerous beaver dams hadflooded portions of the wetland and beaveractivity was evident adjacent to the mainchannel. The width of the main branch ofthe stream varied from 1.65 to 2.50 m, andthe depth varied from 25 to 62 cm. Pool areasaway from the crossing location were widerand deeper, at 3.10 and 0.75 m, respectively.The stream had a sandy, silty bottom withfew cobbles, and a natural gradient close to1%. The width of the wetland at thecrossing location was 25 to 30 m. Thewetland is comprised of grasses, taller sedges,

and dead or dying spruce trees (Figure 2).The distinct division between the grassesand taller sedges indicated a 3- to 5-year floodevent boundary.

Planning and designBridges are typically the Alberta-Pacific’s

road engineers’ first choice for crossingfish-bearing streams (Alberta-Pacific 2003).However, the width of the wetlands meant abridge would need to be close to 30 m inlength. The road engineers also consideredalternative structures such as a closed-bottomculvert. A culvert was expected to cost lessthan a bridge and would be a two-lanecrossing (compared to a single lane for abridge), thus increasing road safety. For aclosed-bottom structure, a structural-plateculvert would be more rigid and better suitedto the fill requirements at the site comparedto a helical (spun) culvert. A thickness of 4 mmwas suggested for the structure and may nothave been available for a helical (spun) culvert.

To proceed with building a closed-bottom structure along a fish-bearing stream,federal authorizations and provincial notifi-cations were required. Alberta-Pacificapplied for and received an authorizationfrom Fisheries and Oceans Canada for the“harmful alteration, disruption, or destruction(HADD) of fish habitat” arising from theculvert installation, pursuant to subsection35(2) of the Fisheries Act (DJC 1985). Suchan application also triggers an environmentalreview of the proposed activities on theresource in question under the CanadianEnvironmental Assessment Act, whichconcluded that the project was not likely tocause significant adverse environmental effects.Both approvals were subject to the mitigation(erosion and sediment control) and compen-sation (fish-habitat enhancement) measures

Figure 1. View ofthe wetlanddepression andright-of-wayclearing on far sideof crossing.

Figure 2. Upstreamof the crossingshowingmeanderingchannel throughgrassy wetland(photo courtesy ofAlber ta-Pacific).

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specified in the application. In-stream workactivities were scheduled to avoid migration,spawning, and incubation periods of residentfish species.

Liland Engineering Ltd. of Sexsmith,Alberta surveyed the stream 300 m bothupstream and downstream of the crossinglocation, and prepared the designs. Thesurvey established the gradient of the naturalchannel and cross-sections of the channel weremeasured at 100-m intervals (3 upstream and3 downstream). A cross-sectional view wasestablished for the road crossing itself,showing the existing ground, the proposedroad surface, and the placement of the culvertsuperimposed below the proposed roadgrade. This last view also showed 5 m of fillover the top of the culvert. The designedgradient for the culvert was 0.8%. All designswere signed and sealed by a member of theAssociation of Professional Engineers,Geologists, and Geophysicists of Alberta.

Hydrological planning for wetland areascan be uncertain, in part due to the wetlands’holding/storage capacities during high rainevents and the delayed passage of waterthrough a wetland. Unlike a lake where thestorage capacity can be easily viewed andestimated, a wetland’s capacity is partiallyhidden below ground. In this case, hydro-logical designs for the crossing were generatedby analyzing the data from a nearby streamgauge, and extrapolated to suit the targetstream’s drainage area (11.4 km2). Thecrossing was designed to allow passage of the1:50 year flood event (Q50) of 10 m3/s. Theculvert is also expected to pass the 1:100 yearflood event (Q100) of 16.5 m3/s (flowvelocity of 2.7 m/s) without overtopping theroad. The 1:10 year flood event (Q10) wascalculated as 1.1 m3/s, corresponding with athree-day delay from the actual event.

Erosion control plans for the site includedgeotextile fences across the stream anddiversion channel at various strategic locations,and across the ditchlines entering the crossinglocation. Fibrous matting was to be placedalong ditchlines and staked down. Handseeding of exposed soils with a local

reclamation mix was to be done concurrentwith the construction of the crossing.Alberta-Pacific’s road engineer and/orbiologist were to visit the site during con-struction to observe and document anysediment-related concerns.

Materials andequipment

The closed-bottom structural-platecorrugated-steel round culvert was suppliedunassembled by Atlantic Industries Ltd. Onceassembled, the culvert measured 3.36 m indiameter and 50 m long, and had a wallthickness of 4 mm and corrugation profileof 152 × 51 mm. The end area of the culvertwas 8.86 m2 and each end was fabricated witha step-bevel. The culvert will accommodatethe weights of loaded off-highway loggingtrucks (approximately 68 tonnes grossvehicle weight). Maximum recommendedcover over this structure is approximately20 m (AISI 1995).

The primary equipment used duringconstruction were a John Deere 230 LCexcavator and a John Deere 450 crawlertractor. John Deere 270 and 330 excavatorswere also used. An articulating and a tandemend-dump truck delivered pit-run andcrushed aggregate and retrieved excavatedmaterial.

Other equipment and supplies includedthe following:• survey equipment: level with tripod, rod,

stakes, and flagging tape• dewatering equipment: Honda GX240,

6-kW (8-hp) pump with 9-cm (3.5-inch)intake hose, geotextile, 60 m of corru-gated metal pipe (600-mm diameter)

• embedding equipment: Bobcat 773front-end loader, sheets of plywood

• compaction equipment: jumping-jackhand-held compactor, Ingersoll Rand203-cm vibrating-drum pad-foot roller,lengths of 2 × 4 dimensional lumber

• erecting crew: compressor and air ratchet,torque-wrench, scaffolding, truck withcrane

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• sediment and erosion mitigation:geotextile and wooden stakes, fibrousmatting, reclamation seed mixture

Site preparationThe site preparation is presented in the

following steps: stream diversion, tote road,excavation, bedding preparation, and survey-ing.

Stream diversion

At the beginning of the construction, theexcavator prepared a diversion trench on thecamp side of the stream crossing through theedge of the wetland area (Figure 3), connect-ing the downstream end to a backwater/me-ander of the stream. The upstream side ofthe trench was not connected to the mainstream at this time. The diversion trench hadfilled with water due to the high water tableand seepage associated with the wetland area.Two fences made of geotextile were con-structed downstream to slow water move-ment and promote the settling of fines (Fig-ure 4). The excavation was to be used as agravity-fed open-trench bypass for the stream.

The dewatering plan was altered to aclosed gravity-fed system to allow equipmentto travel over the bypass section during con-struction and to lessen any sediment deliveryto the open trench. The original open trenchwas utilized by placing a series of 600-mm-diameter corrugated metal pipes along thelength of the trench to carry the stream flow.The pipes were joined together by couplersand then covered with fill. Also, the opentrench at the outlet of the diversion pipe waslined with geotextile to separate soil fromthe water flow. The total length of thediversion was approximately 50 m.

Tote road

A tote road was built so machinery couldpass and continue roadbuilding past thecrossing (Figure 5), and to give heavyequipment access to both sides of the culvertduring installation.

Excavation

Two excavators worked in tandemduring the initial excavation. One removedthe earth through the length of the dewateredstream section and placed this material uphill.The second then moved this material oneboom-swing further from the constructionsite. The uphill excavator placed the materialin a peaked pile. The excavated material wasplaced along the edge of the right-of-way onboth approaches to the crossing.

Figure 3. Lookingdownstream alongthe open diversiontrench (before thedecision wasmade to use roundculver ts).

Figure 4. Fencemade of geotextilenear the outlet ofdiversion trench.

Figure 5. Tote roadwhich allowedequipment to passthe culver tinstallation site.Arrow shows theabrupt and distinctboundary betweenthe wetland areaand forested area(photo courtesy ofAlber ta-Pacific).

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Bedding preparation

The bedding for the culvert was preparedby a series of lifts. First, the excavator removedan additional 1 m of soil below the targetelevation and spread pit-run aggregate alongthe length of the excavation. This “bottom”lift added additional support for the culvertand established the initial flat workingsurface. This lift was compacted with avibrating-drum pad-foot roller (Figure 6).Approximately 10 cm of sandy material wasthen spread on top of the compacted lift asthe final bedding for the culvert (Figure 7).This lift was not compacted, but left looseto allow the culvert to “settle” itself into thematerial.

Surveying

The majority of the surveying and fieldreferencing took place during the beddingpreparation. A benchmark was establishedand a level and tripod were used to accuratelygauge the gradient/vertical alignment ofthe culvert. Due to the meandering natureof the stream and the wetland in general, thehorizontal positioning of the culvert throughthe proposed road was somewhat forgiving.In fact, during the installation the supervisor/foreman positioned the culvert at a slightlydifferent skew through the wetlands comparedto the original plan. The purpose of thechange was to position the outlet at a betterlocation.

InstallationThe installation is presented in the

following steps: culvert delivery and assembly,backfilling, infilling, stream channel blending/reconnection, stream connection, armouringand reclamation, and compensation works.

Culvert delivery and assembly

The culvert was delivered unassembled.The plates and buckets of bolts wereunloaded and stored along the road (Figure 8)on the camp side of the crossing, approxi-mately 40 m from the excavation.

The erecting crew for the culvert consistedof 5 members, and was on-site for 4 days fora total of 40 hours per crew member. Up tothree plates were joined together on the road,away from the excavation, where there wasample room to work. These pre-assembledsections (connected plates) were thentransported to the construction site on a truckequipped with a crane and lifted into place(Figure 9). The bolts were kept loose untilthe entire assembly was complete to allow

Figure 6. Vibrating-drum pad-footroller used forcompaction duringvarious stages ofconstruction.

Figure 7. Sandybedding preparedto a level surface(photo courtesy ofAlber ta-Pacific).

Figure 8.Unassembledculvert plates andbuckets containingbolts (photocourtesy ofAlber ta-Pacific).

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for plates to be aligned properly. Onceassembled, the erecting crew used an airratchet to cinch the bolts tight and a torquewrench to check the torque-force on a largesample of bolts. Scaffolding, which ran onwheels along the bottom of the culvert, gaveaccess to areas that were unreachable fromthe ground.

Backfilling

Compaction of the initial backfillingunder the haunches of the culvert was donefirst by hand using lengths of 2 × 4 dimensionallumber followed by a jumping-jack stylecompactor. All compacted lifts measuredapproximately 30 cm in height. Shortly afterthe haunches were compacted, rainy weatherdelayed the construction for three weeks. Claysoil was placed at a water-shedding angle nextto the culvert above the lowest bolt holes(Figure 10) during this prolonged shutdown.This hand-placed material helped to keepwater from entering the culvert through thebolt holes, and to shed water away from thecompaction below the haunches.

Backfilling around the outside of theculvert continued once the rainy weather hadchanged, and the threat of construction-relatederosion and suspended sediment had beenreduced. Backfill material was deliverednext to the culvert by the end-dump trucks(Figure 11) and was spread by the crawlertractor (Figure 12). The material within onemetre of either side of the culvert was compactedusing a jumping-jack style compactor, whilethe remaining width of the lift was compactedusing the vibrating drum roller. The backfillingand compaction were completed after 5 shifts(3 day and 2 night), with an average compactedheight of 60 cm per shift.

The roadbuilding crew employed a localtechnique to help prevent any eventual streamflow from piping along the outside of theculvert. Clay from the original excavation wasplaced around the culvert at each end to actas an impermeable “plug” to water flow. Asan alternative, geotextile can be placed underand around the culvert to form a curtain oneither side (Gillies 2003).

Figure 10.Assembled culver tshowing claymaterial placednext to the culvertand above thelowest bolt holes(photo courtesy ofAlber ta-Pacific).

Figure 11. End-dump truckdelivering backfillmaterial (photocourtesy ofAlber ta-Pacific).

Figure 12. Crawlertractor spreadingbackfill material.Note the large pileof excavatedmaterial on the farside of the culvert(photo courtesy ofAlber ta-Pacific).

Figure 9. Truckwith extendedcrane to lift pre-assembledsections into placeduringconstruction. Notethe sections on theback of the truck(photo courtesy ofAlber ta-Pacific).

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Once the material around and over thetop of the culvert had been compacted,additional fill material was delivered to buildthe road to grade. Up to three scrapers movedthe large amount of fill required for the entireroad construction. A geogrid (plastic mesh)was placed between upper lifts, but belowthe final road grade, to reinforce the road andgive it additional lateral strength to help resistsloughing. The geogrid, through confinementand its inherent tensile strength, helps toresist the lateral movements promotedunder load. Sloughing was a concern con-sidering the height of fill above the culvert.The final measured height of fill was closeto 5 m above the culvert and close to 8.5 mabove the original ground level on either sideof the culvert. The running surface of theroad was approximately 8 m wide.

Infilling

The design for infilling the culvertprescribed a minimum of 600 mm depth ofClass 1 rock riprap to be placed along theentire length of the culvert. The measuredactual depth of infill material was 600 to800 mm, and the rock was 200 to 550 mmin diameter. This rock will offer resting areas,in the form of velocity shadows, for fishduring migration through the culvert andpromote the settling of sand and gravel.Hydrological tables show that a flow eventwith a mean velocity of approximately3.9 m/s would be necessary to transport thesmaller rock from within the culvert. Thiscan be considered an extremely high flowevent. The infill material is considered partof the compensation measures required forthis closed-bottom structure.

Infilling started once the backfill hadreached the top of the culvert, but before theroad was built to design grade. The designdepth for the infill material was measuredand spray painted along the inside wall ofthe culvert to help guide the placement ofmaterial. A Bobcat front-end loader deliveredthe infill material through the length of theculvert. The primary excavator placed theinfill material into the front-end loader’s

bucket (Figure 13). A staging area just outsideof the culvert was prepared by placingwooden pallets for the loader to work on.These pallets kept the staging area frombecoming excessively muddy, and kept themajority of the soil material from beingcarried into the culvert on the loader’s tires.Plywood was placed through the length ofthe culvert to protect the loader’s tires frombolts, and was eventually removed once itwas no longer required.

The loader travelled forward into theculvert to deliver the rock riprap infill material,and reversed out of the culvert. Two workersinside the culvert rolled and manipulated therock to cover the bottom of the culvertevenly from side to side. The infilling of theculvert took 12 hours to complete.

Stream channel blending/

reconnection

In order for the stream to enter the culvertwithout making an abrupt turn, a section ofstream channel was reconstructed. Onemeander upstream of the culvert was isolatedfrom the main flow path and a straightsection of channel was constructed.Geotextile was laid along the streambanksof this straightened channel and roundedrock similar to that used inside the culvertwas placed on top as armouring. The recon-structed section of stream blended in to thenatural stream approximately 15 m from theinlet, and a 15–30 cm difference in streambedelevation occurred which resulted in a rifflecharacteristic (Figure 14).

Figure 13.Excavator placinginfill material intothe bucket of thefront-end loaderduring the infillingof the culvert(photo courtesy ofAlber ta-Pacific).

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Eliminating the flow in the upstreammeander will lower future sediment inputsto the stream because the meander waseroding the toe of a steep and un-vegetatedravelling bank (Figure 15). The meander maystill function as a backwatering/refuge areafor aquatic wildlife.

The stream channel downstream of theculvert also had some modifications. Althoughthe outlet of the culvert was purposefullypositioned to flow into a downstream meanderof the stream, a short redirection of thechannel was necessary. The streambank alongthis redirection, and portions of the originalstreambank, were armoured using roundedrock (Figure 16).

Stream connection

During the final armouring of thestreambanks along the upstream side of theculvert, the main channel of the stream wasredirected through the culvert. The excavatorplaced fill material to block the stream’s flowthrough the meander area, forcing the flowthrough the newly created channel. Rockarmouring was also placed over this fill.During the reconnection, the stream elevationdropped as the flow entered the new channel.To help alleviate this difference in elevation,the excavator placed sand within the rifflesection to promote a more gradual transition.

Armouring and reclamation

Fillslopes were armoured above andaround the culvert at both the inlet andoutlet. The armouring extended to just belowthe road surface and up to 3 m on each sideof the culvert (Figure 17). Geotextile fencingwas installed around the entire armouredareas. The bottoms of the geotextile fenceswere placed in a hand-dug trench, andwooden support stakes were placed at 2-mintervals. The fillslopes above the culvertwere 15–20 m in length and had an averagegradient of 40%.

Ditchlines immediately entering thewetlands area were protected against furthererosion by use of fibrous matting (Figure 18).Geotextile fences were also constructed in

Figure 15. Arrowpoints to un-vegetated andravelling bank.

Figure 16. Outlet ofculvert showingstreambankarmouring.

Figure 17. Outlet ofculvert showingfillslope armouringand geotextilefencing.

Figure 14. Inlet ofculvert showinglength ofreconstructedstream channel,size and amount ofrock, and stream-riffle section nearthe end of thearmouredstreambanks.

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this area to slow water velocity and promotedeposition of sediment. Rounded cobbles andboulders were placed along one of theditchlines as armouring because of its steeperslope. The exposed soils were seeded with areclamation mix at the completion of theproject.

Compensation works

To compensate for the destruction and/or alteration of fish habitat, specific conditionswere directed by Fisheries and Oceans Canadawithin the authorization document that wasinitially presented by the proponent of theproject. Specified compensation workswere correlated to the predicted area of losthabitat (150 m2) and, in this case, primarilymade reference to the placement of root wadsupstream and downstream of the culvertcrossing. The root wads were strategicallyplaced to offer shade and bank-scourprotection. They will also offer protectionfor fish from overhead predation, addhabitat diversity, and give micro-habitat flowcharacteristics (Figure 19).

Project costsFERIC’s estimate of project costs is

shown in Table 1. The purchase and deliveryof the culvert accounted for approximately46% of the total installation cost, whilethe delivered aggregate accounted forapproximately 14%. The remaining 40%was accounted for in the cost of the heavyequipment, labour, and the other materials.

The costs presented also includebuilding the road up to grade approximately20 m on either side of the culvert. If thecomplete road approach to the crossing sitewas included (50 m on either side of theculvert), an additional $70 000 in roadworkcosts would be included. This cost would begenerated primarily by the scraping anddelivery of fill material, and its spreading andcompaction.

Cost comparison for alternative

product

During the planning stage, the roadengineer considered different products forcrossing the stream. The professional advicegiven to the road engineer regarding a culvertwas that its walls should be at least 4 mmthick. To meet this criteria, a structural plateproduct was chosen, as the thickest wall fora helical (spun) corrugated-steel culvert was3.5 mm. Although product tables presentwall thickness for helical culverts up to4.2 mm, this thickness is rarely sold and isdifficult to obtain.

If a thinner wall thickness was acceptable,a comparable product would have been ahelical corrugated-steel round culvert. Forexample, a culvert with the same length andcorrugation profile as the one used in thisinstallation, but with a slightly largerdiameter at 3.4 m and a slightly thinner wallthickness of 3.5 mm (with a maximum coverover structure of approximately 12 m),would be delivered in 4 sections on 4separate trucks and would require 3 couplers

Figure 18. Fibrousmatting andgeotextile fencesplaced acrossditchline (photocourtesy ofAlber ta-Pacific).

Figure 19. Rootwads placedupstream ofculvert withinmain channel ofstream.

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at $250 each. The freight to deliver thesections would be the same as the structuralplate ($2000 per truck) and the price permetre for the culvert is approximately$800, totalling $48 800 for the culvert tobe delivered. The helical culvert wouldtherefore have a delivered price of $43 200less than the structural plate. Additionalsavings may also have been realized duringthe placement of the culvert as there wouldnot be the need for bolting plates together,although the time to secure couplers tolarge round culverts can take 1.5 hours each(Gillies 2003).

A thinner structural-plate culvert wouldalso cost less. The next lower thicknessavailable is 3 mm (with a maximum coverover structure of approximately 14 m) withthe same diameter and corrugation profile asthis installation. This would cost $1 375/m,as compared to $1 800/m for the 4-mm-thick structural-plate culvert. This lower costequates to a savings of $21 250, when allother factors remain the same.

The cost of installing a single-lane bridgeat this location was estimated to be similarto or higher than the structural-plate culvert.

Cost category Quantity Unit cost ($) Total cost ($)

Materialsstructural plate culvert (delivered) 50 m 1 800 90 000delivery of culvert 1 delivery 2 000 2 000delivered pit-run aggregate (bottom lift) 270 m3 22 5 940delivered 2-cm minus crushed (backfill) 300 m3 42 12 600delivered rounded field stone (infill, stream channel, and armouring) 200 m3 50 10 000geotextile fence 450 m2 1.5 675geogrid for road 2 rolls 1500 3000fibrous matting 5 rolls 110 550wooden stakes 50 pieces 1 50plywood sheets 20 sheets 25 500lumber 10 pieces 12 120

Equipmentexcavator (20–25 t) (John Deere 230) 160 h 130 20 800excavator (35–40 t) (John Deere 330) 32 h 155 4 960articulating end-dump truck 32 h 140 4 480tandem end-dump truck 32 h 130 4 160crawler tractor (5–10 t) (John Deere 450) 40 h 110 4 400drivable compactor 16 h 105 1 680Bobcat loader 12 h 95 1 140jumping-jack compactor 4 wk 250 1 000pumps and hoses 4 wk 250 1 000

Laboursite survey 16 h 30.5 488mapping (site plan) 8 h 30.5 244culvert erecting crew (5 people and equipment) 4 d 5 000 20 000forest worker(s) (culvert infill, geotextile fences) 76 h 30.5 2 288supervision/foreman (also surveyor) 20 d 300 a 6 000

Total 198 075

a Supervisor/foreman rate shown is approximately one-half the total daily rate, because the supervisor/foremanspent time away from the stream crossing attending to other duties.

Table 1. Estimate of project costs

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The length of the bridge deck would havebeen approximately 30 m to span the entirewetland. It was unclear whether or not a shortcauseway could be built at each approach toshorten the bridge length; if permitted, thisconstruction may require approvals to workwithin the watercourse area. A single-lanebridge was not desirable for this crossing.Factors such as engineering costs for the design,the desired vertical alignment for the road,and safety of a single versus two-lane crossingall played a role when making the finalchoice.

Conclusions andimplementation

The 3.36-m-diameter, 50-m-longstructural-plate round culvert was installedat a cost of $198 000. The road was built toa Class 3 standard. Large amounts of fill wereplaced along the approaches to achieve thevertical alignment typical of such crossings,and a two-lane crossing with excellentsightlines for driving resulted (Figure 20). AHADD was applied for and authorizationwas received for the construction of aclosed-bottom culvert along a fish-bearingstream. The HADD specified compensationmeasures. The culvert was infilled withrounded rock to create habitat featureswithin the culvert. The rock will also providea roughness factor which will reduce watervelocity and increase deposition within theculvert. Root wad structures were built withinthe main stream channel. Short sections ofthe stream channel were reconstructed toaccommodate placement of a straight culvertalong a meandering stream.

Observations were made on-site whichmay be useful during future installations:• A culvert of this length cannot be

delivered as one pre-assembled section.Two or three sections can be pre-assembled and delivered, but they wouldneed to be transported on separatetrucks. The pre-assembled optionshould be carefully considered whenordering a culvert of this size. The cost

of additional delivery trucks may bejustified when considering the cost ofthe erection crew and/or timing window.In this case, the culvert was deliveredunassembled.

• When assembling the culvert on-site,connecting two or three sections beforeattaching them to the main portion ofthe culvert streamlined the process.Bolting culvert sections together awayfrom the excavation was easier and moreconvenient than working with individualsuspended sections.

• Air quality within the culvert can becompromised when operating diesel- orgas-powered machinery within theculvert. Workers should be advised andequipped for this risk, and the airquality should be monitored. If pro-longed machinery use is anticipated,fans can be used to force air into or outof the culvert.

• Typically, the backfill material around aculvert is delivered by an excavator, onebucket of material at a time. By buildinga tote road, the dump trucks had accessnext to the culvert and time was savedduring delivery of backfill material. Theoptions for delivery of backfill need tobe assessed for each site and volumerequired.

• Closed-bottom structures along newlybuilt roads can be perceived to removehabitat from the riparian system. In thiscase, the habitat affected was commonlyavailable upstream and downstream of

Figure 20. View ofroad surfaceacross theinstalled culvert(photo courtesy ofAlber ta-Pacific).

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the crossing. The introduction of cobblesand small boulders through the lengthof the culvert gave the stream new di-versity, which may prove beneficial tothe aquatic system. Root wads placedalong the stream bank and pool areas alsoprovided new features.

• The need for precise elevation readingswas highlighted by the elevation differ-ence between the reconstructedstreambed and the natural streambed. Inthis case, a 15- to 30-cm drop created ariffle. A 50-cm drop in elevation wouldhave been much more challenging toaccommodate. To avoid large differences,a semi-permanent benchmark should beestablished at the site survey stage (e.g.,while collecting data for the engineereddesign), and referenced frequently whilesurveying during the construction phase.

• The structural-plate culvert is not con-sidered watertight due to the numerousbolt holes. If a watertight culvert isnecessary, each bolt hole exposed towater flow may require a gasket. If ahelical culvert is used, the couplers tothe culvert should be sealed.

• When removing and storing largeamounts of excavated fill, utilizingtrucks to end-haul the material may bemore efficient than excavators workingin tandem.

• Excavated material should be well peaked(water shedding) or covered with a tarpif heavy rains are expected to reduceerosion of the pile and/or suspendedsediment. Excavators can produce awell-peaked pile by continually placingmaterial higher on a pile. Conversely,end-dump trucks can only produceindividual piles correlated to a singleend-dump of material.

• Compensation measures dictatedwithin the authorization of a HADDwere reasonable and proposed within theapplication. The crew built the root wadstructures easily and quickly, and anabundance of root wads were availableon-site. Compensation works are typicallyin line with Fisheries and OceansCanada’s mandate for a net gain (no netloss) in fish habitat across the country.

• All best management practices areworthy of attention, but none were asimportant in this case as the rainy-weather shutdown. Heavy rains combinedwith machinery activity would havecreated an unacceptable level of erosionand higher probabilities of sedimentreaching the fish-bearing stream.

ReferencesAlberta-Pacific Forest Industries Inc. 2003.

Alberta-Pacific watercourse crossingmanual. Boyle, Alta. 33 pp.

American Iron and Steel Institute (AISI).1995. Handbook of steel drainage andhighway construction products, Canadianedition. Washington, D.C. 411 pp.

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AcknowledgementsThe author expresses his appreciation to

Dawn Safar, Tony Gaboury, Kevin Ledieu,and Roy Crawford of Alberta-Pacific ForestIndustries Inc. for their cooperation andassistance during the course of this project.The author also thanks FERIC staff forreport reviews, graphics and layout work, andfinal edit.