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Edmonds Northstream Pipe Culvert 4-29-16.pdf
City of Edmonds NORTHSTREAM PIPE ABANDONMENT AND CULVERT REHABILITATION Under Puget Drive/SR 524 Structural Evaluation April 29, 2016 PREPARED FOR PREPARED BY CITY OF EDMONDS NORTHSTREAM PIPE ABANDONMENT AND CULVERT REHABILITATION EXECUTIVE SUMMARY This report documents culvert conditions and presents improvement options for Northstream culvert at Puget Drive/SR 524 for the City of Edmonds, Snohomish County, Washington. The report summarizes the culvert assessment, develops preliminary design alternatives to rehabilitate or replace it, and provides options for abandoning an existing upstream culvert. Field data collection, hydrologic and hydraulic calculations, opinions of probable construction cost, and concept designs are included. Two options were developed for replacing the existing Northstream culvert under Puget Drive. The options both assume trenchless construction methods to reduce impacts to the state route infrastructure and traffic. Option one is a complete replacement of the culvert using the trenchless construction method of auger boring. The opinion of probable construction cost for Option 1 is $733,000. Option two improves the existing culvert by installing a cured in place liner and is our recommended option. The opinion of probable construction cost for Option 2 is $312,000. The designs for the culverts are presented in concept drawings, narratives, engineering calculations, and itemized opinions of probable construction cost in this report. Also included in this study is a culvert assessment and development of repair or abandonment options for an old 30-inch concrete culvert, approximately 470 feet long, that once conveyed Northstream. A construction project in 2006 diverted flows from Northstream into a new culvert. That project did not include abandonment of the old culvert. Although Northstream was diverted, water is currently flowing through the culvert. This assessment also investigates the source of these flows and impacts on abandonment and improvement options. Four abandonment and improvement options with concept drawings, narratives, engineering calculations, and itemized opinions of probable construction cost have been developed and presented in this report. The options have cost ranges between $111,000 and $269,000. Option 2 is recommended; it would slipline the lower portion of the culvert to allow water collecting in the culvert to drain into Northstream while filling those portions of the culvert under City roads and a residence with grout or CDF. The opinion of probable construction cost for Option 2 is $111,000. City of Edmonds i Northstream Pipe Abandonment and Culvert Rehabilitation Table of Contents Page No. ....................................................................................................................................................V ACRONYMS ............................................................................................................................................1 INTRODUCTION PD....................................................................................................................................................2 ROJECTESCRIPTION B...............................................................................................................................................................2 ACKGROUND .......................................................................................................................................................3 METHODS CCA....................................................................................................................................3 ULVERTONDITIONSSESSMENT HA....................................................................................................................................................6 ABITATSSESSMENT NCPD/SR524.......................................................................................................8 ORTHSTREAMULVERTUNDERUGETRIVE ...................................................................................................17 CULVERT REPAIR OR REPLACEMENT TE.............................................................................................................................................17 RENCHLESSVALUATION ABO1................................................................................................................................................17 UGEROREPTION ABICNS.............................................................................18 UGERORENSTALLATIONONSIDERATIONSATTHEORTHSTREAMITE CIPPO2....................................................................................................................................21 UREDNLACEIPEPTION CIPPRCNS....................................................................................22 EHABILITATIONONSIDERATIONSATTHEORTHSTREAMITE SSCC..............................................................................................................22 ITEPECIFICHALLENGESANDONSIDERATIONS AD................................................................................................................................23 DVANTAGESANDISADVANTAGES ONCSPD/SR524..........................................................................................25 LDORTHSTREAMULVERTOUTHOFUGETRIVE ............................................................................................31 CULVERT REVISE OR ABANDON OPTIONS O1:NPO.......................................................................................................................................31 PTIONEWIPEUTLET O2:S.....................................................................................................................................................31 PTIONLIPLINE O3:ECPO..........................................................................................................32 PTIONXISTINGONCRETEIPEASANUTLET O4:AC................................................................................................................................33 PTIONBANDONTHEULVERT ................................................................................................................................................39 CONCLUSION ................................................................................................................................................42 REFERENCES .................................................................................................................................................44 APPENDICES APPENDIX A Î CALCULATIONS APPENDIX B Î COST ESTIMATES APPENDIX C Î PUGET DRIVE 30 STORM MAIN REPAIR PRE-DESIGN REPORT APPENDIX D Î CONCEPT PLANS (under separate cover) TABLES TABLE1.CULVERTSUMMARY...........................................................................................................................8 TABLE2.PERMITSUMMARY............................................................................................................................36 City of Edmonds iii Northstream Pipe Abandonment and Culvert Rehabilitation PHOTOS PHOTO1.JOINTSEPARATIONATOUTLET.........................................................................................................10 PHOTO2.OUTLETWITHPLUNGEPOOL............................................................................................................10 PHOTO3.DOWNSTREAMCHANNELCONDITIONS.............................................................................................12 PHOTO4.DOWNSTREAMSUBSTRATECONDITIONS..........................................................................................12 PHOTO5.STORMTRIBUTARYABOVEDOWNSTREAMOUTLET..........................................................................13 PHOTO6.DOWNSTREAMOUTLET....................................................................................................................13 PHOTO7.UPSTREAMCULVERTINLET...............................................................................................................14 PHOTO8.UPSTREAMCHANNEL,JUSTABOVECULVERT....................................................................................15 PHOTO9.SIXFOOTUPSTREAMCHANNEL;GRAVELANDSANDNEARCULVERT................................................15 PHOTO10.UPSTREAMCHANNELWITHGRAVEL,COBBLE,SAND,ANDLWD......................................................16 PHOTO11.SANDANDGRAVELLOADINGABOVEACTIVECHANNEL,APPROXIMATELY150TO200FEET UPSTREAMFROMCULVERT..............................................................................................................................16 PHOTO12.AUGERBORINGMACHINE..............................................................................................................17 PHOTO13.BROKENCULVERTSECTION(STA.5+24)UNDER12 TH AVEFROM2006INSPECTION..........................34 TH PHOTO14.BROKENCULVERTSECTION(STA.5+24)UNDER12AVENFROM2014INSPECTION.......................34 PHOTO15.WATERFLOWENTERING30PIPE(STA.4+65)VIAAN8INCHPIPEFROMTHEEXISTINGDITCH ALONGPUGETDRIVE........................................................................................................................................35 PHOTO16.DEBRISBLOCKAGE(STA.2+94)NEARTRANSITIONFROM30INCHPIPETO24INCHPIPE.................35 City of Edmonds iv Northstream Pipe Abandonment and Culvert Rehabilitation ACRONYMS BFM bonded fiber matrix BFW bankfull width CB Catch Basin CIPP Cured-In-Place Culvert CMP corrugated metal pipe CP corrugated plastic CPCB cast-in-place concrete box GIS geographic information system GPS global positioning system LWD large woody debris MH Manhole NA not applicable NMFS National Marine Fisheries Service PE polyethylene RCBC reinforced concrete box culvert RCP reinforced concrete pipe RSP round steel pipe SR state route USACE U.S. Army Corps of Engineers USFWS U.S. Fish and Wildlife Service WAC Washington Administrative Code WDFW Washington State Department of Fish and Wildlife WDNR Washington State Department of Natural Resources WSDOT Washington State Department of Ecology WSDOT Washington State Department of Transportation WWHM Western Washington Hydraulic Model City of Edmonds v Northstream Pipe Abandonment and Culvert Rehabilitation CITY OF EDMONDS NORTHSTREAM PIPE ABANDONMENT AND CULVERT REHABILITATION INTRODUCTION The City of Edmonds requested Reid Middleton and GeoEngineers to perform a structural condition assessment of the existing Northstream culvert under Puget Drive/SR 524, City of Edmonds, Snohomish County, Washington. This report summarizes the culvert assessment, develops preliminary design alternatives to rehabilitate or replace it, and provides options for abandoning an existing upstream culvert. Field data collection, hydrologic and hydraulic calculations, construction cost, and concept designs for the culvert structure and stream channels are included. Figure 1 provides the location of the culvert assessed. Northstream Culvert Location. City of Edmonds 1 Northstream Pipe Abandonment and Culvert Rehabilitation ProjectDescription The overall goal of this study is perform a condition assessment of the Northstream culvert under Puget Drive/SR 524, develop alternatives to rehabilitate and replace the culvert, and analyze abandoning the upstream culvert. A habitat assessment associated with the roadway culvert is also included. The culvert condition assessments include site investigation of the general stability and hydraulic-related conditions and a culvert structural investigation. Conceptual design recommendations are developed to improve and replace the culverts, including cost estimates. Permitting implications for the improvement options are also included. A detailed description of methods and findings is found in the following sections. Background The Northstream culvert at Puget Drive is a 30-inch concrete culvert. The outlet on the north side of the road runs under Puget Drive for 91 feet to a manhole on the south side of Puget Drive. This manhole, MH 8-1165, per the City of EdmondsÓ GIS map, receives flows from two culverts--an old 30-inch concrete pipe and a new 30-inch high density polyethylene (HDPE) pipe. The HDPE pipe currently conveys Northstream and was constructed in 2006 when the 30-inch concrete pipe failed. Both culverts parallel each other roughly for approximately 400 feet to the east. The 30-inch HDPE pipe is generally located under the ditch along the south edge of Puget Drive thth and goes under 11 Place N and 12 Avenue N. The 30-inch concrete pipe east, flows through thth MH 8-366, then crosses 11 Place N, goes east under a house at 1318 N 11 Place, beneath private properties, landscaping, and driveways where it changes to a 24-inch pipe and then back th to 30-inch pipe under 12 Ave N to MH 8-1167 adjacent to the new HDPE inlet for Northstream th east of 12 Ave N. See Exhibit A.1 in Appendix C. The upstream ends of the two pipes th terminate at the daylighted Northstream area east of 12 Avenue N. At this location, Northstream flows into a 24-inch corrugated metal pipe that connects to the 30-inch HDPE. One of the goals of this study is to determine the source of the water that flows though the old 30-inch concrete pipe. See Exhibits A.1 and A.2 in Appendix C. City of Edmonds 2 Northstream Pipe Abandonment and Culvert Rehabilitation METHODS CulvertConditionAssessment Culvert condition assessments were performed in February of 2016. The culverts were not entered, and destructive testing was not performed. The interior of the culvert was observed using handheld spotlights. A video inspection was reviewed along with a similar study for these culverts, entitled Puget Drive 30 Storm Main Repair Pre-Design Report, April 2014, prepared by CHS Engineers, Inc. and included in Appendix C. The site and culvert investigations are divided into three categories with corresponding criteria that are used as a checklist when assessing culverts. The categories are (1) Geotechnical, (2) Hydraulic, and (3) Structural. The categories are listed below with criteria and brief descriptions of each and their impacts on the culvert or indications of culvert conditions. The culvert is rated for each criteria that contributes to an overall culvert rating. The rating levels are good, fair, poor, and critical. Geotechnical Ratings Embankment Popouts/Voids: The embankments are observed for settlement, instability, sinkholes, and movement that may affect the culvert and stream or be caused by a failing culvert. Pavement Cracks/Patches: Pavement repairs or cracking above a culvert could be caused by a failure of the culvert below. SAG-Roadway/Guardrail: Movement or slumping can be traced to culvert failure below. Hydraulic Ratings Channel Alignment: The alignment or angle of the channel thalweg relative to the culvert alignment can impact the system hydraulics. Good: Angle measured from upstream channel to centerline of culvert barrel is o from 0 to 15 degrees. Fair: Angle measured from upstream channel to centerline of culvert barrel is o from 15 to 45 degrees. Poor: Angle measured from upstream channel to centerline of culvert barrel is o from 45 to 75 degrees. Critical: Angle measured from upstream channel to centerline of culvert barrel is o from 45 to 75 degrees. City of Edmonds 3 Northstream Pipe Abandonment and Culvert Rehabilitation Embankment Protection: Additional protection may be required to prevent erosion and sluffing of embankment material. Good: No deficiencies. o Fair: Minor erosion. o Poor: Severely undermined, significant erosion needing repairs. o Critical: Scour of embankment undermining roadway or threatening the stability o of the embankment. Scour Inlet/Outlet: Scour around the culvert can remove material that is supporting the culvert and causing it to fail with corresponding slope failure. Good: No undermining of culvert. o Fair: Minor undermining of culvert. o Poor: Significant undermining of culvert. o Critical: Extensive undermining of culvert. o Structure Ratings Blockage: Sediment can accumulate and decrease the capacity of the culvert. Good: Accumulation 0% to 10%. o Fair: Accumulation 10% to 30%. o Poor: Accumulation 30% to 75%. o Critical: Accumulation Greater than 75%. o Cracking: Cracking of the culvert material can lead to settlement and collapse of the culvert. Good: Hairline cracks. o Fair: Longitudinal cracks up to 1/8 inch. o Poor: Longitudinal cracks 1/8 inch to 1/4 inch. o Critical: Sections collapsed or severe cracking. o Invert Condition: Erosion of pipe material from the bottom of the culvert can lead to culvert collapse or water leaking and flowing through the embankment and causing erosion and embankment settlement. City of Edmonds 4 Northstream Pipe Abandonment and Culvert Rehabilitation Good: Superficial corrosion or scaling. o Fair: Minor corrosion and erosion of concrete with exposed aggregate. o Poor: Pitting, spalling, exposed corroded rebar visible. Seepage of water from o culvert to embankment. Critical: Loss of invert material, holes. Water flowing through embankment o along the outside of the pipe barrel. Open Joints: Material seeping into the culvert can cause blockages reducing capacity. Joints that are coming apart also indicate settlement and movement and ultimately failure. Good: No openings. o Fair: Minor separation. o Poor: Significant separation, 1- to 3-inch gap, seepage of backfill. o Critical: Severe separation, 3-inch gap or larger, large voids in fill, significant o backfill in culvert. Out of Round: A culvert that is being squashed or crushed can lead to failure. Alignment/Settlement: Checking the culvert alignment and looking for a full moon of daylight indicates the culvert is not settling, failing, or moving. Good: Minor. o Fair: Offsets of sections up to 1 inch. o Poor: Significant settlement, misalignment, offsets 1 to 3 inches. End sections o dislocated. Critical: Severe settlement and misalignment, offsets 3 inches. o Headwall/Wingwall: Can prevent sloughing and erosion of the embankments around inlets and outlets and keep surrounding material out of the stream and culvert. Walls are checked for cracking, spalling, overtopping, and plumbness. Drift: Woody material, debris, and trash can wash into and collect in and around culverts, ultimately reducing capacity. Good: Minor accumulation. o Fair: Significant accumulation, 10% to 30%. o City of Edmonds 5 Northstream Pipe Abandonment and Culvert Rehabilitation Poor: Extensive accumulation, 30% to 75%. o Critical: Severe accumulation, greater than 75%. o Vegetation Obstruction: Trees, branches, brush, shrubs, weeds, and grasses growing around inlets and outlets can eventually block or reduce capacity. Good: No impact to flow. o Fair: Minor growth, restriction is 10% to 30%. o Poor: Significant growth, restriction is 30% to 75%. o Critical: Extensive growth, restriction is greater than 75%. o The criteria above are listed for each individual culvert, including our related observations and rating for each criteria in the individual culvert summary portion of this report. HabitatAssessment Habitat assessment consisted of evaluating in-stream physical properties regarding potential fish and wildlife habitat and a general assessment of the surrounding basin. Publicly available data sources (mapped and published documents) were assessed prior to the fieldwork. These sources included: WDFW SalmonScape (http://apps.wdfw.wa.gov/salmonscape/): SalmonScape maps hydrography, fish distribution, and passage barriers throughout the state. Some irregularities exist between the toggled hydrography layer and the basemapÓs embedded channel lines. WDNR FPARS (http://www.dnr.wa.gov/BusinessPermits/Topics/ ForestPracticesApplications/Pages/fp_fpars.aspx): This system shows the regulated stream-type database used by cities and counties throughout the state. Mapped drainages are typically either F (fish bearing) or N (non-fish) type, occasionally with a perennial (p) or seasonal (s) addition. These hydrography layers were created at a coarse spatial scale and are not regularly updated. WDFW PHS (http://wdfw.wa.gov/mapping/phs/): This database is similar to SalmonScape; however, it focusses more on state-priority habitat or species, not specifically salmon. Cutthroat trout distribution is mapped by PHS not SalmonScape, as well as more detailed wetland habitat layers. USGS StreamStats (http://water.usgs.gov/osw/streamstats/Washington.html): This system is used to determine basin-level characteristics and other more complicated calculations not possible with the sites listed above. Flow modeling for ungauged systems is largely accomplished with the support of this system. City of Edmonds 6 Northstream Pipe Abandonment and Culvert Rehabilitation Google Earth or similar aerial photography: Using aerial photography, especially historical data to assess how sites have changed, provides information about site conditions. Edmonds Shoreline Inventory 2007. Data provided by the City was reviewed after completing the desktop study, and relevant maps were printed for reference during the field assessment. Stormwater conveyance and elevation survey maps were of particular use during this field work for orientation and comparison purposes. Physical stream measurements and observations were taken during the site assessment using standard stream monitoring equipment: An engineer-scaled stadia rod, GPS location, rangefinder equipped with inclination (gradient) measurement capability, camera, and field notebook. Characteristics measured include stream bankfull width (BFW), channel gradient (where it appeared stable and indicative of the systemÓs state), sediment composition (particularly noting potential cached material behind the upstream inlet), and specific habitat features, such as large woody debris (LWD), deep pools, or side channels/tributary confluences. City of Edmonds 7 Northstream Pipe Abandonment and Culvert Rehabilitation NorthstreamCulvertunderPugetDrive/SR524 Existing Conditions Table 1. Culvert Summary. Northstream Culvert under Puget Drive/SR 524 Existing Conditions Î Site Description, Habitat, and Fish Passage Conditions Culvert 30 Concrete Structural Condition Fair Î limited longitudinal cracks and joint separation Watercourse Northstream Fish Species None mapped Fish Passage Presumed total barrier Habitat Quality Moderate downstream, high upstream Mapped Upstream Habitat None The Northstream creek culvert under Puget Drive is a 30-inch concrete culvert that is 91 feet long with a slope of 4.4 percent under 8 to 10 feet of fill. The culvert outfalls on the north side of Puget Drive into a low area where Northstream continues westerly. This low area is surrounded by a 10 feet high gabion wall to the south, a 1:1 slope to the east, and receives flows from a second outfall that is a 12-inch concrete pipe that discharges runoff from Puget Drive. This 12-inch pipe is connected to Catch Basin 8-87 and a storm sewer constructed of catch basins and pipes that covey runoff from Puget Drive. The 30-inch culvert penetrates the gabion wall where it is exposed without fill over the top of it west of the wall for 12 feet. The 30-inch culvert connects to MH 8-1165 on the south side of Puget Drive that receives flows from two culverts; an old 30-inch concrete pipe and a new 30-inch HDPE pipe. The 30-inch th HDPE conveys stormwater from Northstream, 11 Place N and Puget Drive. The majority of the th flows in the old 30-inch concrete pipe is stormwater runoff from 12 Avenue N and Puget Drive, with some flows from unknown sources. These unknown sources are most likely groundwater. Culvert Condition Assessment The culvert conditions were observed and evaluated using the criteria described in the Culvert Condition Assessment section of this report. The following was observed: Overall Condition Assessment Summary Overall Rating Puget Drive Culvert: Fair The culvert is generally in good condition; however, it is given an overall rating of fair because of some longitudinal cracks and the outlet conditions. The outlet end of the culvert is being undermined by flows from the adjacent 12-inch culvert that outfalls above the 30-inch culvert. City of Edmonds 8 Northstream Pipe Abandonment and Culvert Rehabilitation These flows run under the exposed portion of the 30-inch culvert, which over time will erode the soil supporting the culvert, cause joint separation, and ultimately cause culvert sections to disconnect, fail, and move into the stream. This eroding of base soils may explain the current minor joint separation in the outlet location only, which is not evident in the 2004 pipe video. There is also a minor plunge pool with a 1-foot drop from the outlet that could contribute to additional erosion at the outlet area. Detailed Condition Assessment Geotechnical Ratings: Embankment Popouts/Voids: Good. Pavement Cracks/Patches: Good. SAG-Roadway/Guardrail: Good. Hydraulic Ratings: Channel Alignment: Inlet Î Poor at the manhole, Good at the Northstream InletÎ Outlet Î Good. Embankment Protection: Inlet Î Good InletÎ Outlet Î Poor. Scour Inlet/Outlet: Fair - Outlet has approximately 1-foot drop to plunge pool. Structure Ratings: Blockage: Good. Cracking: Fair, minor (< 1/8) longitudinal cracks. Invert Condition: Fair, minor erosion with exposed aggregate. Open Joints: Fair, Joints at the outlet end, 3 sections, have some separation. Out of Round: Good. Alignment/Settlement: Fair, outlet area is being undermined by 12-inch culvert flows. Headwall/Wingwall: Fair. Drift: Good. Vegetation Obstruction: Fair. City of Edmonds 9 Northstream Pipe Abandonment and Culvert Rehabilitation Photo1.Jointseparationatoutlet. Photo2.Outletwithplungepool. City of Edmonds 10 Northstream Pipe Abandonment and Culvert Rehabilitation Publically mapped information is limited for this site, as neither FPARS, SalmonScape, nor PHS map the channel extending to or beyond Puget Drive. These sources show a Type-N (FPARS) channel extending east from Puget Sound and terminating at Grandview Street, over 1,000 feet west of the project area. The StreamStats tool shows a channel extending through the project area and up to the west extent of Maplewood Park; however, this area is designated Ðlimited functionalityÑ due to the urbanized landscape. The City of Edmonds watershed map (http://www.edmondswa.gov/maps-text/2012-04-13-23-02-50.html) shows this drainage in its presumed location, showing eight crossings downstream of Puget Drive (http://www.edmondswa.gov/maps-text/2012-04-13-23-02-50.html). While not mapped by state agencies and confined within degraded urban corridors, the channel is presumed to provide or potentially provide productive fish habitat based on its physical characteristics. WAC 222-16- 031 defines a fish bearing channel for Western Washington as having two or more feet of defined channel within the bankfull width for channels of 16 percent or less gradient. Additionally, the CityÓs shoreline inventory report (2007) references biologists observing fish within Northstream during work in 2002. Conditions within and surrounding the channel reflect the urban, highly developed nature of the landscape. Downstream of the culvert, the channel runs through the backyard of a single-family residence. This reach varies between 4- and 7-foot bankfull channel width and commonly features vertical banks between 1 and 4 feet, often comprised of large landscape rocks (Photo 3). Small footbridges span the channel in multiple locations and constructed vertical drops between 0.5 and 1.5 feet were commonly noted. The downstream reach abuts mowed lawns and patio features, lacking mature riparian vegetation. Sediment conditions within this reach are predominantly sand with scattered gravel deposits comprising roughly 25 percent of the streambed substrate. A small (12-inch) storm culvert discharges water to the channel approximately 5 feet upstream of the downstream outfall (Photo 5). Flow from this pipe runs alongside the 30-inch Puget Drive culvert, under the lowest section of pipe, and into the creek. At the 30-inch pipe outfall (Photo 6), a water surface drop (about 8 inches) has developed a plunge pool 9 feet long, 7 feet wide, and about 1 foot maximum depth. This area is the only section of the downstream channel with significant shading vegetation. City of Edmonds 11 Northstream Pipe Abandonment and Culvert Rehabilitation Photo3.Downstreamchannelconditions. Photo4.Downstreamsubstrateconditions. City of Edmonds 12 Northstream Pipe Abandonment and Culvert Rehabilitation Photo5.Stormtributaryabovedownstreamoutlet. Photo6.Downstreamoutlet. City of Edmonds 13 Northstream Pipe Abandonment and Culvert Rehabilitation The stream is culverted for approximately 600 feet, including the 30-inch concrete pipe under th Pl N, and a 30-inch Puget Drive, a 30-inch HDPE pipe from the south side of Puget Drive to 11 concrete pipe upstream to the inlet. The length and age of this system almost certainly produces a total fish passage barrier. th The culvert inlet east of 12 Ave N features a metal 36-inch pipe equipped with a vertical overflow entrance and grated trash racks (Photo 7). Minimal small debris racking on the inlet was noted. These features appear to be relatively new construction and in good condition. Upstream channel conditions are more natural as the stream flows through Maplewood Park. The channel flows through a flat at the inlet, confined valley approximately 50-feet wide, bordered by Puget Drive to the north and residential development to the south (Photo 8). The channel features short, shallow banks, and the area outside the channel shows wetland conditions. Riparian width steadily increases moving upstream. The upstream channel averages 2.5 percent gradient (from field measurements) and field measured 6-foot BFW (Photo 9), with areas of dynamic braiding about 150 feet above the inlet. Substrate features a more natural sand, gravel, and cobble mix within the banks (Photo 10); however, large sand and small gravel deposits were noted within 200 feet of the inlet (Photo 11). Reconfiguration of the existing culvert should carefully consider the potential impacts, upstream and downstream, of mobilizing this cached streambed material. Photo7.Upstreamculvertinlet. City of Edmonds 14 Northstream Pipe Abandonment and Culvert Rehabilitation Photo8.Upstreamchannel,justaboveculvert. Photo9.Sixfootupstreamchannel;gravelandsandnearculvert. City of Edmonds 15 Northstream Pipe Abandonment and Culvert Rehabilitation Photo10.Upstreamchannelwithgravel,cobble,sand,andLWD. Photo11.Sandandgravelloadingaboveactivechannel,approximately150to200feet upstreamfromculvert. City of Edmonds 16 Northstream Pipe Abandonment and Culvert Rehabilitation CULVERT REPAIR OR REPLACEMENT The City of Edmonds requested that we evaluate various options to replace and repair the culvert under Puget Drive/SR524. Because of the high volume of traffic on the road, closing the state route for a substantial time would create significant traffic problems. Therefore, trenchless methods are preferred over traditional cut-and-cover culvert construction methods. An evaluation follows of the various trenchless culvert construction methods and a description of our recommendations that include two options. Reid Middleton was also asked to provide an evaluation and development of options for abandoning/repairing the old 30-inch concrete culvert upstream of the Puget Drive culvert. Those options are provided below. TrenchlessEvaluation Several trenchless options can be considered for construction of a new culvert or replacement/rehabilitation of an existing culvert. Trenchless methods for construction of a culvert could include (but not necessarily be limited to) auger boring, pipe ramming, and microtunneling. Trenchless options for replacement or rehabilitation of an existing culvert can include slip lining, pipe bursting, and cured-in-place pipe (CIPP). For this evaluation, two methods of trenchless technologies were considered because of their applicability to the site conditions and project objectives: (1) Auger bore for construction of a new culvert and (2) CIPP for rehabilitation of the existing culvert. These methods and their applicability to the project are described below. AugerBoreOption1 Auger boring is a trenchless method by which a casing is advanced through the soil column while augers remove the soil from within the casing as the pipe is jacked into the embankment. Ten to 20- foot sections of casing pipe are jacked sequentially from one side of the embankment to the other. An auger bore track and boring head system are used to place, direct, and advance the casing pipe from the launching pit to the receiving pit. Launching and receiving pits are typically constructed with shored excavations that stabilize excavation walls and allow for safe operation of Photo12.AugerBoringMachine equipment within the launching and City of Edmonds 17 Northstream Pipe Abandonment and Culvert Rehabilitation receiving pits. Once the auger bore casing is installed and soils are cleaned out, the casing can be connected to existing piping. Auger boring is best suited for embankments with greater than two pipe diameters of cover. Auger boring works best in medium dense to dense sand or medium stiff to stiff clay soils that are above the groundwater table. Gravelly soils, or formations with cobbles and boulders, and hard rock may present challenges for the auger bore method. Workspace considerations for the auger bore method can also present challenges. The auger bore launching pit typically measures 25- to 35-feet long and 15-feet wide in order to house equipment necessary to advance the casing and auger (remove) the soils from within the casing. Receiving pits typically measure between approximately 10-foot by 10-foot and 15-foot by 15-foot, as work within the receiving pit usually involves making connections to existing or new facilities. The auger bore method was chosen for the Northstream project for further consideration for several reasons. There is sufficient depth of cover between the culvert elevation and Puget Drive that will provide some risk mitigation of settlement. The project provides the possibility of constructing a new culvert along a different alignment to replace the existing culvert. In addition, there is sufficient area for launching and receiving pit workspaces. AugerBoreInstallationConsiderationsattheNorthstreamSite A new auger bore is envisioned for this site, with installed trenchless alignment beginning at the easterly side of the existing culvert outlet and extending to the southeast to an existing manhole th within 11 Place North, near the intersection with Puget Drive. The length of the auger bore would be approximately 120 feet. Two scenarios for installation of a culvert can be considered depending on the need to mitigate risk of corrosion of the culvert pipe. The first scenario installs a 30-inch steel casing that would act as the final culvert pipe. However, to mitigate the corrosion potential of steel culvert pipe, a second scenario would include installing a 36-inch steel casing by auger bore methods and then installing a 30-inch HDPE culvert pipe inside the 36-inch casing. The annulus between the 36-inch casing and 30-inch galvanized culvert pipe would be filled with grout. The launching pit would be located within the creek bed at the pipe outlet. th The receiving pit would be located at the intersection of Puget Drive and 11 Place North near the existing manhole for the 30-inch HDPE pipe. The launching pit would be approximately 35-feet long by 15- to 20-feet wide and fitted into the existing stream valley at the outlet of the existing 30-inch concrete culvert. The launching point would likely be located at the base of the embankment/gabion wall adjacent to Puget Drive and easterly of the existing 30-inch culvert. The length of the launching pit will depend largely on the length of pipe sections to be jacked. Twenty-foot long pipe sections are assumed for this study. Constructing the launching pit would likely require removal of trees and shrubs in and City of Edmonds 18 Northstream Pipe Abandonment and Culvert Rehabilitation around the stream valley for the 36-inch concrete culvert outlet. A shoring system would be required to cut the slope on the right bank of the stream (referenced looking downstream) and maintain stabilization of the gabion walls between the stream and Puget Drive. This shoring system could be a sheet pile or soldier pile wall approximately 10-feet high and 50-feet long. th The receiving pit would be located within 11 Place North, near MH 8-1166 that was installed as part of the 30-inch HDPE culvert project. The receiving pit would likely measure 15 by 15 feet and be centered on the existing MH 8-1166 to provide a slope of 4.4 percent, which matches the slope of the existing 30-inch culvert. A concept plan and profile for the new auger bore culvert is presented in Figure 1 and Figure 2 in Appendix D. Hydrologic calculations were performed to determine flow rates for the new culvert using the WADOE Western Washington Hydraulic Model 2012. Once the flow rates were determined, Mannings Equation was used to the size the culvert. The new culvert will have capacity for both the 25-year and 100-year storm events. Challenges to the auger bore method of construction at this site are related mostly to the workspaces. However, the unknown subsurface conditions and potential utility conflicts also present challenges. As discussed above, a relatively robust launching pit shoring plan will be required for placement to provide a suitable area for equipment and maintain safe working conditions within the launching pit. Shoring will also be required at the receiving pit, but standard trench boxes may be able to be used for the receiving pit shoring. Because of the limited access points to the launching pit, equipment and pipe sections would likely need to be moved into the launching pit by cranes positioned on Puget Drive, which would require temporary and intermittent closure of at least one lane of Puget Drive. Till outwash and glacial drift deposits are mapped near the site, but site-specific borings have not been conducted. Site-specific borings would need to be conducted to verify the feasibility of an auger bore from a subsurface condition standpoint. Existing utilities, such as the sewer line that runs down the east side of Puget Drive and overhead powerlines on the east side of Puget Drive, also present design challenges. At this time, it appears these challenges can be overcome through further investigation and thoughtful design of an auger bore. Before augering and installing the new culvert, it is recommended that the exposed outlet of the 30-inch culvert sections be removed to provide additional launch space. Bypass piping can then be attached to the culvert to divert Northstream flows around the launch pit site to a point downstream of the work. A second bypass pipe will be needed for the 12-inch culvert, so those flows can also be routed around the launch site. Once the new culvert is in place and the auger bore equipment is removed, the launch pit area should be restored to a natural condition. This restoration would require grading, landscaping, and stream rehabilitation, including lining the stream bed with a sediment mixture designed to mimic expected natural channel bed material. Also, additional piping for the 12-inch culvert is recommended, so those flows will outfall directly into Northstream. City of Edmonds 19 Northstream Pipe Abandonment and Culvert Rehabilitation Traffic control and possibly occasional lane closures on Puget Drive may be required for th mobilizing and demobilizing the launch pit activities. Closure with a detour of 11 Place North adjacent to Puget Drive may be required while the receiving pit is being constructed, new pipe installed, the pit filled in, and the street repaved. Land owner permissions and temporary construction easements may also be required. This section summarizes many of the considerations presented above into the site-specific advantages and disadvantages of using the auger bore method to construct a new culvert beneath Puget Drive. Advantages of the auger bore method include: The pipe can be up-sized if desired. A new pipe can be installed that will not be susceptible to future settlement beneath the pipe as observed at the outlet of the existing 30-inch concrete culvert. Installation of a new culvert that may have a longer design life than a rehabilitation of the existing culvert. Disadvantages of the auger bore method include: Because the soil is removed as the pipe is jacked in the ground, there can be a high risk of settlement over the pipe for minimal cover installations (less than 10 feet). To reduce settlement risk, the augers can be moved into the casing (away from the face) to reduce the likelihood of over excavation at the face. Extensive grading, sheet pile, or soldier pile wall construction and vegetation removal is required at the launching pit location. th Relatively long-term closure and rehabilitation of 11 Place North is required, although there is an available detour. An auger bore installation is more costly compared to a CIPP rehabilitation. Subsurface explorations (borings) are required to design an auger bore. Auger boring carries inherent construction risks, including obstructions and roadway settlement. High groundwater conditions can present significant challenges to the auger bore method of construction. City of Edmonds 20 Northstream Pipe Abandonment and Culvert Rehabilitation Bypass of water flow is required during auger boring operations to maintain launching and receiving pit workspaces that are free of water. Work in the launch pit area may require a temporary construction easement. Preliminary Cost Estimates The culvert improvements construction cost for the auger bore option is $733,000. An itemized opinion of probable construction cost is provided in Appendix B. The cost assumes installation of a 36-inch steel casing by auger bore methods and installation of a 30-inch HDPE culvert pipe inside the 36-inch casing. CuredInPlacePipeOption2 CIPP is a trenchless rehabilitation method that generally consists of inserting a liner composed of fiberglass cloth and several other materials that are impregnated with resin into an existing pipe through access points, such as manholes. Prior to installation of the CIPP, the pipe is typically inspected for debris, roots, damage, offset joints, ovality, or other anomalies that do not allow for CIPP installation. The pipe is then prepared, usually by mechanical cleaning and grinding (if necessary), to remove roots, protruding laterals, or other obstructions in the pipe. After cleaning and depending on site conditions, an inverted liner that is impregnated with resin is inserted into the pipe by either direct inversion or pulled-in-place methods. The liner is then inverted using water or air pressure and cured using UV light, steam, or hot water to form a tight fitting insert to the existing pipe. The curing process involves a temperature controlled heating and cooling process to cure the resin impregnated liner. CIPP is opened at both ends once installed, cured, and cooled. If service laterals are present in the pipe, the laterals can usually be restored after curing the liner by robotic means or manned entry. Finally, an end sealing procedure may be used to restrict water from infiltrating and tracking down or around the host pipe. To ensure that the CIPP is installed properly, Closed Circuit Television (CCTV) inspection is conducted. Equipment needed may range from relatively small trailers to large semi-trucks for the installation and curing of the CIPP. This equipment can typically be staged in a single traffic lane of a roadway. Required equipment will depend on the contractorÓs means and methods and pipe size being rehabilitated. CIPP is used most often to rehabilitate water and sewer pipes with diameters ranging between about 4 inches to 120 inches. However, gas and chemical pipelines may also be suitable for CIPP rehabilitation. CIPP can be designed for partially deteriorated pipe conditions (i.e., existing pipe may have displaced joints, cracks, or corrosion), where the pipe is structurally able to support soil and surface loads, or for a fully deteriorated pipe condition (i.e., severe corrosion, missing pipe, crushed pipe) where the existing pipe has insufficient strength to support all soil City of Edmonds 21 Northstream Pipe Abandonment and Culvert Rehabilitation and surface loads. However, collapsed pipe or offset joints (about 40 percent of the diameter) may prohibit the use of CIPP without point excavation to repair the offset. CIPPRehabilitationConsiderationsattheNorthstreamSite A CIPP rehabilitation is envisioned for this site that would take place from the storm drain manhole located at the intersection of the more recently installed 30-inch HDPE bypass pipe and the older 30-inch concrete pipe. The liner would either be directly inverted or pulled through the existing 30-inch concrete culvert from the culvert outlet. Based on visual inspection, the existing 30-inch concrete culver appears to be open; but there are pipe connections within the existing pipe that appear offset. It appears that these seams are offset by maybe 10 percent of the pipeÓs diameter and, therefore, would not pose concern for limiting CIPP rehabilitations. The trucks used to install the CIPP may be able to be staged in the grass boulevard between Puget Drive and the existing residences to the south. If this area is not suitable, a single traffic lane would need to be closed temporarily during the CIPP installation and curing process. In th both cases, 11 Place N will likely need to be closed with a detour during CIPP installation to allow the trucks to be staged near the storm drain manhole. There would likely be very little work required at the culvert outlet, and machinery may not be needed to access this area. Although the CIPP effort does not require work at the outlet of the Puget Drive culvert, some improvements are recommended in this area. The 12-inch concrete should be extended to the daylighted portion of Northstream, so runoff does not flow under the 30-inch culvert and erode the supporting soils. A concept plan for the new CIPP is presented in Appendix D, Figure 3. Hydrologic calculations were performed to determine flow rates for the CIPP culvert using the DOE Western Washington Hydraulic Model 2012. Mannings Equation was then used to the size the culvert once the flow rates were determined. The CIPP culvert with a smaller diameter (2 to 4 inches less) than the current diameter will have the capacity for both the 25-year and 100-year storm events. SiteSpecificChallengesandConsiderations Typically the contractor who installs the CIPP also performs a design of the liner material to match the existing pipe conditions. Therefore, the contractor will be required to perform a pre- inspection of the 30-inch concrete pipe to verify the CIPP design. CIPP is a suitable solution for rehabilitation of the culvert; however, measurements of ovality and pipe connection offset during inspection by a CIPP contractor are recommended. Another challenge may be the overhead power line that runs parallel to the south side of Puget Drive. This power line may conflict with the CIPP equipment and require a work-around that can be coordinated with a CIPP contractor. City of Edmonds 22 Northstream Pipe Abandonment and Culvert Rehabilitation During the CIPP installation, flows from both the old 30-inch concrete pipe and a new 30-inch HDPE pipe will be diverted from the culvert under Puget Drive. It is anticipated that these pipes will be plugged temporarily and water pumped from MH 8-366, which is located directly thth upstream and in the driveway of 1323 11 Place N and MH 8-1166 located within 11 Place N. The stormwater will be pumped in pipes or hoses placed on the ground surface along the south side of Puget Drive to MH 8-1257 located adjacent to Olympic Ave. It is anticipated that this work will be performed during the summer when stormwater flows are low, so the additional stormwater added to the system at Olympic Ave will not create a capacity problem. AdvantagesandDisadvantages This section summarizes many of the considerations presented above into the site-specific advantages and disadvantages of using the CIPP method to rehabilitate the existing 30-inch concrete culvert beneath Puget Drive. Advantages to CIPP rehabilitation methods include: CIPP does not require excavation into slopes at the culver outlet. CIPP rehabilitation can be completed through existing manholes and will not require excavation. The liner can be designed to withstand soil, hydrostatic, and surface loads in many circumstances. Although visual inspection did not find lateral connections, lateral connections can be restored by robotic means or manned entry (if applicable for a 30-inch pipe) if present. Required workspace area is relatively limited compared to the auger bore method. CIPP installation and curing will take one to two days to complete, limiting the closure of th 11 Place N. If a temporary one-lane closure within Puget Drive is required, the closure would likely be relatively short (one day). CIPP has been used successfully to rehabilitate pipes with similar sizes. The risk that the CIPP curing process may result in deficiencies in the final product (discussed below), this risk is relatively low to moderate but highly dependent on quality control. City of Edmonds 23 Northstream Pipe Abandonment and Culvert Rehabilitation Disadvantages to the CIPP rehabilitation method include: Additional inspection may be required to verify that the CIPP method is suitable for the culvertÓs current condition. Except for common sizes, liners are not usually stocked and must be made specifically for each project. Bypass of water flow is required during the entire installation of the CIPP. The curing process must be monitored carefully or the desired CIPP may not perform as expected. Impregnation of resins into the CIPP material can be inconsistent resulting in weak spots in the cured product. A temporary construction easement may be required for the trucks parked next to Puget Drive. Preliminary Cost Estimates The estimated culvert improvements construction cost for the CIPP option is $312,000. An itemized opinion of probable construction cost is provided in Appendix B. City of Edmonds 24 Northstream Pipe Abandonment and Culvert Rehabilitation OldNorthstreamCulvertSouthofPugetDrive/SR524 Existing Conditions Old Northstream Culvert South of Puget Drive/SR 524 Existing Conditions Î Site Description, Habitat, and Fish Passage Conditions Culvert 30Ñ Concrete and 24Ñ Concrete th Structural Condition Critical under 12 Ave N.; Poor overall th Watercourse 12 Avenue N. and unknown source most likely ground water The old culvert is south of Puget Drive and approximately 470 feet long, with an average slope of 5.3 percent under 10 to 20 feet of fill. The 30-inch concrete pipe connects on the downstream end to MH 8-1165, moving upstream it connects to MH 8-366 in a private driveway at ththth 1323 11 Place N, then crosses 11 Place N, goes east under a house at 1318 11 Place N, beneath private properties, landscaping, and driveways where it changes to a 24-inch pipe and th then back to a 30-inch pipe, under 12 Ave N to MH 8-1167 adjacent to the new HDPE inlet for th Northstream east of 12 Ave N. The 24-inch section of pipe is approximately 200 feet. History The following historical information is from Puget Drive 30 Storm Main Repair Pre-Design Report, April 2014, prepared by CHS Engineers, Inc.: Originally, North Stream flowed in a typical open stream bed. In the 1940s, North Stream served as the source of drinking water for a portion of Edmonds. A concrete th headworks/inlet structure was placed just east of 12 Ave and routed a portion of the stream into wood stave pipe that served Edmonds. Sometime in the 1950s, a plat was developed, and the stream was diverted into a 30-inch concrete pipe. The pipe was laid in or near the original stream bed and then fill material was placed over the area. The pipe invert averages about 19 feet below current grade. There is no information available concerning the original construction, alignment, fill materials, or means of compaction. At some point (1960s?), a 200 linear foot section of the 30-inch pipe failed and was replaced by 24-inch concrete. The transition between the 30-inch and 24-inch pipe was done by inserting the 24-inch pipe into the barrel of the 30-inch, resulting in a 3- to 4-inch vertical lip within the pipe. In 2006, following the Earth Tek report, a parallel 30-inch HDPE pipe was installed due north via directional drilling and re-connected back into the 30-inch concrete pipe in a new structure, just downstream of the 24-inch transition and just before the pipe passes under Puget Dr. (SR524). Northstream was diverted into the HDPE pipe, and a 54-inch manhole structure was constructed at the inlet City of Edmonds 25 Northstream Pipe Abandonment and Culvert Rehabilitation of the 30-inch concrete pipe, effectively capping it from the stream flows. No further action was taken on the 30- or 24-inch concrete pipe. In the winter of 2014, water began to flow heavily out of a landscaping berm at the southeast intersection of Puget Dr. and Olympic Ave, approximately 200 linear feet westerly (down gradient) from the connection manhole where the HDPE and concrete pipe connect (STA 1+00). The flow coincided with debris blocking the inlet to the 30-inch HDPE pipe and causing the water level to rise th significantly (+2 feet) upstream of the 12 Ave inlet. The flow subsided shortly after the debris was removed, and the stream level returned to its high flow banks. It is suspected, but not definitely shown, that the rise in water level allowed the water to locate/pressurize the abandoned inlet to the old wood stave water supply pipe and release at the weakest point. Originally, this old culvert conveyed Northstream. In the majority of the flows in the old 30-inch concrete pipe is stormwater runoff from 12th Avenue North and Puget Drive, with some flows from unknown sources. These unknown sources are most likely groundwater. (This highlighted paragraph is by Reid Middleton not CHS.) CULVERT CONDITION ASSESSMENT A video inspection was performed in 2014 for the old culvert. The video was reviewed by CHS Engineers, Inc., and Reid Middleton. The following excerpt is from the CHS report regarding their review of the video inspection. Reid Middleton reviewed the video and concurs with CHSÓs observations. On February 28th, 2014, the upper and middle reaches of the 30/24 concrete pipe were video inspected. Annotated copies of the inspection report and selected screenshots are attached in Appendix B \[sic of CHS report\]. The screenshot locations are also identified on the existing plan and profile drawing attached in Appendix A . \[sic of the CHS report\] The video inspection also included ground locates of a sonde that was attached to the camera tractor. The data showed that the previous survey alignment is relatively accurate. The video began at the upstream inlet (STA 5+60) and proceeded westerly for 270 linear feet before being blocked by debris at the transition to 24-inch pipe. The pipe was found to be in very poor condition. In several locations, the crown, invert, and haunches of the pipe are fully cracked; and the pipe is deformed into an oval. Many of the joints are pulled or offset. There are several areas where groundwater infiltration is evident. There are several capped or partially filled connections and two vertical risers that are buried below surface grade. One of the risers appears to have an active connection to the north that drains the roadside swale into the pipe. The video inspection then resumed by entering the connection manhole \[CB 8-1165\] between the 30-inch concrete and 30-inch HDPE pipe (STA 1+00) and proceeded easterly. The pipe transitions to 24 inches within 10 linear feet of the manhole. The City of Edmonds 26 Northstream Pipe Abandonment and Culvert Rehabilitation camera progressed approximately 190 linear feet before again becoming blocked by debris approximately 10 linear feet short, but within view, of the end of the upper reach inspection (STA 2+90). The middle reach of the pipe has many of the same faults observed in the upper reach, but the faults are generally to a lower degree and further apart. Again, there are several instances where the pipe is receiving groundwater. The pipe does pass below the residential home at 1318 11th Place N. Video inspection of the lower reach was not included in the scope. Review of the 2005/2006 video of the lower reach revealed several significant cracks, but the pipe was maintaining a round shape. A review of the 2005/2006 video inspection and comparing that with the current work showed very consistent conditions. Many of the more severe faults were present in 2006 and do not appear to have significantly worsened in the past 8 years. It is likely that the current pipe is stable, but highly susceptible to even minor seismic events. Redirecting the stream flow into the HDPE barrel has also prevented additional scour from occurring around damaged portions of the concrete pipe. Reid Middleton performed a site visit on February 26, 2016, and observed the following: th The 12 Avenue N storm system has a 12-inch pipe from MH 8-345 that outfalls into the th Puget Drive ditch west of 12 Ave N. Runoff from the ditch enters a concrete pipe, th located approximately 60 feet west 12 Ave N, that directs flows to the south toward the old culvert. A dye test was performed on March 1, 2016, and dye was added to the stormwater in the ditch before entering the concrete pipe. The dye was then observed in the old culvert stormwater at MH 8-1165. th The majority of the flows in the old culvert appear to be from the 12 Ave storm system. However, there are additional flows from pipes connected to the old culvert that have been observed in the video. The video observation indicates that these additional flows from pipes are small seeps that indicate groundwater. Additional site investigation can be performed before the final submittal to attempt to identify the source of this water. Additional site investigation could involve the following: Smoke test the old culvert and observe where the smoke exits the system. th Divert the 12 Ave flows from entering the old culvert to determine what percentage of the flows are from this system. Perform another video inspection. Perform additional dye testing. City of Edmonds 27 Northstream Pipe Abandonment and Culvert Rehabilitation Overall Condition Assessment Summary th Overall Rating Puget Drive Culvert: Critical under 12 Ave N; poor in other locations. The culvert is in critical condition in the location where the top is cracked and pushed down th under 12 Ave N. The pipe is in poor condition in other areas because of longitudinal cracks, joint separation, and an uneven invert or lip where the pipe size changes. Detailed Condition Assessment The culvert conditions were observed and evaluated using the criteria described in Culvert Condition Assessment. The following was observed: Overall Rating Culvert: Critical. Geotechnical Ratings: Embankment Popouts/Voids: Not applicable. Pavement Cracks/Patches: Good. SAG-Roadway/Guardrail: Good. Hydraulic Ratings: Channel Alignment: Not applicable. Embankment Protection: Inlet Î Not applicable. Scour Inlet/Outlet: Not applicable. Structure Ratings: Blockage: Poor, debris in culvert, debris dam where the culvert changes diameter from 30-inches to 24-inches. Cracking: Critical, longitudinal cracks (>1/8 foot) on top of pipe, crack failure along top. Invert Condition: Not applicable. Open Joints: Poor, separation with sediment entering culvert. Out of Round: Critical, top is cracked and pushed down in two locations under th 12 Ave N. City of Edmonds 28 Northstream Pipe Abandonment and Culvert Rehabilitation Alignment/Settlement: Fair. Headwall/Wingwall: Not applicable. Drift: Poor. Vegetation Obstruction: Not applicable. CULVERT IMPROVEMENTS th The old culvert no longer conveys Northstream. The runoff from 12 Ave N currently entering the old culvert needs to be rerouted into the 30-inch HDPE pipe. Once that is accomplished, only runoff from the unknown sources (possibly groundwater) will be entering the old culvert. Further investigation could be performed to determine these sources as discussed above. Options for abandoning and revising the culvert are developed and presented below. Options presented generally include the following: th Abandon and fill the old culvert with grout or CDF under the house at 1318 11 Place N th and under 11 Place N to prevent failure of the pipe to cause settlement of the structure or a sinkhole in the CityÓs roadway. th Abandon and fill the old culvert with grout or CDF under 12 Ave N to prevent failure of the pipe from causing a sinkhole in the CityÓs roadway. th Route the stormwater runoff from 12 Ave N away from the concrete pipe that connects to the old culvert. This can be accomplished by plugging the concrete pipe that is connected to the old culvert and grading the ditch along Puget Drive. This would direct th the ditch flows west along the ditch to CB 8-365 at 11 Place N that is connected to MH 8-1166 and the 30-inch HDPE pipe that conveys Northstream. th The stormwater runoff from 12 Ave N can also be diverted from the old culvert by constructing a pipe from MH 8-345 at 12th Ave N that directs the runoff east to the inlet of the 30-inch HDPE/24-inch CMP pipe that conveys Northstream. Traffic control and a th detour would be required on 12 Ave N. It is still recommended that the concrete pipe that connects to the old culvert be plugged and the ditch graded to prevent runoff from Puget Drive from entering the old culvert and directing the ditch flows west. Some of the options below recommend not abandoning portions of the old culvert so that groundwater and possibly surface water can continue to be collected and conveyed to Northstream. The portion of the old culvert that remains open should be minimized to the section that has connections seeping water into the old culvert from approximately Station 3+50 to Station 5+00. Abandoning the remaining portion and filling with CDF is recommended. Preventing the continued movement of water collected in the old culvert could possibly create City of Edmonds 29 Northstream Pipe Abandonment and Culvert Rehabilitation water problems for improvements adjacent to and down gradient of the site. Continued use of the old culvert under structures, roads, and improvements is not recommended. City of Edmonds 30 Northstream Pipe Abandonment and Culvert Rehabilitation CULVERT REVISE OR ABANDON OPTIONS Option1:NewPipeOutlet This option would only abandon those portions of the culvert that are described above and would thth maintain the old culvert between west of 12 Ave N and east of the house at 1318 11 Place N. th Place N that would go An outlet pipe would be constructed from the old culvert east of 1318 11 north to the 30-inch HDPE pipe. This new pipe would allow the existing old culvert that is not abandoned to continue to collect groundwater and possibly surface water and convey it to Northstream. See Appendix D, Figure 4. Option 1 Preliminary Cost Estimates The estimated culvert improvements construction cost for Option 1-New Pipe Outlet is $269,000. An itemized opinion of probable construction cost is provided in Appendix B. Advantages of Option 1: Water collected in the old culvert would be diverted to Northstream without backwatering. Pipe would be completely abandoned under the house and City roads. Disadvantages of Option 1: Highest cost option. The outlet pipe would be 20 feet deep and would demolish the driveway, fencing, and th landscaping in the backyard of the house at 1318 11 Place N and require replacement. A new easement may be required depending on the location. There is a 35-foot easement shown on the survey drawing east of the house that could work. Portions of the old pipe would not be abandoned. Option2:Slipline This option would only abandon those portions of the culvert that are described above and would thth maintain the old culvert between west of 12 Ave N and east of the house at 1318 11 Place N. th An outlet pipe would be sliplined in the old culvert from east of 1318 11 Place N house and go west through the old culvert to MH 8-1165. This sliplined pipe would allow the existing old culvert that is not abandoned to continue to collect groundwater and possible surface water and convey it to Northstream. See Figure 5 in Appendix D. City of Edmonds 31 Northstream Pipe Abandonment and Culvert Rehabilitation The estimated culvert improvements construction cost for Option 2 - Slipline is $111,000. An itemized opinion of probable construction cost is provided in Appendix B. Water collected in the old culvert would be diverted to Northstream without any backwatering. Cost would be lower than Option 1. Disruption to surrounding homeowners would be minimized. No easements required. There would still be a stormwater pipe under the house. However, the risk would be reduced due to the size, age, material, and that it would be encased in grout or CDF. Option3:ExistingConcretePipeasanOutlet This option would only abandon those portions of the culvert that are described above and would thth maintain the old culvert between west of 12 Ave N and east of the house at 1318 11 Place N. For this option, the existing concrete pipe that conveys runoff from the Puget Drive ditch into the old culvert would be used to convey flows from the old culvert to the ditch. Water collected in the old culvert would be backed up in the old culvert and then backwater into the concrete pipe, which would outfall into the ditch, then flow west in the ditch into CB 8-365, and ultimately flow into Northstream. The pipe would need to be extended approximately 10 feet from the concrete pipe down the ditch to maintain water flowing west in the regraded ditch. See Appendix D, Figure 6. Option 3 Preliminary Cost Estimates The estimated culvert improvements construction cost for Option 3 Î Existing Pipe as Outlet is $115,000. An itemized opinion of probable construction cost is provided in Appendix B. Advantages of Option 3: Water collected in the old culvert would be diverted to Northstream. The pipe under the house would be completely abandoned. Cost would be lower than Option 1. City of Edmonds 32 Northstream Pipe Abandonment and Culvert Rehabilitation Disruption to surrounding homeowners would be minimized. No easements required. Disadvantages of Option 3: Water collected in the old culvert would be diverted to Northstream; however, the backwater within the old culvert system would be relatively high in elevation to drain groundwater into the ditch. Maintaining backwatered groundwater that has inundated the old culvert system may still present a risk for groundwater problems to improvements down gradient. Option4:AbandontheCulvert This option would abandon the entire length of the culvert and fill it with CDF from MH 8-1165 to MH 8-1167. See Figure 7 in Appendix D. Option 4 Preliminary Cost Estimates The estimated culvert improvements construction cost for Option 4 Î Abandon Culvert is $116,000. An itemized opinion of probable construction cost is provided in Appendix B. The pipe would be completely abandoned, and the risk of pipe failure causing sink holes or settlement of structures would be eliminated. Cost would be lower than Option 1. Disruption to surrounding homeowners would be minimized. No easements required. Water collected in the old culvert would be blocked, creating a risk for water problems to improvements down gradient. City of Edmonds 33 Northstream Pipe Abandonment and Culvert Rehabilitation Broken culvert section (Sta. 5+24) under 12th Ave N from 2014 inspection. th Photo13.Brokenculvertsection(Sta.5+24)under12Avefrom2006inspection. Photo14.Brokenculvertsection(Sta.5+24)under12 th AveNfrom2014inspection. City of Edmonds 34 Northstream Pipe Abandonment and Culvert Rehabilitation Photo15.Waterflowentering30pipe(Sta.4+65)viaan8inchpipefromtheexisting ditchalongPugetDrive. Photo16.Debrisblockage(Sta.2+94)neartransitionfrom30inchpipeto24inchpipe. PERMITTING DISCUSSION Permit requirements should be considered concurrently with project design development. Fulfilling the requirements of various local, state, and federal agencies requires managing multiple documents and submittal timelines to accomplish a smooth, on-schedule construction kickoff. Work below the Ordinary High Water (OHW) of the stream will trigger required SEPA City of Edmonds 35 Northstream Pipe Abandonment and Culvert Rehabilitation compliance, HPA permitting through WDFW, Section 404 permitting with the U.S. Army Corps of Engineers (USACE) (including potential ESA consultation with the USFWS, NMFS, and Tribes), Section 401 Water Quality Certification through WA Ecology, as well as all relevant local (City) permits. While many of these permits have become more streamlined over the years, it is important to submit on-time, accurate, and complete work to minimize the back/forth edits that can delay and sometimes completely derail projects indefinitely. Early coordination with relevant regulatory agencies is encouraged. Where possible, it is ideal to design the project to minimize the required permits. If a permit from the USACE is not required due to no fill being placed in Northstream, City of EdmondsÓ critical areas code will guide the permitting process. Table 2 summarizes the permits that could be required, depending on the project design chosen. Items below provide additional details and discussion about specific permit requirements. Table 2. Permit Summary. Regulating Preparation Time Processing Time Permit Required Document Type Agency (approximate) (approximate) SEPA Checklist, SEPA, Critical Project/Site City of Areas, fill/grade, Narrative, 2-3 weeks 3-9 months Edmonds stormwater application forms, drawings Apply via APPS <1 week (after WDFW HPA system, info very 1-4 months JARPA completed) similar to JARPA Application Exploratory forms, Project WSDOT Boring, Right-of-2-3 weeks 1-4 months narrative, way drawings 401 Water JARPA form and 1 Ecology 3-4 weeks4-12 months Certification drawings JARPA form and 1 USACE Section 404 CWA 3-4 weeks6-12 months drawings Concurrent with JARPA if Biological 1 USFWS/NMFS ESA Consultation 3-4 weeksno effect, several months if Evaluation may-affect 1.In general, the JARPA form, figures, and a Biological Evaluation can be completed concurrently within this time frame. Washington hydraulic code requires that new culverts be designed to allow for fish passage. Given the design constraints surrounding the project area (dense residential development, slopes, confined access), this will be difficult to accommodate. Early consultation, prior to significant design effort, is recommended to determine fish presence and required design criteria. Substantial downstream culverts exist on this system to be considered in this determination. City of Edmonds 36 Northstream Pipe Abandonment and Culvert Rehabilitation Planning construction to avoid placing regulated fill within Northstream could negate the requirement for a Corps 404 permit. It should be understood that the USACE makes the final determination where they have regulatory jurisdiction over a permit, and it is recommended that consultation with the USACE is initiated as a Ðnext stepÑ for this project. A violation could occur if work commences without a USACE permit. Nationwide Permit (NWP) 33 authorizes temporary construction, access, and dewatering within waters of the U.S. and requires pre-construction notification (submitting a JARPA form) to the USACE. Satisfying requirements of Section 7 ESA requires a Biological Evaluation (BE) to be submitted with the JARPA package and is tied to the federal permit nexus. If no federal permit is required, compliance with ESA will be through the local critical areas ordinance Title 23 Natural Resources (http://www.codepublishing.com/WA/Edmonds/). Due to the lack of documented fish presence or other ESA-listed species in the area, it is expected that a Ðno effectÑ determination will be achieved and confirmed by the USACE, negating consultation with USFWS and NMFS. A Ðmay affect, not likely to adversely affectÑ determination will require USFWS/NMFS concurrence and could increase permit processing time. Ecology Section 401 water certification can be achieved within the JARAPA form by describing surface/storm water protection and temporary erosion and sediment controls to be used during construction. Permit coverage under NWP 33 requires individual Ecology Section 401 review. Impacts to Northstream creek or the wetland complex upstream of the culvert inlet should be expected to require some type of mitigation if any fill or disturbance is anticipated. This will likely entail restoration of the wetland area upstream of the crossing or restoration work downstream of the crossing outfall. Construction grading permits from the City of Edmonds. WSDOT construction permit for work occurring within WSDOT right-of-way, including approvals for the geotechnical investigation, traffic control plan, and right-of-way plan. Permitting Summary Existing development (roads, residences, etc.) surrounding this crossing will impact both design, public involvement, and permitting considerations. These facets of culvert replacement should be developed concurrently, adapting one to meet changes to the other and vice versa. The project is a bit unusual, since the jurisdiction assertion by the federal government is somewhat unknown at this time. It is recommended that the next step in this project is to initiate communication with the appropriate agencies to discuss the design parameters and jurisdictional status of Northstream creek. City of Edmonds 37 Northstream Pipe Abandonment and Culvert Rehabilitation Construction Document Considerations Conceptual design is based on information collected during site visits, the habitat survey, hydrology calculations, reviewing existing studies, videos, and surveys. The following items require additional evaluation during the next design steps and construction document phase: 1.Geotechnical investigation of the road prism and surrounding soils. Performing this work within the WSDOT right-of-way will require special permitting that is time consuming and will be on the design schedule critical path. 2.Additional topographic surveying to complement the existing survey at the outlet area north of Puget Drive and stormwater and other structures that were constructed after the survey was performed. 3.A dewatering plan to address system flow bypass and construction safety. 4.Constructibility requirements, including retaining walls, launching and receiving pit design, steep slope access and staging locations, and culvert materials to be used. City of Edmonds 38 Northstream Pipe Abandonment and Culvert Rehabilitation CONCLUSION The Northstream culvert under Puget Drive/SR 524 in the City of Edmonds was investigated for structural integrity, environmental conditions related to permitting requirements, and construction options due to development constraints. The culvert is in generally good condition; however, it is given an overall rating of fair because minor longitudinal cracks have developed along the pipe run and outlet conditions exhibit undermining potential. An adjacent 12-inch culvert outfalls above the Northstream creek culvert and creates scour conditions that are damaging the Northstream culvert outlet. Habitat conditions for Northstream were assessed up and downstream of the culvert system. In-channel and riparian conditions were much more th natural upstream, north of Puget Drive and east of 12 Avenue North, where the creek flows through Maplewood Park. A permitting approach was developed with recommendations to collaborate with local and state agencies early in the next design step. This assessment studied options for improving or replacing the culvert. Because of the high volume of traffic on Puget Drive, focus was placed on analyzing trenchless construction methods. Two trenchless options were developed because of their applicability to the site conditions and project objectives. Option 2 is the recommended option: Option 1 - Auger bore for construction of a new 30-inch steel culvert to replace the old 30-inch concrete culvert. The new culvert outlet would not change locations, but the inlet would be th moved east to 11 Place North. Concept design drawings and cost estimates were developed. The opinion of probable construction cost is $733,000. Option 2 - CIPP for rehabilitation of the existing culvert would reuse the old culvert and add a new cured in place lining and outlet improvements. Concept design drawings and cost estimates were developed. The opinion of probable construction cost is $312,000. Option 2 is recommended based on the following: The culvertÓs fair condition makes it an excellent candidate for CIPP. CIPP is lower in cost than Option 1, a new auger bore replacement culvert. CIPP does not require launching and receiving pits and has less disruption to roads and the site compared to Option 1. Construction methods for the recommended outlet improvements (adjacent 12-inch pipe extension and scour prevention) are the same for both options. CIPP has less inherent risk, such as unforeseen site conditions and roadway settlement. CIPP will take only one or two days to complete, which will reduce roadway closure durations. A structural assessment of the old Northstream culvert located upstream was also completed. th This culvert is in critical condition, specifically under 12 Avenue North where the crown of the pipe is cracked and sagging. The pipe is in poor condition in other areas due to longitudinal cracks, joint separation, and an uneven connection where the pipe size changes along its run. City of Edmonds 39 Northstream Pipe Abandonment and Culvert Rehabilitation Four options were assessed for partial or full abandonment. Option 2, Sliplining, is recommended based on the following: Option 1 - New Pipe Outlet: This option would only abandon (fill with CDF) those portions of the culvert under houses and roads and would maintain the old culvert in areas that are collecting the majority of the water. An outlet pipe would be constructed to convey water to Northstream from the portions of the existing old culvert left in place. th Also, stormwater from 12 Avenue North would be diverted from the old culvert. The opinion of probable construction cost is $269,000. Option 1, New Pipe Outlet, is not preferred based on the following: High cost. Significant disruption to homeownersÓ properties. Option 2 - Sliplining: This option would only abandon (fill with CDF) those portions of the culvert under houses and roads and would maintain the old culvert in areas that are collecting the majority of the water. An outlet pipe would be constructed through the abandoned downstream culvert that would convey water to Northstream from the th portions of the existing old culvert left in place. Also, stormwater from 12 Avenue North would be diverted from the old culvert. The opinion of probable construction cost is $111,000. Option 2, Sliplining, is recommended based on the following: Water draining into the old culvert would be diverted to Northstream by the sliplined pipe. The sliplined pipe installation would not disrupt City streets or homeownersÓ properties. Cost is lower than constructing a new outlet pipe by cut-and-cover methods. The portion of the old culvert under structures and roads would be filled with grout or CDF. Option 3 - Existing Concrete Pipe as an Outlet: This option would abandon (fill with CDF) only those portions of the culvert under houses and roads and would maintain the old culvert in areas that are collecting the majority of the water. Water would be allowed to fill the old culvert and flow out of the old culvert through an existing 8-inch concrete th pipe. This existing 8-inch pipe currently conveys runoff from Puget Drive and 12 Ave th N. into the old culvert. Also, stormwater from 12 Avenue North would be diverted from the old culvert. The opinion of probable construction cost is $115,000. Option 3, Existing Concrete Pipe as an Outlet, is not preferred based on the following: The existing 8-inch concrete pipe is too high in elevation to be an effective outlet for water that collects in the old culvert. City of Edmonds 40 Northstream Pipe Abandonment and Culvert Rehabilitation Option 4 - Abandon the Culvert: This option abandons the entire length of the culvert th and fills it with CDF. Stormwater from 12 Avenue North would be diverted from the old culvert. The opinion of probable construction cost is $116,000. Option 4, Abandon the Culvert, is not preferred based on the following: An outlet for water collecting in the old culvert would not be provided. There are two elements from the recommended options that are considered critical and need immediate attention within the next several years. The first task extends the existing 12-inch culvert outfall to the downstream stream channel north of Puget Drive. This work prevents further pipe joint separation at the 30-inch culvert outlet. The other critical task includes grout th filling a portion of the abandoned culvert under 12Avenue, which is currently cracked and failing. vlj\\ \\21cp\\16\\005 edmonds northstream pipe abandonment & culvert rehab\\reports\\edmonds northstream pipe culvert 4-29-16.docx\\jld-mad City of Edmonds 41 Northstream Pipe Abandonment and Culvert Rehabilitation REFERENCES Barnard, R. J., J. Johnson, P. Brooks, K. M. Bates, B. Heiner, J. P. Klavas, D.C. Ponder, P.D. Smith, and P. D. Powers (2013), Water Crossings Design Guidelines, Washington Department of Fish and Wildlife, Olympia, Washington. http://wdfw.wa.gov/hab/ahg/culverts.htm Brotherton Pipeline, 2016, personal communication with Jim Brotherton (owner) of Brotherton Pipeline, Inc in Gold Hill, Oregon. City of Edmonds Critical Areas Code, Titles 23: Natural Resources. http://www.codepublishing.com/WA/Edmonds/ City of Edmonds online interactive GIS web application City of Edmonds, 2007. Shoreline Inventory and Characterization Report. http://www.ecy.wa.gov/programs/sea/shorelines/smp/mycomments/edmonds/InvChar.pdf City of Edmonds Watershed Mapper. Accessed March 2016. http://www.edmondswa.gov/maps-text/2012-04-13-23-02-50.html Goduto, V. and Atalah, Alan, ÐDesign and Construction Cost of a Water Line Underneath I-75 in Bowling Green, OhioÑ (2013), Construction Management Faculty Publications. Paper 6 Google Earth. Accessed February 2016. ODOT, 2014, Oregon Department of Transportation Highway Division Hydraulics Design Manual, April 2014 USACE, 2012. UserÓs Guide for Nationwide Permits in Washington State. June 15, 2012. http://www.nws.usace.army.mil/Portals/27/docs/regulatory/NWPs/2012%20NWP%20Us ers%20Guide.pdf USGS, 2016. Streamstats Washington interactive mapper. Accessed February 2016. http://water.usgs.gov/osw/streamstats/Washington.html Washington Administrative Code (WAC) 222-16-031. Interim water typing system. Accessed February 2016. http://apps.leg.wa.gov/wac/default.aspx?cite=222-16-031 Washington Administrative Code (WAC) 222-600. Hydraulic Code Rules. Accessed February 2016. http://app.leg.wa.gov/WAC/default.aspx?cite=220-660 WDFW, 2009, ÐFish Passage and Surface Water Diversion Screening Assessment and Prioritization Manual,Ñ Olympia, Washington. Washington Department of Fish and Wildlife. WDFW, 2016a. Priority Habitats and Species (PHS) interactive mapper. Accessed February 2016. http://wdfw.wa.gov/mapping/phs/ City of Edmonds 42 Northstream Pipe Abandonment and Culvert Rehabilitation WDFW, 2016b. SalmonScape interactive mapper. Accessed February 2016. http://wdfw.wa.gov/mapping/salmonscape/ WDNR, 2016. Forest Practices Application Review System. Accessed February 2016. http://fortress.wa.gov/dnr/app1/fpars/viewer.htm WSDOT, 2016. Fish Passage Barrier Map. Accessed February 2016. http://www.wsdot.wa.gov/data/tools/geoportal/?config=fish-passage-barriers City of Edmonds 43 Northstream Pipe Abandonment and Culvert Rehabilitation APPENDICES City of Edmonds 44 Northstream Pipe Abandonment and Culvert Rehabilitation APPENDIX A CALCULATIONS City of Edmonds Appendix A Northstream Pipe Abandonment and Culvert Rehabilitation WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Northstream Culvert Site Name: Northstream Culvert Site Address: Puget Drive City : Edmonds Report Date: 3/10/2016 Gage : Everett Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 0.80 Version : 2015/09/18 DEVELOPED LAND USE Name : Upstream Tributary Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat 98.9 Pervious Total 98.9 Impervious Land Use acre ROADS FLAT 80.2 Impervious Total 80.2 Basin Total 179.1 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Flow Frequency Flow(cfs) 0501 2 Year = 28.1303 5 Year = 40.0941 10 Year = 49.3911 25 Year = 62.8294 50 Year = 74.1532 100 Year = 86.6759 Land use Calculation Impervious percentage based on Zoning and dwelling units per acre. Upstream Tributary Area includes: 104.6 acres in RS-8 Zoning = 6 DU/Acre 61.3 acres in RS-12 Zoning = 4 DU/Acre 13.2 acres of Park Zoning Per Table 2.3.2 of DOE Stormwater Management Manual for Western Washington: 6 DU/AC = 52% impervious 4 DU/AC = 42% impervious Park Area = 0% impervious Basin Delineation based on Edmonds Interactive GIS System. See Basin Delineation Map BASIN DELINEATION MAP Legend Storm Line Ditch and Creek Administrative Boundaries Parcels ReZones PRD RoW Zoning RS-6 RS-8 RS-10 RS-12 RSW-12 RS-20 RS-MP RM-3 RM-2.4 RM-1.5 RM-EW BD1 BD2 BD3 BD4 BD5 OR WMU BP BN FVMU BC BC-EW CG CG2 CW MP1 MP2 MU P OS Sections Boundary Sections Edmonds Boundary ArcSDE.GIS.PROPERTY_BUILDINGS 9,027 1: Notes Basin Map used to calculate pipe capacity of Culvert rehab options 0752.251,504.5Feet 1,504.5 This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. WGS_1984_Web_Mercator_Auxiliary_Sphere © City of EdmondsTHIS MAP IS NOT TO BE USED FOR DESIGN OR CONSTRUCTION Northstream Culvert RehabPIPE SIZING, TABLE 1 PROJ: BY:MAD(Runoff by WWHM) FILE:H:\\21Cp\\16\\005 Edmonds Northstream Pipe Abandonment & Culvert Rehab\\Hydraulics\\\[Pipe Sizing-Northstream Creek.xlsx\]100 YR DATE:3/10/2016 For City of Edmonds (Pipe Capacity by Manning's Eqn.) Storm:100 YR Inc.Pipe%VelocFlow AreaRunoffnDiamSlopeLengthCapacCapacFullTimeRemarks Capacity FromTo(Acre)(cfs)Value(inch)(%)(feet)(cfs)Used(ft/sec)(min) Check 179.1086.600.01230.004.40152.0093.2192.9118.990.13 Puget Drive @ Northstream Creek PASS 179.1086.600.01028.004.4081.0093.0693.0621.760.06 CIPP Option PASS Page 1 of 2 Northstream Culvert RehabPIPE SIZING, TABLE 1 PROJ: BY:MAD(Runoff by WWHM) FILE:H:\\21Cp\\16\\005 Edmonds Northstream Pipe Abandonment & Culvert Rehab\\Hydraulics\\\[Pipe Sizing-Northstream Creek.xlsx\]100 YR DATE:3/10/2016 For City of Edmonds (Pipe Capacity by Manning's Eqn.) Storm:25 YR Inc.Pipe%VelocFlow AreaRunoffnDiamSlopeLengthCapacCapacFullTimeRemarks Capacity FromTo(Acre)(cfs)Value(inch)(%)(feet)(cfs)Used(ft/sec)(min) Check 179.1062.800.01230.004.40152.0093.2167.3718.990.13 Puget Drive @ Northstream Creek PASS 179.1062.800.01028.004.4081.0093.0667.4921.760.06 CIPP Option PASS Page 2 of 2 APPENDIX B COST ESTIMATE City of Edmonds Appendix B Northstream Pipe Abandonment and Culvert Rehabilitation THIS COST ESTIMATE IS APPROXIMATE AND SHOULD BE USED ONLY FOR PRELIMINARY PLANNING PURPOSES. ACTUAL CONSTRUCTION, CHANGED CONDITIONS, LABOR RATE CHANGES, OR OTHER FACTORS BEYOND THE CONTROL OF THE CONSTRUCTION BIDS MAY VARY SIGNIFICANTLY FROM THIS STATEMENT OF PROBABLE COSTS DUE TO TIMING OF THIS COST ESTIMATE IS APPROXIMATE AND SHOULD BE USED ONLY FOR PRELIMINARY PLANNING PURPOSES. ACTUAL CONSTRUCTION, CHANGED CONDITIONS, LABOR RATE CHANGES, OR OTHER FACTORS BEYOND THE CONTROL OF THE CONSTRUCTION BIDS MAY VARY SIGNIFICANTLY FROM THIS STATEMENT OF PROBABLE COSTS DUE TO TIMING OF THIS COST ESTIMATE IS APPROXIMATE AND SHOULD BE USED ONLY FOR PRELIMINARY PLANNING PURPOSES. ACTUAL CONSTRUCTION, CHANGED CONDITIONS, LABOR RATE CHANGES, OR OTHER FACTORS BEYOND THE CONTROL OF THE CONSTRUCTION BIDS MAY VARY SIGNIFICANTLY FROM THIS STATEMENT OF PROBABLE COSTS DUE TO TIMING OF THIS COST ESTIMATE IS APPROXIMATE AND SHOULD BE USED ONLY FOR PRELIMINARY PLANNING PURPOSES. ACTUAL CONSTRUCTION, CHANGED CONDITIONS, LABOR RATE CHANGES, OR OTHER FACTORS BEYOND THE CONTROL OF THE CONSTRUCTION BIDS MAY VARY SIGNIFICANTLY FROM THIS STATEMENT OF PROBABLE COSTS DUE TO TIMING OF THIS COST ESTIMATE IS APPROXIMATE AND SHOULD BE USED ONLY FOR PRELIMINARY PLANNING PURPOSES. ACTUAL CONSTRUCTION, CHANGED CONDITIONS, LABOR RATE CHANGES, OR OTHER FACTORS BEYOND THE CONTROL OF THE CONSTRUCTION BIDS MAY VARY SIGNIFICANTLY FROM THIS STATEMENT OF PROBABLE COSTS DUE TO TIMING OF THIS COST ESTIMATE IS APPROXIMATE AND SHOULD BE USED ONLY FOR PRELIMINARY PLANNING PURPOSES. ACTUAL CONSTRUCTION, CHANGED CONDITIONS, LABOR RATE CHANGES, OR OTHER FACTORS BEYOND THE CONTROL OF THE CONSTRUCTION BIDS MAY VARY SIGNIFICANTLY FROM THIS STATEMENT OF PROBABLE COSTS DUE TO TIMING OF APPENDIX C PUGET DRIVE 30 STORM MAIN REPAIR PRE-DESIGN REPORT PREPARED BY CHS ENGINEERS, LLC, APRIL 2014 City of Edmonds Appendix C Northstream Pipe Abandonment and Culvert Rehabilitation Pre-Design Report April, 2014 Prepared for: City of Edmonds Stormwater Division Prepared by: CHS Engineers, LLC 12507 Bel-Red Road, Suite 101 Bellevue, WA 98005 Tel: (425) 637-3693 This report was prepared by and under the supervision of a Professional Engineer licensed in the State of Washington. 1.Vicinity Map and Pipe Identification For this report the pipe under inspection has been separated into three segments; Lower Reach that currently conveys North Stream and is joined into the Lower Reach. Lower HDPE Middle Upper 2.Problem pe that previously routed North Stream underneath of private property and three roadways. The pipe is known to be in very poor condition and has the potential to collapse and cause sink holes and ground settlement along the pipe path. Page 2 of 8 3.Scope CHS Engineers (CHS) was tasked by the City of Edmonds to review prior studies, update the video inspection and develop alternatives for the abandonment/repair/replacement of the pipe main with a focus o (Middle and Upper Reach). 4.Prior Reports A previous report was prepared by Earth Tek of Bellevue, WA in June 2006. The report was not portion of the concrete main. The report did prepare a surface topography survey and traced the approximate location of the pipe. Through smoke testing, the report identified only 1 (one) active connection. Given the unknowns concerning portions of the pipe, the report concluded with a recommendation for the installation of a replacement pipe on a new route. 5.History North Stream served as the source of drinking water for a portion of Edmonds. A concrete headworks/inlet structure was placed th just east of 12 Ave and routed a portion of the stream into wood stave pipe that served Edmonds. pipe was laid in or near the original stream bed and then fill material was placed over the area. The pipe construction, alignment, fill materials or means of compaction. result drilling and re-new structure, just down stream of the and just before the pipe passes under Puget Dr. (SR524). North Stream was diverted into effectively capping it from the stream flows. No furth pipe. In the winter of 2014 water began to flow heavily out of a landscaping berm at the SE intersection of Puget Dr. and Olympic Ave, approximately 200 LF westerly (down gradient) from the connection manhole where the HDPE and concrete pipe connect (STA 1+00). The flow coincided with debris water level to rise significantly upstream of th the 12 Ave inlet. The flow subsided shortly after the debris was removed and the stream level It is suspected, but not definitely shown, that the rise in water level Page 3 of 8 allowed the water to locate/pressurize the abandoned inlet to the old wood stave water supply pipe and release at the weakest point. 6.2014 Video Inspection th On Febuary 28, 2014 the Annotated copies of the inspection report and selected screen shots are attached in Appendix B. The screen shot locations are also identified on the existing plan and profile drawing attached in Appendix A. The video inspection also included ground locates of a sonde that was attached to the camera tractor. The data showed that the previous survey alignment is relatively accurate. The video began at the upstream inlet (STA 5+60) and proceeded westerly for 270 LF before being found to be in very poor condition. In several locations the crown, invert and haunches of the pipe are fully cracked and the pipe is deformed into an oval. Many of the joints are pulled or off set. There are several areas where groundwater infiltration is evident. There are several capped or partially filled connections and two vertical risers that are buried below surface grade. One of the risers appears to have an active connection to the north that drains the roadside swale into the pipe. The video inspection then resumed by entering the connection manhole \[CB 8-1165\] betwe of the manhole. The camera progressed approximately 190 LF before again becoming blocked by debris approximately 10 LF short, but within view, of the end of the upper reach inspection (STA 2+90). The middle reach of the pipe has many of the same faults observed in the upper reach, but the faults are generally to a lower degree and further apart. Again, there are several instances where the pipe is th receiving groundwater. The pipe does pass below the residential home at 1318 11 Place N. Video inspection of the lower reach was not included in the scope. Review of the 2005/2006 video of the lower reach revealed several significant cracks, but the pipe was maintaing a round shape. A review of the 2005/2006 video inspection and comparing that with the current work showed very consistent conditions. Many of the more severe faults were present in 2006 and do not appear to have significantly worsened in the past 8 years. It is likely that the current pipe is stable, but highly susceptible to even minor seismic events. Redirecting the stream flow into the HDPE barrel has also prevented additional scour from occurring around damaged portions of the concrete pipe. 7.Project Goals The primary goal is to ensure that further failure of the concrete pipe does not create a void or sinkhole that would damage the property and roadways above. Secondary goals would include: Page 4 of 8 Not increasing the local groundwater table. Changes in the groundwater table could lead to settlement issues. Eliminating the risk of having a storm pipe underneath of a structure. Maintaining footing and downspout discharges points. Providing a redundant discharge path for North Stream. 8.Feasible Alternatives Do Nothing collapse at any time. The risk would approach certainty during a moderate or large seismic event. Following a partial collapse, it would be reasonable to expect large voids and sediment transport downstream. Locating and isolating repair points could be problematic and any form of open cut emergency repair is likely to be more disruptive and more expensive, due to the size of pipe and depth of cover, than any of the rehabilitations alternatives described below. Slip Line Middle and Upper Reach (Refer to Exhibit C.1 from STA 1+20 to STA 5+60. The annular space between the HDPE and the concrete would be filled with concrete grout mix. Two drywell structures would be constructed via open cut excavation to collect and direct groundwater into The drywell risers would also serve as connection points for footing drains, downspouts and surface flows. This alternative would maintain the storm main alignment under the residence, but at a greatly reduced risk. Pro Restores pipe structural integrity Con Maintains groundwater infiltration to Active pipe under residence pipe. Need for easements Provides overflow capacity for North Stream flows. Budgetary Project Cost = $280,000.00 Page 5 of 8 Slip Line Upper Reach & Re-Connect, Abandon Middle Reach (Refer to Exhibit C.2 HDPE and the concrete would be filled with concrete grout mix. Two drywell structures would be The drywell risers would also serve as connection points for footing drains, downspouts and surface flows. At STA 3+10, within the existing storm easement, the storm main would turn new saddle manhole, via open cut excavation. The middle reach, STA 1+20 to STA 3+10 would grouted solid and abandoned in place. This alternative would address most of the project goals. Pro Con Restores pipe structural integrity Need for easements Maintains groundwater infiltration to pipe. Provides overflow capacity for North Stream flows. Removes active pipe segment under residence. Budgetary Project Cost = $327,000.00 Abandon Upper and Middle Reach, Reconstruct Upper (Refer to Exhibit C.3) This alternative would grout solid and abandon in-place the existing middle and upper reach. Then install new collection piping to pickup footing drains and downspouts connections from the neighboring properties and route to the open ditch to the north. Pro Lower cost than other construction Con alternatives Need for easements Removes active pipe segment under Does not collect ground water. residence. Page 6 of 8 Does not provide a secondary flow path for high or blocked stream flows. Budgetary Project Cost = $201,000.00 CIP Lining of Lower Reach (Refer to Exhibit C.1 C.3) It was noted during the review of the 2005/2006 video inspection that the lower reach is exhibiting many of the same cracking faults as the upper reach, but had not progressed to the point of failure. A Cured-In-Place (CIP) structural liner can be installed between the outlet (STA 0+00) and the joining manhole (STA 1+00) to ensure that the pipe provides several more decades of service. The CIP liner would reduce the interior diameter by conjunction with any of the alternatives listed above or independently. The CIP liner installation would require the diversion of the North Stream flow for 3 to 4 days. Budgetary Project Cost = $86,000.00 Page 7 of 8 Appendix A Appendix B Video Inspection Reports & Photos Appendix C Alternatives Appendix D Cost Estimates Page 8 of 8 Pic1-FailingCrown Pic2-Cloggedconnection Pic3-Flowintoburiedriser Pic4-Encrustedconnection Pic5-30"transitionto24". Viewlookingwest. Pic6-30"to24"transition. Viewlookingeast. Pic7-Holeat2:00,filledwithrock. Pic8-Offsetjointin24"pipe. Pic9-Blockingdebrisandviewu/s oftransitionto30". COST ESTIMATE Date:3/27/2014 By:EH Project:451302 Subject:Puget Drive Storm Checked: Owner:EdmondsFull Slip Line Alternate C.1 Type:Pre-design Item #QtyUnitC1-LC2-MUnit $$Total 1Mobilization1LS$ 15,000.00$ 15,000.00 2Traffic Control1LS3000$ 3,000.00$ 3,000.00 318" HDPE DR17 Slip Line465LF150$ 150.00$ 69,750.00 4Annular Grout1040CF22.25$ 22.25$ 23,140.00 5Inlet Modification1LS10000$ 10,000.00$ 10,000.00 6Drywell Install2EA18000$ 18,000.00$ 36,000.00 78" collector reconnect50LF85$ 85.00$ 4,250.00 8Yard Restoration1LS10000$ 10,000.00$ 10,000.00 9$ -$ - 10$ -$ - 11$ -$ - $ -$ - $ -$ - Subtotal$ 171,140.00 10.0%Tax$ 17,120.00 Slip line entire length, grout, install 2 drywell 12.0%CM$ 20,540.00 risers 20.0%Contingency$ 34,230.00 Construction (CN)$ 243,030.00 15.0%Engineering (PE)$ 36,500.00 Project Total (K)$ 280,000.00 COST ESTIMATE Date:3/27/2014 By:EH Project:451302 Subject:Puget Drive Storm Checked: Owner:EdmondsPartial Slip Line - Abandon - Connect Alternate C.2 Type:Pre-design Item #QtyUnitC1-LC2-MUnit $$Total 1Mobilization1LS16000$ 16,000.00$ 16,000.00 2Traffic Control1LS8000$ 8,000.00$ 8,000.00 318" HDPE DR17 Slip Line240LF150$ 150.00$ 36,000.00 418" HDPE DR17 Open Cut70LF250$ 250.00$ 17,500.00 5Annular Grout1500CF22.25$ 22.25$ 33,375.00 6Inlet Modification1LS10000$ 10,000.00$ 10,000.00 7Drywell Install2EA18000$ 18,000.00$ 36,000.00 88" collector reconnect50LF85$ 85.00$ 4,250.00 972" MH xdeep1LS15000$ 15,000.00$ 15,000.00 10Yard Restoration2LS12000$ 12,000.00$ 24,000.00 11$ -$ - $ -$ - $ -$ - Subtotal$ 200,125.00 10.0%Tax$ 20,020.00 Slip line east 240, grout, connect to 30" hdpe 12.0%CM$ 24,020.00 barrell to north, grout and abandon 200 LF between CB 295 and Easement, install drywell 20.0%Contingency$ 40,030.00 riser and structure Construction (CN)$ 284,195.00 15.0%Engineering (PE)$ 42,700.00 Project Total (K)$ 327,000.00 COST ESTIMATE Date:3/27/2014 By:EH Project:451302 Subject:Puget Drive Storm Checked: Owner:EdmondsAbandon - Partial Reconstruct Alternate C.3 Type:Pre-design Item #QtyUnitC1-LC2-MUnit $$Total 1Mobilization1LS12000$ 12,000.00$ 12,000.00 2Traffic Control1LS8000$ 8,000.00$ 8,000.00 38" CPP150LF125$ 125.00$ 18,750.00 4Annular Grout2100CF22.25$ 22.25$ 46,725.00 5Inlet Modification0LS10000$ 10,000.00$ - 6Drywell Install0EA18000$ 18,000.00$ - 78" collector reconnect50LF85$ 85.00$ 4,250.00 872" MH xdeep1LS15000$ 15,000.00$ 15,000.00 9Yard Restoration1LS18000$ 18,000.00$ 18,000.00 10$ -$ - $ -$ - $ -$ - Subtotal$ 122,725.00 10.0%Tax$ 12,280.00 Grout and abandon exist. 30" and 24". 12.0%CM$ 14,730.00 Construct local collection pipe across lots 2 & 3 and route to new connection on 30" HDPE pipe. 20.0%Contingency$ 24,550.00 Construction (CN)$ 174,285.00 15.0%Engineering (PE)$ 26,200.00 Project Total (K)$ 201,000.00 COST ESTIMATE Date:3/27/2014 By:EH Project:451302 Subject:Puget Drive Storm Checked: Owner:EdmondsAdditive - Lower Reach CIPP Liner Alternate C.4 Type:Pre-design Item #QtyUnitC1-LC2-MUnit $$Total 1Mobilization1LS3000$ 3,000.00$ 3,000.00 2Traffic Control1LS4000$ 4,000.00$ 4,000.00 330" CIPP Liner - Structural100LF325$ 325.00$ 32,500.00 4Stream bypass Pumping4days2000$ 2,000.00$ 8,000.00 5Stream bypass Piping1LS5000$ 5,000.00$ 5,000.00 6$ -$ - 7$ -$ - 8$ -$ - 9$ -$ - 10$ -$ - $ -$ - $ -$ - Subtotal$ 52,500.00 10.0%Tax$ 5,250.00 Install Cured-In-Place Liner from existing 12.0%CM$ 6,300.00 junction to stream daylight. 20.0%Contingency$ 10,500.00 Construction (CN)$ 74,550.00 15.0%Engineering (PE)$ 11,200.00 Project Total (K)$ 86,000.00 APPENDIX D CONCEPT PLANS (separate cover) City of Edmonds Appendix D Northstream Pipe Abandonment and Culvert Rehabilitation