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University Ave Embankment Failure funding D~~~E ~Yk-~ MEMORANDUM January 25, 2006 TO: The Honorable Mayor and City Council Members FROM: Michael C. Van Milligen, City Manager SUBJECT: ER Project No. ER - 2100 (636) -- 58 - 31 University Avenue Embankment Failure ER Funding - Betterment Cost Justification I respectfully recommend Mayor and City Council approval for the City to request consideration for Federal Emergency Relief Funding to complete permanent repair work for the University Avenue Embankment Failure project. (iJj ,:;fJti ~ Mict~ael C. Van Milligen MCVM/jh Attachment cc: Barry Lindahl, Corporation Counsel Cindy Steinhauser, Assistant City Manager Gus Psihoyos, City Engineer i, ~ . DU~~E ~Yk.~ City of Dubuque 50. W. 13th Street Dubuque, IA 52001 (563) 589-4270 (563) 589-4205 FAX January 9, 2006 Mr. LeRoy Bergmann Secondary Roads Engineer Iowa Department of Transportation Office of Local Systems 800 Lincoln Way Ames, Iowa 50010 Phone: Fax: 515.239.1528 515.239.1966 RE: ER Project No. ER - 2100 (636) -- 58 - 31 University Avenue Embankment Failure ER Funding - Betterment Cost Justification Dear Mr. Bergmann: The City of Dubuque has submitted a Detailed Damage Inspection Report (RRW-31-01) and requested consideration and approval for Federal Emergency Relief (ER) Funding to complete permanent repair work for the above referenced project site. The following supplemental information is provided for your review and demonstrates justification that it would be beneficial for the FHWA to authorize the expenditure of ER Betterment Funds for the permanent repair of the University Avenue Embankment Failure site to prevent the potential future damages from another flood event. DAMAGE SUMMARY Since the damages to University Avenue occurred on a minor arterial as per the Federal Functional Classification System map for Dubuque, repairs are not FEMA eligible, thus the City is requesting that the site be considered for Federal ER Funding eligibility. The site is located in the 3300 block of University Avenue. On May 22, 2004 heavy rains resulted in a flooding event that adversely affected approximately 500 feet of embankment on the north side of University Avenue. The existing creek located along the bottom of the slope became flooded and caused the toe of the slope to erode and scour, which caused the embankment slope to fail. The failed slope is in a near vertical position that has encroached within approximately four feet of the existing curb line at several locations and has undermined a section of the adjacent supported roadway. Within the road right-of-way there are several existing underground and overhead utilities in the immediate area of the embankment failure. These utilities are main service lines for much of the west end of Dubuque. The owners of the utilities expressed concern that it is not possible to temporarily relocate these service lines. Should future rain events result in similar flooding, further erosion and scour may occur which could cause damage to extend to the existing roadway and severely damage the existing utilities. SITE HISTORY As a result from the May 1999 flood event, prior damage had occurred along an approximate 100-foot section of the northerly side of the 3300 block of University Avenue. In December 1999, a temporary pile-bracing wall was constructed within City right-of-way to prevent further undermining of the roadway and to protect the existing overhead and underground utilities in the area. No permanent repairs were performed. This event, in May, 2004 resulted in an additional 350 feet of the embankment experiencing damage to some degree. COST ESTIMATES The following cost information is provided to show that it would be beneficial for FHWA to spend betterment funds to prevent the potential future damages from another ER event. All the information and documentation used to calculate the costs is contained within the project file kept at the City of Dubuque Engineering Office and is available for review by FHWA. COST TO RESTORE TO PRE-FLOOD CONDITION The proposed construction would be to restore the existing embankment to a 1: 1 slope and armor the bank with revetment. This is not considered to be a permanent solution due to the potential for the toe of the slope to continue to erode and the potential slope failure which would occur due to the unstable 1: 1 slope. Should future rain events result in similar flooding and scour, the potential slope failure plane could cause damage to extend under the existing roadway and severely damaging the City watermain and other existing utilities. The embankment failure section is approximately 500 feet long with variable widths and depths. The depth of the failure varies from approximately 30 feet to 6 feet. To reconstruct the slope and armor the bank with riprap resulting in a 1:1 slope would restore the embankment to a pre-flood condition. The existing slope was heavily vegetated which reinforced the embankment soils and held the steep slope in place. The construction to restore the pre-existing 1: 1 embankment would incorporate the placement of stabilization stone and riprap along the toe of the slope since it is not possible to recreate the vegetative root structure which previously stabilized the embankment. In addition there is approximately 150 feet of PC curb and gutter and 200 feet of w- beam guardrail damaged due to undermining of the roadway. In order to place the embankment material and revetment an additional 350 feet of PC curb and gutter and 300 feet of w-beam guardrail will need to be removed and replaced to facilitate top side construction. With the removal of the curb and gutter a 500 feet by 2 feet section of HMA patch will be necessary. To fill in the eroded area within the right of way, to protect with riprap, and repair damaged roadway, would cost approximately $156,100. Some of this repair will be to an area that was damaged prior to May 22, 2004. This proposed repair may not prevent future mitigation of the creek towards University Avenue. I Description of Work I Quantity I Unit Cost I Cost Earthwork, Embankment-In-Place 4,000 CY $ 15.50 $ 62,000 Engineering Fabric 1,500 SY $ 2.25 3,375 Revetment, Class E 1,200 Tons $ 18.00 21,600 Curb & Gutter, P.C. Concrete, Per Plan 500 LF $ 14.00 7,000 Guardrail, Removal and Replace 500 LF $ 7.75 3,875 Roadway Pavement, HMA Patch 75 Tons $ 90.00 6,750 Traffic Control Lump Sum $ 7,500 7,500 Erosion Control Lump sum $ 15,000 15,000 Mobilization Lump sum $ 9,000 9,000 Right-of-Way Acquisition Lump sum $ 20,000 20,000 I RESTORE TO PRE-FLOOD CONDITION - TOTAL: POTENTIAL RISK TO THE ER PROGRAM $156,100 I There are two known major slope failures in this area - in the years 1999 and 2004. The damage to be repaired in both years was similar in extent. The estimated cost for restoration for the 2004 event is approximately $156,100. If a 5 year cycle of failure and the 2004 restoration cost estimate is assumed, the cost of restoration in a 15 year period is $468,300. Potentially, the ER program has a $468,300 risk exposure over the next fifteen years. PROPOSED BETTERMENT JUSTIFICATION Heavy rains similar to those of May 22, 2004 could result in additional damage to the existing roadway and utilities. Due to the high average traffic volumes on University Avenue and the proximity of the many utilities to the embankment it is necessary to determine a method to protect the area with a permanent type repair. Two alternates were investigated in evaluation of a proposed betterment. Repair Alternate No. 1 considered relocation of the existing stream to accommodate the construction of a 2.5:1 armored slope. This alternate will require right-of-way acquisition from the abutting property owner and an individual permit from the Army Corps of Engineers (COE). The City retained the Office of the State Archaeologist to complete a Cultural Resources Evaluation of the impacted area. The determination has been made that there are no items of archeological significance within the proposed project corridor. The City has already contacted the COE and based on the findings of the Cultural Resources Evaluation, preliminary indications are that the COE does not anticipate significant issues through the permit process. The second Repair Alternate NO.2 does not relocate the stream or require an individual permit from the COE, instead a soldier pile retaining wall is constructed along the embankment toe of slope and the existing stream, thus minimizing the impacted area. REPAIR ALTERNATE NO.1 RELOCATION OF STREAM TO ACCOMIDATE A 2.5: 1 SLOPE Repair Alternate No. 1 proposes to move and realign the existing stream away from the existing embankment toe of slope creating a more stable 2.5 : 1 slope, and placing stabilization stone and riprap on the embankment slope which will reinforce and prevent future erosion and scour. As a result of moving the stream bed, an existing sanitary sewer located along the bottom of the existing slope will require approximately 450 feet of sanitary sewer to be relocated. Approximately 500 feet of guardrail will have to removed and reinstalled and there will be 500 feet of curb and gutter that will need to be replaced. Upon completion of the embankment repair, it is anticipated that approximately a 500 feet by 2 feet section of HMA roadway patch will be necessary to repair the northerly edge of pavement. Repair Alternate No. 1 will require a permanent construction I maintenance easement or right-of-way acquisition from the abutting land owner. City staff has met with the property owner and obtained a preliminary verbal agreement for a permanent construction easement to gain access to the abutting property to complete the repairs. However, if negotiations are unsuccessful, eminent domain procedures may be required. I Description of Work Quantity I Unit Cost I Cost Earthwork, Embankment-In-Place 4,500 CY $ 15.50 $ 69,750 Excavation, Class 13 2,100CY $ 8.00 16,800 Clearing and Grubbing Lump Sum $ 15,400 15,400 Engineering Fabric 1,500 SY $ 2.25 3,375 Revetment, Class E 1,650 Tons $ 18.00 29,700 Curb & Gutter, P.C. Concrete, Per Plan 500 LF $ 14.00 7,000 Guardrail, Removal and Replace 500 LF $ 7.75 3,875 Roadway Pavement, HMA Patch 75 Tons $ 90.00 6,750 Sanitary Sewer Relocate w/Utility Access 450 LF $ 195.00 87,750 Seeding, Fertilizing, Mulch 2,800 SY $ 6.75 18,900 Topsoil, Furnish and Place 2,800 SY $ 8.75 24,500 Traffic Control Lump Sum $ 7,500 7,500 Erosion Control Lump sum $ 15,000 15,000 Mobilization Lump sum $ 9,000 9,000 Right-of-Way Acquisition Lump sum $ 25,000 25,000 I ALTERNATE NO.1-TOTAL: I $ 340.300 I REPAIR ALTERNATE NO.2 CONSTRUCTION OF A SOLDIER PILE RETAINING WALL AT THE TOE OF SLOPE Repair Alternate NO.2 considers the construction of a soldier pile retaining wall adjacent to the embankment toe of slope and the existing stream and would not require stream relocation or an individual permit from the COE. The wall initially investigated would require drilling sockets into the existing rock below the normal channel streambed and then placing HP 12x53 at 8'-4" on center into the socket, then installing precast concrete panels or planks between the soldier piles. The total length of the wall would be approximately 375 feet and the wall height examined will allow for a minimum 3:1 slope from the guard rail to the top of the wall. Due to the presence of existing overhead power lines and the vertical distance between the roadway and the existing stream bed, it does not appear that top side construction will be an option and that construction of the soldier pile retaining wall will occur along the bottom of the embankment slope. As a result, it is anticipated that less roadway curb and guardrail will be impacted and only 150 feet of curb and gutter and 200 feet of w-beam guardrail damaged due to undermining of the pavement will need to be replaced and reinstalled. Upon completion of the embankment repair, it is anticipated that approximately a 200 feet by 2 feet section of HMA roadway patch will be necessary to repair the northerly edge of pavement. Scouring during future events would be prevented by placing revetment at the toe of the wall and keying the soldier pile into the bedrock. Repair Alternate No. 2 will also require a permanent construction I maintenance easement or right-of-way acquisition from the abutting land owner. I Description of Work I Quantity I Unit Cost I Cost Earthwork, Embankment-In-Place 3,500 CY $ 15.00 $ 54,250 Clearing and Grubbing Lump Sum $ 15,400 15,400 Excavation, Class 13, Channel 475 CY $ 20.00 9,500 Soldier Pile Wall System, Furnish & Install 375 LF $ 1275.00 478,125 45-HP12x53 with Precast Concrete Panels Revetment, Class E 150 Tons $ 18.00 2,700 Curb & Gutter, P.C. Concrete, Per Plan 200 LF $ 14.00 2,800 Roadway Pavement, HMA Patch 25 Tons $ 90.00 2,250 Guardrail, Removal and Replace 200 LF $ 7.75 1,550 Engineering Fabric 400 SY $ 2.25 900 Topsoil, Furnish and Place 700 SY $ 8.75 6,125 Seeding, Fertilizing, Mulch 2,000 SY $ 6.75 13,500 Traffic Control Lump Sum $ 7,500 7,500 Erosion Control Lump sum $ 15,000 15,000 Mobilization Lump sum $ 15,000 15,000 Right-of-Way Acquisition Lump sum $ 15,000 15,000 I ALTERNATE NO.2 - TOTAL: I $ 639.600 I . '. BETTERMENT JUSTIFICATION The proposed betterment (Repair Alternate No.1) will require fewer funds than the future risk to the ER Program and demonstrates justification that it would be beneficial for the FHWA to authorize the expenditure of ER Betterment Funds for the permanent repair of the University Avenue Embankment Failure site to prevent the potential future damages from another flood event. Repair Alternate No.2, although it reduces the impact on the existing channel, has a greater cost than the Repair Alternate No. 1 option. As a result of the pre-existing condition and the previously sustained damage in May 1999, the City, Iowa DOT and FHWA staff agreed that the prior embankment failure area would not be eligible for ER funding and that only 80% of the estimate of probable cost would be considered eligible. Based on the cost for Repair Alternate No.1, the eligible cost for ER funding is as follows: Repair Alternate No. 1 - Cost Estimate = Eligible Cost - Adjusted = $340,300 80% x $340,300 = $272,240 80% x $272,240 = $217,792 20% x $272,240 = $ 54,448 ER Funding Request City Cost Share = = Should you have any questions or need additional information, please contact me at 563/589-4270. Sincerely, wSW Robert D. Schiesl, P.E. Assistant City Engineer City of Dubuque Enclosure cc: Michael Van Milligen, City Manager Cindy Steinhauser, Assistant City Manager Gus Psihoyos, City Engineer Roger R. Walton, P.E., District Engineer Ken Vanna, P.E., Local Systems Engineer Max Grogg, PE, FHWA - Iowa Division