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HomeMy WebLinkAboutItem 06 - East Outfall Sanitary Sewer LineMEMO TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL FROM: ROGER NELSON, CITY MANAGER MEETING DATE: APRIL 20, 2004 SUBJECT: REPAIR SERVICES FOR THE EAST OUTFALL SANITARY SEWER LINE RECOMMENDATION: City Council consider approval of the procurement of services for the repair of the East Outfall sanitary sewer line from Insituform Technologies Inc. in the amount of $292,090.50, authorize staff to execute the required documents and take any necessary action. FUNDING: Funds are available in the Infiltration/Inflow project for needed sanitary sewer system repairs. Account 200-48940-534-5-000001 SW 1999 Utility Bonds BACKGROUND: The East Outfall sanitary line, constructed in 1994, is a combination of 24 inch, 30 inch and 36 inch concrete pipe serving most of the area east of the wastewater treatment plant on Shady Brook. In addition to collecting flows from gravity lines in the area, this line also receives flows from the Denton Creek, Hilton, and Gaylord lift stations, which are three of the largest in the City. Several weeks ago the line collapsed in the vicinity of Dooley Street and Wildwood Drive. City staff made emergency repairs and restored service. Investigation of the failure revealed that the concrete pipe had deteriorated to the point of failure. High levels of hydrogen sulfide gas released from the wastewater had degraded the interior of the pipe. Failure of this type is unusual. The design life of the system was in excess of 30 years and failure after 10 years was unexpected. Freese and Nichols was immediately contacted and their investigation revealed that the pipe installed was the pipe that was specified in the project. Inspection records indicated nothing unusual during the installation. April 14, 2004 (1:51 PM) The pipe system was specifically designed to provide added protection from hydrogen sulfide gas deterioration. The concrete pipe was designed with special aggregate and additives and a one and one-half inch added wall thickness to protect against the predicted deterioration. Ten years ago there were very few options in selecting a pipe material and concrete pipe was the only viable alternative for a pipe system of this size. Staff, with the assistance of Freese and Nichols Inc., investigated the failure to ascertain the condition of the system and to identify the needed repairs. Additionally the investigation will continue as to the reason for the accelerated deterioration of the pipe and the possibility of legal recourse/recovery in the event material defect or workmanship can be shown to be the cause of failure. Further failure of this line could have catastrophic results and the need to repair the system is imperative. Several repair processes were studied. Sliplining, pipe bursting, and cast -in-place liners were evaluated. The cast -in-place liner was the best alternative. The liner is a reinforced fiberglass resin, will restore the pipe to original condition and is immune to hydrogen sulfide deterioration. Important benefits to this process are that the pipeline carrying capacity will not be reduced, the construction period is very short, and service through the line can be maintained during the construction process. The cost for the repair is $292,090.50 and will be performed by Insituform Technologies wt Inc. This procurement will be made under the Interlocal Cooperation Act, Chapter 791, Texas Local Government Code that states that any entity participating through an interlocal agreement satisfies any bidding requirements required under State law. Council approved the interlocal agreement and participation in the Cooperative during the Council meeting on September 18, 2001. This purchase will be made through the Cooperative's e-commerce Internet Web site at www.buyboard.com. Staff recommends approval of the procurement of repair services from Insituform Technologies Inc. in the amount of $292,090.50. MS/ms April 14, 2004 (1:51 PM) J CL Q LL Q f - =p (O f- Qp W J @,.Freese d h 1 C 1 1 o Lso Inc. Engineers Environmental Scientists Architects 4055 International Plaza, Suite 200 Fort Worth, Texas 76109 817 735-7300 817 735-7491 fax www.freese.com March 29, 2004 Mr. Matt Singleton Via Fax: 817-410-3051 Asst. Director of Public Works E-mail: malts@ci.grapevine.tx.us City of Grapevine 501 Shady Brook Drive Grapevine, TX 76051 RE: East Outfall Wastewater Sewer Rehabilitation Dear Mr. Singleton: The purpose of this letter is to update the City of Grapevine on the progress of our assessment regarding the cause or causes contributing to the rapid deterioration in the 24 -inch and 16 -inch segments of the East Outfall Sewer line. Freese and Nichols is assisting the City in the development of a multiphase approach to assess and recommend expeditious and economical rehabilitation for the 24- and 16 -inch sections of the East Outfall Sewer line which have deteriorated. Concurrently, Freese and Nichols is assessing the cause or causes which have contributed to the rapid deterioration of these segments. Freese and Nichols will also develop long-term recommendations and assess the remaining segments of the pipeline. In February 2004, the East Sewer Outfall experienced a section failure in the 24 -inch reinforced concrete pipe (RCP), which the City repaired with a 24 -inch PVC pipe. During the repair, it was noted by the City, that corrosion had occurred and the City videoed the entire length of the East Outfall line. The East Outfall includes sections of 24 -inch RCP, 16 -inch ductile iron pipe (DIP), 30 - inch RCP and 36 -inch RCP. The video shows severe corrosion of the 24 -inch RCP and 16 -inch DIP. The condition of the 30 -inch and the 36 -inch RCP sections do not show the same degree of corrosion. The City requested that Freese and Nichols assess the problem and recommend remedial measures. The most immediate concern is the remediation of the 24 -inch RCP and 16 -inch DIP. Freese and Nichols is presently proceeding with the following assessment approach: 1. Assess and recommend remediation for the 24 -inch RCP and 16 -inch ductile iron pipe. As part of this assessment, Freese and Nichols considered the following remediation methods: a. Insituform (cured -in-place) b. Pipe bursting c. Slip lining d. Open out Mr. Matt Singleton March 30, 2004 Page 2 of 3 A recommendation has been made to use an insituform system for the rehabilitation. 2. Assessment of the 30 -inch and 36 -inch RCP for determination of useful life is ongoing. Core samples are being considered to assess the degree of corrosion. Assessment of the original installation is being made. The original pipe was specified as a sulfide resistant pipe. Specifications required that the pipe contain at least 75% limestone aggregate, which is resistant to sulfide, Type -II hydrogen sulfide resistant cement, and additional concrete cover to protect the reinforcing steel. The ductile iron pipe was specified to have a polyurethane protective liner. A broken piece of the 24 -inch RCP was submitted to Kleinfielder Testing Laboratories for petrographic examination of concrete samples. The results of the petrographic examination of that concrete sample determined that the limestone content of the total aggregate was estimated to be approximately 60%. That the characteristics of the residual cement were consistent with a Type -II or a Type -V Portland Cement. Evidence suggested that sulfate or other acid attack had caused deterioration and paste loss on the inner surface of the pipe. A copy of the Kleinfielder report is attached. 4. Assess the cause or causes for the deterioration of the 24 -inch and 16 -inch pipe sections and assess control measures for hydrogen sulfide within these sections. BACKGROUND: The East Outfall wastewater line, which runs from approximately Boyd Drive following Wildwood Road to Peach Street adjacent to the wastewater treatment plant, was designed in 1993/1994. The length, size and pipe material for each segment is shown in an attachment. The design flows were taken from the City of Grapevine's wastewater collection system Master Plan of 1985 prepared by Freese and Nichols, Inc. The East Outfall main was designed for a design life of a minimum of 50 years. The City of Grapevine provided inspection during construction and testing phases for the project and Freese and Nichols provided design services and general representation during construction. The pipes selected for the project was a modified reinforced concrete pipe with rubber gasket joints. Non -corrosive pipe materials in the required sizes were not commercially available in the 1993/94 design period. The reinforced concrete pipe was specified to be modified for improved resistance to hydrogen sulfide attack, per the standards for design of concrete pipe. The pipe' designwas modified requiring the inside cage of reinforcement steel to have a minimum cover of 1 %2 -inches.' The pipe design also was modified to specify sulfide resistant Type -II cement conforming to ASTM C-150. The pipe was specified to have at least 75% limestone aggregate. Lifecycle calculations were generated to determine predicted hydrogen sulfide corrosion by using the American Concrete Pipe Association "Hydrogen sulfide and Corrosion Prediction Program." The program assessed the average yearly rate of corrosion in the sanitary sewer system of unlined circular concrete pipe. Conservative values were used for all chemical characteristics of the wastewater flow. Design flow increments of 25, 50, 75, and 100 percent were analyzed to determine the most corrosive condition for each segment of the pipe. A copy of the 1994 design report and corrosion prediction program is attached. Wastewater characteristics were assumed to be a conservative value of BOD 5 -day of .300 Mr. Matt Singleton March 30, 2004 Page 3 of 3 09 mg/1 at a temperature 32 ° centigrade. Recent wastewater collection system testing performed by the Trinity River Authority on behalf of City of Grapevine, indicates that the BOD 5 -day at the Boyd manhole was 180 mg/1 and dissolved hydrogen sulfide was <.1 mg/1. Status update regarding the assessments: 1. Freese and Nichols has completed evaluation of rehabilitation options and has recommended cured -in-place piping (insituform), this option provides for no reduction in pipe capacity and is a non -corrosive material which provides for a minimal external disruption to surface conditions. The operation is conducted without excavation and would involve minimal disruptions for traffic control and sewer bypass pumping. A copy of the Opinion of Probable Construction Cost for the alternatives considered is attached. 2. Assessment of installation and determination of cause or causes. Based upon the results of the petrographic examination report, the pipe did not meet the minimum 75% limestone aggregate specified. The report concludes that approximately 60% of the total aggregate is limestone. An assessment is being conducted to determine the impact that this reduction in limestone aggregate would have on the predicted design life for the pipe. The wastewater characteristics of the one sample taken indicate that the wastewater strength is well within the assumed wastewater characteristics used in the original predictive model. However, additional testing may be warranted to determine if this is a representative sample or if the system may experience occasionally higher levels of wastewater strength at higher temperatures. The 1994 design for the outfall was based upon the City's 1985 Wastewater Collection System Master Plan. At the time of the 1993/1994 design the Hilton Lift Station force main had not been constructed. The accelerated deterioration could be a combination of factors including the pipe material not meeting specifications, the formation and release of hydrogen sulfide from the Hilton Force Main and/or other biological and chemical constituents in the wastewater. We trust that this provides the City with a status of our assessment to date regarding the East Outfall sewer line. We will keep you updated as we proceed through the assessments. If you should have any questions regarding this information, please advise. Very truly yours, Freese and Nichols, Inc. Michael G. Morrison, P.E., DEE Vice President MAMGM\Grapevine pipe.doc KLEINFELDER An employee owned company March 29, 2004 Project 41950 Mr. Coy M. Veach, P.E. Freese and Nichols, Inc. 4055 International Plaza, Suite 200 Fort Worth, Texas 76109-4895 Subject: Concrete Pipe Examination Storm Drain Line Grapevine, Texas Dear Mr. Veach: As requested, the concrete petrographic examination has been completed for the referenced project. The examination included a determination of the aggregate type and quantity, and the cement type. It is understood that the project specifications required a minimum 75 percent of limestone aggregates and a Type II cement. Based on the results of the examination provided by Wiss, Janney, Elstner (WJE), it appears that approximately 60 percent of the total aggregate is a limestone and the cement type is consistent with either a Type II or V Portland cement. The Petrographic Examination Report is attached for your review. It was a pleasure to be of service to you on this project and we look forward to serving you on future projects. Please contact us if you have any questions or comments. Sincerely, KLEINFELDER Roy' . Grant, P.E. Michael M. Shiflett, P.E. Attachments: Petrographic Examination of Concrete Sample — 4 pages cc: Mr. Michael G. Morrison, P.E. FW04LO57 Copyright 2004 Kleinfelder Page 1 of 1 March 29, 2004 KLEINFELDER 6800 Manhattan Boulevard, Suite 200, Fort Worth, TX 76120 (817) 429-6692 (817) 429-7869 fax WJEr NIC, I NT r r T's AkCH ITECT5 I MATERIALS SCIENTISTS CONCRETE PIPE Petrographic Examination of a Concrete Sample Fort Worth, Texas Derek Cong, Ph.D. Senior Petrographer Final Report 26 March 2Q04 WJE No. 2004.1406 Prepared for., Kleinfelder 6800 Manhattan Boulevard, Suite 200. Fort Worth, Texas 76120 Prepared by; Wiss, Janney, Elstner Associates, Inc, 13581 Pond Springs Road #107 Austin, Texas 78729 512.835.0940 tel 1512.835.6268 fax UNG INEERS WJE � ARCHITECTS A4s1TER1A1_i SCIENTISTS CONCRETE PIPE SamplePetrographic Examination of a Concrete Fort Worth, Texas INTRODUCTION At the request of Roy Grant, P.E., of Kleinfelder located in Fort Words, Texas, Wiss, Janney, Elstner Associates, Inc. (WJE) has performed a petrographic examination of one concrete sample reportedly taken from a precast concrete pipe. The purpose of the investigation was to estimate the mix proportions and general characterization of the concrete. Accordingly, the sample was examined using methods given in ASTM C856, Standard Practice for Petrographic Examination of Hardened Concrete. Based on the provided information, the specification required that the concrete contain at least 75 percent limestone aggregates by weight of the total aggregate, and the use of Type II portland cement. RESULTS Sample Received for the investigation was one curved piece of concrete measuring approximately 6 x 6 x 1-3/4 in. Both the inner and outer surfaces of the sample were eroded. Some fine aggregate particles were slightly exposed on the outer surface and many coarse aggregate particles were exposed on the inner surface. Imprints of steel wire were present on the inner surface of the sample, with no evidence of corrosion. The sample was cut parallel to the diameter of the pipe using a diamond blade rock saw. One of the saw - cut surfaces was then lapped with progressively finer grinding media. The lapped sections and freshly fractured surfaces induced in the laboratory were examined using a stereomicroscope at magnifications up to 90X. Powder mounts of the paste were prepared and examined using a petrographic microscope at magnifications up to 600X. Petrographic Examination Aggregate The coarse aggregate was gravel having a nominal maximum size of 1/4 in. The gravel contained a major amount of quartzite and limestone, and a minor amount of chert and feldspar. The fine aggregate was natural sand that contained primarily quartz, limestone and feldspar. The aggregate was well graded, uniformly distributed, and tightly bonded to the paste. The total limestone content was estimated to be approximately sixty percent of the total aggregate. Paste The paste was dark gray, hard, dense, uniform, and had a semiconchoidal texture. Unhydrated and residual Portland cement particles were abundant and predominately ferrite phases. The abundant ferrite phase was consistent with a Type H or Type V portland cement. No supplementary cementitious ENGINEERS WJE ARCHITECT5 MKFERIALS SCIENTI rs materials, such as fly ash or ground granulated blast furnace slag, were detected. Calcium hydroxide crystals from the cement hydration were small and abundant. Based on the compositional and textural characteristics of the paste, the water to cement ratio (w/c) of the concrete was estimated to be in the range of 0.30 to 0.35. The cement content was estimated to be 7 to 7- 1/2 bags per cubic yard. Air -Void System The concrete was non -air -entrained and had an estimated air contents of 1 to 2 percent. Most voids were large, irregular, and coated with a thin layer of ettringite, which indicates that the concrete had been exposed to moisture. Surface and Other Features The exposed surfaces of the sample were eroded. The erosion on the outer surface was minimal and appeared to be due to exposure to the environment. The erosion on the inner surface of the sample appeared to be caused by sulfate attack or some other type of acid attack. A substantial amount of the paste was lost and coarse aggregate particles were exposed. Silica gel was detected on the existing surface, which was likely the end -product of the deterioration. In many cases of sulfate attack, there are often layers of deteriorated paste that contained gypsum, ettringite and silica gel. Such a layer was barely detectable in the sample and no gypsum or ettringite was detected on the exposed inner surface. CONCLUSIONS Based on the petrographic examination, the concrete pipe represented by the sample was non -air - entrained and contained siliceous and calcareous gravel coarse aggregate and natural siliceous and calcareous sand fine aggregate. The limestone content in the total aggregate was estimated to be approximately sixty percent. The w/c of the concrete was estimated to be in the range of 0.30 to 0.35 and the cement content was estimated to be 7 to 7-1/2 bags per cubic yard. The characteristics of the residual cement were consistent with a Type Il or Type V portland cement. The overall quality of the concrete appeared to be very good. Evidence suggested that sulfate attack or other acid attack had caused deterioration and paste loss on the inner surface of the pipe. NOTE: Samples will be discarded after three months unless other disposition is requested. Charges will be made for storage after that period. Concrete Pipe Final Report: 26 March 2004 Petrographic Examination of a Concrete Sample Page 2 fi .i \ r�4 ✓ tt y�' � sS "` vas