SPECIAL SPECIFICATION 5787 Manhole Rehabilitation

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1 2004 Specifications CSJ SPECIAL SPECIFICATION 5787 Manhole Rehabilitation 1. Description. Repair, rehabilitate, or replace deteriorated, leaking, or structurally unsound existing sanitary sewer manholes and cleanouts. 2. General. A. References. ASTM C Standard Practice for Preparing and Testing Specimens from Shortcrete Test Panels. ASTM D Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft). B. Performance Requirements. Perform work needed to make manholes structurally sound, improve flow, prevent entrance of inflow or groundwater, prevent entrance of soil or debris, and provide protection against hydrogen sulfide gas attack. Manufacturer's Product Support: When requested by the Engineer, provide a representative employed by the manufacturer having technical training in admixture and manhole wall liner available for consultation on site upon 48 hours notice. C. Submittals. 1. Installer Qualifications. Submit qualifications to the Engineer of installers of liners and wall repair systems. List the installer s personnel who have satisfactorily completed the manufacturer s training in product application within the previous 2 years. Include the date of certification for each person. 2. Product Data. Submit product data, including surface preparation instructions and application instructions, from pre-approved manufacturer of wall repair materials, hydraulic cements, quick-set mortars, specialized sealants, grouts, manhole inserts, manhole frame covers, and frame-to-manhole seals. D. Project Conditions. 1. Manholes Containing Mechanical or Electrical Equipment. Drawings may not show locations of flow monitoring equipment. If a manhole contains any mechanical hardware or electrical flow monitoring equipment, immediately notify the Engineer

2 3. Materials. Reschedule work in such manholes until equipment has been removed and further instructions are given. Do not subject manholes with mechanical hardware or electrical equipment to diversion or bypass pumping. Damage to installed equipment, due to the Contractor s failure to adhere to this instruction, will be repaired by the Owner and cost of repairs charged to the Contractor. 2. Field Location of Manholes, Cleanouts, and End of Lines. Assume responsibility for locating and uncovering manholes, cleanouts, and ends of lines. If unable to locate manholes, cleanouts, or ends of lines, notify the Engineer in writing. Manholes may be located within the project limits which are not part of the system being rehabilitated. Properly identify manholes before starting work. A. Wall Cleaning Materials. 1. High Pressure Water. Provide water at 3,500 psi minimum force. 2. Cleaners. Furnish detergent or muriatic acid capable of removing dirt, grease, oil, and other matter which would interfere with bond of sealing material to wall; refer to sealing material manufacturer s recommendations. B. Wall Repair Materials. 1. Hydraulic Cements. Use a blend of cement powders or hydraulic cement to stop active leaks in the manhole structure. 2. Quick-set Mortar. Use a quick-set mortar to repair wide cracks, holes, or disintegrated mortar. C. Manhole Wall Liners, Bench Forming, and Repair Materials. Ensure standard products are pre-approved before use. D. Manhole Covers, Frame Inserts, and Frame-To-Manhole Seals. Furnish new covers and frames that comply with Item 471, Frames, Grates, Rings, and Covers. Furnish watertight covers and frames, each having at least 3 bolts and a gasket to seal the cover to the frame, as manufactured by Neenah Foundry Company, Vulcan, or approved equal. Provide manhole inserts including new dishes, gaskets, and relief valves. Select appropriate watertight inserts to fit the walls and frames of the manholes

3 Provide stainless steel (18 gauge minimum) inserts; Southwestern Packing and Seals Rain Stopper, or approved equal. Stamp the inserts with the words, "Property of Crosby MUD." Provide inserts that have a handle of plastic-coated stainless steel installed on the body of the insert dish. Attach the handle with a #6 high-grade stainless steel rivet. Furnish each dish with a factory-installed 5-ft.-long, 3/16 in. braided stainless steel retaining cable to connect the dish to the manhole frame. Furnish frame-to-manhole seals as manufactured by Cretex or approved equal. Provide Adeka Ultraseal P201 or approved equal, sealing materials between adjustments rings and manhole frames. 4. Construction. A. Protection. Provide barricades, warning lights, and signs for manhole or cleanout removal excavations. Comply with Item 502, Barricades, Signs, and Traffic Handling. Do not allow soil, sand, debris, or runoff to enter the sewer system. B. Excavation. Excavate in accordance with Item 400, Excavation and Backfill for Structures. Perform work in accordance with OSHA standards. Employ a trench safety system as required in Item 402, Trench Excavation Protection. C. Diversion Pumping. Install and operate diversion pumping equipment to maintain sewage flow and to prevent backup or overflow as specified in the Special Specification, By-Pass Pumping (Sanitary Sewer). In the event of accidental spill or overflow, immediately stop the overflow and take action to clean up and disinfect spillage. Promptly notify the Engineer so that required reporting can be made to the Texas Commission on Environmental Quality and U.S. Environmental Protection Agency. D. Manhole Wall Cleaning. Clean the bench/invert floor and interior walls of manholes by removing deleterious material, including dirt, grease, and other debris. Use high pressure water at a minimum force of 3,500 psi. If required, use detergent or muriatic acid to remove grease, oil, and other matter which would interfere with bond between existing manhole wall and approved repair materials. Prepare interior surfaces as recommended by the wall liner material manufacturer. Remove brick steps and cast iron steps before installing the wall lining. E. Manhole Wall Sealing. Seal active leaks in manhole structures with a blend of cement powder or hydraulic cement. Remove loose or defective wall material. Wipe or brush surfaces clean before applying hydraulic cements

4 To stop leaks, drill weep holes at the bottom of the manhole walls to relieve hydrostatic pressure. After the leaks are stopped, plug pressure-relief holes using hydraulic cement materials. Lead wool may also be used to plug large leaks. Repair wide cracks, holes, and disintegrated mortar with quick-set mortars following manufacturer's instructions and recommendations. Reshape manhole inverts before wall-sealing work. Apply concrete to cleaned manhole benches as specified in Item 420, Concrete Structures. After active leaks have been stopped, clean and prepare walls for application of selected liner material. Properly apply the sealing compound to provide the minimum required uniform coating to the wall surface. Prevent foreign material from entering adjoining pipes. Remove droppings of foreign and wall sealant materials before they harden on the bottom of the manhole. Strictly follow product manufacturers published instructions and recommendations for surface preparation, application, and proportioning. F. Manhole Removal and Replacement. When indicated on the plans or instructed by the Engineer, excavate and properly remove and dispose of the existing manhole, including the base. Employ a trench safety system and keep the excavation dry from sewage flow and surface or ground water. Replace the manhole with a new manhole as specified in the Special Specification, Sanitary Sewers. Construct or reconstruct drop connections whenever the flowline elevation of an influent line is more than 24 in. above the bench elevation. Sewer pipe up to 6 ft. outside new manholes may be replaced with new sewer pipe in conjunction with manhole removal and replacement, at no additional cost to the Department. Properly backfill replacement manholes as required in the Special Specification, Sanitary Sewers. Furnish replacement manholes with new 32-in. frames and covers as specified in Item 471, Frames, Grates, Rings, and Covers. G. Manhole Benches/Inverts. Remove obstructions and loose materials from benches before shaping inverts. Form smooth, U-shaped inverts having minimum depths of onehalf the pipe diameter and channel it across the floor of the manhole using an approved manhole rehabilitation material. Control the flow to allow sufficient setting time for material used. Make finished benches and inverts smooth and without defects which would allow accumulation of debris

5 H. Manholes Covers and Frames. Adjust manhole frames and covers found above or below grade and reset loose frames. Combine precast concrete adjustment rings so that the elevation of the installed frame and cover extends 6 in. above the natural ground in unpaved areas. In paved areas, set flush and smooth with pavement grades. Apply an approved sealant between the top adjustment ring and the manhole frame. Apply a minimum of 2 beads of sealant 1/2-in. wide and 3/4-in. high. Apply an approved manhole cementitious lining material between the rings and apply a minimum of 1 in. of lining material to the inside and outside face of the adjustment rings. Install new watertight manhole covers and frames at locations shown on the plans or as directed. Use new frames and covers. I. Manhole Inserts. Install stainless steel manhole inserts at locations shown on the plans or as directed. Exercise care in selecting the proper insert dish to fit properly with the manhole frame and cover. Ensure the insert flange has an outside diameter 3/16 in. less than the inside diameter of the manhole frame. Once proper fit is established, clean the manhole frame surface of dirt, grit, and debris with a wire brush. Fully seal the insert on the manhole frame, providing a watertight seal. Securely attach the retaining tether to the manhole frame following the manufacturer s instructions, with a tamper-proof anchoring device. Replace damaged, tight-fitting, or missing inserts identified before final inspection at no cost to the Department. For new sanitary sewer manholes subject to loading or differential movement at manhole frames, and for rehabilitated manholes, install manhole chimney seals to prevent inflow between manhole frames and masonry chimneys. Refer to Item 471, Frames, Grates, Rings, and Covers. J. Frame-to-Manhole Seals. Ensure surfaces on which the sleeve or extension is to be compressed, are circular, clean, reasonably smooth, and free of loose material and excessive voids. If a surface is rough or irregular and would not provide an effective seal, smooth it with an approved microsilica-enhanced grout. Repair flaws in manhole frames, such as cracks, pits, or protrusions, by filling with concrete or grinding smooth. This type of surface work will need to be done on manholes that have not been lined; manholes that have been lined should not need any surface work in order to install the seal. Install seals following the manufacturer s installation instructions. Arrange for the manufacturer s representative to train the Installer s personnel in the proper methods of installing seals and assist the Installer and Contractor with any problems they might encounter installing the seals. If internal surfaces of the chimney or corbel section of the manhole exceed a slope of 1 in 3, do not use a frame-to-manhole seal. Install frame-to-manhole seals so as to prevent water migration between manhole frames and manhole structures

6 K. Field Quality Control. Inform the Engineer immediately if materials being used are not producing required results or need modification. The Engineer has the right to stop the use of any material at any time. L. Inspection. After manhole wall sealing or manhole rehabilitation is complete, visually inspect the manholes in the presence of the Engineer. Check for cleanliness and for elimination of active leaks. At the completion of manhole rehabilitation, assist the Engineer in verifying the installation of the minimum coating thickness of concrete liner. Test several points on manhole walls. Repair verification points before final acceptance for payment. M. Testing. Perform leakage testing for manholes in accordance with the Special Specification, Sanitary Sewers. N. Backfill. Backfill and compact soil in the area of excavation surrounding manholes in accordance with Item 400, Excavation and Backfill for Structures. In unpaved areas, grade the surface at a uniform slope of 1 to 5 from the manhole frame to natural grade. Provide at least 4 in. of topsoil complying with Item 160, Topsoil and seed according to Item 164, Seeding for Erosion Control. 5. Measurement. A. Rehabilitated Manholes. Manhole wall lining (including bench repair) will be measured by the vertical foot to the nearest tenth of a foot, measured from the bottom of the frame to the top of the bench. If the bench is not required, measurement will be from the bottom of the frame to the top of the effluent pipe. B. Adjustment of Manholes (Watertight). Adjustment using a new watertight manhole frame and cover, including raising or lowering the height of the cover within one vertical foot, will be measured by each manhole adjustment. C. Adjustment of Manholes. Adjustment of an existing manhole frame and cover, including raising or lowering the height of the cover within one vertical foot, will be measured by each manhole adjustment. D. Manhole Frames and Covers. New or existing manhole frame and cover adjustment of over one foot will be measured by the vertical foot, measured to the nearest tenth of a foot. E. Manhole Inserts. New manhole insert dishes will be measured by each new manhole insert dish installed. 6. Payment. The work performed and materials furnished in accordance with this Item and measured as provided under Measurement will be paid for at the unit price bid for Manhole Rehabilitation, Adjust Manhole (Watertight), Adjust Manhole, Manhole (Frame and Cover), and Manhole Inserts. This price is full compensation for equipment, materials, labor, tools, and incidentals

7 Backfill, including cement-stabilized sand, is incidental to rehabilitated manholes; no separate payment will be made. Measurement for pavement restoration will be in accordance with Item 400, Excavation and Backfill for Structures under Cutting and Restoring Pavement