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SECTION 7500 STORM SEWER MANHOLE CONSTRUCTION Revision 5 – January 2008 Page 1 of 5 PART 1 GENERAL 1.1 SCOPE: A. This item includes the work necessary for the construction and installation of storm sewer manholes. B. The Contractor may, at his option, use cast-in-place type manholes, provided the Engineer approves all details of construction. 1.3 REFERENCE SPECIFICATIONS: A. Shoring and dewatering for construction of all sanitary sewer manholes shall conform to Articles H.5 and H.6, respectively, of the General Conditions for the City of Woodburn, OR PART 2 PRODUCTS 2.1 AGGREGATES: A. Aggregates shall conform to the requirements of Section 2300, of the Standard Construction Specifications. 2.2 PORTLAND CEMENT CONCRETE: A. Concrete used in the construction of the manhole base and other structures specified shall be so proportioned and mixed as to meet Class 3500. There shall be a minimum of 6-sacks of cement per cubic yard of concrete. B. Portland cement shall conform to the requirements of Section 2000, Concrete, of the Standard Construction Specifications. 2.3 METAL REINFORCEMENT: A. Metal reinforcement shall conform to the requirements of ASTM A615, grade 60, deformed bars and otherwise conform to Section 2100, Reinforcement, of the Standard Construction Specifications. 2.4 FORMS: A. Exterior surfaces shall be formed with steel or plywood. Other surfaces shall be formed with matched boards, plywood, or other approved material. Trench walls, rock, or earth will not be an acceptable form material. 2.5 PRECAST MANHOLES: A. Materials shall conform to the requirements of ASTM C478. Cones shall have the same wall thickness and reinforcement as riser sections. ---PAGE BREAK--- SECTION 7500 STORM SEWER MANHOLE CONSTRUCTION Revision 5 – January 2008 Page 2 of 5 B. Prior to delivery of precast manhole sections to the job site, yard permeability tests may be required at the point of manufacture. The precast sections to be tested will be selected at random from the stockpiled material, which is to be supplied to the project. All test specimens will be mat tested, and shall meet the permeability test requirements of ASTM C14. C. Precast manhole sections shall consist of circular sections in standard nominal inside diameters of 42, 48, 54, 60, 72, 84, or 96 inches, as specified. Heights of sections shall be multiples of 12- inches. Heights of manhole section 72-inches through 96-inches in diameter shall be as required to fit site conditions. Other sections shall be 24-inch riser and flattop sections. 2.6 PRECAST BASES: A. Precast manhole bases may be used provided all the details of construction are approved prior to construction. 2.7 MH FRAMES AND COVERS: A. Manhole frames and covers shall East Jordan Iron Works model No.2600 for frame and 2603 for cover, or approved equal. 2.8 JOINT MATERIALS: A. MORTAR: 1. Mortar shall conform to Section 2050 of these specifications. B. NON-SHRINK GROUT: 1. Non-shrink grout shall conform to Section 2050 of these specifications. C. PREFORMED PLASTIC GASKETS: 1. Preformed plastic gaskets shall meet all the requirements of Federal Specifications SS- S-00210. D. RUBBER GASKETS: 1. Materials shall conform to ASTM C443. 2.9 MANHOLE STEPS: A. Manhole steps shall conform to the requirements as listed below: Structural Steel Galvanized ASTM M111 and A123 Reinforcing Steel Galvanized ASTM A615 and A123 Plastic with Reinforcing Steel ASTM C478 and A615 ---PAGE BREAK--- SECTION 7500 STORM SEWER MANHOLE CONSTRUCTION Revision 5 – January 2008 Page 3 of 5 2.10 PIPE ANCHORS: A. Anchor bolts and anchor straps for inside drop pipe connections shall be stainless steel. 2.11 PIPE AND FITTINGS: A. Pipe and fittings shall conform to the applicable portions of Section 7100, Storm Sewer Pipe Installation, of the Standard Construction Specifications. 2.12 PIPE AND FITTINGS: A. Pipe and fittings shall conform to the applicable portions of Section 7100, Storm Sewer Pipe Installation. Tees, ells and other fittings for drop manholes shall be of the same material as the pipe in the adjacent trench. 2.13 PIPE STUB-OUTS FOR SERVICE CONNECTIONS: A. Pipe stub-outs for service connections shall conform to the applicable portions of Section 7100, Storm Sewer Pipe Installation, and are to be of the same size and kind of material as the service connection pipes. 2.14 PIPE STUB-OUTS FOR FUTURE SEWER CONNECTIONS A. Pipe Stub-outs shall be the same type as approved for use in the lateral, main or trunk sewer construction. Strength classification shall be the same class as in adjacent trenches. Where there are two different classes of pipe at a manhole, the higher strength pipe will govern classification. Watertight plugs shall be furnished with each stub-out and shall be adequately braced against hydrostatic or air pressures. PART 3 EXECUTION 3.1 FOUNDATION STABILIZATION: A. If, in the opinion of the Engineer, unstable material exists that will not support the manhole or other structure, the Contractor shall excavate below grade and backfill with foundation stabilization material in accordance with Section 3800 Trenching and Backfill of the Technical Specifications and Article F(2) “Extra Work”, if applicable, in the General Conditions. 3.2 PIPE CONNECTIONS: A. Special care shall be taken to see that the openings through which pipes enter the structure are completely watertight. All pipe shall be connected to manholes according to the manufacturer’s recommendations. All rigid non-reinforced pipes entering or leaving the manhole shall be provided with flexible joints within 1-foot of the manhole structure and shall be placed on firmly compacted bedding. B. Concrete pipe connections to storm manholes shall be grouted water tight with non-shrink grout conforming to subsection 2.8(B)(1)(2) of this Section. ---PAGE BREAK--- SECTION 7500 STORM SEWER MANHOLE CONSTRUCTION Revision 5 – January 2008 Page 4 of 5 C. PVC pipe shall be connected to storm manholes using an approved adaptor specifically manufactured for the intended service. PVC pipe adapters shall be Fernco CMA, Romac LCT, Tylox Manhole Adapters, Vassally Series 32850, Kor-N-Seal, Sealtite, Z-Lok-XP, or approved equal commercial products. Field-fabricated water stops or improvised adapters shall not be used. Adapters requiring the use of grout for installation shall be anchored and finished using non-shrink grout conforming to subsection 2.8(B)(1)(2) of this Section. 3.3 PRECAST CONCRETE MANHOLES: A. GENERAL 1. Precast manhole components may be used to construct standard, drop, and carry- through manholes. Storm manholes less than 6-feet in depth measured from the spring line of the pipe to the bottom of the lower riser ring shall be flattop manholes as shown in Standard Drawing No.7500-1. B. BASES 1. If bases are cast in place, the concrete shall be consolidated by mechanical vibration. The concrete shall be screeded off in such a manner that the first manhole section to be placed has a level uniform bearing for the full circumference. 2. If bases are precast, the base section shall be carefully placed on the prepared bedding so as to be fully and uniformly supported at true grade and alignment. 3. The invert shall be constructed to a section identical with that of the sewer pipe. Where the size of sewer pipe is changed at the manhole, the invert shall be constructed to form a smooth transition without abrupt breaks or unevenness of the invert surfaces. Where a full section of concrete sewer pipe is laid through the manhole, the top shall be broken out to the spring line of the pipe for the full width of the manhole, and the exposed edge of the pipe completely covered with mortar. During construction, the Contractor shall divert existing flows of water or sewage from new concrete or mortar surfaces to prevent damage to the fresh concrete or mortar until the initial set has been achieved. C. SECTIONS 1. All lift holes shall be thoroughly wetted, then completely filled with mortar, and smoothed and pointed both inside and out to ensure water tightness. 2. Preformed plastic or rubber gaskets shall be used on all storm manholes. All mortar joints between precast elements shall be thoroughly wetted, then completely filled with mortar. Storm sewer MH’s shall be made water-tight. 3.4 GRATES, FRAMES, AND COVERS: A. Manhole frames, grates and covers shall be installed in such a manner as to prevent infiltration of surface or ground water between the frame and the concrete of the manhole section. All mortared storm sewer manhole necks and all riser ring joints made with mortar shall be ---PAGE BREAK--- SECTION 7500 STORM SEWER MANHOLE CONSTRUCTION Revision 5 – January 2008 Page 5 of 5 constructed using an approved commercial concrete bonding agent applied to all cured concrete surfaces being mortared. No joints, necks or frames on storm manholes shall be mortared without and approved bonding agent. B. Manhole frames shall be installed flush with finished grade when in improved streets and covers shall fit flat. 3.5 BACKFILL: A. Backfill around MH with same material as specified for pipeline(s) entering and exiting MH. 3.6 MEASUREMENT AND PAYMENT: A. MANHOLE - Manholes will be paid per each at the unit price established in the Bid for the type and diameter MH installed and field verified. Price will include all materials and equipment for a 6-foot depth MH. B. EXTRA DEPTH – MHs over 6-feet in depth will be paid for to the nearest 0.1-foot at the unit price established in the Bid for every foot over 6-feet included in the cost of the new MH. PART 4 TESTING 4.1 GENERAL A. Generally there shall be no hydrostatic or vacuum testing of storm sewer manholes. In the event the engineer determines that the material of the manhole is suspect in quality the contractor shall supply 28-day compressive break test for the lot, which the manhole was supplied from. The break test(s) may be required per the submittal process. END OF SECTION