SECTION 02620
PRECAST REINFORCED CONCRETE
SANITARY MANHOLES
PART 1.00 GENERAL
1.01 DESCRIPTION
A. Work included:
The Contractor shall furnish all labor, materials, equipment, and incidentals required and install all precast concrete units including tops in accordance with the Drawings and these Specifications.
1.02 RELATED WORK
A. Unit Masonry
B. Miscellaneous Materials
C. Water Tight Joints
1.03 REFERENCES
A. American Society for Testing and Materials (ASTM):
1. ASTM A- 185 Steel Welded Wire Fabric for Concrete Reinforcement
2. ASTM C33 Concrete Aggregates
3. ASTM C39 Compressive Strength Cylinder Specimens
4. ASTM C478 Precast Reinforced Concrete Manhole Sections
5. ASTM C497 Testing of Manhole Sections
6. ASTM C990 Joints for Concrete Pipe, Manholes, and Precast Box Sections Using Preformed Flexible Joint Sealants
7. ASTM C 1244 Standard Test Method for Concrete Sewer Manholes by the Negative Air Pressure (Vacuum) Test
B. American Association of State Highway and Transportation Officials (AASHTO):
1. AASHTO M55- Steel Welded Wire Fabric for Concrete Reinforcement
2. AASHTO Ml 99 Precast Reinforced Concrete Manhole Sections
3. AASHTO M198 Joints for Concrete Pipe, Manholes and Precast Box Sections Using Preformed Flexible Joint Sealants
4. AASHTO T22 Compressive Strength Cylinder Specimens
5. AASHTO T280 Testing of Manhole Sections
C. Occupational Safety and Health Standards (OSHA):
1. OSHA 29 CFR 1910.27 Steps and Ladders
D. State of Connecticut Department of Transportation (CTDOT):
1. Form 815 and Supplements
1.04 SUBMITTALS
A. Shop Drawings: Submit shop drawings under provisions of Section 01340. Show pertinent dimensions, steel, and concrete strength
B. Quality Control Submittals: Submit manufacturers certification indicating compliance with specified performance and design requirements.
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C. Test Reports: Submit test reports for concrete strength under provisions of Section 01410.
1.05 DELIVERY. STORAGE, AND HANDLING
A. Comply with provisions of Section 01610.
B. Delivery of new product.
C. Store units in an upright position.
PART 2.00 - PRODUCTS
2.01 MANUFACTURERS
A. Precast Manholes: Connecticut Precast Corporation, Monroe, CT (203) 268-8688 or equivalent.
B. Manholes Frames and Covers: Campbell Foundry, North Haven, CT or equivalent.
2.02 MATERIALS
A. Manhole Bases: Bases shall have a monolithic base slab with riser barrel conforming to ASTM C478, AASHTO M199, and designed for AASHTO 1120 loading.
B. Manhole Risers: Riser sections shall have a minimum 5 wall for 48 diameter, 6 wall for 60 diameter, 7 wall for 72 diameter, 8 wall for 84 diameter, 9 wall for 96 diameter, 11 wall for 120 diameter, and 12 wall for 144 diameter and conform to ASTM C478 and AASHTO M199.
C. Manhole Top Slabs: Top Slabs shall have a minimum thickness of 8 and conform to ASTM C478 and designed for AASIITO 1120 loading.
D. Manhole Steps: Manhole steps shall be ~ diameter steel reinforced copolymer polypropylene conforming to ASTM C478, AASHTO M-199 and OSHA 29 CFR 1910.27. Steps shall be placed in vertical alignment in preformed holes as per step manufactures instructions. The steps shall resist a pullout force of over 1500 lbs. Eng lugs shall have a reflecting material insert.
E. Concrete: Concrete shall air entrained in accordance with CTDOT specifications and have a minimum concrete compressive strength of 4,000 PSI at 28 days. Concrete shall be placed in forms and vibrated in such a manner to make a dense uniform product. Concrete shall have a minimum density of 150 PSI and absorption of 5o/o~8%.
F. Coating: Exterior surfaces of manholes shall have two coats of an approved asphalt coating applied according to manufactures recommendations. An alternate to the exterior coating shall be a concrete admixture that is applied to the concrete with batching and demonstrates a reduction in water absorption below five percent.
0. Pipe Connections: Pipes shall be connected to the manhole walls using an approved flexible sleeve. Approved connections shall be Press-Seal Corporation, Kor-N-Seal by NPC, Inc., A-Lok or Z-Lok by A-Lok Products, or approved equal conforming to ASTM C990.
H. The Engineer prior to use shall approve Extension/adapter rings.
I. Joint Sealant: Joint sealant shall be an approved butyl rubber conforming to ASTM C478 and ASTM C990.
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top of pagePART 3.00 - EXECUTION
2.01 INSTALLATION
A. The manholes shall be constructed according to the sizes shown on the Drawings and as specified herein. Install at elevations and locations on the Drawings or as otherwise directed by the Engineer.
B. Place the Precast base units on a granular sand base with a minimum thickness of six inches after compaction or of greater thickness and compaction if specified elsewhere. The granular sub base shall be check for level prior to setting.
C. Pipe openings shall be sealed by the Contractor with cement mortar and shall be sized to accept pipes of the specified size(s) and material(s).
D. After setting of precast base section, the joint shall be clean free of dirt or other unsuitable materials. A butyl joint sealant conforming to ASTM C990 shall be applied to the joint area and then the next precast section installed. Set all sections in plum. When setting sections ensure that the manhole steps are set in vertical alignment. After two sections are joined together. The interior and exterior of the joints shall be grouted.
E. Joining Pipe to Manholes
1. If manhole base sections are equipped with flexible sleeves, slide pipe through sleeve until the end of the pipe is flush with the inside wall of manhole. Install and secure sleeve to pipe with stainless steel clamp is required. If flexible sleeve is a compression type, such as A-Lok type, no external stainless steel clamp is required.
2. If the joint is a grouted joint, place pipe through hole in manhole base section until end of pipe is flush with inside wall of manhole. Place a water stop device on the pipe. Mix and place concrete all around pipe, to full manhole wall thickness. Make a watertight joint.
F. Plug holes, in the concrete sections made for handling with a non-shrink grout and/or the rubber plugs.
G. Install tops according the Drawings at finished grade. Adjust to grade with brick or masonry conforming to ASTM C32 or pre-approved precast grade rings.
2.02 FIELD TESTING
A. General: Provide all equipment and personnel necessary, and make all tests required to demonstrate tint the work of this section has been completed in strict accordance with the design and the specified requirements.
B. Inspection: All units shall be inspected to be sound. There shall be no visible leakage through the walls or pipe connections.
C. Testing: Testing on Sanitary Precast Concrete Manholes shall be by Vacuum Testing in accordance with ASTM C 1244. All vacuum testing shall be preformed prior to backfilling of manhole. The test procedure shall be as follows:
1. Plug, seal, and brace all pipes entering the manhole to prevent them from dislodging during the test. Pipe plugs shall be installed beyond boot seals.
2. Firmly secure vacuum testing equipment to manhole as per recommendations.
3. Start vacuum and seal and necessary leaks around the testing equipment bladder.
4. Attain a vacuum of 10 Hg.
5. Time pressure drop to 9 Hg. Record time. If time to drop 1 Hg is less than 1 minute, manhole shall be passed. If manhole does not pass, the Contractor shall locate leak(s) and repair and retest until satisfactory.
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top of page6. Release Vacuum and backfill manhole in accordance with specifications herein.
D. Repair: Any defect found shall be repaired as approved by the Engineer. The repair method shall be of sound principle to ensure compliance with this specification.
END OF SECTION
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