00470.00 394 Section 00470 - Manholes, Catch Basins, and Inlets
Description
00470.00Scope - This Work consists of constructing manholes, catch basins, inlets, siphon boxes,
slope protectors, and other similar Structures. Construct the St ructures of C ommercial Grade Concrete, corrugated metal, or other M aterial , with necessary frames, covers, gratings, and other fittings and hardware. References to manholes, inlets, siphon boxes, and slope protectors refer to standard Structures of specific design and use, and are identified on the Plans . The term "concrete" refers to C ommercial Grade Concrete.
00470.01Cast -in-Place and Precast Construction - Concrete manholes shall be cast -in-place or
precast, as shown or specified. Concrete inlets and siphon boxes may be either cast -in-place or precast.
Materials
00470.10Materials - Furnish Materials mee ting the following requirements:
Concrete Drain Tile ............................................................................ 02410.10(i) Corrugated Metal Pipe ......................................................... 02420.10, 02420.40 Joint Material ....................................................... 02440.40, 02440.50, 02440.60 Metal Frames, Covers, Grates, and Steps ............................................ 02450.30 Nonreinforced Concrete P ipe ................................................................ 02410.10 Polyethylene Pipe .................................................................................. 02415.10 Polyvinyl Chloride Pipe, Schedule 40 .................................................... 02415.50 Reinforcement ...................................................................... 02510.10, 02510.40
00470.11Precast Concrete Manholes and Bases - Furnish cones with the same wall thickness
and reinforcement as riser sections. Prior to delivery of precast manhole sections to the Project Site , yard permeability tests may be required at the point of manufacture. The precast sections to be tested will be selected at random from th e stockpiled M aterial to be supplied to the Project. All test specimens will be mat tested, and shall meet the permeability test requirements of ASTM C497.
Precast manhole sections shall consist of circular sections in one of the following standard nominal inside diameters:
42 inch 54 inch 72 inch 96 inch 132 inch 48 inch 60 inch 84 inch 120 inch 144 inch Heights of sections shall be multiples of 6 inches, except heights of manhole sections 72 inches through 96 inches in diameter shall b e as required to fit site conditions.
00470.12Cap Screws - Cap screws and washers for watertight manhole covers shall be stainless
steel with 60,000 psi minimum tensile strength conforming to the requirements of ASTM A453.
00470.13Inside Drop Manhol e Connectors - Furnish stainless steel anchor bolts and anchor
straps for inside drop pipe connections.
00470.41 395 00470.14 Pipe and Fittings - Furnish pipe and fittings as specified and conforming to the applicable portions of Section 00445. Use tees, ells and other fittings for drop manholes made from the same material as the pipe connecting to the manhole.
00470.15Pipe Stubouts for Future Sanitary Sewer Connections - Pipe stubouts shall be the
same type and strength classification as approved for use in th e lateral, main or trunk sewer construction. Where there are two different classes of pipe at a manhole, the higher strength pipe will govern strength classification. Furnish watertight plugs with each stubout and adequately brace against hydrostatic or air test pressures.
00470.16Sanitary Sewer Manhole Carry-Through - All sanitary sewer carry -through pipes and
fittings through storm sewer manholes shall be ductile iron conforming to Section 02420.
00470.17Base Drain Backfill - Furnish Aggregate base or selected granular backfill Material that is
free from silts or other fines.
Construction
00470.40General :
manhole or other Structure , excavate below grade and backfill with trench foundation stabilization Material according to Section 00405.
connecting pipe through the full thickness of the wall flush with the inner face of the wall. Ensure that pipe connections to the Structure are completely watertight. Connect all pipe to manholes according to the manufacturer's recommendations.
Grout concrete pipe connections to manholes so they are watertight, using non- shrink grout according to 02440.50.
Connect flexible pipe to manholes using an adapter specifically manufactured for the intended service. Flexible pipe adapters are required to be watertight after installation. Follow the manufacturer's recommendations. Do not use field- fabricated water stops or improvised adapters. Adapters requiring the use of grout for installation shall be anchored and finished using non -shrink grout conforming to 02440.50.
00470.41Precast Concrete Manholes - Precast manhole components may be used to construct
standard, drop and carry -through manholes.
off the concrete so that the first manhole section to be placed has a level, uniform bearing for the full circumference.
If bases are precast, carefully place the base section on the prepared bedding so as to be fully and uniformly supported at true grade and alignment.
Construct the invert to match that of the sewer pipe. Where the size of the sewer pipe is changed at the manhole, construct the invert 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, break out the top to the springline of the pip e for the full width of the manhole, and completely cover the exposed edge of the pipe with mortar. During construction divert existing 00470.42 396 flows of water or sewage away from new concrete or mortar surfaces to prevent damage to the fresh concrete or mortar un til the initial set has been achieved.
and smooth and point both inside and out to ensure watertightness.
sections.
cone. In Roadways and other areas intended for traffic, a minimum of one 24-inch diameter precast riser is required between the cone and manhole cover frame. When grout is used, do the following:
• Clean and wet the surfaces to be joined with water. • Apply non- shrink grout to the lower portion of the bell or groove of the section already laid and to the upper portion of the spigot or tongue of the section being laid. • Clean the joint recesses, fill completely with non- shrink grout and wipe to a smooth finish both inside and out. • Do not allow free water to come in contact with grout joints within 24 hours after the mortared joints are finished. • Protect the completed joints against rapid drying.
beds to prevent infiltration of surface water or groundwater between the frame and the concrete of the manhole section. If concrete is to be poured around the frames, coat the portion of the frame that will contact the concrete with hot asphalt before placing the concrete. Set frames, covers and grates true to t he locations and grades established. Clean bearing surfaces and provide uniform contact. The use of a bolt adjustment system for frames from the QPL is allowed. Secure all fastenings. Construct all mortared, sanitary sewer manhole necks and all riser r ing joints made with non- shrink grout using an approved commercial concrete bonding agent applied to all cured concrete surfaces being grouted.
00470.42Precast Concrete Catch Basins and Inlets - Install precast catch basins and inlets to the
specified line and grade. Grade adjustments using a bolt system from the QPL is allowed.
00470.43Cast -in-Place Concrete Construction :
protectors according to Section 00440. Finish all inside surfaces smooth and free of depressions or protrusions. Form exterior surfaces with steel, plywood or other approved Materials. Form other surfaces with matched boards, plywood, or other approved Material . Do not cast directly again st trench walls, Rock , or earth.
of cast -in-place catch basins. Forms shall be tight and well braced, with chamfered corners. Remove all water and debris prior to placing concrete.
Consolidate the concrete immediately after placement with an approved vibrator. Limit vibration time to that necessary to produce satisfactory consolidation without causing segregation. Screed the top surface and trowel exposed surfaces to a smooth finish, free from marks or irregularities. Radius exposed edges with a steel edging tool. After forms are removed, patch any defects in the concrete with an approved mortar mix. 00470.71 397 Immediately after removal of forms and final finishing, cure according to 00440.40(e).
00470.45Steps - Fasten steps to the manhole walls according to the manufacturer's
recommendations and as shown.
00470.46Corrugated Pipe Slope Protectors - Construct corrugated metal slope protectors
accordi ng to the Plans and the applicable requirements of Section 00445.
00470.47Concrete Inlet Base Drains - Provide concrete inlets with base drains leading from
abutting Aggregate base or selected granular backfill M aterial. Use nonreinforced concrete pipe, concrete drain tile, polyethylene pipe or polyvinyl chloride (PVC) plastic pipe for basin drains. Place and compact backfill without damaging pipe or inlet.
00470.48Concrete Manhole Installation Requirements :
Finishing, Cleaning up, and Testing
00470.70Cleaning - Upon completion, clean each Structure of accumulated silt, debris or foreign
matter of any kind and keep clean until F inal Acceptance of the Work .
00470.71Sanitary Manhole Acceptance Testing - Field -test all sanitary sewer manholes for
acceptance by either hydrostatic or vacuum testing after completion of backfilling, compaction and surface restoration, including paving. If the manhole fails the test, make necessary repairs by an approved method, and retest the manhole. Repair and retest the manhole until a satisfactory test is obtained.
and outlets and fill the manhole with water. Fill each manhole to the rim at the start of the test. Leakage in each manhole shall not exceed 0.3 gallons per hour per foot of head above the invert. Determine leakage by refilling to the rim using a calibrated container. Manholes may be filled 24 hours prior to the time of testing to permit normal absorption into the manhole walls.
pipes entering the manhole. Place the test head in or on top of the manhole ring. Draw a vacuum of 10 inches of mercury on the manhole, close the valve on the vacuum line of the test head, and shut off the vacuum pump. Measure the time for the vacuum to drop to 9 inches of mercury. The manhole is acceptable if the time for the vacuum reading to drop from 10 inches of mercury to 9 inches of mercury meets or exceeds the values in the following table:
00470.80 398 Minimum Test Times For Various Manhole Diameters Diameter (inches) 30 or less 33 36 42 48 54 60 66 72 Depth *
8 or less 11 12 14 17 20 23 26 29 33 10 14 15 18 21 25 29 33 36 41 12 17 18 21 25 30 35 39 43 49 14 20 21 25 30 35 41 46 51 57 16 22 24 29 34 40 46 52 58 67 18 25 27 32 38 45 52 59 65 73 20 28 30 35 42 50 53 65 72 81 22 31 33 39 46 55 64 72 79 89 24 33 36 42 51 59 64 78 87 97 26 35 39 46 55 64 75 85 94 105 28 39 42 49 59 69 81 91 101 113 30 42 45 53 63 74 87 98 108 121
* Depth is measured from the top of the manhole to the lowest invert. ** Test times for manhole depths between those shown in this table may be calculated by interpolation.
Measurement
00470.80Measurement - The quantities of manholes, inlets, catch basins, siphon boxes, slope
protectors, and other Structures will be measured on the unit basis.
Payment
00470.90Payment - The accepted quantities of Work performed under this Section will be paid for
at the Contract unit price, per unit of measurement, for the following items:
Pay Item Unit of Measurement
In items (c), (d) and (k) the type of Structure will be inserted in the blank. Payment will be payment in full for furnishing and placing all Materials, and for furnishing all Equipment , labor and Incidentals necessary to complete the Work as specified.
00470.90 399 No separate or additional payment will be made for:
• earthwork not covered as trench or ditch excavation pipe connections Rock backfill Aggregate base backfill • drain tile acceptance testing locator posts