604CATCH BASINS, DROP INLETS, AND MANHOLES

New Hampshire Department of Transportation Standard Specifications – 2016 Description

1.1This work shall consist of furnishing and constructing catch basins, drop inlets, and manholes; with frames, grates or manhole

covers, as shown on the plans or as ordered. Sawed pavement, common structure excavation to the depth specified in 206.4.1, bedding if required, and backfill shall be included in this work.

1.2This work shall consist of reconstructing, including adjusting, existing catch basins, drop inlets, and manholes as shown on

the plans or as ordered.

1.3This work shall also consist of furnishing and installing frames, grates or manhole covers, as shown on the plans or as ordered.

Materials

2.1Precast concrete sections shall confor m to AASHTO M 199 . The concrete shall be Class AA, meeting the requirements

of Section 520 except as noted herein.

2.2Reinforcing shall be steel, or structural fibers. Steel shall conform to the requirements of Section 544. Fibers shall only

be utilized in structures with 4 ft. or less inside diameter and shall be as listed on the Qualified Products List.

2.3Precast concrete sections shall conform to AASHTO M 199. The concrete shall be Class AA, meeting the requirements of

Section 520 except as noted herein. 2.3.1 Except for components cast using the dry cast process, precast concrete components shall not have the forms removed until a minimum compressive strength of 2000 psi has been achieved. Once initial set of the concrete has occurred, precast components shall not be moved until a minimum compressive strength of 2000 psi has been achieved. Concrete cylinders shall be made, in accordance with AASHTO T 23, at the last placement of the day. 2.3.2 Curing of precast sections. 2.3.2.1 All precast concrete units shall be coated with a white pigmented curing compound before being stored outside. The membrane curing compounds used under this method shall be Type 2 (white pigmented) Class B conforming to AASHTO M 148 and must appear on the Qualified Products List, Section 520. The compound shall be properly agitated immediately before each use. A minimum coverage rate of 1 gallon per 200 square feet shall be used. 2.3.2.1.1 Where concrete is to be bonded with fresh concrete or coatings applied, curing compound shall be removed. 2.3.2.2 Prior to placement of the curing compound, all precast concrete units shall be subjected to curing by any one of the methods described below. The manufacturer shall provide minimum/maximum temperature thermometers to monitor curing temperatures unless otherwise specified. If, at any time, curing temperatures fall below the specified minimum for the chosen curing method, the curing period shall be increased accordingly. No unit shall be subjected to freezing temperatures until eighty percent of the specified 28 day compressive strength has been reached. 2.3.2.3 Units which are exposed to freezing before reaching the required 28 day compressive strength may require additional testing for compressive strength, as directed by the Materials and Research Bureau. Additional testing, wh en required, will be performed on cores taken from the hardened concrete. 2.3.2.4 Steam Curing. The units shall be cured in a suitable enclosure as approved by the Bureau of Materials and Research. The enclosure shall be designed to minimize the loss of heat and moisture while allowing for the uniform circulation of steam around the entire unit. The interior surfaces of the enclosure and the surface of the unit shall be moist at all times. Steps shall be taken to prevent localized “ hot spots” caused by the steam lines. The enclosure shall be free from outside drafts. 2.3.2.4.1 Steam curing shall not begin until a preset period has been completed. The preset period begins when the last concrete has been placed and continues until the concrete obtains initial set. Prior written approval from the Bureau of Materials and Research is required when preset periods of less than two hours are to be used. 2.3.2.4.2 During the preset period, moderate heat may be applied to the enclosure to maintain the initial temper ature of the concrete. The maximum temperature inside the enclosure during the preset period shall be the initial temperature of the concrete, plus 9o F. 2.3.2.4.3 After the preset period is complete, steam shall be injected into the curing enclosure. The temperature inside the enclosure shall not be increased at a rate greater than 36 F o per hour. A moist atmosphere will be maintained at a temperature between 104 F o and 185 F o for a period of not less than 12 hours. The temperature inside the enclosure shall then be decreased at a rate not exceeding 36 F o per hour until the ambient temperature outside the enclosure is reached. The manufacturer shall provide automatic temperature recorders to continuously record the curing temperature inside the enclosur e. The concrete strength shall be determined by testing cylinders cured in the same environment as the concrete they represent. New Hampshire Department of Transportation Standard Specifications – 2016 2.3.2.5 Water Spray Curing. Curing shall begin as soon as the concrete has hardened sufficiently to prevent surface damage from the water spray. All exposed surfaces of the precast unit shall be kept wet with a continuous fine spray of water in an enclosure maintained at a temperature of not less than 68 F o for 72 hours or until 80% of the 28 day compressive strength is reached. The concrete strength shall be determined by testing cy linders cured using the water spray method and kept in the same environment as the concrete they represent. 2.3.2.6 Saturated Cover Curing. The saturated covers used under this method shall be burla p, meeting the requirements of 520.2.6.1. Curing shall begin as soon as the concrete has hardened sufficiently to prevent surface damage from the satura ted burlap. All exposed concrete surfaces on the precast unit shall be covered with burlap, saturated w ith water before applying. The burlap will be kept saturated and the units kept at a temperature of not less than 68 degrees F for 72 hours or until 80% of the 28 day compressive strength is reached. The concrete strength shall be determined by testing cy linders cured using the saturated cover method and kept in the same environment as the concrete they represent. Additional curing time may be necessary to meet the strength requirements. 2.3.2.7 Moisture Retention Curing. Units cured in accordance with t hese methods shall be maintained at a minimum temperature of 50 º F for 7 days or until 80% of the 28 day compressive strength has been reached . Additional curing time may be necessary to meet the strength requirements. The concrete strength shall be det ermined by testing cylinders cured in the same environment as the concrete they represent. Moisture retention curing shall be accomplished by either of the following 2 methods. 2.3.2.7.1 Membrane Curing Compound. 2.3.2.7.1.1 The membrane curing compound shall be applied to the concrete surface after finishing, as soon as the free water on the surface has disappeared and no water sheen is visible, but not so late that the liquid curing compound will be absorbed into the concrete. When curing compound cannot be applied within the above requirements, the manufacturer shall instead immediately begin curing the unit in accordance with one of the other curing methods contained in this specification, until c uring compound can be applied. When curing compound is to be used in conjunction with any other method of cure, the Engineer shall be notified prior to the start of production. When this method is used in conjunction with the dry cast process, the curing room shall be kept at 100% humidity until a minimum compressive strength of 2000 psi has been obtained. 2.3.2.7.1.2 When the forms are removed prior to 7 days, the exposed concrete surfaces shall be wet with water within one half hour of form removal and shall be kept wet until the curing compound is applied. Be fore application, the concrete shall be allowed to reach a uniformly damp appearance with no free water on the surface, and then the compound shall be applied immediately. 2.3.2.7.1.3 This method of curing shall not be used on any concrete surface that is to have plastic concrete bonded to it. Another approved method of curing shall be used when this condition exists. 2.3.2.7.2 Curing Covers. 2.3.2.7.2.1 The curing covers used under this method shall conform to AASHTO M 171. Curing covers shall be placed immediately following the finishing operation or form removal, whichever is applicable. Care shall be taken not to damage any exposed concrete surfaces during cover placement. Curing covers shall be placed and secured and be of such condition as to minimize the loss of moisture and temperature. When it is necessary to use more than one curing cover, the edges shall be lapped a minimum of 12”.

2.4Clay brick shall conform to the requirements of AASHTO M 91, Grade MS. The use of concrete brick will not be permitted.

2.5Concrete masonry units shall conform to the requirements of ASTM C 139 and shall have a minimum compressive strength

of 3,000 psi when tested by the method in AASHTO T 140.

2.6Cement mortar shall conform to Section 707.

2.7Castings shall be gray iron conforming to AASHTO M 306. Castings shall be proof load tested.

2.8Steel grates shall be of structural steel conforming to AASHTO M 183M ASTM A 36/A 36M. The grates shall be fabricated

as shown on the plans or approved. All top edges shall be flush, and all rivets shall be tight and properly headed. After fabrication, the grates shall be galvanized in accordance with AASHTO M 111 or ASTM A 153 as applicable.

2.9Prefabricated adjustment rings for catch bas ins, drop inlets and manholes shall conform with 2.7 or as approved by the

Engineer.

2.10Polyethylene liner material shall conform to the requirements of AASHTO M 294, Section 6.0, but not have a wall thickness

less than 1/4”.

New Hampshire Department of Transportation Standard Specifications – 2016 Construction Requirements

3.1Concrete construction shall conform to the requirements for structural concrete. Masonry shall conform to the requirements

for the respective type. Joints shall be full mortar joints not more than 1/2” wide. Exposed joints shall be neatly finished. Masonry shall fit neatly and tightly around the pipe. 3.1.1 Reinforced precast sections shall not be shipped from the manufacturing facility until the eighth day from the date of manufacture, except when the supplier provides test results demonstrating that the design strength has been achieved. 3.1.2 Special structures shall be as shown in the plans.

3.2In accordance with the provisions of AASHTO M 105, 17.2, following are the “ other matters of workmanship and finish ”

required: Frames and grates or frames and covers shall be matched before being incorporated in the work. Grates and covers shall make full and even bearing on the underlying surface to fit into the frames without rocking.

3.3When reconstruction or adjustment of existing structures is spec ified, the frames and grates or covers shall be removed and

the walls reconstructed as required. The frames and grates or covers shall be cleaned and reset at the required elevation. 3.3.1 Prefabricated adjustment rings may be used and shall be installed in accordance with the manufacturer’s recommendations.

3.4Structures within the limits of bituminous concrete pavement shall be temporarily set at the elevation of the bottom of the

binder course or as ordered. After the binder course has been compacted, these structures shall be set at their final grade. Backfill necessary around such structures after the binder course has been completed shall be made with Class AA concrete unless otherwise ordered.

3.5Upon completion, each structure shall be cleaned o f silt debris, or other matter of any kind and shall be kept clean until

Acceptance of the Work.

3.6Excavation and backfill shall conform to 206.3. Sawed pavement shall conform to 628.3.4.

3.7Sewer manholes constructed or reconstructed shall be tested after all connections have been made according to the

requirements of the Department of Environmental Services, Water Division.

3.8Surface preparation for drainage structures to be treated with water repellent shall be sufficient to remove dust, dirt, oil, wax,

other coatings, efflorescence and other foreign materials. All surfaces shall be dry prior to t he application of water repellent. 3.8.1 Treatment shall be performed in accordance with the other applicable provisions of Section 534.

3.9Polyethylene liners shall be manufactured and installed in accordance with the NHDOT Standard Plans.

Method of Measurement

4.1Catch basins, drop inlets, and manholes will be measured from the bottom of the metal frame or concrete cover to the inside

bottom top of the base.

4.2Reconstructing/adjusting catch basins, drop inlets, or manholes w ill be measured by the linear foot, vertically to the nearest

0.1 of a foot, between the bottom of the metal frame or concrete top and the top of the undisturbed portion of the existing structure.

4.3Frames with grates or manhole covers together be a will unit and will be measured by the number of each unit installed,

except when they are a part of a structure measured under 4.1.

4.4Polyethylene liners will be measured by number of each installed.

Basis of Payment

5.1The accepted quantities of catch basins, drop inlets, and manholes, which includes the necessary frames and grates or covers,

of the type and diameter specified will be paid for at the Contract unit price per unit complete in place, including sawed pavement, common structure excavation and setting to final grade to the depth specified in 206.4.1, bedding if required and backfill with the following stipulations: 5.1.1 For catch basins and manholes other than special catch basins and manholes, up to the first 8 ft. will be paid for as one unit. Any additional depth required will be paid by dividing the addi tional depth by the 8 ft. unit depth. Payment will be to the nearest tenth of a unit. 5.1.2 For drop inlets other than special drop inle ts, up to the first 5 ft. will be paid for as one unit. Any additional depth required will be paid by dividing the additional depth by the 5 ft. unit depth. Payment will be to the nearest tenth of a unit. 5.1.3 Payment for structures indicated as “ special” will be made by the complete unit of the depth shown on the plans. When an increase of 6 ” or greater is ordered from the depth shown, the unit depth will be adjusted in proportion that the constructed New Hampshire Department of Transportation Standard Specifications – 2016 depth, measured to the nearest foot, bears to the depth shown on t he plans. The proportion will be computed to no more than 2 decimal places. 5.1.4 All rock structure excavation, any common structure excavation below the depth specified in 206. 4.1 and excavation of unsuitable material below the bottom of the catch basin, drop inlet, and manhole will be paid as provided in Section 2 06. Over excavation for bedding purposes in ledge and backfill for said over excavation will be subsidiary. 5.1.5 No extra allowance will be made for structures constructed in accordance with 3.4. 5.1.6 Water repellent treatment for new drainage structures will be subsidiary.

5.2The accepted quantities of reconstructed/adjusted catch basins, drop inlets, and manholes will be paid for at the Contract unit

price per linear foot complete in place, including reinstalling existing frames and grates or co vers. A minimum of 1 foot of reconstructing/adjusting will be paid for each structure measured. 5.2.1 No payment will be made for reconstructing/adjusting portions of the above structures which are unnecessarily disturbed. 5.2.2 No separate payment will be made for excavation for reconstructing/adjusting the above structures.

5.3The accepted quantities of frames and grates or manhole covers will be paid for at the Contract unit price per each unit

complete in place, including setting to final grade.

5.4Testing of sewer manholes required in 3.7 will be subsidiary.

5.5The accepted quantities of polyethylene liner will be paid at the Contract unit price per each installed complete in place.

Pay items and units:

604.0007 Polyethylene Liner Each

KEY TO ITEM NUMBERS FOR CATCH BASINS, DROP INLETS AND MANHOLES Item Number Unit .A B C Item Number Section Number .A Structure Type B Grate and Frame Type C Diameter .1 Catch Basins Type___,___ft. Diameter Unit 1 Blank 2 Type B 3 Type C 4 Blank 5 Type E 6 Type F 8 With Frames and Grates Furnished by Others 9 Special .2 Drop Inlets Type___,___ft. Diameter Unit 1 Blank 2 Type B 3 Type C 4 Type D- 5 Type E 6 Type F 8 With Frames and Grates Furnished by Others 9 Special

New Hampshire Department of Transportation Standard Specifications – 2016 .24 Drop Inlets D-___ Unit 1 Blank 2 Type B 3 Blank 4 Blank 5 Type E 6 Type F .3 Manholes Unit 1 Sewer Manholes,___ft. Diameter 2 Drainage Manholes,___ft. Diameter 9 Special .4 Reconstructing/Adjusting Catch Basins and Drop Inlets Linear Foot .5 Reconstructing/Adjusting ___Manholes Linear Foot 1 Sewer 2 Drainage 3 Electrical 4 Telephone .6 ___Manhole Covers and Frames Each 1 Sewer 2 Drainage .7 Grates and Frames, Type___ Each 1 Blank 2 Type B 3 Type C 4 Blank 5 Type E 6 Type F Examples:

604.126 Catch Basin Type B, 6 ft. Diameter

604.226 Drop Inlet Type B, 6 ft. Diameter

604.242 Drop Inlet Type D-B

604.326 Drainage Manholes, 6 ft. Diameter

604.51Reconstructing/Adjusting Sewer Manholes

New Hampshire Department of Transportation Standard Specifications – 2016

Description

This work shall consist of furnishing (unless pipe is provided) and installing underdrains at the locations shown or ordered.

Pipe, common structure excavation, support membrane, graded aggregate, sand cushion, and backfill where specified shall be included in this work. 1.1.1 Furnishing and installing underdrain flushing basins as shown on the plans or ordered shall also be included in this work.

Aggregate underdrain shall consist of furnishing and installing support membrane, graded aggregate, pipe, if ordered,

common structure excavation, and backfill as necessary. Materials

Perforated corrugated steel pipe and coupling b ands shall conform to the applicable requirements of AASHTO M 36, Type

III. The minimum allowable metal thickness of 6 ” underdrain pipe shall be 0.052” ; the minimum allowable metal thickness in underdrain pipe larger than 6” shall be 0.064”.

Perforated corrugated aluminum pipe and coupling bands shall conform to the applicable requirements of AASHTO M 197.

Polyvinyl Chloride (PVC).

2.3.1 Manufacturers of Polyvinyl Chloride (PVC) pipe must participate in and maintain compliance with, the AASHTO “ National Transportation Product Evaluation Program” (NTPEP) that audits producers of plastic pipe. A certificate of compliance, as required by 106.04, shall be provided for each shipment. 2.3.2 Smooth-wall perforated and un-perforated polyvinyl chloride pipe, bends and cleanouts shall conform to AASHTO M 278. Perforated polyvinyl chloride profile wall pipe shall conform to AASHTO M 304. 2.3.3 Basis of acceptance and test requirements of polyvinyl chloride pip e shall conform to AASHTO M 278 or AASHTO M 304 for the respective type of pipe.

Polyethylene.

2.4.1 Manufacturers of polyethylene pipe must participate in and maintain compliance with, the AASHTO National Transportation Product Evaluation Progra m (www.ntpep.org) that audits producers of polyethylene pipe a Certificate of Compliance as required by 106.04 shall be provided for each shipment. 2.4.2 Polyethylene drainage tubing 6” in diameter shall conform to AASHTO M 252, TypeS, with either Class 1 or Class 2 perforations. Perforated corrugated polyethylene pipe of nominal sizes 12 to 36” diameter shall conform to AASHTO M 294, with Class 1 perforations. Lengths for all sizes shall not exceed 20 ft. 2.4.3 Basis of acceptance and test requirements of polyethylene pipe shall conform to AASHTO M 252 or AASHTO M 294 for the respective type of pipe. The approval criteria can be obtained from the Bureau of Materials and Research. A certificate of compliance, as required by 106.04, shall be provided for each shipment.

Pipe Underdrain, Materials Per Contractor's Option.

2.5.1 When the item reads 6” pipe underdrain (Contractor’s option), it shall be the Contractor's option whether he furnishes perforated corrugated steel pipe, perforated corrugated aluminum pipe, perforated polyvinyl chloride pipe or perforated corrugated polyethylene drainage tubing.

Sand cushion shall be so graded that 90 to 100 percent by weight will pass a 1/2 ” sieve, and not more than 12 percent will

pass a No. 200 sieve.

Underdrain backfill shall meet the requirements of 209.2.1.

Molded pull boxes for underdrain flushing basins shall conform to 614.2.6.

Aggregate for aggregate underdrain shall conform to Table 703-1, Standard Size #4.

Support membrane shall be non-woven geotextile and conform to Item 593.131 - Geotextile, Subsurface Drainage, Class 3,

Non-woven. Construction Requirements

Trenches shall be excavated to the dimensions and grade shown or ordered. A mini mum 2 ” sand cushion in common

excavation and a 6” sand cushion in rock excavation shall be placed in the bottom of the trench for its full width and length to the grade of the bottom of the pipe.