2022 Sewer Replacement Project Connections to Existing Structures or Sewer Mains
Nashua, NH 02533-3
SECTION 02534
FILL SEWER PIPE TO BE ABANDONED
PART 1 - GENERAL
1.01
1.02
1.03
WORK INCLUDED:
The existing sewer pipe to be abandoned in place shall be completely filled with
"Flowable Fill" after the sewerage has been re-routed through the new sewer main.
The work shall include all materials, labor, pumping, shoring, and cleanup required
to complete this item.
RELATED WORK:
Section 02631, PRECAST MANHOLES AND CATCH BASINS
SUBMITTALS: IN ACCORDANCE WITH REQUIREMENTS OF THE
GENERAL SPECIFICATIONS, SUBMIT THE FOLLOWING:
The contractor shall submit his proposed method for filling the pipe to be abandoned
to the Engineer for approval two (2) weeks prior to scheduling the work. The
"Flowable Fill" mix shall be comprised of Portland cement, water, sand and other
additives to insure that the material shall flow the entire length of the pipe and
completely fill the void. The mix design for the "Flowable Fill" shall be submitted to
the Engineer for approval.
PART 2 - PRODUCTS - NOT APPLICABLE
PART 3 - EXECUTION
3.01 INSTALLATION:
A No work shall be done without approval from the Engineer. The contractor shall
demonstrate to the Engineer by visual inspection or other means that the existing
pipe has been completely filled.
B. All work shall be done with the proper tools and by careful workmen competent to
do work.
END OF SECTION
2022 Sewer Replacement Project Fill Sewer Pipe To Be Abandoned
Nashua, NH 02534-1
SECTION 02631
PRECAST MANHOLES AND CATCH BASINS PART 1 -
GENERAL
1.01 WORK INCLUDED:
A. This Section covers all precast manholes and catch basins complete, including, but not limited
to, bases, walls, cones, mortar, inverts, frames and covers.
B. Work shall comply with City of Nashua Standard Specifications for Sewers and Drains
(Appendix A).
102 RELATED WORK:
A. Section 01330, SUBMITTALS
B. Section 02085, POLY VINYL CHLORIDE GRAVITY PIPE AND FITTINGS
C. — Section 02300, EARTHWORK
D. Section 02745, ROAD RESTORATION
1.03 = SYSTEMDESCRIPTION:
A. Precast sections shall conform in shape, size, dimensions, materials, and other respects to the details
indicated on the drawings or as ordered by the Engineer.
B. — All manholes and catch basins shall have precast concrete bases, risers and cone sections. Invert
channels shall be formed of brick and mortar upon the base.
C. Catch basins shall have a 4-foot deep sump unless otherwise specified.
1.04 REFERENCES:
A. The following standards form a part of this specification as referenced:
American Society for Testing and Materials (ASTM)
ASTM A48 Gray Iron Castings
ASTM C32 Sewer and Manhole Brick
ASTM C144 _— Aggregate for Masonry Mortar
ASTM C207 Hydrated Lime for Masonry Purposes
ASTM C478 _ Precast Reinforced Concrete Manhole Sections
ASTM C923 Specification for Resilient Connectors Between Reinforced Concrete
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-1
Manhole Structures and Pipes
ASTM C1244 Standard Test Method for Concrete Sewer Manholes by the
Negative Air Pressure (Vacuum) Test.
American Association of State Highway and Transportation Officials (AASHTO)
AASHTO M198Joints for Circular Concrete Sewer and Culvert Pipe Using
Flexible Watertight Gaskets
Occupational Safety and Health Administration OSHA 29 CFR 1910.27
Fall Prevention Protection
1.05 SUBMITTALS: IN ACCORDANCE WITH REQUIREMENTS OF GENERAL
SPECIFICATIONS, SUBMIT THE FOLLOWING:
A. — Six sets of manufacturer literature of the materials of this section shall be submitted to the Engineer
for review.
B. _ Tests reports as required shall be submitted to the Engineer.
PART 2 - PRODUCTS
2.01 | PRECAST CONCRETE SECTIONS:
A. All precast concrete sections shall conform to ASTM C478 with the following exceptions and
additional requirements:
1. The wall thickness of precast sections shall be as designated on the drawings, meeting
the following minimum requirements:
Section Diameter (Inches) Minimum Wall Thickness (Inches)
48 5
60 6
2 7
84 8
2. Type II cement shall be used except as otherwise approved.
3. Sections shall be steam cured and shall not be shipped until at least five days after having
been cast.
4. Minimum compressive strength of concrete shall be 4000 psi at 28 days.
5. No more than two lift holes may be cast or drilled in each section.
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-2
B.
C.
I
J.
6. The date of manufacture and the name or trademark of the manufacturer shall be clearly
marked on the inside of each precast section.
7. Acceptance of the sections will be on the basis of material tests and inspection of the
completed product.
8. Circumferential steel reinforcement in walls and bases shall be a minimum of 0.12 sq.
in/lin. ft. for 4-foot diameter sections and 0.15 sq. in./lin. ft. for S- and 6-foot diameter
sections. Reinforcing shall extend into tongue and groove.
Conical reducing sections shall have a wall thickness not less than 5-inches at the bottom and wall
thickness of 8-inches at the top. Conical sections shall taper from a minimum of 48-inches
diameter to 30-inches diameter at the top, as shown on the drawings.
Except where insufficient depth of cover dictates the use of a shorter base, bases shall be a minimum
of 4 feet in height.
Slab top sections and flat riser sections (Grade Rings) shall conform to the contract
drawings, with particular attention focused upon the reinforcing steel and be designed to meet or
exceed an H-20 Loading requirement.
The tops of the bases shall be suitably shaped by means of accurate ring forms to receive the riser
sections.
Precast sections shall be manufactured to contain wall openings of the minimum size to receive
the ends of the pipes, such openings being accurately set to conform with line and grade of the sewer
or drain. Subsequent cutting or tampering in the field, for the purpose of creating new openings or
altering existing openings, will not be permitted except as directed by the Engineer.
"Drop-over" manholes shall be placed where indicated on the drawings. The Contractor shall
accurately measure the diameter of the existing outlet pipe and inform the manufacturer of
its size, so that the "Drop-over" type opening can be cut into the precast manhole base. The
bottom shall be precast; or cast in place by the Contractor as required by the Engineer. The
invert channel shall be formed of brick and mortar, as specified in this specifications section. The
sub-base shall be a compacted, level foundation of crushed stone, at least 6-inches thick, as
specified in Section 02300 EARTHWORK, but shall vary to the depth necessary to reach sound
undisturbed earth.
All manholes and catch basins shall be coated on the exterior with a bituminous damp-
proofing coating.
The Engineer reserves the right to reject any unsatisfactory precast section and the rejected unit shall
be tagged and removed from the job site immediately.
The Engineer may also require the testing of concrete sections as outlined under Physical
Requirements in ASTM C478 with the Contractor bearing all testing costs.
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-3
2.02 BRICK MATERIALS:
A. — Brick shall be sound, hard, and uniformly burned brick, regular and uniform in shape and size, of
compact texture, and satisfactory to the Engineer. Bricks shall comply with ASTM C32, for Grade
SS, hard brick, except that the mean of five tests for absorption shall not exceed 8 percent by
weight.
B. — Rejected brick shall be immediately removed from the work and brick satisfactory to the
Engineer substituted.
C. Mortar shall be composed of portland cement, hydrated lime, and sand in which the volume of sand
shall not exceed three times the sum of the volumes of cement and lime. The proportions of
cement and lime shall be as directed and may vary from 1:1/4 for dense hard-burned brick to
1:3/4 for softer brick. In general, mortar for Grade SS Brick shall be mixed in the volume
proportions of 1:1/2:4-1/2; portland cement to hydrated lime to sand.
D. Cement shall be Type II portland cement as specified for concrete masonry.
E. Hydrated lime shall be Type S conforming to ASTM C207.
F. The sand shall comply with ASTM C144 specifications for "Fine Aggregate," except that all of the
sand shall pass a No. 8 sieve.
2.03 FRAMES, GRATES AND COVERS:
A. Castings shall be of good quality, strong, tough, even-grained cast iron, smooth, free from scale,
lumps, blisters, sandholes, and defects of every nature which would render them unfit for the service
for which they are intended. Contact surfaces of covers and frame seats shall be machined to
prevent rocking of covers.
B. _ Allcastings shall be thoroughly cleaned and may be subject to a careful hammer inspection at the
Engineer's discretion.
C. Castings shall be ASTM A48 Class 30B or better.
D. The surface of the manhole covers shall have a diamond pattern with the cast words
"DRAIN" or "SEWER," whichever 1s appropriate.
E. Manhole frames shall be 6-inch height with 32-inch covers for 30-inch openings, 370 pounds
minimum by EJIW, No. LA326-5-000 or approved equal.
G. Catch basin castings shall be NHDOT Standard 3-sided 8-inch frame with Alternate Grate - Type
B or approved equal.
H. — Catch basin frames set against curbing shall have three flanges only.
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-4
2.04 LEACHING CATCH BASINS
A. Leaching catch basins shall conform to the requirements for Products, Paragraph 2.1 herein.
B. _ Thestructure perforations shall be as detailed in the Contract Drawings.
C. Stone for backfill around the leaching catch basin shall conform to NHDOT Item 304.5, Crushed
Stone, Course. materials shall be top grade (100% solids, vulcanized) butyl rubber and shall meet
or exceed AASHTO M-198.
2.05 SEWER MANHOLE ACCESSORIES:
A. — Gasket materials shall be top grade (100% solids, vulcanized) butyl rubber and shall meet or
exceed AASHTO M-198.
B. Couplings at the manhole-pipe interface shall be made with a rubber seal system (with or without
stainless steel straps) meeting the requirements of ASTM C923 and recommended for this type of
connection.
C. Stubs installed as specified and indicated on the drawings shall be short pieces of the same class
pipe as that entering the manhole and shall have erther stoppers or end caps as shown on the
drawings. Stoppers or end caps shall be especially designed for that application.
2.06 CATCH BASIN ACCESSORIES:
A. — Anoil and debris trap shall be furnished and installed on outlet pipes in all catch basins. The trap
shall be The Eliminator® as manufactured by Groundwater Rescue, or approved equal.
2.07 PRECASTHEADWALLS
A. Precast headwalls shall conform to the details on the plans. Shea Concrete Products or equal.
PART 3 - EXECUTION
3.01 INSTALLATION:
A. PRECAST SECTIONS:
1. Precast bases shall be supported on a compacted level foundation of crushed stone, as
specified in Section 02300 EARTHWORK, at least 6-inches thick, but shall vary to the
depth necessary to reach sound undisturbed earth.
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-5
4.
Precast reinforced concrete sections shall be set vertical and with sections in true
alignment.
Butyl rubber joint sealant shall be installed between each concrete section. Catch basin
sections do not require joint sealant if so indicated on the drawings.
All holes in sections used for handling the sections shall be thoroughly plugged with mortar.
Mortar shall be one part cement to 1-1/2 parts sand, mixed slightly damp to the touch (just
short of "balling"), hammered into the holes until it is dense and an excess of paste appears
on the surface, and then finished smooth and flush with the adjoining surfaces.
B. BRICK WORK:
1.
Bricks shall be moistened by suitable means, as directed, until they are neither so dry as to
absorb water from the mortar nor so wet as to be slippery when laid.
Each brick shall be laid as a header in a full bed and joint of mortar without requiring
subsequent grouting, flushing or filling, and shall be thoroughly bonded as directed.
The brick inverts shall conform accurately to the size of the adjoining pipes. Side inverts
shall be curved and main inverts (where direction changes) shall be laid out in smooth curves
of the longest possible radius which is tangent to the centerlines of adjoining pipe.
C. CASTINGS:
1.
Cast iron frames, grates and covers shall be as specified. The frames and covers shall be
set by the Contractor to conform accurately to the grade of the finished pavement,
existing ground surface, or as indicated on the drawings. Frames shall be adjusted to meet
the street surface.
Cast iron manhole frames and covers not located in paved areas shall be set 6-inches above
finished grade, at a height as directed by the Engineer, or as indicated on the drawings. The
top of the cone shall be built up with a minimum of | course and a maximum of 5 courses
of brick and mortar used as headers for adjustment to final grade.
Frames shall be set concentric with the top of the concrete section and in a full bed of mortar
so that the space between the top of the concrete section or brick headers and the bottom
flange of the frame shall be completely filled and made watertight. A thick ring of mortar
extending to the outer edge of the concrete shall be placed all around the bottom flange.
The mortar shall be smoothly finished to be flush with the top of the flange and have a slight
slope to shed water away from the frame.
Covers and/or grates shall be left in place in the frames, for safety reasons, except while
work is being performed.
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH
02631-6
D. ACCESSORIES:
1. All accessories shall be installed in accordance with manufacturer's instructions.
2. Stubs shall be set accurately to the dimensions indicated on the drawings. Stubs shall be
sealed with suitable watertight plugs.
3.02 LEAKAGE TESTS FOR SEWER MANHOLES:
A. Leakage tests shall be made by the Contractor and observed by the Engineer on each
manhole. The test shall be by vacuum or by water exfiltration as described below:
B. VACUUM TEST:
1. The vacuum test shall be conducted in accordance with ASTM C1244. Test results will be
judged by the length of time it takes for the applied vacuum to drop from 10 inches of
mercury to 9 inches. If the time is less than that listed in Table 1 of ASTM C1244, the
manhole will have failed the test. Test times from Table 1 are excerpted below.
TABLE 1 Minimum Test Times for Various Manhole Diameters
Diameter (Inches)
Depth (Feet) 48 60 72
Times (Seconds)
0-12 30 39 49
12-16 40 52 67
1620 50 65 81
90-24 59 78 97
26-30 74 98 121
2. If the manhole fails the initial test, the Contractor shall locate the leaks and make proper
repairs. Leaks may be filled with a wet slurry of accepted quick setting material. If the
manhole should again fail the vacuum test, additional repairs shall be made, and the manhole
water tested as specified below.
C. WATER EXFILTRATION TEST FOR SEWER MANHOLES:
1. After the manhole has been assembled in place, all lifting holes shall be filled and pointed
with an approved non-shrinking mortar. All pipes and other openings into the manhole
shall be suitably plugged and the plugs braced to prevent blow out. The test shall be made
prior to placing the shelf and invert. If the groundwater table has been allowed to rise above
the bottom of the manhole, it shall be lowered for the duration of the test.
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-7
2. The manhole shall be filled with water to the top of the cone section. If the excavation
has not been backfilled and observation indicates no visible leakage, that is, no water visibly
moving down the surface of the manhole, the manhole may be considered to be
satisfactorily water-tight. If the test, as described above, 1s unsatisfactory as determined
by the Engineer or 1f the manhole excavation has been backfilled, the test shall be
continued. A period of time may be permitted if the Contractor so wishes, to allow for
absorption by the manhole. At the end of this period, the manhole shall be refilled to
the top of the cone, if necessary, and a measuring time of at least 8 hours begun. At the
end of the test period, the manhole shall be refilled to the top of the cone, measuring the
volume of water added. This amount shall be extrapolated to a 24-hour loss rate and the
leakage determined on the basis of depth. The leakage for each manhole shall not
exceed one gallon per vertical foot for a 24-hour period. If the manhole fails this
requirement, but the leakage does not exceed 3 gallons per vertical foot per day, repairs
by approved methods may be made as directed by the Engineer to bring the leakage
within the allowable rate of one gallon per foot per day. Leakage due to a defective section
or joint or exceeding the 3 gallon per vertical foot per day, shall be cause for rejection of the
manhole. It shall be the Contractor's responsibility to uncover the reyected manhole as
necessary and to disassemble, reconstruct or replace it as directed by the Engineer. The
manhole shall then be retested and, if satisfactory, interior joints shall be filled and pointed.
3. | No adjustment in the leakage allowance will be made for unknown causes such as leaking
plugs, absorption, etc. It shall be assumed that all loss of water during the test is a result
of leaks through joints or through the concrete. Furthermore, the Contractor shall take
any steps necessary to assure the Engineer that the water table 1s below the bottom of the
manhole throughout the test.
4. If the groundwater table is above the highest joint in the manhole, and there is no leakage
into the manhole, as determined by the Engineer, such a test can serve to evaluate water-
tightness of the manhole. However, if the Engineer is not satisfied with the results, the
Contractor shall lower the water table and carry out the test as described hereinbefore.
3.03 CLEANING:
All new manholes shall be thoroughly cleaned of all silt, debris and foreign matter of any kind,
prior to final inspection.
END OF SECTION
2019 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-8
