[HISTORY: Adopted by the Town of Lee as indicated in article
histories. Amendments noted where applicable.]
[Adopted as Appendix D, Part II, Sec. I, of the 1971 Code]
A.
No person shall make any excavation in any public way, or remove
earth or gravel therefrom, without first having obtained a written
permit therefor from the Superintendent of Public Works.
B.
The Superintendent of Public Works shall require the applicant for
such permit to file a bond or cash deposit, in such amount and with
such sureties, if any, as may be satisfactory to him or her, to guarantee
full compliance with the terms, provisions, conditions and requirements
of such permit.
Underground utilities, such as gas, electric, telephone, television
cable, etc., shall not be laid over a sewer or water main, except
for service line connections. A separate trench shall be excavated
a minimum of 18 inches to the side of the sewer or water main for
any other utility installations.
[Adopted by the Department of Public Works February 2004]
Note: Portions of these construction standards were formerly
promulgated as part of the Lee Subdivision Regulations dated May 1,
1970. The Subdivision Regulations have been revised and reissued by
the Lee Planning Board effective February 2, 2004. These Construction
Standards are no longer part of the Subdivision Regulations except
by reference, and may be amended by the Lee DPW from time to time.
Reference to the Lee Subdivision Regulations is still required for
matters not covered herein.
A.
It is the intent that no street or way shall be constructed in the
Town of Lee unless the street or way is constructed in accordance
with the Lee Planning Board's Subdivision Regulations, and with
the specifications, materials and details contained in this publication,
"Construction Standards for Roads and Municipal Utilities." The design
and construction standards are subject to change by the Lee DPW, and
the standards to be used shall be those that are adopted and in effect
at the time the road is designed and submitted for approval.
B.
Except where otherwise specified, required, and approved by the Town,
all materials and methods of construction used shall conform to the
requirements of the Commonwealth of Massachusetts, Mass. Highway Department,
Standard Specifications for Highways and Bridges, most recent edition,
as amended. This is referred to as "MHD Standard Specifications" in
both these Construction Standards and the Lee Subdivision Regulations.
C.
Any matters not covered in the MHD Standard Specifications, Lee Subdivision
Regulations, or these Construction Standards shall be designed and/or
constructed in accordance with other applicable codes, regulations,
and accepted engineering and/or construction practice. The design
engineer may propose alternative design and/or construction standards,
and provide reference to the alternative codes or standards for consideration
by the Lee DPW.
D.
Wherever the MHD Standard Specifications use the following terms,
the intent and meaning shall be interpreted by substituting the following:
|
Term
|
Substitute:
| |
|---|---|---|
|
Commonwealth
|
Town of Lee or Town
| |
|
Department
|
Lee Department of Public Works
| |
|
Engineer
|
Lee DPW Superintendent
|
E.
Any discrepancy between the plans, specifications or construction
standards shall be resolved in favor of the stricter requirement,
unless the Lee DPW determines it is in the Town's best interest
to accept a lesser requirement.
F.
As each construction operation is completed, it shall be inspected
and approved by the appropriate Town agency prior to starting work
on the succeeding operation.
G.
The subdivider of the land being improved shall keep an up-to-date
set of the approved construction plans available for inspection by
the Lee DPW and other approving agencies at the construction site
at all times during the work day.
H.
Upon completion of the construction, the construction plans shall
be updated, annotated, and labeled as "RECORD PLANS." These must indicate
any changes or revisions made during construction, tie measurements
to underground structures and utilities, pipes, valves, service connections,
and other pertinent information. A hard copy of the record plans shall
be submitted to the Lee DPW. It is also desirable to submit an electronic,
digitally formatted copy of the plan. The current digital requirements
and formats should be obtained from the Lee DPW.
A.
General.
(1)
Geometric design of streets is based on the estimated average daily
traffic (ADT) expected on the street and the character of the neighborhood.
Refer to the street hierarchy and street design criteria in the Subdivision
Regulations for specific requirements.
(2)
Street construction standards also vary according to the type of
use and the particular site conditions, as summarized in Table 2.1.[1]
[1]
Editor's Note: Table 2.1 is included as an attachment to this chapter.
(3)
Refer to the Typical Cross Sections of Streets in the Subdivision
Regulations.
B.
Materials. Materials shall conform to the following requirements,
unless an acceptable substitute is approved in advance by the Town.
(Refer to MHD Standard Specifications and the relevant portions of
the Lee Subdivision Regulations, Article IV, Construction Standards.)
(1)
Bank run gravel borrow (except maximum stone size = four inches.
Reclaimed asphalt pavement may be used for subbase, provided it meets
the grain size and compaction requirements.). M 1.03.0 Type a
(2)
Processed gravel borrow (except maximum stone size = 1 1/2 inches).
M 1.03.1
(3)
Dense graded crushed stone for subbase. M 2.01.7
(4)
Crushed stone for subdrains. M 2.01.5
(5)
Geotextile (subdrains). M 9.50.0 Type II
(6)
Geotextile (subgrade stabilization). M 9.50.0 Type III
(7)
Slot-perforated corrugated plastic pipe (subdrains). M 5.03.9
(8)
Bituminous concrete pavement. (Native Stone may be allowed in the
top course, subject to DPW approval.) M 3.11
(9)
Asphalt emulsions (tack coat). M 3.03.0
C.
Construction methods. Construction shall conform to the following
requirements, unless an alternate method is approved in advance by
the Town. (Refer to MHD Standard Specifications and the relevant portions
of the Lee Subdivision Regulations, Article IV, Construction Standards.)
(1)
Clearing and grubbing: § 101.
(2)
Excavation: § 120.
(3)
Excavation for structures: § 140.
(4)
Embankment: § 150.
(5)
Grading: § 170.
(6)
Gravel subbase: § 401.
(7)
Dense graded crushed stone for subbase: § 402.
(8)
Gravel base course: § 405.
(9)
Shoulders: § 445.
(10)
Class I bituminous concrete pavement, Type I-1: § 460.
(11)
Bituminous concrete berms: § 470.
(12)
Curb, curb inlets, curb corners, and edging: § 501.
(13)
Sidewalks, wheelchair curb ramps, and driveways: § 701.
(14)
Topsoil and seeding: §§ 751 and 765.
(15)
Erosion and sedimentation controls: § 767.
D.
Erosion and sedimentation controls shall be installed and maintained
throughout the construction period until the entire site is fully
stabilized and revegetated. Requirements, materials and construction
methods shall conform to other applicable regulations, including the
Massachusetts Wetlands Protection Act and U.S. EPA NPDES Stormwater
General Permit for Construction Activities.
E.
Inspection. The owner shall arrange for Town inspections of the street
construction and utilities at the following milestones, and the work
shall be satisfactorily completed prior to beginning the subsequent
operation.
(1)
Completion of clearing, grubbing and stripping;
(2)
Completion of subgrade preparation;
(3)
Installation of storm drainage system;
(4)
Installation of water and sewerage systems, as applicable;
(5)
Completion of gravel base, including installation of conduits for
underground wiring under and along roadway;
(6)
Base course paving, and curbing if applicable;
(7)
Final paving, sidewalks, and grassed shoulders;
(8)
Final completion, including established vegetation, street trees,
street signs, monuments, and other applicable required improvements.
A.
General. The sanitary sewer system shall be designed and constructed
in accordance with these requirements, and as required by the Lee
Subdivision Regulations, good engineering practice, and Massachusetts
DEP requirements for municipal sewer systems.
B.
Materials. Materials shall conform to the following requirements,
unless an acceptable substitute is approved in advance by the Town.
(Refer to MHD Standard Specifications and the relevant portions of
the Lee Subdivision Regulations, Article IV, Construction Standards.)
(1)
Sewer pipe: polyvinyl chloride (PVC) gravity sewer pipe: ASTM D3034,
Type PSM, SDR 35, integral bell and spigot with push-on joints.
(2)
Fittings: Wye connections shall be the same material as the sewer
main. Saddles shall be used only for connection to an existing main.
(3)
Sanitary sewer manholes, precast concrete:
(a)
General: precast reinforced concrete sanitary manholes complying
with ASTM C478. All precast sanitary manholes shall be factory-coated
with black bitumastic waterproofing.
[1]
If precast concrete manhole is not feasible, concrete block
manholes may be used with the prior approval of the Lee DPW. Concrete
blocks shall be solid, precast segmental concrete masonry units. The
entire outside of the manhole shall be parged with two coats of Portland
cement mortar, and field coated with two coats of black bitumastic
waterproofing.
(b)
Pipe connectors: Manholes shall be supplied with flexible, watertight
adapters, such as a neoprene "boot" with stainless steel straps, inserts,
or gaskets, conforming to ASTM C923, and suitable for the pipe materials
used. Field installed (in preformed or field-cored hole) with watertight
resilient compression fitting, mechanically tightened, may be used
when necessary.
(c)
Top: precast concrete, of concentric cone, eccentric cone, or
flat slab top type, as required. The top riser section shall terminate
at least 18 inches below finished grade to provide for proper adjustment
of the frame and cover.
(d)
Base: precast concrete, with monolithic base section with integral
floor and watertight cast-in neoprene pipe connectors or preformed
or cored hole with compression pipe connectors. Provide extended base
in wet conditions as indicated on the plans or as directed.
(e)
Riser sections: precast concrete risers with join to mate with
other sections, in height of one foot, two feet, three feet, or four
feet as required.
(f)
Gaskets: precast concrete sections shall be installed with round
rubber-gasketed joints conforming to ASTM C443.
(g)
Steps: ductile-iron, aluminum, or nonmetallic, integrally cast
into manhole sidewalls. Steps shall be spaced at 12 inches.
(h)
Frame and cover: ductile-iron conforming to ASTM 536, 24 inches
inside diameter, heavy-duty suitable for H-20 loading, indented top
design, with lettering cast into top reading "SEWER."
[1]
Manufacturer: to be approved by Lee DPW.
(i)
Grade ring for adjusting frame and cover to finished grade:
Precast concrete grading rings shall be used whenever possible. Manhole
bricks, ASTM C-32, Grade MS, may be used up to three courses maximum,
well parged and stable.
(j)
Mortar and parging: ASTM C-270, Type S, using ASTM C-150, Type
11 portland cement.
(k)
Sewer brick: clay or shale brick, hard burned, AASHTO M114,
Grade MW, or ASTM C-32, Grade SM.
(5)
Sewage pump systems.
(a)
Low-pressure sewer systems shall consist of individual sewage
grinder pump systems discharging through low-pressure sewer laterals
to a common sewer force main. Each lateral shall have a double check
valve and curb stop near the property line. This type of sewerage
system is subject to special review and approval by the Lee DPW, with
equipment and materials to be selected and approved during the design
process.
(b)
Municipal sewage pump station and force main. This type of system
is subject to special review and approval by the Lee DPW and Massachusetts
DEP, with equipment and materials to be selected and approved during
the design process.
C.
Construction methods. Construction shall conform to the following
requirements, unless an alternate method is approved in advance by
the Town. (Refer to MHD Standard Specifications and the relevant portions
of the Lee Subdivision Regulations, Article IV, Construction Standards.)
(1)
General.
(a)
Sewer lines shall be installed true to line and grade using
laser beam control.
(b)
The sewer system shall be constructed to be watertight under
all conditions.
(c)
Sewer pipe shall be installed with at least 10 feet horizontal
clearance from a water main. Should conditions prevent this and the
sewer pipe must cross a water pipe, the pipes shall cross as close
to a right angle as possible, and the sewer pipe shall pass under
the water main with at least 18 inches of clearance below the invert
of the water main. If this is not possible, the water main must be
constructed with mechanical restrained joint glands used for a distance
of at least 10 feet on each side of the sewer, and one full length
of the water main should be centered over the sewer so both joints
will be as far from the sewer as possible. Encasement of both the
water main and sewer line may also be used in this condition.
(d)
Install sewer pipe with at least four feet of cover over pipe,
or the maximum possible. If depth of cover will be less than three
feet, report to Engineer prior to installation for consideration of
alternative pipe materials, bedding, concrete encasement, or other
protective measures.
(e)
Sewer pipe shall not be installed when weather conditions are
unsuitable. Pipe shall be installed in the dry. De-water trench as
required.
(2)
Installing sewer mains.
(a)
Install pipe in accordance with the manufacturer's requirements.
All sewer pipes shall be placed on sand bed or crushed stone bed.
(b)
Both ends of the pipe and the gasket shall be thoroughly cleaned
prior to making the joint. The spigot end shall be fully seated in
the bell end, taking care to assure that the gasket is properly seated.
(c)
As soon as possible after the joint is made, place and tamp
granular backfill material under the haunches and along each side
of the pipe up to the "spring line" to prevent the pipe from shifting
off line or grade. Proper line and grade of the installed sewer line
shall be verified before placing the next section of pipe.
(d)
All trenches and excavations shall be backfilled immediately
after the pipe is laid therein, unless other protection of the pipeline
is directed. Under no circumstances shall water be permitted to rise
in unbackfilled trenches after pipe has been placed.
(e)
No material shall be used for backfilling that contains stones
having any dimension greater than four inches, frozen earth, debris
or earth with a high void content for backfill up to a level of two
feet over the top of the pipe. Only selected materials shall be used,
and the backfilling shall be placed in uniform layers not exceeding
12 inches in depth up each side. Each layer shall then be placed carefully
and compacted. Puddling or water flooding for consolidation of backfill
material is not allowed.
(f)
Care shall be taken to prevent imposing undue live or impact
loads on the exposed surface of the trench. The backfill shall be
a noncohesive material, vibrated or tamped in layers not exceeding
12 inches in depth.
(g)
Where more than one pipeline is laid in the same trench and
the invert elevations are not identical and where no concrete cradle
or encasement is provided for the support of the higher pipeline,
its foundation shall be considered to be yielding.
(h)
When bridging is required to support a portion of the pipeline
over such yielding trench bottoms, the pipeline itself shall not be
considered to provide bridging strength, and supplementary materials
for this purpose must be provided. Where pipe connects with the outside
face of manhole walls or with the outside face of walls of other structures,
there shall be a pipe joint such that slight flexibility or motion
can take place in the plane of the wall face.
D.
Inspection and testing.
(1)
General.
(a)
Perform testing of completed piping in accordance with the requirements
of the local authorities having jurisdiction and as specified herein.
(b)
The contractor shall test all sections of the sewer mains for
leakage and furnish all necessary materials, equipment and labor to
perform the tests as herein specified and as directed by the Engineer.
(c)
All sewers shall be cleaned and inspected for major defects
before testing.
(d)
Any section of the sewers which fails to pass the tests shall
have the defects located and, without additional compensation, repaired
or replaced and retested until the work is satisfactory to the Engineer.
(2)
Record survey. Prior to final inspection of the sewerage system,
the contractor shall supply the Engineer with a record survey plan
indicating:
(a)
Surveyed as-built elevation of the invert of each sewer pipe
at each manhole, sewer service at building, stub end of service, and
other pertinent locations.
(b)
The measured distance along each sewer line between sewer structures,
taps, branches, horizontal or vertical bends, fittings, crossings
of other utilities, presence of bedrock or groundwater, and other
pertinent features.
(c)
The computed slope of each pipe run.
(d)
Tie measurements to all underground sewer structures such as
service stubs, cleanouts, etc.
(e)
The surveyed rim elevation of each manhole.
(3)
Visual test. All sewer lines shall be inspected visually by the contractor
in the presence of the Engineer to verify accuracy of alignment, grade,
and freedom from debris and obstructions, and other defects.
(4)
Infiltration test. All sewer lines installed below the groundwater
level shall be tested for infiltration by low-pressure air testing
or by water testing as described below:
(a)
Isolate test section of sewer from upstream sections using watertight
plugs installed in manholes. (Sewer service wye branches shall be
capped with watertight end caps during installation.)
(b)
Measure infiltration flowing out of the test section of sewer
line through the downstream test manhole during a twenty-four-hour
period by means of a weir or other measuring device acceptable to
the Engineer.
(c)
The maximum allowable infiltration, including gains through
intermediate manholes and sewer service stubs, shall not exceed 300
gallons per inch of pipe diameter per mile per day for any section.
(5)
Exfiltration test. All sewer lines and manholes shall be tested for
exfiltration. The method of test shall be by low-pressure air test,
or by water test as described below:
(a)
Isolate each sewer pipe run (including the upstream manhole)
with watertight plugs.
(b)
Fill line to the top of the precast concrete manhole or other
structure at the upstream end of the sewer run (provided that the
lowest point is not under more than 25 feet of head).
(c)
Determine the loss of water over a twenty-four-hour period by
measuring the amount of water necessary to refill line to starting
level.
(d)
The maximum allowable exfiltration losses through manholes shall
not exceed 300 gallons per inch of pipe diameter per mile per day
for any section.
(e)
The maximum allowable exfiltration for pipes shall not exceed
the requirements set forth in the UNI-Bell PVC Pipe Association's
UNI-B-6-90 or most recent edition.
A.
General design and construction criteria.
(1)
The water supply and distribution system shall be adequate to handle
the necessary flows, based on the complete development of the tract.
(2)
The demand rates for all users shall be considered in computing the total system demand. Where fire protection is to be provided in accordance with Subsection A(3) below, the system shall be capable of providing the required fire demand plus the required maximum daily residential demand. The maximum daily demand shall be calculated by multiplying the average daily flow (calculated based on Title 5 flow rates) by a factor of 1.5 (150%).
(3)
The design of the water distribution system shall be adequate to
provide fire protection calculated as per ISO standard Fire Suppression
Rating Schedule or per AWWA M31, Manual of Water Supply Practices
- Distribution System Requirements for Fire Protection, National Fire
Protection Association (NFPA) Standard 24, Installation of Private
Fire Service Mains and their Appurtenances, latest edition, or by
other calculation using accepted engineering methods approved by the
Lee DPW in advance.
(4)
The design and construction of the water distribution system shall
comply with all applicable state and local laws and regulations, including
but not limited to Massachusetts DEP Drinking Water, 310 CMR 22.00,
and Massachusetts Uniform Plumbing Code, 248 CMR 2.00.[1]
[1]
Editor's Note: See now the Uniform State Plumbing Code, 248
CMR 10.00.
(5)
Design capacity of water mains shall be sufficient to maintain a
minimum pressure of 20 pounds per square inch (psi) at street level
under all flow conditions in the water main.
(6)
Water mains shall be a minimum diameter of eight inches except at
the end of a permanent cul-de-sac or approved dead-end water main.
A six-inch main may be used only when it serves not more than 10 dwelling
units and only one fire hydrant.
B.
Materials. Materials shall conform to the following requirements,
unless an acceptable substitute is approved in advance by the Town.
(Refer to MHD Standard Specifications and the relevant portions of
the Lee Subdivision Regulations, Article IV, Construction Standards.)
(4)
Valve boxes.
(5)
Service connections:
(a)
Curb stop to house connections shall conform to AWWA standards.
Confirm manufacturer and style with Lee DPW.
(b)
Corporation stop as per AWWA standards. Confirm manufacturer
and style with Lee DPW.
(d)
Meter horns: with two valves on all installations. Confirm manufacturer
and style with Lee DPW.
(6)
Cross-connection controls and backflow preventers as required (e.g.,
for swimming pools, irrigation systems, sprinkler systems, etc.).
(7)
Pressure-reducing valves where required by Lee DPW. Confirm manufacturer
and style with Lee DPW.
C.
Methods of construction.
(1)
General:
(a)
Do not operate any valves on the public water system without
the prior approval of the municipal Water Department.
(b)
Coordinate with municipal Water Department before performing
any operations on the public water system, including tapping water
main, flushing lines, flow testing, excavation, backfilling, and pavement
repair.
(2)
Water mains:
(a)
Minimum cover six feet in paved areas; minimum five feet cover
in unpaved areas; maximum seven feet cover all areas unless otherwise
approved.
(b)
Pipe bedding and backfill and installation methods shall conform
to the pipe manufacturer's recommendations.
(c)
Ductile iron water main pipe joints shall be gasketed push-on
joints or mechanical joints.
(d)
Disinfect and flush water mains and appurtenances as described
below.
(4)
Thrust restraint: All pipe bends, tees, valves, end caps, hydrant
branches, vertical bends, etc. shall be properly thrust restrained
for the maximum design pressure of the water main.
(5)
Fire hydrant assembly:
(a)
Comply with AWWA-M17.
(b)
Maximum 500 feet between hydrants, hydrants on all dead ends,
and at high points to expel air.
(c)
Verify bury depth of existing and proposed water mains in advance
of ordering hydrant assembly. Assure that the hydrant length is adequate
to provide proper clearance to the bottom of the pumper nozzles.
(d)
Install hydrant valve anchored to water main tee. Provide proper
thrust restraint. Install hydrant branch water line.
(e)
Set hydrant plumb and to grade, with all nozzles clear above
finished grade by at least 18 inches but no more than 24 inches. Locate
pumper nozzle perpendicular to and facing roadway.
(f)
Provide a drainage pit 36 inches square by 24 inches deep filled
with washed crushed stone to six inches above drain opening.
(g)
Install thrust restraint for hydrant.
(h)
Provide five-foot radius around all fire hydrants clear of any
obstructions and with a slope less than 5%.
(i)
Paint hydrant with primer and two coats of finish enamel; color
per municipal standards.
(6)
Disinfection:
(a)
Disinfection of the water distribution system shall conform
to ANSI/AWWA C651. The completed pipeline is to be disinfected with
a chlorine concentration of approximately 50 ppm prior to being placed
in service. The introduction of this chlorine may be accomplished
using one of the following methods:
(b)
Regardless of the method employed, the chlorinated water is
to remain in the new pipeline for a period of at least 24 hours (unless
otherwise directed). During this period, proper precautions are to
be taken to prevent this chlorinated water from flowing back into
the existing system.
(c)
After all disinfection and leakage/pressure testing is completed,
the contractor shall blow out the new water mains under the direction
of the Engineer and/or the Water Department. Blowing out of the main
is to be accomplished at as high a velocity as possible consistent
with the ability of the area around the blow-off point to drain the
water. After clean water substantially free of chlorine is obtained
at the blowoff point, the flow of water at reduced rates is to be
continued for at least one hour.
(d)
The contractor shall have the water in the main tested by an
independent state-registered testing laboratory selected by the owner.
Testing shall be done in accordance with AWWA testing and disinfection
requirements. Coliform count shall be zero. Submit written report
of test results to Town, owner and Engineer. Do not put new main into
service until proper disinfection is achieved according to test results.
D.
Inspection and testing.
(1)
All water mains or service lines shall be flushed clean and inspected
for major defects before testing.
(2)
The water main shall be pressure tested and leak tested.
(3)
The contractor shall test all sections of the water mains for leakage
and dynamic pressure and furnish all necessary materials, equipment
and labor to perform the tests as herein specified and as directed
by the Engineer. Pressure testing shall comply with NFPA 24, latest
edition.
E.
Record data. Prior to project closeout, submit record data of work
installed under this section:
(1)
Tie measurements and depths at all valves, bends, service connections,
curb stops.
(2)
Notation of locations, volume and characteristics of any trench rock
excavation or groundwater conditions encountered.
(3)
Notation of locations and characteristics of all utility crossings,
whether live or abandoned; clearance, condition, etc.
A.
General.
(1)
Storm drainage systems shall be designed, constructed and maintained
with capacity to handle the runoff from a one-hundred-year design
storm, and provisions shall be made for overland flow of excess runoff
from more severe storms or in case drain inlets or pipes are clogged.
(2)
Drain inlets in a closed drainage system shall be designed with sufficient
inlet capacity for the one-hundred-year storm. The capacity shall
be determined considering the size and type of the grate openings,
curb inlet opening, depth of ponding at inlets, spacing between inlets,
pipe capacity, and other factors based on good engineering practices.
(3)
Drain inlets in streets shall have bicycle-safe grates.
(4)
Storm drains shall discharge into a storm drain system that has capacity
for the design flow. Free discharge into a watercourse shall be protected
from scour and erosion by means of energy dissipaters, stilling basins,
scour aprons, or other method.
(5)
Stormwater runoff from developed sites shall be controlled and increased
rates of runoff shall be detained or retained so that the peak rate
of runoff under the developed condition (assuming maximum allowable
buildout) does not exceed the peak rate of runoff for the pre-development
condition. Detention shall be provided for at least the two-, ten-
and twenty-five-year storm events. The runoff from the one-hundred-year
storm shall be analyzed and shown that it will not increase downstream
flooding. The stormwater basin shall have an emergency spillway with
capacity to handle the one-hundred-year storm without overtopping
the embankment.
(6)
Design engineers shall determine pipe size based on the design runoff,
conduit inlet conditions, and hydraulic capacity.
(7)
No pipe in the storm drainage system shall be less than 12 inches
in diameter. Any pipe handling the flow from two or more drain inlets
shall be at least 15 inches in diameter.
(8)
Drain pipes shall have a minimum slope of 1% (2% preferred) and be
sufficient to provide scour velocity.
B.
Materials.
(1)
Frames and grates (3 and 4 flange), H-20, bicycle-safe if in roadway.
M8.03.0 and M8.03.2
(2)
Frames and covers for drain manholes, heavy-duty H-20, 24 inches
inside diameter, diamond plate cover, marked "DRAIN." M8.03.0
(3)
Cement concrete bricks and blocks. M4.05.1
(4)
Precast concrete units. M4.02.14
(5)
Polyvinyl chloride (PVC) drain pipe and fittings: ASTM D3034, SDR-35,
with gasketed joints per ASTM F477, elastomeric-seal gaskets. Perforated
or unperforated as per plans.
(6)
Smooth-bore corrugated polyethylene pipe (SBCPE) with high-density
polyethylene (HDPE), with soil-tight O-ring joints. Equivalent to
Advanced Drainage Systems, Inc., Type N-12, or Hancor. Perforated
or unperforated as per plans.
(7)
Reinforced concrete pipe (RCP). M5.02.1
(8)
Ductile iron pipe - cement lined (DIPCL). M5.05.3
(9)
Geotextile (subdrains) nonwoven, needle punched, polyester. M 9.50.0
Type II
(10)
Washed crushed stone - 1/2 inches - 3/4 inches (for weep holes
and bedding). M2.01.5
(11)
Concrete, Class D, 4,000 psi. M4.02.00
(12)
Reinforcing steel, Grade 60 steel bars. M8.01.0
(13)
Special pipe couplings and fittings: rubber or elastomeric sleeve
and band assembly fabricated to match outside diameters of pipes to
be joined, for nonpressure joints.
(14)
Precast concrete catch basins: ASTM C858, precast, reinforced
concrete, designed according to ASTM C857 for structural loading.
Include sump, depth, shape, and dimensions indicated, with provision
for rubber gasket joints.
(a)
Gaskets between riser sections: round rubber gasket joints,
ASTM C923.
(b)
Grade rings: include two or three reinforced-concrete rings,
of six- to nine-inch total thickness, that match a twenty-four-inch-diameter
frame and grate.
(c)
Steps: not required.
(d)
Pipe connectors: ASTM C923 (ASTM C923M), resilient, of size
required, for each pipe connecting to base section.
(e)
Frames and grates for catch basins, H-20, bicycle-safe if in
roadway. Consult with Lee DPW for manufacturer and type.
(15)
Precast concrete manholes: ASTM C478 (ASTM C478M), precast,
reinforced concrete, of depth indicated, within provision for rubber
gasket joints.
(a)
Base section: six-inch minimum thickness for floor slab and
four-inch minimum thickness for walls and base riser section, and
having a separate base slab or base section with integral floor.
(b)
Riser sections: four-inch minimum thickness, forty-eight-inch
diameter, and lengths to provide depth indicated.
(c)
Top section: eccentric cone type, unless concentric cone or
flat-slab-top type is indicated. Top riser section shall end at least
12 inches below finished grade to allow for proper adjustment of frame
and cover.
(d)
Gaskets: ASTM C443 (ASTM C443M), rubber.
(e)
Grade rings: include two or three reinforced-concrete rings,
of six- to nine-inch total thickness, that match a twenty-four-inch-diameter
frame and cover.
(f)
Steps: fiberglass, individual steps or ladder. Include a width
that allows a worker to place both feet on one step and is designed
to prevent lateral slippage off the step. Cast steps or anchor ladder
into base, riser, and top section sidewalls at twelve-inch to sixteen-inch
intervals. Omit steps for manholes less than 60 inches deep.
(g)
Pipe connectors: ASTM C923 (ASTM C923M), resilient, of size
required, for each pipe connecting to base section.
(h)
Frames and covers: ASTM A536, Grade 60-40-18, heavy-duty ductile
iron. Include twenty-four-inch inside diameter by seven- to nine-inch
riser with four-inch minimum width flange, twenty-six-inch-diameter
cover. Include indented top design the lettering cast into cover.
(16)
Wood post and rail safety "awareness" fence. M9.05.3
C.
Methods of construction.
(1)
General.
(a)
Stake out the locations and elevations of all existing and proposed
piping, drainage structures, and other utilities in the vicinity before
proceeding with work on the system to check whether conflicts may
exist. Confirm locations of catch basins relative to curblines. Any
discrepancies between the information shown on the drawings and the
actual conditions found in the field shall be reported at once to
the Engineer for resolution.
(b)
Unless otherwise stated, all pipes shall have sand bedding.
Precast concrete structures shall be set on six inches of crushed
stone bedding.
(2)
Drain pipes.
(a)
All storm drain pipes shall be laid true to line and grade between
structures using laser-beam control.
(b)
Pipe bedding, installation and backfill methods shall conform
to the pipe manufacturer's recommendations. Where the pipe is
installed in conditions with poor subgrade or bedrock, shallow depth
of cover, deep cover, or other adverse conditions, install special
bedding, encasement, and backfill as required to protect the pipe.
(c)
No changes in drain structure locations, grades or elevations
shall be made by the contractor without prior approval.
(d)
Pipes located within 10 feet of areas subject to vehicular traffic
shall be backfilled with select granular borrow and compacted in accordance
with the applicable section of these specifications.
(e)
When using flexible pipe materials such as corrugated polyethylene,
the contractor shall take special precautions to protect against crushing
or deflection of pipe. Any such crushed or deflected pipe shall be
removed and replaced.
(3)
Catch basins and drain manholes.
(a)
Construct in accordance with MHD Standard Specifications Section
201.
(b)
Set catch basins and drain manholes on crushed stone bed.
(c)
Install structures to line and grade.
(d)
Install weep holes at each catch basin. Install drain pit outside
of weep holes with 1/4 cubic yard of crushed stone completely surrounded
by a filter fabric envelope.
(e)
Connect subdrains and other pipes into catch basins.
(f)
Catch basins shall have minimum two-foot-deep sumps, or deeper
where required.
(g)
Where required, catch basin outlets shall be equipped with oil
and grease hoods.
(h)
No more than two catch basins shall be connected together. Outlets
from two or more catch basins shall discharge to daylight or be connected
to a drain manhole.
(i)
Any existing storm drains, area drains, roof leaders, subdrains,
tile drains or other drainage pipes which are encountered in the excavation,
whether or not they are shown on the plans, shall be protected, repaired,
replaced, abandoned or connected into the new storm drainage system
as directed by the Engineer.
(j)
No sanitary sewer drain shall be connected into the storm drains.
Any storm drains which are found to tie into sanitary sewers shall
be disconnected and repiped into the storm drain.
(4)
Drainage castings.
(a)
Frames for grates and covers of basins, manholes and inlets
shall be set in accordance with Section 201 of the MHD Standard Specifications.
(b)
The final setting of frames shall be performed after the binder
course paving has been placed so as to match the finished grade of
the top course. At the option of the contractor, binder course may
pave over the structure, which shall be protected with a steel plate.
Pavement shall then be removed and the frame reset to proper line,
square to the curbline, and at the proper grade relative to finished
grade. A concrete collar shall be poured completely around the frame
to the top of binder course.
(c)
Set catch basin frames and grates one inch below adjacent finished
grade to assure proper flow to inlet. Set concrete collar to accept
full thickness of top course at frame. Rake out the top course pavement
to form a "hopper" approximately two feet on each side of the casting.
Do not allow a "feather edge" of pavement.
(6)
Stormwater basin.
(a)
General.
[1]
Construct the stormwater basin as early in the construction
as possible for use as a temporary sedimentation basin.
[2]
Stormwater basin shall be constructed and operational for stormwater
storage prior to construction of the piped storm drainage system.
[3]
Accumulated sediments shall be removed from the sediment basin
during the construction period before they accumulate to 50% of the
sediment storage capacity.
[4]
Prior to final completion of the project, and after the site
is stabilized with permanent vegetation, all sediments shall be removed
from the stormwater basin (and other sediment traps, catch basin sumps,
pipes, and other portions of the storm drainage system).
(b)
Earthwork and outlet structures.
[1]
Construct the excavation and form the embankment using suitable
soils (low permeability), placed and compacted in accordance with
MHD Standard Specifications.
[2]
Construct the basin to the lines and grades shown on the plans,
taking care to assure the elevations and volumes are achieved. The
top elevation of any embankment shall be crowned approximately six
inches above the design grade to allow for settlement.
[3]
Detention basins with a permanent pool deeper than 18 inches
and an embankment height of six feet or more shall have a "safety
shelf" at least four feet wide built into the water-side embankment
approximately one foot to 1 1/2 feet above the normal water level.
[4]
Design and construct other components of the detention basin
in accordance with applicable codes, requirements, and good engineering
practice; such as: sediment forebay, water quality devices, outlet
structures, trash racks, anti-vortex devices, emergency spillways,
stilling basins, pipe outlets, anti-seep collars.
[5]
Where appropriate, install an "awareness fence" (such as wood
post and rail) around the perimeter of the stormwater basin to alert
people that the basin is subject to rapid water rise, and may have
slippery slopes.
[6]
The subdivider's engineer shall review the construction
for conformance to the plans, and arrange for compaction testing and
other quality control measures to assure proper construction in conformance
with the approved plans.
D.
Inspection and testing.
(1)
Storm drainage system shall be inspected for conformance to the approved
plans, and for proper function, prior to final paving.
(2)
Remove accumulated sediments from all catch basins, drain manholes,
drain pipes, sediment traps, and stormwater basins prior to final
inspection.
(3)
Test earth embankments of stormwater basins for proper compaction.
(4)
Conduct as-built survey to verify critical elevations and grades.
(5)
Inspect drain pipes visually for proper line and grade between structures.
(6)
Prepare record plan indicating locations and elevations of underground
structures, tie measurements, and other features.
