STANDARD CONSTRUCTION REQUIREMENS AND DETAILS
CITY MANAGER-The City Manager or his designee (s).
CONTRACTOR-The successful Bidder to whom a contract has been awarded
and who has executed the contract documents.
CUL-DE-SAC-A street with only one outlet that terminates in a
vehicular turnaround. A turnaround may
be circular or T-shaped/hammerhead design.
DEDICATION-The granting by a landowner of specified permanent rights
or land for public use, as shown by a written instrument or drawing.
EASEMENT-A lawful right or privilege of use for a specified purpose over land
owned by another party.
ENGINEER-The City Engineer of the City of Oak Ridge or other representative duly
authorized by the City Engineer.
INSPECTOR-The Engineering Technician or other representative duly
authorized by the City Engineer.
INVERT-The lowest point in the internal cross section of a pipe or other
culvert.
PLANS-The approved plans, profiles, standard details, supplemental plans, and
working drawings, which show the location, dimensions, and details of the work
to be done.
RIGHT-OF-WAY-Land owned by a government agency, reserved for streets,
utilities and other public uses.
STANDARD REQUIREMENTS-The general term comprising all the directions, provisions,
and requirements contained or referred to in this book entitled “Standard
Construction Requirements and Details” (SCRD) and in any subsequent revisions
or additions to this book.
SUBGRADE-That portion of the roadbed prepared as a foundation for the pavement
structure.
VARIANCE-The official provision, by the Planning Commission, of an exemption
from compliance with the terms of conditions of these regulations due to a
unique hardship related to physical characteristics of the property as provided
in Article I, G of the Subdivision Regulations.
AASHTO American
Association of State Highway and Transportation Officials
A.B.S. Acrylonitrile
Butadiene Styrene
ANSI American
National Standards Institute
ASTM American
Society of Testing and Materials
AWWA American
Water Works Association
F Fahrenheit
ft. Foot
fps Feet
per second
gpd Gallons
per day
gpm Gallons
per minute
ID Internal
Diameter
lbs. Pounds
MSL Mean
Sea Level
TDEC Tennessee
Department of Environment and Conservation
TDOT Tennessee
Department of Transportation
NFPA National
Fire Protection Agency
N.E.C. National
Electric Code
OD Outside
Diameter
P.C. Point
of Curvature
P.E. Professional
Engineer
psi Pounds
per square inch
P.T. Point
of Tangency
P.V.C. Point
of Curvature on Vertical Curve
P.V.T. Point
of Tangency on Vertical Curve
Qmax Maximum Discharge
Qmin Minimum
Discharge
RH Relative
Humidity
RLS Registered
Land Surveyor
SCRD Standard
Construction Requirements and Details
SCS Soil
Conservation Service
sec. Second
s.f. Square
feet
V Volts
VAC Voltage-Alternating
Current
Return to Section 1.02 Abbreviations
The intent of these construction requirements and
details is to describe the level of performance to be met when constructing any
infrastructure public improvements within the City.
All construction shall conform to the requirements
and dimensions on the approved construction plans, Subdivision Regulations,
Erosion Control and Storm Water Management Ordinance, Zoning Ordinance, Code of
Ordinances of the City of Oak Ridge, the requirements of the Electric
Department, or as stated in these SCRD.
All work not explicitly described in these documents shall be
constructed in accordance with applicable standards to be found in the latest
edition of the TDOT Standard Specifications for Road and Bridge Construction
and its applicable amendments, or the TDEC, Division of Water Pollution Control
and Division of Water Supply. The
design of streets, storm drainage systems, and grading plans shall be signed
and sealed by a qualified Engineer, Architect or Landscape Architect licensed
in the State of Tennessee. The design
of water systems, sanitary sewer systems and flood control projects shall be
signed and sealed by a qualified Engineer licensed in the State of Tennessee.
It
is the intent of this document to provide guidance for the designer, developer
and constructor of developments and facilities within the City. The City, based on technical merit and
justification by the project designer, will consider materials and practices
differing from or not covered by this document for approval during the design
development stage. The primary interest
of the City is to require materials and methods that employ practices meeting
or exceeding standards known to the trade.
Current specifications and/or the latest revisions shall apply in all
cases where materials are referenced by this document.
During
the construction phase of a project, equal or better materials not specified
may be used provided documentation and samples, necessary for the City to determine
their acceptability, are submitted a MINIMUM of FOURTEEN days before they are
to be used on the construction site.
The City will issue a WRITTEN APPROVAL if the submitted data and samples
are acceptable as an equal material.
Concrete shall be only plant-mixed or transit-mixed
concrete conforming to ASTM C33 for aggregates and to ASTM C94 for ready-mixed
concrete. Any concrete placed that has
a slump over four inches as per ASTM C143, or has a batched time of more than
90 minutes is unacceptable. Concrete
shall not be deposited on frozen subgrade.
Concrete shall not be placed when the air temperature is below 40
degrees Fahrenheit, and the predicted low temperature for the next 24 hour
period is less than 32 degrees Fahrenheit unless proper freeze protection is
provided. All concrete when placed in
the forms shall have a temperature of between 50 and 90 degrees Fahrenheit and
shall be maintained at a temperature of not less than 50 degrees Fahrenheit for
at least 72 hours for normal concrete and 24 hours for high early strength
concrete, or for as much time as is necessary to secure proper rate of curing
and designed compressive strength.
Concrete shall be air entrained with five to seven
percent air. Retarders and accelerators
shall be used only if approved by the City.
The
work of clearing and grubbing shall consist of the cutting, removal, and
satisfactory disposal of all vegetation and all surface debris.
Clearing
and grubbing shall be conducted in a manner to prevent damage to vegetation
that is intended to remain and to prevent damage to adjacent property.
Open
burning of vegetative materials cleared from land is allowed only under certain
conditions. A burning permit must be
obtained from the Fire Department.
Material larger than six inches in diameter may not be burned unless an
approved pit burning operation, including the use of an air curtain destructor,
is employed.
Earthwork
shall be defined as removal of earth from its natural location, or as the
depositing of such material into the proper fill areas as designated on the
plans.
Rock
excavation shall be defined as removal of all rock or boulders that cannot be
economically excavated by proper use of a power shovel or without the use of
explosives. A written PERMIT FOR
BLASTING must be obtained from the Fire Department in accordance with paragraph
2.08 A.
Existing
public streets or highways shall be kept open to traffic at all times by the contractor
unless permission to close these streets, or portions thereof, is granted by
the City. Public notice of street
closures may be required by the City.
Proper
and sufficient traffic control such as barricades, lights, signing and other
protective devices shall be required to be installed according to the latest
edition of the “Manual on Uniform Traffic Control Devices.” The City may require the submission of a
Traffic Control Plan showing traffic control measures during all phases of
construction.
The
presence of a City Inspector at the work site shall in no way lessen the
contractor or developer’s responsibility for conformity with the approved plans
and specifications. City inspectors
perform inspections based on availability of time and all elements of
construction cannot be reviewed at the time of their construction. Any materials and/or workmanship found not
to be in conformance to the approved plans and specifications, at any stage of
development, shall be rejected by the City.
The contractor/developer shall have no claim for losses suffered due to
any necessary removals or repairs resulting from unsatisfactory work or
unacceptable materials. Any work, which
has been covered without the inspector’s approval, shall, at the inspector’s
request, be uncovered and be made available for inspection at the contractor’s
expense.
During
the course of designing, and prior to construction of a utility or street
project, permits from the City, State and Federal government, if applicable,
must be obtained. It is the
responsibility of the owner/developer to ensure that all fees and applications
for permits are submitted.
A grading permit application may be
obtained at the Municipal Building in the Community Development
Department. See Section
4.00, Soil Erosion and Sedimentation Control for further details.
A curb cut permit including a site
plan must be submitted to the City for approval. A permit application may be obtained at the Municipal Building in
the Community Development Department. A
minimum of five working days should be allowed for approval/disapproval except
for arterial street curb cuts. Access
to an arterial street must be reviewed by the Traffic Safety Advisory Board and
approved by City Council, which will take approximately one month.
A burning permit shall be obtained a
minimum of 24 hours prior to any burning.
This permit is obtained from the Fire Department.
A written permit for blasting is
required any time there is to be transportation, use or storage of explosive
materials. This permit is required a
minimum of 24 hours before bringing such materials into the City and can be
obtained from the Fire Department.
Proof of insurance (original policy in the amount of $1,000,000 public
liability) and a State of Tennessee Explosive Users Identification card are
required.
After
approval by the City, plans for sanitary sewer/water extensions and State
highway entrances shall be submitted to the appropriate State agency as
required. It is the responsibility of
the owner/developer to ensure that all submittals of plans, permit applications
and fees are made.
For any proposed extension of the public sewer or
water system, approval from the TDEC is required. Privately maintained sewer or water systems may require approval
by the TDEC as directed by the City.
Fee schedules and application forms may be obtained from the TDEC.
Owners/developers must obtain permission from the
TDEC to discharge storm water from any construction or grading activity that
disturbs five acres or more of land.
Application for permission can be obtained by submitting a Notice of
Intent (NOI) on a State NOI form to the TDEC with a copy provided to the City.
Owners/developers may be required to
obtain permits from the TDEC and/or US Army Corps of Engineers and/or Tennessee
Valley Authority for work in or around “Waters of the State”, wetlands or other
watercourses.
A permit from TDOT is required for any proposed
entrance onto a State highway. The
State highways include State Routes 58, 61, 62, 95, and 170. Contact TDOT, Region 1 Traffic Division
office in Knoxville.
When
allowed by the City, tree/shrub planting in the right-of-way shall be
controlled by the following planting methods:
Trees
planted in the right-of-way shall be positioned so that when mature,
intersection sight distances will not be limited and street safety will not be
adversely affected. Trees shall not be
located over existing water mains, sewer mains, or electric power lines and
shall be at least 15 feet from a fire hydrant.
All
trees planted in the right-of-way shall be watered and maintained by the
owner/developer for a period of one year after planting or until suitable
maintenance is provide by the City or by occupants of properties by prior
agreement with the City.
All
streets within the City of Oak Ridge shall conform to the City Comprehensive
Plan both as to the general alignment and right-of-way widths.
All
public streets shall be designed and constructed as specified herein and in
accordance with Subdivision Regulations unless the TDOT Standard Specifications
are applicable. The TDOT standards
shall be used on all existing State roads, extensions of existing State roads,
or roads to be maintained by the TDOT.
When a street is planned for future
extension or to additional developable property, a temporary turn-around shall
be provided and paved and roadway standards shall meet overall requirements of
the future full build-out roadway. Curb
for such turn-arounds need not be provided unless it is essential to control
drainage. Additional right-of-way for
such turn-arounds may be provided by a temporary easement, which would lapse
when the road is extended.
Arterial streets shall have a
minimum right-of-way width of 90 feet with a minimum lane width of 12
feet. Where on-street parking is
desired, an additional eight feet of pavement shall be required for each
parking lane. When arterial streets are
also State highways, the TDOT may require higher standards.
NOTE: ALL STREETS THAT FOLLOW ARE DESCRIBED IN
THE OAK RIDGE ZOINING ORDINANCE AS SECONDARY AND MINOR ROADS.
Collector streets are used for
through traffic rather than for providing access to adjoining properties. Access to adjacent property should be
planned and controlled so that minimum disturbance is made to the
traffic-moving efficiency of the collector street. Major collector streets shall have a minimum right-of-way width
of 80 feet and a minimum lane width of 12 feet. Where parking is desired on the right-of-way, an additional eight
feet of pavement shall be required for each parking lane.
Minor collector streets have two
open ends once completely developed; each end generally connects with another
street. One or more other streets may
intersect it between its two open ends.
Property fronting on either side of the street may have access to the
street. Minor collector streets may
carry through traffic within the immediate vicinity. Minor collector streets shall have a minimum right-of-way of 70
feet and a minimum lane width of 12 feet.
Local streets are used primarily for
providing access to adjacent properties.
Vehicles moving on these streets should have an origin or destination in
the immediate vicinity, and all types of through traffic should be minimized
through initial design of its connections with other streets. Local streets should have a minimum
right-of-way width of 50 feet and a minimum pavement width of 28 feet. Marginal access streets, dead-end streets,
or one of several other types may perform the function of local streets. Minimum design standards for streets in
low-density developments are provided in Standard Detail 3.17.
Marginal access streets may be
required along expressways, arterials and collector streets to provide access
to abutting properties and shall be located on the right-of-way. The right-of-way shall be contiguous with
right-of-way of the major street and extend a minimum of 10 feet beyond the
back of the outside curb of the marginal access streets. The minimum roadway width shall be 24
feet. The Zoning Ordinance further
regulates such streets.
Dead-end streets are local streets
having only one open end providing no access to another street. No other street intersects between the two
ends, and dead-end streets shall have a minimum right-of-way width of 50 feet
and a minimum pavement width of 28 feet.
They shall be provided at the closed end with a turn-around having an
outside street diameter of at least 80 feet and a street right-of-way diameter
of at least 100 feet as detailed in Standard Detail 3.01
A “hammer-head” or other
non-circular turn-around design may be approved by the Planning Commission as a
variance in cases of difficult topography or similar unusual situations,
provided that such design can accommodate the turn-around of fire, solid waste
collection, and delivery vehicles as determined by the City.
Alleys are minor roadways which
afford a secondary means of vehicular access to the back or side of properties
otherwise abutting a street, and which may be used for public utility
purposes. Alleys generally have two
open ends, and each end connects with a street. Alleys shall have sufficient pavement width to adequately serve
the anticipated vehicular traffic.
When a subdivision has a unified
plan which utilizes a more innovative approach to street standards not meeting
the above standards in Section A(1-7), the Planning
Commission with advice from the City, may approve a different standard which
should be equal to or better than the above standards. A traffic engineering impact study may
justify sections of reduced roadway and right-of-way width.
All streets shall conform to the
City Comprehensive Plan when applicable or shall be designed and located in
proper relation to existing streets and environment. The alignment of arterial and collector streets should be direct
as possible but consistent with topography and preserving developed properties
and community values. Residential
streets shall be designed to discourage high-speed traffic and minimize
excessive cuts, fills and through traffic.
Traffic calming principles may be required if the basic design does not
discourage traffic speeds, which are inappropriate for the type of street being
planned.
The design of streets shall conform
to the curve controls in Table 3.2 at the end of this
section.
Minimum tangent lengths between
reverse curves on arterial and collector streets shall be computed to provide
for superelevation transition lengths in accordance with the TDOT Standards
Specifications. Local streets and other
lower classified streets not requiring superelevation should provide a minimum
tangent length of 75 feet between reverse curves. The minimum tangent length of an approaching intersection should
be 50 feet for local and lower classified streets measured from pavement
edge. All intersections of streets
classified as collector or greater should have a tangent section not less than
100 feet approaching the intersection.
Compound horizontal curves with the
same direction of curvature shall have the radius of the flatter circular arc
no more than one and one-half times the radius of the sharper circular
arc. Streets shall intersect each other
at right angles whenever possible. The
minimum desirable intersection angle is 80 degrees unless physically
impossible, but at no time shall a street intersect any other street at less
than 60 degrees.
Intersections with arterial streets
should be at least 800 feet apart.
There should be a minimum of 200 feet between centerlines of street jogs
on collectors and 125 feet between centerlines along other streets.
Superelevation is to be used on all
arterials and collectors.
Superelevation shall conform to the TDOT and AASHTO standards for
superelevation design.
Street grades shall be established
with respect to existing topography to avoid excessive grading and filling, and
the removal of existing trees and vegetation whenever practical.
The minimum grade allowed on any
street shall be one-half of one percent.
Maximum grade allowed shall be seven percent for arterial streets, nine
percent for collector streets and 12 percent for other streets.
At every street intersection, one
street will be considered the major street and the other will be considered the
minor intersecting street. Questions
regarding which intersecting street is to be the major/minor street will be resolved
by the City. Major street grades will
be carried through the intersection with no break in centerline grade or cross
slope to the outside edge of through lane.
Minor street grades shall connect at the edge of the major street with a
smooth connection using crest or sag vertical curves or spline curves if
necessary to approximate a vertical curve.
Grades approaching an intersection through vertical curves should not
exceed five percent for the last 100 feet before the intersection. Minor grade breaks (less than two percent)
at the intersecting edge of pavement will be acceptable for local streets. Minor street intersecting road grades should
be set to direct storm drainage away from the major street edge and toward the
beginning (PC) of curve at the curb return.
Maximum grades and vertical curve
controls found in Table 3.2 shall be followed at all
times.
A minimum radius of 25 feet measured
to the face of curb shall be required where local streets intersect.
A minimum radius of 30 feet measured
to the face of curb shall be required where a local street intersects with a
collector street. It is recommended
that the designer consider larger radii or three centered compound curves where
needed to provide for turning movements of larger vehicles.
A minimum radius of 40 feet will be
required where collectors intersect arterial streets.
Cul-de-sac and “hammerhead”
turn-arounds shall be designed as shown in Standard Detail 3.01.
Non-residential and residential
driveways shall conform to the City Zoning Ordinance, Section 6-603, “Vehicle
Access Control” for driveway width, radii, spacing, etc. Where new driveways are constructed at an
existing curb and gutter or sidewalk section, the driveway must be constructed
in accordance with Standard Details
3.02 and 3.03 for
concrete driveway aprons. New
residential curb cuts on existing streets with curb and gutter that are
maintained by the City shall be installed by the City at the owner’s expense
unless otherwise approved by the City.
When a residential driveway serves a
residence located more than 150 feet from a public roadway, the driveway should
be at least 12 feet wide, be minimally passable in all weather conditions, and
constructed at a maximum slope of 12 percent to assure proper fire protection.
To eliminate numerous driveway curb
breaks and to reduce maintenance costs, the use of valley curb and guttering
similar to Standard Detail 3.09,
is preferred in residential areas.
Street curb and gutter shall be standard 2’ 3” or 2’ 6” curb and gutter
as shown on Standard Details
3.05 and 3.09 unless
otherwise approved by the City. Curb
and gutter shall be machine formed unless otherwise approved by the City. Where curb and gutter is used, mineral
aggregate base course shall be required to extend beyond the curb and gutter in
accordance with Standard Detail
3.04. Standard Detail 3.06 shows a
standard method of removing existing concrete curb and gutter. Standard Detail 3.08 shows a
minor drain through a curb.
In all subdivisions the
owner/developer shall provide a cement concrete curb or curb and gutter, the
face of which shall not be less than six inches in height unless otherwise
approved by the City. Backfill shall
normally slope toward the curb. Curbs
or curb and gutter shall be machine formed unless otherwise approved by the
City. Standard Detail 3.07 shows a
typical machine formed curb section.
All Parking Lots shall conform to
the City Zoning Ordinance, Section 6-606, “Required Off-Street Parking.”
Sidewalks shall be constructed in
accordance with the latest edition of the TDOT, Standard Specifications for
Road and Bridge Construction with the following incorporated changes:
(a) The width of
sidewalks shall be in accordance with the City Subdivision Regulations.
(b) Minimum thickness
of a sidewalk shall be four inches. At
locations where a driveway crosses a sidewalk, a six-inch minimum depth is
required. Sidewalks shall have a
uniform slope toward the roadway of two percent with a tolerance of one percent
unless otherwise indicated on the plans.
The unpaved utility strip between the sidewalk and the back of curb
shall have a grade of not less than four percent nor greater than six percent
sloped toward the roadway. For typical
sidewalk sections and details, see Standard Detail 3.10.
(c) Sidewalk
construction shall meet the requirements of the Americans with Disabilities Act
(ADA) Accessibility Guidelines for Buildings and Facilities found in 36 CFR
(Code of Federal Regulations) Chapter XI, Part 1191. Typical handicap ramp details for sidewalk construction are shown
on Standard Details 3.11, 3.12 and 3.13.
(d) Materials
·
Concrete: Concrete used shall meet the requirements of
the TDOT Standard Specifications for Class “A” Structural Concrete.
·
Asphalt
Walkways: Where permitted, asphalt
walkways shall be constructed of the TDOT-approved “E” mix (min. two inch
thickness) for asphaltic concrete material with four inch minimum thickness of
base material over compacted subgrade.
·
Curing
Compound: A membrane-curing compound
shall be applied on concrete sidewalks as soon as possible after finishing. The compound shall conform to the
requirements of Liquid Membrane-Forming Compounds for Curing Concrete, ASTM
C309.
·
Base
Material: All concrete sidewalks shall
have four inches of base material consisting of one and one-half inch maximum
size mineral aggregate base from an approved material plant and shall meet
requirements of Section 3.04.
(e) Construction Methods
·
Excavation: Excavation required for the construction of
sidewalks and driveways shall be to the established lines and grades as shown on
an approved plan.
·
Fine
Grading: The contractor shall do all
necessary filling, leveling and fine grading required to bring the subgrade to
the exact grades specified and compacted to 90 percent standard density in
accordance with ASTM D698. Any
undercutting excavation may be filled with gravel thoroughly compacted in place
to the satisfaction of the City.
·
Forms: Forms shall be of a material and section
satisfactory to the City, straight, free from warp and of a depth equal to the
thickness of the finished work. They
shall be securely staked to line and grade maintained in a true position during
the depositing of concrete.
·
Finishing: Concrete sidewalks shall be finished to a
true, even surface. They shall be
troweled and then brushed transversely to obtain a smooth uniform brush
finish. Joints and sides shall be edged
with suitable tools.
·
Joints:
Expansion joints for sidewalks shall be formed, using expansion joint material
of an approved type and shaped to the section.
Expansion joints shall be placed in the sidewalk at 40-foot intervals or
as otherwise approved by the City.
Expansion joints shall also be placed at all intersections, sidewalks
with concrete driveways, curbs, formations and other sidewalks and at other
locations adjacent to old concrete work.
Similar material shall be placed around all obstructions protruding into
or through sidewalks or driveways. All
expansion joints shall be one-half inch in thickness. Edges of all construction and expansion joints and other edges of
all sidewalks shall be finished to approximately a one-fourth inch radius with
a suitable finishing tool. Sidewalks
shall be grooved with a grooving tool on five-foot spacing in accordance with
the TDOT Standard Specifications. When
sidewalk is against the curb, expansion joints and tooled grooves shall match
those in the curb.
Intersections shall be designed to
meet the minimum horizontal and vertical sight distance standards provided in
the latest edition of A Policy on Geometric Design of Highways and Streets
published by AASHTO. Minimum sight
distances for street intersection designs governed by passenger vehicles are
provided in Table 3.1.
Design sight distances for vehicle turning movements shall be listed on
all roadway plans submitted to the City for approval and shall meet the minimum
requirements as shown below.
Minimum Sight Distance Along Major
Street
For a Passenger Vehicle Stopped on
the Cross Road
|
|
Sight Distance (Feet) for Two Lane
Major Road |
|
|
Design Speed MPH |
Passenger Vehicle Crossing
Intersection |
Passenger Vehicle Turning Left or
Right |
|
25 |
240 |
285 |
|
30 |
300 |
350 |
|
40 |
400 |
570 |
|
50 |
500 |
840 |
Table 3.1 (Cont’d)
|
|
Sight Distance (Feet) for Four
Lane (Undivided) Major Road |
|
|
Design Speed MPH |
Passenger Vehicle Crossing
Intersection |
Passenger Vehicle Turning Left or
Right |
|
25 |
290 |
300 |
|
30 |
340 |
360 |
|
40 |
450 |
580 |
|
50 |
560 |
855 |
For Single Unit and Semi-trailer sight distance
requirements, refer to the latest version of A Policy on Geometric Design of
Highways and Streets published by AASHTO when design is governed by the
larger design vehicles.
Sight distances shown are based on driver eye height of 3.5
feet and height of object at 4.25 feet.
Driver’s eye position located 20 feet from edge of through lane on the
major road. Sight distance shall be
measured along the path on the major street.
Table values are based on level grades and right angle
intersections. See AASHTO Policy for
sight distance adjustments when necessary.
Utility placement in the
right-of-way shall be in accordance with Standard Detail 3.15. Deviations from standard placement
requirements will be considered by the City.
The following standards will be
required for the grading, soil stabilizing, preparation of the subgrade, placement
of crushed stone base, priming, and application of pavement for all residential
streets and right-of-ways.
All streets shall be graded to such
a width that pavements and sidewalks can be constructed generally to the plans
indicated on Standard Detail
3.14. A utility strip six feet or
more behind the back of curb is required on both sides of the roadway. Sidewalk may occupy some or all of this
utility strip. This utility strip shall
normally be sloped toward the roadway.
All boulders, tree stumps, organic
material, soft clay, spongy material and any other objectionable material shall
be removed to a depth of at least two feet below the graded surface in cuts,
and the natural ground in fills. This
objectionable matter shall be removed from within the right-of-way limits and
disposed of in such a manner that it will not become incorporated in the fills,
nor in any manner hinder proper operation of the roadway drainage systems. Rock, when encountered, shall be removed to
a depth of 12 inches below the subgrade.
Where necessary, additional easements shall be required over and above
normal right-of-way dedication to maintain banks and drainage where fill or cut
extends beyond the right-of-way. Trees,
stumps and all other vegetation in fill areas shall be removed prior to
filling.
In order to ensure proper bond and
prevent slipping between the original ground and the fill, the surface of the
original ground shall be scarified to a reasonable depth. Where fills are made on hillsides or slopes
steeper than 4:1 (4 Horizontal:1 Vertical), steps shall be cut into the
original ground before filling is begun.
The selected fill material shall be
placed in layers which, when compacted, shall not exceed eight inches. Each layer shall be spread evenly and shall
be thoroughly blade mixed during spreading to ensure uniformity of material in
each layer.
The
moisture content of the fill material shall be such that the fill can be
compacted to the specified standard Proctor dry density as determined by ASTM
D698. If the moisture content of the
fill material is below the amount needed to create the necessary density, the
proper amount of water shall be added.
Similarly, if the moisture content of the fill material is above the
needed amount necessary to create the specified density, the fill material
shall be aerated by blading or other satisfactory method until the moisture
content of the fill material is satisfactory.
After
each layer has been placed, mixed and evenly spread, it shall be compacted to
95 percent of maximum density as determined by ASTM D698. However, not less than 98 percent maximum
density, standard Proctor method, at optimum moisture will be acceptable for a
depth of nine inches below the subgrade under all proposed paving areas shown
on the plans. Compaction shall be by
means of tamping or sheeps foot rollers, multiple-wheel pneumatic-tired rollers
or other types of rollers or equivalent which will be able to compact the fill
to the desired density. Rolling shall
be accomplished while the fill material is at the optimum moisture content
range. Rolling of each layer shall be
continuous over its entire area and sufficient trips shall be made by the
rolling equipment to ensure that the specified density has been obtained.
Excavating
of cut areas shall continue until these areas conform to the lines, grades,
slopes, and typical cross-sections shown on the accepted plans. Placing, spreading, filling, and compacting
areas to be filled shall also be continued alternately until these areas
conform with the lines, grades, slopes, and typical cross-sections shown on the
accepted plans.
Banks of cuts and fills shall be
graded to slopes not exceeding 2:1 (2 horizontal:1 vertical). The City may grant an exception in instances
where unusual soil or topographic conditions warrant a deviation from these
established maximum slopes. When slopes
in excess of 2:1 are deemed necessary, the slope must be adequately stabilized
to prevent erosion and degradation.
Slopes 2:1 or less shall be sodded or planted with soil-fixing grass,
shrubs or vines. The viability of such
soil-fixing grass, shrubs and/or vines shall be guaranteed by the subdivider
for a period of one year from date of planting or final acceptance whichever is
latest. For additional cut and fill
slope requirements, the City’s “Erosion Control and Storm Water Management
Ordinance” should be consulted.
Soil
samples for California Bearing Ratio (CBR) tests shall be collected by an
independent testing laboratory to determine the required pavement design. Subgrade conditions shall be based upon
corrected soaked CBR values at 0.1-inch penetration as per ASTM D1883. Soil samples used for the CBR tests shall be
obtained at intervals not greater than 1,000 feet. Where field conditions warrant, the City may require additional
tests at intervals less than 1,000 feet.
The CBR of the soil tested will be compared to those in the following Table CBR-1. The
Table indicates the three major soil types found in the area and the usual
range of CBR values to be expected.
|
Cherty-Clay |
7.01-or greater |
Good |
|
Weathered Shale |
4.01-7.00 |
Fair |
|
Silty-Clay |
1-4.00 |
Poor |
Required pavement design Structural Numbers for respective
subgrade CBR values are as follows:
TABLE CBR-1
|
7.01 or greater |
2.30 |
|
4.01-7.00 |
2.85 |
|
1-4.00 |
3.25 |
Structural Number values per inch of thickness are provided
below for each of the major pavement components:
TABLE CBR-1
|
Mineral Aggregate Base |
0.14 |
|
TDOT “BM” Mix Bituminous Base |
0.40 |
|
TDOT “D” or “E” Mix Asphaltic
Surface |
0.40 |
The
maximum dept of “D” or “E” Mix shall be two inches, and the minimum depth of
“BM” mix shall be two and one-half inches on any project. The following Table CBR-2
lists typical depths of pavement materials suggested to meet the required
Structural Numbers for various subgrade CBR ranges.
|
CBR Range |
Required Structural No. |
Base (Inches) |
“BM” Mix |
“D” or “E” Mix |
|
7.01 or greater |
2.30 |
5 |
2 ˝” |
1 ˝” |
|
4.01-7.00 |
2.85 |
6 |
3 ˝” |
1 ˝” |
|
1-4.00 |
3.25 |
6 |
4 ˝” |
1 ˝” |
Alternative
paving materials and methods, such as concrete, may be used if the developer
provides a professional engineer’s report, acceptable to the City, to
substantiate that the proposed design meets the established bearing strength
guidelines for soil types identified.
Rigid pavement design shall follow the latest AASHTO method.
No
fill material shall be placed, spread, or rolled while the ground or fill is
frozen or thawing or during unfavorable weather conditions. When heavy rains interrupt the work, fill
operations shall not be resumed until the moisture content of the fill material
is within a range that will permit compaction to a minimum density of 95
percent (98 percent for top nine inches of subgrade) in accordance with ASTM
D698.
All public bridges or private
bridges serving more than one property are to be designed to withstand HS-20
highway loading unless otherwise approved by the City and shall be properly
signed and sealed by a Tennessee Professional Engineer. Bridge design and construction should be in
accordance with the AASHTO, Standard Specifications for Highway Bridges.
All
streets and parking lots shall be marked in accordance with the TDOT Standard
Specifications or the latest revisions of the MUTCD. Thermoplastic pavement markings shall be required in areas of
existing thermo-plastic markings, on arterial streets, high volume collector
streets, and may be required on other streets if deemed necessary by the City
for improved safety and durability such as high volume intersections. All specialty markings (i.e. pavement
arrows, stop bars, etc.) shall be thermoplastic markings. The City may require painted guide markings
prior to placement of thermoplastic permanent markings.
Mineral
Aggregate Base material shall be in conformance with the TDOT Type A, Grade D,
Section 903.05, and shall be placed in accordance with the TDOT Section
303. The compacted density shall not be
less than 95 percent of maximum density determined in accordance with ASTM
D698. The minimum thickness shall be
five inches in accordance with Table CBR-2.
If
required, the prime coat shall be applied in accordance with the TDOT Section
402 at a rate of approximately 0.35 gallons per square yard of base stone.
All
roads must have a layer of bituminous base applied in accordance with the TDOT
Section 307, Grade BM. The depth of the
layer will be determined by the results of the CBR test performed on a
representative subgrade soil sample. Table CBR-2 lists the required pavement layer thickness
for typical soil CBR values expected to be found in this region.
The
wearing surface shall consist of a minimum one and one-half inch asphaltic
concrete surface course conforming to the TDOT Section 411, Grade D or E and
shall be installed in conformance to the TDOT Section 407.
No
construction shall be conducted until the following applicable items have been
obtained: all grading permits, state
permits (if applicable), performance bonds if required, and City of Oak Ridge
subdivision and plan approval if required.
No base materials shall be placed on
a roadway until the subgrade, underlying utilities including storm, water,
sewer, and all appurtenances have been inspected and meet or exceed these
requirements.
Field density testing should be
completed for each layer of fill placed and, as a minimum, will be required for
every other layer of fill placed in accordance with Section
3.03. A minimum of one test per
1,000 square yards of surface area placed will be required for each tested
layer of fill. Field density testing of
the finished subgrade in cuts and fills will be required with a minimum of one
test per 1,000 square yards of subgrade surface area. Proof rolling of finished subgrade with a loaded tandem dump
truck shall be required.
Field density testing of mineral
aggregate base construction will be required at a frequency of one test per
1,000 square yards of surface area for each layer of mineral aggregate base
constructed. Proof rolling of finished
mineral aggregate base shall be required before placement of bituminous layers.
Field density testing of Bituminous
Base and Asphaltic Concrete surface courses will be required as specified in
the TDOT Section 407.15 except that frequency of testing shall be based on
division of the pavement into 5,000 square yard lots with five density tests
per lot.
All field and laboratory testing of
earthwork, subgrade, mineral aggregate base, bituminous base and asphaltic
concrete surface shall be performed by a city-approved independent testing
laboratory and provided at the expense of the developer. Test reports shall be submitted to the City. The City may also require the submittal of
an asphalt job mix formula before paving operations begin.
No
concrete shall be placed until the forms have been set and the City has
approved subgrades.
Subgrade shall be excavated to the
required depth, and shaped to the proper cross-section. Where tree roots are encountered, they shall
be removed to a depth of one foot below finished subgrade for the full width of
excavation. The subgrade shall be
stable and thoroughly compacted.
Forms shall be set and maintained
true to the required lines, grades, and dimensions. Forms shall be constructed with material of such strength and
rigidity to prevent any appreciable deflection between supports. Straight forms shall be within a tolerance
of one-eight inch in ten feet from a true line horizontally or vertically. Forms shall be thoroughly cleaned of all
dirt, mortar and foreign material before being used. All inside form surfaces shall be thoroughly coated with
commercial quality form oil.
When
required, fire lanes shall be a minimum width of 20 feet and shall be properly
marked and signed to designate the access as a “fire lane” as specified by the
Fire Chief. The surface of the fire
lane shall be paved with an all weather-driving surface suitable for fire
fighting equipment.
Street
signs within subdivisions, which will be maintained by the City, shall be
installed by the developer and shall be consistent with the Manual for Uniform
Traffic Control Devices and Supplements.
All signs shall be purchased and installed by the developer before
recording of the final plat so as to be in place prior to any issuance of
building permits. All signs on the
public right-of-way, which are not consistent with the Manual for Uniform Traffic
Control Devices, must be approved by the City and privately maintained.
Where
new streets connect to existing streets, saw cutting and/or milling of the
existing city street shall be performed along the edge of the existing street
at a length equal to the width of the new street’s pavement. The width and depth of milling shall be
determined by the City.
|
|
Vertical Curve
Controls |
||||||
|
|
Minimum Design
Speed (MPH) (1) |
Maximum
Superelevation (ft/ft) (2) |
Minimum Radii
(ft) |
Maximum Grade |
Length Crest |
Absolute Minimum
Length Crest |
Length Sag |
|
Expressways |
Design standards
shall conform to Federal and TDOT standards |
||||||
|
Arterial Streets |
50 |
0.06 |
850 |
7% |
160A |
150’ |
110A |
|
Collector Streets |
40 |
0.04 |
575 |
9% |
80A |
100’ |
70A |
|
Local Streets |
30 |
Normal Crown |
300 |
12% |
30A |
80’ |
40A |
|
Marginal Access
Streets |
30 |
Normal Crown |
300 (3) |
12% |
30A |
80’ |
40A |
|
Dead End Streets
(Cul-de-Sacs 600 ft or less) |
25 |
Normal Crown |
150 |
12% |
20A |
50’ |
30A |
Table 3.2
A - Algebraic
difference in grades
1.
Design
speed shall be at least five-(5) mph greater than posted speed.
2.
The
superelevation tables found in A Policy on Design of Urban Highways and
Arterial Streets – 1990 or latest edition published by the American Association
of State Highway and Transportation Officials will be used for determining the
actual rate of superelevation “e” at various radii. Superelevation transitions shall be designed in accordance with
TDOT standards.
3.
Radii
may be reduced at turnouts and intersections.
Temporary
and permanent erosion control measures shall be provided for all land
disturbing work in accordance with the City of Oak Ridge Erosion Control and
Storm Water Management Ordinance and a storm water management plan approved by
the City. A grading permit shall be
obtained from the City prior to beginning site work. Temporary measures shall be installed and inspected by the City
for compliance prior to any other land disturbing activity. All temporary measures shall be maintained
until the permanent measures have taken effect. All permanent erosion control measures shall be incorporated into
the work at the earliest practical time.
Temporary and permanent measures shall be coordinated to provide
effective and continuous erosion control throughout the construction and post-construction
period to minimize siltation of streams, lakes, reservoirs and other
impoundments, ground surfaces, and other property.
Silt
fences shall be installed at the toe of all fill slopes and any other necessary
locations as directed by the City. Silt
fences shall be erected in accordance with Standard Detail 4.01.
To
minimize erosion, diversion ditches/berms should be designed for and installed
at the top of major cut and fill slopes and at any other necessary locations as
directed by the City. Berms and slope
drains on fill sections should be considered as needed. Diversion ditches shall be installed in
accordance with Standard Detail
4.08.
Construction
entrances shall be installed at all points of access to construction
sites. Any access point, which is not a
construction entrance, should be barricaded to prevent its use. Construction entrances shall be installed in
accordance with Standard Detail
4.07. The City may require
additional measures, such as vehicle washing, to assure control of sediments on
site.
Sediment/filter
basins shall be installed at all points where accumulated runoff is released to
natural drainage channels required by design or as directed by the City. Sediment/filter basins shall be sized to
hold 1,800 cubic feet of sediment for every acre of denuded area tributary to
the structure. Typical sediment/filter
basins are shown on Standard
Details 4.02 and 4.05.
Seeding
and mulching is required immediately upon completion of construction
phases. All disturbed areas shall be
dressed with topsoil to a depth of three inches. The top two inches shall be pulverized to provide a uniform
seedbed. Agricultural lime should be
applied at the rate of 100 lbs./1,000 square feet immediately before
plowing. Seed should be tall fescue
applied at the rate of 2.5 lbs./1,000 square feet.
Fertilizer
(5-10-10 or equivalent) should be applied to all disturbed areas at a rate of
20 lbs./1,000 square feet. Mulching
should consist of small grain straw applied at a rate of 100 lbs./1,000 square
feet.
If active construction ceases in any
area for more than 30 days, all disturbed areas shall be seeded, mulched, and
tacked unless written approval is granted by the City.
All vegetation shall be maintained
for a period of one year from planting or until suitable maintenance is
provided by the City or occupants of properties. Planting should be done during favorable weather conditions.
After construction is complete, all
disturbed areas shall receive a permanent ground cover in accordance with the
seeding and mulching schedule as identified in the latest edition of the TDOT
Standard Specifications unless temporary measures are acceptable by the City.
After construction is complete, all
points of storm water release shall be protected by riprap dissipation pads or
other measures designed to reduce discharge velocities to non-erosive
levels. The dissipation pads shall be
designed and constructed with either an engineering fabric or washed stone
barrier between the dissipation pad and the natural ground. Calculations shall be furnished to indicate
the sufficiency of the dissipation pads specified. Riprap pad design shall be in accordance with SCS or other
commonly accepted methods.
All
computations and assumptions used to formulate a storm water management plan
shall be submitted to the City for review.
Refer to the TDEC requirements for storm water management plans and the
City Erosion Control and Storm Water Management Ordinance for design criteria.
Return to
Section 4.00 Soil Erosion & Sedimentation Control
Trenches
for water distribution lines, sanitary sewer lines, force mains, and storm
sewer lines shall be excavated to the required depth to permit installation of
the pipe along the lines and grades shown on the construction drawings. The minimum trench width at the top of the
pipe shall be at least 16 inches greater than the outside diameter of the pipe
to allow for proper compaction. Where
excavation is in rock, the rock shall be removed to a depth of at least six
inches below finished pipe grade and shall be backfilled with materials in
accordance with these specifications.
Where wet soil conditions are encountered, trenches shall be stabilized
with #2 stone and with a base layer of #57 stone.
All
pipes shall be laid in accordance with the manufacturer’s recommendations. The subgrade at the bottom of the trench
shall be shaped to secure uniform support throughout the length of the
pipe. A space shall be excavated under
the bell of each pipe to provide space to relieve bearing pressure on the bell
and to provide room to adequately make the joint. Open ends of water and sanitary sewer pipe shall be plugged with
a standard plug or cap at all times when pipe laying is not in progress. Trench water shall not enter the pipe. Backfill material shall be free from
construction material, debris, frozen material, organic material, or unstable
material. Backfill material shall be free
from stones greater than four inches in diameter.
Trench backfill under new and
existing roadways and extending to three feet beyond the back of curb or edge
of shoulder, measured perpendicular from the centerline shall be in accordance
with Standard Details 5.01
and 7.12.
All pavement cuts must have approval
from the City. All trenches shall be
properly backfilled at the end of each working day unless otherwise approved by
the City. All pavement cuts shall be
repaired within a maximum of three days from the date the cut is made. If conditions do not permit a permanent
repair within the given time limit, permission to make a temporary repair must
be obtained from the City.
In
locations where open pipe trenches are not allowed as determined by the City,
dry bore and jack operations may be allowed.
Smooth wall steel pipe may be jacked through dry bores slightly larger
than the pipe bored progressively ahead of the leading edge of the advancing
pipe. The spoil material shall be
mucked by the auger back through the pipe during the boring operation. As dry boring progresses, each new section
of the encasement pipe shall be butt-welded to the section previously jacked
into place.
In the event that an obstruction is
encountered during the boring and jacking operation, the auger is to be
withdrawn and the excess pipe is to be cut off, capped, and filled with 1:3
cement grout at a sufficient pressure to fill all voids before moving to
another boring site.
Size and wall thickness of smooth
wall encasement pipe shall be as follows:
|
Pipe Size (O.D.inc.) |
Wall Thickness (in.) |
|
12 ľ |
0.188 |
|
16 |
0.250 |
|
18 |
0.250 |
|
20 |
0.250 |
|
24 |
0.250 |
|
30 |
0.312 |
|
36 |
0.375 |
Casing pipe shall be installed with
a minimum cover of four feet under pavement surface.
All carrier pipe shall be mechanical
joint ductile iron pipe resting on treated timber skids as shown on Standard Detail 5.02 so as to
prevent damage to the pipe joints. Pipe
joints shall not contact the interior of the casing pipe. No blocks or spacers shall be wedged between
the pipe and the top of the casing.
Casing pipe shall have the following minimum sizes:
|
Carrier Pipe Size (in.) |
Wall Thickness (in.) |
|
4 |
12 ľ |
|
6 |
12 ľ |
|
8 |
18 |
|
10 |
20 |
|
12 |
24 |
|
14 |
26 |
|
16 |
28 |
Water
distribution systems shall be constructed in accordance with the latest edition
of the TDEC “Public Water Systems Design Criteria.” If discrepancies are found between the TDEC and City
requirements, the more stringent shall apply.
All public water mains shall be
located within dedicated right-of-ways and/or dedicated easements with a
minimum width of 10 feet, centered about the pipe. An easement of 15 feet shall be required where the depth is greater
than five feet but less than eight feet.
An easement of 20 feet shall be required where depths are greater than
eight feet. Pipe systems shall be
arranged in loops unless otherwise permitted by the City. No part of any structure, including foundations
and overhangs are permitted in an easement.
Where deemed appropriate by the
City, all systems in non-residential areas will have proper metering and
backflow prevention devices installed as close to the existing city-owned main
as possible. Final determination of
their location shall be at the sole discretion of the City.
In residential areas, in order to
obtain maximum available fire flow, mains shall be a minimum of six inches in
diameter. Four-inch mains are permitted
on residential cul-de-sacs less than 400 feet in length provided no fire
hydrants are required on the cul-de-sac and adequate pressure is
available. Use of two-inch mains shall
be considered for short cul-de-sacs and permanent dead ends where future growth
is not feasible and where justified by hydraulic analysis.
In non-residential districts,
six-inch water mains are acceptable where fire flows of 1,000 gpm at 20-psi
residual pressure can be achieved.
Maximum deflection for PVC pipe
shall be five percent. Cast iron or
ductile iron fittings are required if deflection will be more than five
percent.
When PVC pipe is installed, an
insulated solid copper locator wire, minimum size #12, shall be installed with
the pipe. The wire shall be installed
under the pipe prior to pipe placement.
The locator wire shall be pulled up to the ground surface in all valve
boxes and splices should be made in valve boxes. All splices should be made with a corrosive resistant connection
as approved by the City. The locator
wire shall follow the entire length of the main.
No water mains shall be laid on rock
until the rock has been covered by a minimum of six inches of fine graded
stone. PVC water mains shall be bedded
in #57 stone with three inches minimum under the main and six inches minimum
over the main in accordance with Standard
Detail 6.01. Ductile iron pipe may
optionally be bedded with Class I, II or III materials in accordance with ASTM
D2321 and Section 7.01F(6).
PVC pipe will require brass or
bronze saddles for all service taps.
Direct taps are permissible on ductile iron pipe.
All water mains shall be installed
with a minimum cover of 30 inches measured from the top of the pipe to the
finish grade.
Water mains shall be at least 10
feet measured horizontally edge-to-edge from existing or proposed sanitary
sewer, storm sewer or sewer manhole. If
the elevation of the bottom of the water main is at least 18 inches above the
top of the sewer, a horizontal separation of at least three feet is allowed.
Under normal conditions, water mains
crossing sanitary sewers or storm sewers shall be laid to provide a vertical
separation of at least 18 inches between the bottom of the water main and the
top of the sewer.
Where a water main crosses over an
existing sanitary or storm sewer and the vertical separation is less than 18
inches, the water main shall be encased in concrete or in one length of steel
encasement ductile iron pipe centered at the point of crossing.
Where a water main crosses over a
new sanitary or storm sewer and the vertical separation is less than 18 inches,
the sewer line shall be constructed of water pipe for a distance of at least
nine feet on either side of the point of crossing. The water line pipe shall have one pipe length centered at the
point of crossing.
Where water mains cross under
sewers, a minimum vertical separation of at least 18 inches shall be provided
between the bottom of the sewer and the top of the water main. Both the water main and the sewer line shall
be constructed of water line pipe with a length of water line pipe centered at
the point of crossing. Adequate
structural support shall be provided to prevent excessive deflection of joints
and settling on and breaking the water mains.
When mains are to be installed to a
dead end or stubbed out for future extension, at least one 18-foot joint of
pipe shall be installed with a thrust collar.
A main line valve and blow-off assembly shall be installed on a water
line proposed for future extensions per Standard Detail 6.02. Permanent dead end mains shall be installed
with a blow-off valve in accordance with Standard Detail 6.04.
All pipes shall be installed so that
the manufacturer markings are positioned on the topside of the pipe.
All pipe and appurtenances shall
comply with the latest applicable AWWA and ASTM standards.
Pipe shall be SDR 21, Class 200
pressure rated pipe as long as the working pressure does not exceed 135
psi. Joints shall provide for expansion
and contraction with the use of rubber rings and tapered ends as an integral
part of each full joint. Joints for
Class 200 pipe shall be manufactured per ASTM D3139. Gasket materials shall meet the requirements of ASTM F477. Pipe shall be clearly marked with
manufacturer’s name, nominal diameter, SDR, ASTM D2241, pressure rating, and
NSF approval seal. No solvent cement
couplings will be permitted.
Pipe shall meet the requirements of
AWWA C900. Pipe shall be Class 200, DR
14, integral bell with strength equal to the pipe wall, cast iron OD, 18-foot
length, with joints using a solid elastomeric ring. Pipe, appurtenances, and fittings shall conform to AWWA
C900. All pipes must be clearly marked
with the manufacturer’s name, nominal diameter, DR, pressure class, AWWA C900,
and NSF approval seal.
Pipe shall be Pressure Class 350 up
to and including pipes 12 inches in diameter in accordance with ANSI/AWWA
C150/A21.50. Pipes greater than 12
inches in diameter shall be designed for Pressure Class in accordance with
ANSI/AWWA C150/A21.50. Pipe shall be
manufactured as per AWWA C151 in 18-foot lengths.
Joints shall be of the push-on type
as per AWWA C111. Pipe lining shall be
cement mortar with a seal coat of bituminous material in accordance with AWWA
C104.
Mechanical joint pipe may be required
at the discretion of the City at locations such as stream crossings, fill
sections, etc.
Based on available water flow data
provided by the City, water mains shall provide required fire flow for an area
and shall be large enough in all cases to deliver the flow required for fire
suppression purposes. The amount of
water required and therefore delivered by each fire hydrant shall be no less
than 500 gpm with 20 pounds per square inch residual pressure in residential
areas and no less than 1,000 gpm with 20 pounds per square inch residual
pressure in non-residential areas during times of peak system demand. The requirements of the Insurance Services
Office Commercial Risk Services and related agencies with regulator authority
shall be investigated and complied with, if more stringent than the minimum
flows set forth above. The City may
require a higher flow where building conditions warrant such action.
In any one or more of the conditions
listed below, the developer or builder shall provide a means for adequate fire
protection including but not limited to the installation of a domestic
sprinkler system complying with applicable codes, the installation of an
additional fire hydrant capable of supplying adequate flow, or the installation
of a booster pump to increase flow to an acceptable level at the structure.
a. Any part of the building is more
than five hundred (500) feet from a hydrant measured along an accessible
roadway: or
b. The nearest hydrant provides a water
supply of less than five hundred (500) gpm in residential areas and 1,000 gpm
in non-residential areas at twenty pounds per square inch residual pressure at
periods of peak demand.
c. The elevation difference between the
highest floor of the referenced structure and the nearest hydrant prevents
adequate water flow and pressure for fire protection at that structure.
No objects or obstructions such as
fences, trees, bushes, shrubbery, plants, etc., shall be located within five
feet of any fire hydrant.
Steamer cap shall face the paved
road (or parking area) so that it will be accessible to a fire department
pumper. The center of the steamer cap
will be no less than 18 inches and a maximum of 24 inches from finished grade
level at the hydrant as determined by the final grade of the completed project. For standard fire hydrant installation, see
Standard Detail 6.03.
The maximum distance between fire
hydrants, measured along street centerlines shall be 450 feet.
In buildings required to have a
sprinkler fire protection system installed, one accessible hydrant (either
public or private) will be located not more than 100 feet from the fire siamese
connection. For buildings with a
sprinkler system, there will be one accessible hydrant provided on each of two
opposing sides of the building. The
hydrant required for the sprinkler system may be counted as one of these
hydrants. There shall be additional
hydrants provided to meet the requirement of a maximum 550-foot distance
between a hydrant and any part of the building first floor. The hydrant (s) will be situated not less
than two feet and not more than10 feet from the curb of an access road, parking
area, or public road. If situated in a
parking area, there will be an area of NO PARKING marked around the hydrant for
an area of 15 feet on all sides.
Example: A non-residential building of a 20,000 square feet area,
sprinkled, would need a minimum of two hydrants (one within 100 feet of the
sprinkler siamese connection and one on the opposing side of the building).
Paved access of a minimum 20 feet in
width shall be required within 100 feet of two sides of each non-residential
building. Paved access shall be
required to be within ten feet of each required fire hydrant.
Emergency access to each side of all
buildings three or more stories in height shall be provided by means of an
unobstructed area of at least 12 feet in width which would support the weight
of a fire ladder truck. This area is
not required to be a permanent roadway, but must be accessible during an
emergency. Prior to completion of
grading and landscaping design, the Fire Department should be consulted.
Hydrants shall conform to AWWA C502
with a minimum valve opening of five and one-fourth inches. Hydrants shall be furnished with a four and
one-half inch steamer and two double two and one-half inch hose connections
with caps and chains, National Standard Threads, one and one-half inch bronze
pentagon operation nut, open left, painted safety yellow, bronze to bronze
seating, a minimum 42-inch bury depth with a break away ground line flange,
break away rod coupling, and mechanical joint inlet. The hydrant bonnet will be designed with a sealed oil or grease
reservoir with O-ring seals and a Teflon thrust bearing. Hydrants, meeting these requirements,
manufactured by Kennedy, Mueller, U.S. Pipe or M&H are acceptable.
Hydrants shall be set plumb,
properly located, with the steamer connection facing the closest curb with the
center of the connection a minimum of 18 inches above final grade. The back of the hydrant opposite the pipe
connection shall be firmly blocked against the vertical face of the trench with
a minimum one-third cubic yard of concrete with care taken to prevent the
hydrant drain holes from being covered or filled with concrete. Double bridle rods and collars shall be
connected from the tee to the valve and from the valve to the hydrant. Rods shall not be less than five-eights of
an inch diameter stock of wrought iron or stainless steel. A minimum of eight cubic feet of stone shall
be placed around the drains. The
backfill around the hydrants shall be thoroughly compacted. Hydrant installation shall be in accordance
with Standard Detail 6.03.
Gate valves shall be installed on
all branches from feeder mains and hydrants according to the following
schedule: three valves at crossings, two valves at tees, and one valve on each
hydrant branch. When a loop section of
water line is connected back into the feeder main within a distance of 200 feet
or less, only one valve will be required in the feeder main.
Where no water line intersections
exist, a main line valve shall be installed at every 100 feet per one-inch
diameter main up to a maximum distance of 1,000 feet between valves. The distance between valves for water lines
10 inches or larger in diameter shall not be greater than 1,000 feet.
Blow-off valves as detailed in Standard Details 6.02 and 6.04 shall be installed at major
low points and at the end of all dead-end water lines as directed by the City
with the exception of water lines six inches diameter and greater which have a
fire hydrant located within 20 feet of the end of the line. Fire hydrants may optionally be used at low
points as directed by the City.
Air release valves as detailed in Standard Detail 6.05 shall be installed
at all major high points of water lines six inches in diameter or larger and at
other locations as directed by the City.
Fire hydrants may be used in lieu of the above requirements.
Gate valves shall be approved by the
City and shall meet all requirements of AWWA C500 for a working pressure of 200
psi for valves up to 12 inches and 150 psi for valves greater than 12
inches. All gate valves shall be
mechanical joint with ductile iron body, Teflon coated interior, resilient
seated gate valve with a non-rising stem and open left with a double O-ring
seal. Resilient seated gate valves
shall meet the requirements of AWWA C509.
Gate valves up to and including 12
inches, shall be installed in a vertical position. Gate valves 16 inches and larger shall be installed only under the
direction of the City and shall be horizontally installed and equipped with
bevel gears, grease case, rollers, tracks scrapers, and a bypass located on the
side of the body. Fully revolving disc
valves shall not require rollers.
Valves 12 inches and larger with
roller and scraper operators shall be installed in a valve pit. All valves 24 inches and greater shall be
installed in a valve pit.
Valve boxes as detailed in Standard Detail 6.06 shall be
cast iron of the screw or telescopic type as approved by the City, with a
five-inch opening and “water” cast on the cover.
Blow-off assemblies shall be
constructed as shown on Standard
Details 6.02 and 6.04. The valves shall be gate types with a
non-rising stem, two-inch operating nut, O-ring seals and mechanical joint
ends.
Pipe fittings shall be ductile iron
designed and manufactured as per AWWA C110.
All sizes of fittings shall be designed for an internal pressure as
specified in AWWA C110. Compact ductile
iron mechanical joint fittings in accordance with AWWA C153 are also
acceptable. Fittings shall be lined
with cement mortar and a seal coat of bituminous material or Teflon, all in
accordance with AWWA C014.
All fittings or components subject
to hydrostatic thrust shall be securely anchored by the use of concrete thrust
blocks poured in place. The reaction
volumes are shown in Standard
Detail 6.07. Concrete for reaction
blocking shall be placed to minimize interference with future removal of
fittings. Material for reaction
blocking shall be 3,000 psi concrete.
Tapping sleeves shall be two piece
split cast iron or ductile sleeves or stainless steel full circle clamp
style. The sleeve shall be mechanical
joint to the main line and flanged to the tapping valve. The City shall approve tapping sleeves and
valves.
The maximum size saddle outlet for
each size of pipe to be tapped shall be as follows:
|
Pipe Size To be Tapped |
Maximum Size Saddle Outlet |
|
6” |
4” |
|
8” |
6” |
|
10” |
8” |
|
12” |
8” |
|
16” |
8” |
|
18” |
8” |
|
20” |
10” |
|
24” and larger |
12” |
Use of stainless steel sleeve may
allow full diameter taps.
Air release valves shall have a
one-inch nominal diameter for eight-inch mains and smaller, and a two-inch
National Pipe Thread inlet for mains 10 inches in diameter and 150 percent of
maximum working pressure in accordance with AWWA C512. All air release valves shall have a separate
shut off valve of approved type. An air
relief valve is shown in Standard
Detail 6.05.
Valves shall be properly located,
operable and at the correct elevation.
The valve box shall be centered over the wrench nut and seated on
compacted backfill without touching the valve assembly. All valve boxes outside of paved areas shall
be encased in a trowel finished one and one-half feet by one and one-half feet
by six-inch thick pad of 3,000 psi concrete with the concrete and cover flush
with the top of the ground. Precast
concrete valve box encasements may be used for valve box encasement outside of
paved areas. Concrete pad and valve box
installation is shown on Standard
Detail 6.06.
All
connections to existing city water mains shall be made by Public Works
personnel at the expense of the developer.
Service taps on new residential water lines being installed shall be
made by the contractor in accordance with City of Oak Ridge standards. Under certain conditions, the City may allow
wet taps to be installed by an approved contractor.
After
formal Council acceptance of subdivisions, the City will maintain all water
service laterals up to the meter. Prior
to City acceptance all repairs are the responsibility of the
contractor/developer. After acceptance
and in the case where a lateral between the main and meter is damaged by
construction, the City will make repairs on an actual cost basis with the
financial responsibility being borne by the party that caused the damage. Repair of damage to the service between the
meter and the structure being served will be the responsibility of the
contractor and must be performed by a properly licensed plumber and shall be
inspected by the City plumbing inspector.
All
services shall be a minimum of three-fourths of an inch. One-inch services are required for double
service lines. The service connection
consists of the pipe and appurtenances between the main and any property
line. All services shall be a minimum
of 24 inches deep. Any services under
roadways must be backfilled with # 57 stone up to the subgrade surface.
Corporation stops shall be brass,
complete with a compression (packed joint) type outlet coupling and AWWA
Standard threads as per AWWA C800. Taps
shall be located at 10:00 or 2:00 on the circumference of the pipe. Service taps shall be staggered at least 12
inches apart and not in a straight line.
The maximum size of direct taps
without a fitting, tapping sleeve or saddle for ductile iron water mains of
pressure Class 350 shall be as follows:
|
4” main |
ľ” tap |
|
6” main |
1 - 1/2” tap |
|
8” main |
1 – 1/2” tap |
|
12” main |
2” tap |
No burned taps will be allowed and
each corporation stop shall have its inlet threads wrapped with Teflon tape and
coated with pipe joint compound.
Service saddles shall be used on all
water mains that are not ductile iron pipe.
Saddles shall be bronze body (85-5-5 waterworks brass) and double strap
for taps over one-inch with silicon bronze nuts and factory installed grade 60
rubber gaskets.
Copper service tubing shall be type
K soft copper tubing as per ASTM B88.
No unions shall be used in the installation of the service connection of
100 feet or less. Service lines more
than 100 feet shall use a three-piece compression coupling. Only one compression coupling shall be used
for each 100 feet or fraction thereof.
Fittings will not be permitted under any roadway surface.
Residential
service lines shall extend from the main to the approved lot corner in a
straight line and end no closer than two feet from the property corner or right-of-way
line. Non-residential service locations
will be considered on a case-by-case basis.
All service lines shall be clearly marked with three-eights inch rebar
per Standard Detail 6.08.
All
meters and meter boxes shall be installed by Public Works personnel or be
installed by a contractor as approved or required by the City. Meters shall not be installed in sidewalk,
driveway or other paved surfaces without prior City approval.
When
a fire protection system is proposed and no anti-freeze or other chemicals are
to be used, a double detector check valve assembly including two check valves,
two gate valves, and four test cocks and bypass detector meter shall be
installed on the sprinkler fire protection line. If any chemicals are proposed to be added to a sprinkler fire
protection system, a reduced pressure principal backflow preventer approved by
the City shall be installed. No
backflow preventer device shall be installed below ground. All irrigation systems shall be provided
with an approved reduced pressure backflow preventer installed above ground or
within an interior structure accessible by the City. All backflow preventers and their installations must have prior
approval by the City before installation.
A post indicator valve shall be
provided at least six feet from the building or on the wall of the building
when backflow prevention devices are contained within a building. Clear and unobstructed access shall be
provided to the double detector check valve assembly.
All new commercial/industrial
facilities shall install a reduced pressure zone backflow preventer on any
incoming potable water lines. The
device shall be installed on the supply line at a location that is in advance
of any internal distribution branches.
The installation and location shall have pre-approval of the City
Environmental Compliance Officer.
All
materials used must have a preliminary inspection by the City Inspector before
they shall be allowed. Materials
rejected by the Inspector shall be immediately removed from the job site.
The contractor shall furnish all
materials, labor and equipment to perform all testing to the satisfaction of
the City. Water mains and appurtenances
must be tested and fully functional prior to the approval of any subdivision
Final Plat.
Calcium Hypochlorite shall be used
for disinfecting water lines in accordance with AWWA Standard for disinfecting
water mains (AWWA C651). All additions
or replacements to the water system shall be chlorinated before being placed in
service. Such chlorination must take
place under the supervision of the City.
Free residual chlorine after 24
hours shall be at least 25 ppm or the City will require that the lines be
rechlorinated.
Flushing of lines may proceed after
24 hours, provided the free residual chlorine analysis is satisfactory. No flushing shall take place unless the City
Public Works Engineering Technician is present. The Technician shall collect samples for bacteriological analysis
24 hours after flushing is completed.
The contractor shall furnish such help as may be required to secure
these samples.
If test results are unsatisfactory,
the contractor shall immediately rechlorinate lines and proceed with such
measures as are necessary to secure sterile lines.
The new water system shall be valved
off from the existing system until a satisfactory bacteriological sample has
been obtained and the Inspector has authorized the use of the new water system.
Hydrostatic
testing shall not be performed until the line segment has been disinfected and
passed bacteriological testing. No gate
valve in the existing City water system shall be operated without authorization
from the City Public Works Department.
A section of line, which is to be hydrostatically tested, shall be
slowly filled with water at a rate, which will allow complete evacuation of air
from the line. No gate valves shall be
operated without a City representative present. Pressure and leakage tests shall be performed in accordance with
AWWA C600 procedures.
The line shall be tested to a
pressure of 150 psi or 1.5 times the working pressure; whichever is greater, as
measured at the highest elevation of the line for duration of two hours. The pressure rating of the pipe, fittings,
valves, and thrust restraints shall be at least 1.5 times the working pressure
of the pipe. Private lines for fire
protection service shall be pressure tested to a minimum 200 psi in accordance
with NFPA standards. The pressure gauge
used in the hydrostatic test shall be calibrated in increments of 10 psi or
less. At the end of the test period,
the leakage will, at the request of the Inspector, be measured with an accurate
water meter.
Allowable test leakage quantities
per 1,000 feet of pipeline in gallons per hour are indicated in the following
table:
|
Avg. Test Pressure-psi |
Pipe Diameter - Inches |
||||
|
4 |
6 |
8 |
10 |
12 |
|
|
150 |
0.37 |
0.55 |
0.74 |
0.92 |
1.10 |
|
175 |
0.40 |
0.59 |
0.80 |
0.99 |
1.19 |
|
200 |
0.43 |
0.64 |
0.85 |
1.06 |
1.28 |
|
225 |
0.45 |
0.68 |
0.90 |
1.13 |
1.35 |
|
250 |
0.47 |
0.71 |
0.95 |
1.19 |
1.42 |
All
visible leaks are to be repaired regardless of the amount of leakage and the
line may be required to be rechlorinated as determined by the City.
After all underground utility
construction and final grading is complete, water lines will be re-tested under
working pressure to confirm no loss of pressure within a 15 minute test period
before final acceptance by the City.
Joint leaks shall be repaired as required by the City.
Line
breaks or punctures shall be repaired with a full circle repair clamp or other
methods as approved by the City.
Line
splits or blowouts shall be repaired by replacing the damaged section with
equivalent pipe material with a ductile iron mechanical joint solid sleeve at
each end.
For pipe of different outside
diameter and/or materials and asbestos cement, use an approved transition
coupling with different end diameters sized specifically for the pipe materials
and pipe outside diameter at each end.
Service
line repairs shall be repaired as follows:
·
A
water service line severed between the water main and the water meter shall be
repaired using new type K copper tubing and bronze or brass three-piece
compression unions.
·
A
corporation stop pulled out of a PVC pipe water main shall have a new service
saddle and a new corporation stop installed on the water main.
·
A
corporation stop pulled out of a ductile iron pipe water main shall have a full
circle repair clamp placed over the old tap hole. A new tap shall be made and a new corporation stop installed on
the water main. A tapped repair clamp
is also acceptable.
The
water system must be accepted by the City in conformance with the SCRD prior to
approval of any subdivision Final Plat.
The water system shall be 100 percent complete, including testing, prior
to Final Plat recording unless approved by the Planning Commission. NO TEMPORARY OR PERMANENT CERTIFICATE OF
OCCUPANCY SHALL BE SIGNED UNTIL THE WATER SYSTEM IS 100 PERCENT COMPLETE AND
ACCEPTED BY THE CITY. Formal acceptance
of water main systems shall be by City Council Resolution upon the request of
the developer and upon submission and approval of “As Built” drawings. The developer shall be responsible for all
maintenance and repairs to the system until formal City Council acceptance.
All non-residential water mains that
serve only one property shall be privately maintained by the property
owner. The City will accept water mains
in conformance with the SCRD that serve multiple properties upon the owner’s
request. Such acceptance includes the submission
and approval of “As Built” drawings and, if necessary, Plats of Corrections for
easements. Formal acceptance of water
mains to be dedicated to the City shall be by City Council Resolution action. The developer/owner shall be responsible for
all maintenance and repairs to the system until formal City Council
acceptance. The water system must be
accepted by the City and shall be 100 percent complete, including testing,
prior to the issue of a Certificate of Occupancy.
Return to
Section 6.00 Water Distribution
Return to Top
Sanitary
sewer construction shall be in accordance with the latest edition of the TDEC
“Design Criteria for Sanitary Sewer Systems.”
If discrepancies are found between the TDEC and City requirements, the
more stringent shall apply.
All public sanitary sewer mains
shall be located in dedicated street right-of-ways and/or in dedicated
easements with a minimum width of 10 feet, centered about the pipe. An easement of 15 feet shall be required
where the depth is greater than five feet, but less than eight feet. An easement of 20 feet shall be required
where the depths below finished grade is greater than eight feet. Special conditions may warrant greater
widths as required by the City. No part
of any structure, including foundations and overhangs, are permitted in an
easement.
Proposed sewers shall be designed to
a proper depth such that all creek crossings shall have at least three feet of
cover between it and the streambed unless otherwise approved by the City. Concrete encasement and ductile iron pipe
with mechanical joints, in accordance with Standard Detail 7.01, shall be
required at stream crossings. All
stream crossings will include check dams in the conduit trench on both sides of
the crossing.
Sanitary sewer mains shall not be
installed under any part of water impoundments, such as detention/retention
basins, except as approved by the City.
The minimum size of public gravity
sanitary sewer mains shall be eight inches.
Sewer extensions should be designed
for projected flows even when the diameter of the receiving sewer is less than
the diameter of the proposed extension.
Pipe diameter changes shall occur in
a manhole with the invert of the larger pipe lowered sufficiently to maintain
the same energy gradient. An approximate
method of securing these results is to place the eight-tenths depth point of
both sewers at the same elevation.
New sewer systems shall be designed
based on the maximum potential development of the contributory area as
determined in consultation with the City.
If a proposed use is know to have a design flow greater than listed
below, the greater flow factor shall be used; otherwise the following flow
factors shall be used:
Land Use
|
Flow Factor
|
|
Office and Institutional |
25 gpd/employee/8 hour shift |
|
Commercial |
150 gpd/1,000 square feet building space/12 hour period |
|
Industrial |
25 gpd/employee/8 hour shift |
These figures cover normal
infiltration; however, an additional allowance shall be made where conditions
are unfavorable. Additional flow
factors and requirements should be reviewed in Appendix 2-A of the latest edition
of the TDEC handbook on “Design Criteria for Sanitary Sewer.”
For existing sewer systems, an
additional allowance shall be made to the above flow factors where the existing
flow exceeds these values.
The relation of peak-to-average
daily flow shall be as follows:
|
Qmax/Qavg. |
Flow (gpd) |
|
4.0 |
|
|
2.5 |
Greater than 3,000 |
Sanitary sewers shall be designed to
carry the projected peak flow at no more than three-fourths full. The recommended minimum velocity for
sanitary sewer lines is three fps. The absolute
minimum velocity allowed is two fps.
The minimum slope for public
sanitary sewers shall be as follows:
|
Main Size (in.) |
Minimum Slope (ft/100 ft) |
|
8 |
0.260 |
|
10 |
0.193 |
|
12 |
0.151 |
Minimum slope values are based on a
Manning’s η value of 0.0115.
Minimum slopes for larger size pipes are provided in the latest edition
of the TDEC “Design Criteria for Sanitary Sewers.”
The minimum slope for the uppermost
reach of a sewer line where no future extensions are planned shall be one
percent regardless of sewer line size.
The maximum slope for sanitary
sewers is 18 percent and the maximum velocity is 15 fps. These limits may be exceeded with the
approval of the City and the incorporation of the following provisions:
a. High velocity manholes, in
accordance with Standard Detail
7.02 shall be used on all sewers with a slope greater than 18 percent.
b. Concrete anchors shall be installed
on all sewers of greater than 18 percent slope at the following spacing:
1.
Not
over 36 feet center to center on grades from 18 percent to 25 percent.
2.
Not
over 24 feet center to center on grades from 25 percent to 35 percent.
3.
Not
over 16 feet center to center on grades exceeding 35 percent.
Sanitary sewer mains shall be deep
enough to serve the adjoining property and allow for sufficient slope in
lateral lines. All sanitary sewer mains
shall have the following minimum covers:
a. Two and one-half feet from the top
of pipe to finished subgrade when under a roadway.
b. Two and one-half feet from the top
of pipe to finished grade when outside a roadway.
The above requirements may be waived
in exceptionable circumstances at the discretion of the City, in which case ductile
iron pipe shall be installed.
Materials for sewer mains to pipe
invert depths of 12 feet below finished grade may be selected from Section 7.01E, Pipe Materials. Sewer mains greater than 12 feet in depth
shall be Pressure Class 350 ductile iron or PVC C900 for the entire run between
manholes.
Pipe trench excavation and
backfilling shall be performed in accordance with Section
5.01. Pipe bedding shall be in accordance
with Section 7.01F(6).
Transitions of pipe material shall
occur only at manholes unless otherwise approved by the City.
Sanitary sewers shall be laid at
least 10 feet horizontally apart from existing or proposed water mains. However, if the top of the sewer main is at
least 18 inches below the bottom of the water main, a horizontal separation of
at least three feet from the closest edges of the pipes is allowed. There shall be a minimum of five feet
horizontal separation between sewer gravity mains and force mains unless
otherwise approved by the City.
Under normal conditions, water mains
crossing sanitary sewers or storm sewers shall be laid to provide a vertical
separation of at least 18 inches between the bottom of the water main and the
top of the sewer.
Where a water main crosses over an
existing sanitary or storm sewer and the vertical separation is less than 18
inches, the water main shall be encased in concrete or in one length of steel
encasement ductile iron pipe centered at the point of crossing.
Where a water main crosses over a
new sanitary or storm sewer and the vertical separation is less than 18 inches,
the sewer line shall be constructed of water pipe for a distance of at least
nine feet on either side of the point of crossing. The water line pipe shall have one pipe length centered at the
point of crossing.
Where water mains cross under
sewers, a minimum vertical separation of at least 18 inches shall be provided
between the bottom of the sewer and the top of the water main. Both the water main and the sewer line shall
be constructed of water line pipe with a length of water line pipe centered at
the point of crossing. Adequate
structural support shall be provided to prevent excessive deflection of joints
and settling on and breaking the water mains.
Sewer line easements shall be
finished and graded smooth, free from rocks, boulders, roots, stumps, and other
debris and seeded and mulched upon the completion of construction.
The downstream manhole (s) of a
sanitary sewer line extension under construction shall be appropriately plugged
to prevent the passage of groundwater, runoff and sediment into the sanitary
sewer system. All water upstream of the
plug shall be pumped out of the sanitary sewer line and all sediment and solids
shall be removed and properly disposed of by the contractor. The plugs shall not be removed until the
entire upstream system is complete and the lines have been inspected by the
City to insure that all possible points of inflow or infiltration have been
secured and all debris removed.
Ductile Iron Pipe shall be designed
as per ANSI/AWWA C150 (A21.50) for a Pressure Class of 350 psi, laying
condition Type 4 Trench.
Pipe joints shall be of the push-on
type as per ANSI/AWWA C111/A21.11. Pipe
lining shall be cement mortar with a seal coat of bituminous material, all in
accordance with AWWA C104.
PVC pipe shall be made of PVC
plastic as defined in ASTM D1784. PVC
pipe shall have integral wall bell and spigot joints with rubber gaskets for
the conveyance of domestic sewage.
Fittings shall be made of PVC plastic as defined in ASTM D-1784. Fittings must be manufactured by pipe
supplier or approved equal, and have bell and/or spigot configurations
compatible with that of the pipe.
All pipe 15 inches in diameter and
less shall have a maximum Standard Dimension Ration (SDR) of 35 in accordance
with ASTM D3034. Where lying conditions
so warrant, and in accordance with manufacturer’s recommendations, lower SDR
values (stronger pipe) may be required.
PVC pipe meeting the requirements of
AWWA C900 may be used for trench depths of 12 feet or greater. Pipe shall be Class 150, DR18, integral bell
with strength equal to the pipe wall, cast iron, O.D., 18 feet lengths, with a
solid elastomeric ring in accordance with ASTM F-477.
PVC pipes 15 inches in diameter and
larger must be manufactured as defined in ASTM F794. Pipe strength shall be equal to or exceed that required for pipe
less than 15 inches in size.
Installation shall consist of either
Class I or Class II bedding material placed six inches below the pipe barrel
and continuing to a minimum of six inches above the pipe in accordance with
ASTM D2321.
The installation shall satisfy the
requirements of the manufacturer and/or the following whichever is more
stringent:
Installation of PVC pipe shall
follow the recommendations of ASTM D2321 “Underground Installation of Flexible
Thermoplastic Sewer Pipe.” Flexible
pipe bedding and embedment material shall be either Class I or Class II. For semi-rigid pipe such as ductile iron
pipe or PVC Truss Pipe, Class III materials may also be used. In any area where the pipe will be installed
below existing or future ground water levels or where the trench could be
subject to inundation, only Class I material shall be used for bedding and
embedment.
The manufacturer’s specifications or
otherwise approved method shall be used in determining the stiffness class of
the pipe to be installed so as to attain the required deflection control. The class of the pipe must be approved by
the City prior to installation.
The maximum allowable deflection
after installation shall be less than five percent of the pipe diameter. The mandrel (go/no-go) deflection test must
be performed on each line prior to acceptance and no less than 30 days after
installation.
PVC pipe shall be produced with bell
and spigot end construction. Joining
will be accomplished by rubber gasket in accordance with manufacturer’s
recommendation, unless otherwise directed or approved by the City. Flexible watertight elastomeric seals in
accordance with ASTM D3212 may also be used.
Each pipe length shall be clearly marked with information including pipe
size, profile number and class number.
The pipe shall be installed so that the manufacturer markings are
positioned on the topside of the pipe.
A minimum trench width shall be the
pipe outside diameter plus 16 inches.
Bedding and embedment material
classifications shall be generally defined as follows and in accordance with
ASTM D2321 and Standard Detail
7.12.
CLASS I – Angular, (one-fourth to
one and one-half inches) graded stone, including a number of fill materials
that have regional significance such as crushed stone and crushed gravel. The material shall be non-plastic with 100
percent passing the one and one-half inch sieve, less than 50 percent passing
the # 4 sieve and less than five percent passing the # 200 sieve.
CLASS II – Coarse sands and gravels
with maximum particle size to one and one-half inches, including variously
graded sands and gravels containing small percentages of fines, generally
granular and non-cohesive, either wet or dry.
Material shall be non-plastic with 100 percent passing the one and
one-half inch sieve, 50 percent more or less of course fraction passing the # 4
sieve and less than five percent passing the # 200 sieve.
CLASS III – Fine sand and clayey
gravels, including fine sands, sand-clay mixtures, and gravel-clay
mixtures. Material may be slightly plastic
with plasticity index (PI) less than seven containing 12 percent to 50 percent
fines passing the # 200 sieve and 100 percent passing the one and one-half inch
sieve and 50 percent more or less of the course fraction passing the # 4 sieve.