[Ord. 1020-2003, 10-10-2003]
A.
Scope: The design standards established in this article are the minimum
acceptable design standards. Parties developing subdivisions in the
City must meet these minimum standards and are encouraged to exceed
them where it is in the best interest of the developer and/or the
City.
B.
Implementation: The City shall prepare standard construction specifications
for implementation of the design standards established in this article.
These specifications shall apply to construction of all streets, utilities,
and public facilities. The City Administrator shall be responsible
for adopting the standard construction specifications in accord with
current good construction practices as required.
[Ord. 1020-2003, 10-10-2003; amended by Ord. 1126-2008, 4-7-2008; Ord. 1150-2009, 9-21-2009]
A.
General: All streets and drainage shall be designed by an engineer
registered in the state of Oklahoma. Designs shall be based on a thorough
geotechnical investigation of the proposed site. Streets shall include
as a minimum the wearing surface, base course, subgrade, subgrade
drainage (if required), concrete curbs and gutters or borrow ditches
where allowable, proper storm drain and inlets, and the drainage structures
necessary to remove stormwater from the right of way.
B.
Geometric Design:
1.
Proposed streets shall intersect one another as nearly at right angles
as topography and other limiting design factors permit.
2.
To the maximum extent possible, minor street intersections with collector
streets shall be three-way "T" intersections. Four-way intersections
involving minor and collector streets shall be avoided unless dictated
by design principles and standards.
3.
Collector street intersections with arterials shall match the location
of existing or proposed collector streets of the adjoining subdivisions
to provide a four-way intersection, unless topography or other limiting
factors prohibit such an intersection.
4.
Typical residential and large lot residential streets shall utilize
design methods to limit operating speed to 25 miles per hour. These
shall include, but are not limited to, use of curves, restricting
straight street to 900 feet or less, and offsetting streets through
"T" intersections.
E.
Subgrade:
1.
Design Testing: The owner shall have borings and soil tests made
to determine the stability and bearing capacity of the subgrade. Such
testing, at appropriate intervals, shall be accomplished by a licensed
engineer specializing in geotechnical investigations and an approved
laboratory. The geotechnical engineer shall coordinate the soil borings
and tests with the street department and obtain approval of the sample
and boring sites prior to executing the fieldwork. When possible,
the City shall have a representative on site during geotechnical investigations.
The City will maintain a list of laboratories and geotechnical engineers
that are not approved for work in the City of Tahlequah. All others
shall be considered approved. A copy of the geotechnical report will
be forwarded with the preliminary plans for the subdivision streets.
This report shall include recommendations for modifications to subgrade
that are required to stabilize the subgrade and/or improve its bearing
capacity.
2.
Material: All subgrade material shall be free of organic matter.
All material with a plasticity index (PI) of 15 or more shall be treated
with appropriate material to reduce the PI to less than 15. Fly ash
meeting ODOT specifications shall be used when the PI is less than
30 and lime meeting ODOT specifications shall be used when the PI
is greater than 30. All material that is nonplastic shall be treated
with appropriate materials to provide a stable, proper strength subgrade.
3.
Preparation: Subgrade shall be prepared to a minimum depth of six
inches by using ODOT standard method 'B' compacted to 95%
standard density.
4.
Special Conditions:
a.
When underground water sources are encountered, they shall be drained
away from the subgrade with appropriate drains approved by the City.
b.
Fill areas through old creek channels, ditches, ponds and other drainage
structures shall be excavated and backfilled with suitable material;
low areas shall have underground drains approved by the City that
will prevent saturation of subgrade. In areas where soil strength
is not sufficient to support the roadway, geotextile fabric may be
used with approval of the City.
c.
In areas where soil strength and/or stability is not sufficient to
support the roadway, rock or rock with geotextile fabric may be used
to improve the subgrade with approval of the City.
F.
Curb and Gutter:
1.
All curb and gutter shall be constructed of 3,500 psi Portland cement
concrete in accordance with the City of Tahlequah standard construction
specifications.
2.
Except where borrow ditches are allowed by code or exception, all
streets built to final width shall be constructed with curb and gutter.
3.
Streets constructed to an interim width shall be constructed with
curb and gutter unless otherwise approved by the City.
4.
All gutters not integral to a concrete pavement shall have a minimum
width of 24 inches and a minimum thickness of six inches.
5.
Curbs on all arterials shall be barrier type at the widened and tapered
portions of intersections and mountable type through the remainder
of the street. These curbs shall have a minimum height of six inches
and a minimum width of eight inches. Exceptions to this criteria will
be granted by the City engineer on a case by case basis.
6.
Curbs on all other streets shall be barrier type and have a minimum
height of six inches and a minimum width of six inches. Exceptions
to this criteria will be granted by the City on a case by case basis.
Exceptions must be requested in writing by the developer prior to
plan submittal.
7.
All curbs shall have handicapped access ramps, in accordance with
the Americans with disabilities act and its supporting standards.
G.
Sidewalks:
1.
Vertical Alignment: Sidewalks in general shall follow the vertical
alignment of the top of curb or the crown of the adjacent street.
They shall be positioned to preclude low areas where water will stand
on the sidewalk or soil will collect.
2.
Drainage Structures: Where sidewalks cross drainage features, an
appropriate drainage structure will be placed under the sidewalk.
Where drainage structures present a danger to pedestrian traffic,
they will have appropriate handrails that meet minimum OSHA standards.
3.
Bridges: When bridges are installed on sidewalks, they shall be of
precast concrete or a design approved by the street department. All
bridges shall have handrails meeting minimum OSHA standards.
4.
Horizontal Alignment: Sidewalks shall be constructed within the street
rights of way at a distance no less than one foot from the abutting
property lines and shall be two feet from the outside curb line of
the street pavements, or as approved by the City.
5.
Construction Material: All sidewalks shall be constructed of 3,500
psi Portland cement concrete in accordance with the City of Tahlequah
standard construction specifications. The finished thickness of Portland
cement concrete sidewalks shall be not less than four inches and the
width shall be not less than five feet.
6.
Further Requirements: Sidewalks shall be designed and constructed
free of obstructions. No fences, utility poles, fire hydrants, or
other structures shall encroach on the paved sidewalk. Sidewalks shall
be designed and constructed to connect to the sidewalks of abutting
subdivisions. Where a drainageway is excluded from a subdivision the
developer shall provide a sidewalk and an associated easement across
the drainageway as part of the adjacent development.
7.
Disability Access: Sidewalks shall provide access in accordance with
the Americans with disabilities act.
8.
Maintenance: After final acceptance of the sidewalk construction
by the City building inspector, maintenance of sidewalks shall be
the responsibility of property owners whose properties abut the right
of way line along which the sidewalk has been constructed.
H.
Pavements:
1.
Pavement Material and Construction: All pavements shall be constructed of either Portland cement concrete or asphaltic concrete, and base courses and thicknesses shall be in accordance with standards in table 7.1, Section 12-480 of this chapter.
2.
Portland Cement Streets:
a.
Portland cement concrete shall be 3,500 psi designed in accordance
with City of Tahlequah specifications.
b.
Portland cement concrete streets shall have either a curb and gutter
or an integrally placed curb of the same mix design as for street
paving. When a curb and gutter are placed separate of the street it
shall conform to the standard curb and gutter requirements. The integrally
placed curb shall be a minimum of six inches wide and the curb face
shall be a minimum of six inches.
c.
Joints in Portland cement paving, curbs, and gutters shall be placed
in accordance with ODOT or Tahlequah standard construction specifications.
d.
Fly ash shall not be substituted for any quantity of cement, where
the concrete will be used to construct public streets or sidewalks.
3.
Asphaltic Concrete Streets:
a.
The asphaltic base course for asphaltic concrete shall be of plant
mixed, hot mix/hot laid asphalt containing 4% to 6% asphalt cement.
b.
The surface course for asphaltic concrete shall be of plant mixed,
hot mix/hot laid asphalt containing 5% to 7% asphalt cement requiring
a total of three inch depth with 1.5 inches of type B asphalt and
1.5 inches of type B asphalt top layer.
c.
The mineral aggregates used in the asphaltic concrete mixture shall
be approved by the City in accordance with the Tahlequah standard
construction specifications.
d.
Asphaltic concrete streets shall have a Portland cement concrete
curb and gutter, and shall be designed in accordance with this chapter.
e.
The owner will provide testing and sampling results for all new sections
of asphaltic concrete streets in accordance with Section 708 of the
ODOT standard specifications.
[Ord. 1020-2003, 10-10-2003]
A.
General:
1.
All storm water runoff shall be subject to review and approval by
the City with regard to analysis, design and construction of drainage
facilities. The appropriate public authority shall have the right
to maintain or to cause to be maintained the drainage system for its
intended purposes. If a storm water master drainage plan is adopted
for the area under consideration, then the provisions of the plan
shall be adhered to.
2.
The drainage system both public and private, may consist of storm
sewers (which are closed conduits); improved channels constructed
in conformity with adopted City standards; unimproved drainageways
left in their natural condition; the areas covered by drainageway
easements for the purpose of providing overland flow; and all appurtenances
to the above including inlets, manholes, junction boxes, headwalls,
dissipators, culverts, etc. All portions of the drainage system that
exist on dedicated street rights of way or property owned by the City
in fee shall be owned and maintained by the City, unless provided
otherwise by agreement or covenant. Improved and natural channels
shall be maintained by the property owners.
3.
The drainage system plans shall show both plan and profile views
of the proposed improvements. Any manhole or access point to the system
that is buried out of sight shall be dimensioned to permanent objects
in the vicinity.
4.
The storm water drainage system shall be designed to receive and
pass the runoff from a 100-year frequency rainstorm under full urbanization.
The design engineer shall prepare and submit a study for the area.
"Full urbanization" is defined as the total development in an area
that is anticipated. The entire flow shall be confined within the
said storm water drainage system.
B.
Design Criteria for Collection System:
1.
The storm water collection system, as may be required by the City,
shall be designed either:
a.
To pass a minimum of the runoff from a five-year frequency rainstorm
in a pipe network with overland flow capacities so that the combination
of any two will pass the runoff from a 100-year frequency rainstorm
under fully urbanized conditions; or
b.
To pass the entire runoff from a 100-year frequency rainstorm in
the pipe network. Should the entire runoff from a 100-year frequency
rainstorm be conveyed in a pipe network, grading shall be designed
to convey the runoff from a five-year frequency rainstorm and shall
be designed to carry flow in the event of inlet blockage or bypass.
2.
The overland flow portion of the collector system shall be confined
to dedicated rights of way, or drainage easements to assure the storm
water can pass through the development without inundating the lowest
level of any building, dwelling, or structure. Drainage easements
shall be shown on the plat.
3.
The rational method of runoff analysis may be used for the design
of the closed pipe networks of the storm sewer system up to drainage
areas of 200 acres. For drainage areas over 200 acres, a hydrograph
method shall be used.
4.
The rainfall intensity curves prepared for TP-40 and national weather
service HYDRO-35 (June 1977) shall be used for design in determining
the rainfall.
5.
The "Oklahoma Department Of Highways Technical Manual" dated April
1970, shall be used for determining the basic "C" values. A weighted
"C" value shall be determined with minimum values of 0.45 for residential,
0.65 for multi-family, and 0.90 for industrial and commercial areas.
Unplatted areas within 300 feet either side of an arterial shall be
either considered commercial or shall be in accordance with the comprehensive
plan in estimating runoff coefficients. The weighted "C" value shall
be increased by 25% for the 100-year frequency rainstorm but shall
not exceed 1.0.
6.
The distance between inlets, as well as the distance to the first
inlet, shall be determined by the following, whichever is less:
a.
For the five-year frequency rainstorm, two driving lanes (20 feet)
must remain open for streets on grade. The depth of flow in the open
lane shall not exceed six inches.
b.
For the 100-year frequency rainstorm one driving lane (12 feet) must
remain open for streets on grade. Further, the depth of flow shall
not exceed curb depth.
c.
A maximum time of concentration of 10 minutes to the first inlet
shall be used for single- or multi-family residential areas.
d.
A maximum time of concentration of five minutes to the first inlet
shall be used for commercial and industrial areas.
e.
Six hundred feet.
7.
At sump locations, the water depth shall not exceed 12 inches above
the top of the curb, or 18 inches above the top of the grate, whichever
is less, for the 100-year frequency rainstorm. Where sump collection
systems are used, an overflow route shall be established in the event
of complete blockage of the sump. The developer may size the inlets
and pipe at the sump location for the 100-year frequency storm and
provide a sod overflow or maintain standard inlet and pipe sizing
and provide a concrete overflow.
a.
When a sod overflow structure is constructed, it shall be lined with
Bermuda grass and shall contain energy dissipators, if required, at
the outflow point.
b.
When a concrete overflow structure is constructed, it shall be constructed
of six-inch thick Portland cement concrete meeting the same requirements
as concrete for sidewalks and shall contain energy dissipators, if
required, at the outflow point.
8.
Runoff from areas greater than 1/2 acre outside the roadway shall
be collected before it reaches the roadway. Parking lots shall have
internal drainage systems so as to reduce concentrated flow into streets.
These requirements shall not apply to residential lots used as single-family
residences.
9.
Where required by depth of flow, inlets shall be located at intersections
to collect the flow to keep it from crossing the intersection. Inlets
at intersections shall be located so they do not encroach upon the
return.
10.
Drainage areas, runoff from ten-year and 100-year frequency rainstorms,
time of concentration, and inlet design for each inlet shall be summarized
and tabulated on the plans. This summary table shall also be a part
of the drainage calculations. The flows and velocities for each pipe
and open channel shall be summarized and tabulated as above.
C.
Open Ditch Requirements:
1.
Trapezoidal channels shall be designed with a hard lined low flow
channel, such as concrete. The low flow channel shall branch off to
pick up any storm sewers discharging into the channel. The top of
the sides of the low flow channel shall be a minimum of six inches
lower than the adjacent main channel bottom, to ensure that the drainage
runs over and into the low flow channel and does not erode around
it. The minimum cross slope on the bottom of the trapezoidal channel
shall be 2%. The easement for the trapezoidal channel shall include
a ten-foot width on the top of the bank for an access road.
2.
Borrow ditches, when allowed, shall not exceed four feet in depth.
Culverts shall be sized to handle the borrow ditch flow. Borrow ditches
shall be designed to carry the runoff from the ten-year frequency
rainstorm. The side slopes on the bank next to the road shall be three
feet horizontal to one-foot vertical. The side slope on the opposite
bank shall be whatever is necessary.
3.
Roughness coefficients for drainage design will be as listed in tables
5-5 and 5-6, figure 5- 5, pages 109 through 123, of "Open Channel
Hydraulics" by Ven Te Chow, published by McGraw-Hill Book Company,
1959.
4.
The minimum velocity in any drainage system shall be 2.5 fps, for
all events of five-year frequency and greater. The maximum velocity
in a pipe shall be 30 fps and the maximum velocity in an unlined ditch
shall be six fps.
D.
Drainage Structure Specifications:
1.
Storm sewers may be constructed of reinforced concrete pipe (RCP),
coated steel pipe, or double wall polyethylene corrugated pipe, depending
on the soil and loading conditions. Minimum pipe size shall be fifteen-inch
diameter.
2.
All storm drains that discharge into a stream shall have a concrete
headwall, wingwalls, apron, and if required to prevent erosion, energy
dissipators. Design shall be in accordance with City of Tahlequah
standard construction specifications.
3.
When the outfall velocity of a pipe or the velocity in a drainage
ditch exceeds six fps, erosion control measures will be taken at the
outfall of the pipe or in the area where the velocity will exceed
six fps.
4.
When RCP is specified it shall be furnished with omniflex joints
or equivalent. When RCP is specified in a noncohesive soil, such as
sugar sand, and the storm drain is within 15 feet of a structure that
would sustain damage from sinkholes, the City may require wrapping
of joints with a nonwoven geotextile fabric such as SUPAC.
5.
Where RCP storm sewers cross streets, they shall be backfilled with
either ODOT type A aggregate base or flowable fill. Where metal or
polyethylene storm sewers cross streets, they shall be backfilled
with flowable fill.
6.
Culverts shall be sized using either Kufter's or Manning's equations or charts and the federal highway administration's inlet control charts for the design flow. The slope used for design shall be the slope of the invert of the culvert. Loading requirements are set out in table 7.1, Section 12-480 of this chapter.
7.
No pipe shall be installed downstream having a diameter smaller than
the pipe from which it is receiving water.
8.
Concrete pipe under streets shall not be less than C-76 Class III.
For back and side yard installations Class II may be used. Corrugated
metal pipes shall meet Oklahoma state highway department gauge requirements
for fill heights, and may be required to be bituminous coated and
lined. Polyethylene corrugated pipe shall meet the requirements of
AASHTO M294.
9.
Junctions between different pipe sizes shall be made with the top
inside of the downstream pipe no higher than the top inside of the
upstream pipe.
10.
A manhole or junction box shall be required at all changes of grade,
changes in alignment, and junctions between two or more different
size pipes.
11.
The horizontal distance between pipes being placed in the same trench
shall be a minimum of 2T + 6." This would include multiple pipe crossings
for culvert purposes.
12.
Radius pipes will be used only on storm sewers having a diameter
of 36 inches and larger. The radius of the curve shall be no less
than five times the diameter of the pipe. The degree of deflection
shall be no greater than 7 1/2° per joint of radius pipe,
or the pipe manufacturer's recommendation, whichever is less.
The City is allowed to require radius pipe, should the energy loss
be excessive and thereby detrimental to the system.
13.
A minimum of six inches cover shall be provided over pipes and box
culverts to the bottom of the subgrade except when the box culverts
are designed and built with the top at grade.
14.
All storm sewers shall be shown in profile, showing flow line, size,
type and grade. Profiles shall show the natural and proposed ground
line at the centerline of the storm sewer. Stationing shall be continuous
through manholes, along the main (longest) line, to the top of the
system. Branch lines shall be stationed, starting from 0 + 00, from
their connection with the main line. Lines shall be stationed on the
profile drawing from left to right increasing upstream.
15.
The radius of curve for a box structure shall be a minimum of three
times the maximum width of the box structure, but not less than 50
feet.
16.
New box culverts and bridges shall have adequate capacity to pass
100-year fully urbanized flows with one foot of freeboard under the
low chord. A backwater analysis shall be provided to illustrate compliance
with this requirement.
17.
Pipes discharging at a steep gradient into drainageways and detention
facilities shall be provided with a headwall and energy dissipators.
A "steep gradient" is defined as an energy grade line whose outlet
velocity is six feet per second or greater.
18.
The centerline radius of a curve on an improved open channel shall
be a minimum of three times the top width at the design flow or 100
feet, whichever is greater.
19.
All improved channels shall be provided with a minimum of one foot
of freeboard above normal depth of flow from a 100-year frequency
rainstorm.
20.
At all bends in improved channels, the amount of freeboard shall
be increased by the following equation:
|
H
|
=
|
V2 b
|
|
64.4 r
|
|
Where:
| |
|
H
|
is height of freeboard in feet.
|
|
V
|
is the average velocity in feet per second.
|
|
b
|
is the width of the channel at the design water surface in feet.
|
|
r
|
is the radius of curvature of the channel centerline in feet.
|
21.
The increased freeboard height shall be maintained a minimum of one
channel width upstream and downstream of the bend.
22.
Culverts in barrow ditches shall be sized to pass ten-year frequency
storm. Sizing shall be based on the engineer's analysis of requirements.
E.
Storm Sewer Requirements:
1.
When storm sewers are constructed in fill areas, all materials in
fill areas shall be compacted to a 95% standard proctor density prior
to the laying of the pipe.
2.
Maximum spacing between manholes or junction boxes shall not exceed
400 feet for pipes of 15 inches in diameter and shall not exceed 500
feet for pipe sizes over 15 inches in diameter.
3.
All junction boxes and manholes shall be built with the standard
manhole ring and cover at grade.
4.
A manhole or junction box shall be constructed at the PC or PT of
all curves in sewers.
[Ord. 1020-2003, 10-10-2003; amended by Ord. 1126-2008, 4-7-2008]
A.
General: When a development will have a significant impact on the
traffic pattern of the adjacent arterial(s), the City may require
the developer to provide additional width to the arterial(s) or other
improvements to mitigate the impact. The street department shall determine
the exact type and quantity of construction necessary to mitigate
each development. The following subsections define the most common
forms of mitigation and when they are used. These subsections are
provided as a guideline only. Each development must be evaluated based
on the traffic into and out of the development, the traffic load on
the arterial, current configuration of the arterial, and final configuration
of the arterial, as shown in the City's major street and highway
plan, or such other plan that may exist.
B.
Constructing Final Configuration Outside Lane:
1.
Definition: This mitigation requires the developer to construct the
outside lane of an arterial.
3.
Special Considerations:
a.
When a traffic signal must be moved, the City will contract for movement
of the signal and the developer shall pay 50% of the final contract
cost.
b.
When the addition of an outside lane will leave an unpaved area between
the new lane and the old pavement, the developer shall design the
intervening lane(s) and the City shall either:
C.
Constructing a Deceleration Lane:
1.
Definition: A deceleration lane is a right turn lane into a development
that has a lane width of not less than 13 feet for a distance of not
less than 100 feet, measured from the centerline of the road on which
the right turn is to be executed, and a 10:1 taper back to the existing
arterial street width.
2.
Basis for Requirement: This type of mitigation will be required when:
3.
Special Considerations:
a.
Deceleration lanes shall not be added to arterials that have been
developed to final configuration, as shown in the City's major
street and highway plan, unless the development generates excessive
traffic or the nature of the traffic requires such a lane.
b.
When a deceleration lane is constructed it will be rebuilt, at City
expense, each time the arterial is widened until the arterial reaches
final configuration.
D.
Constructing an Access Radius with Taper:
1.
Definition: An "access radius with taper" is a radius of at least
50 feet with a five-foot wide section at the end of the radius tapered
2:1 back to the edge of the arterial.
2.
Basis for Requirement: This type of mitigation will be required when:
3.
Special Considerations:
a.
An access radius with taper shall not be routinely added to arterials
that have been developed to final configuration.
b.
When an access radius with taper is constructed, it will be reconstructed,
at City expense, each time the arterial is widened until final configuration
of the arterial is reached.
E.
Constructing a Left Turn Bay:
1.
Definition: A left turn bay shall be, at minimum, 15 feet wide, 80
feet long, and have a ten to one taper back to current arterial width.
2.
Basis for Requirement: This type of mitigation will be required when
the arterial is at 130% of level C capacity or higher and the development
is of the type that will generate a large number of left turns in
a fairly short period of time. Examples would be a factory with over
50 employees or a school.
3.
Special Considerations: The left turn bay will be reconstructed at
City expense each time the arterial is widened until the arterial
reaches final configuration.
F.
Alternatives:
1.
Recommendation: Alternatives to the types of mitigation established
in this section shall be discussed with the street commissioner for
recommendation to the City council.
2.
Payment: When it is in the best interests of the City as determined
by the City council's option, the City may accept funds in lieu
of the actual construction of the mitigation required in this section.
This would normally occur when the City is in the process of designing
an improvement to the arterial that would render the mitigation no
longer required. The amount to be paid shall be an engineer's
estimate approved by the City council.
[Ord. 1020-2003, 10-10-2003]
The following items are required for approval of street and
drainage plans:
A.
Soil test results.
B.
Geotechnical engineer's report.
C.
Pavement design report.
D.
Hydrology and hydraulics report (drainage).
E.
Storm sewer and drainage plans including as a minimum, tabulation
sheets, plan sheets, profile sheets, and standard details.
F.
Street plans including as a minimum, plan sheets, profile sheets,
cross sections, and standard details.
[Ord. 1020-2003, 10-10-2003]
A.
General: Every subdivision shall be provided with a storm water sewer or drainage system adequate to serve the area being platted, and otherwise meeting the approval of the officials having jurisdiction. Such storm water drainage system shall be so designed by the owner's engineer so that property owners located downstream from and upstream from the subdivision shall not be injuriously affected by the construction, operation, or maintenance of such system. Specific design criteria is found in Section 12-472 of this article.
B.
Channel Improvements: When the owner determines it is necessary to
adjust the natural shape or length of a drainage channel affecting
the floodplain, he/she shall make application to the City Administrator.
Any channel improvement must be approved by the City Administrator,
and the floodplain review board before a permit for construction will
be issued. This includes adding fill in an existing floodplain. All
work in the drainage system and/or floodplains must be completed before
the development will be accepted.
C.
Design Criteria for Storm Water Storage:
1.
General:
a.
The detention storage requirements shall accommodate the excess runoff
from a 100-year frequency storm. The excess runoff is that runoff
generated due to urbanization which is greater than the runoff historically
generated under existing conditions, for a given frequency storm.
b.
Peak release rates from developments shall not exceed the existing
runoff that occurred before development for all storm frequencies
up to and including the 100-year frequency storm. As a minimum, the
ten-year and 100-year storms shall be investigated.
c.
Generally, urbanization results in more impervious area, alteration
of times of concentration, and alteration of drainage patterns. If
improvements are made to any natural channel downstream from an area
requiring a forty-eight-inch pipe to discharge a ten-year compensatory
storage must be provided to limit drainage of the 100-year storm to
natural discharge.
2.
Facility Design: For the design of storm water facilities, the following
methods are approved:
|
Method
|
Drainage Area
|
|---|---|
|
HEC-1 Snyder's method
|
Greater than 10 acres
|
|
HEC-1 SCS method
|
2 to 200 acres
|
|
Modified rational approach with volume factors
|
Less than 16 acres
|
|
Graphed method
|
Not over 2 acres
|
3.
Rainfall Information: U.S. weather bureau technical paper no. 40
and national weather service HYDRO-35 (June 1977) shall be used for
rainfall information.
4.
Calculations: The time increment used in developing the rainfall
distribution and in reading off the ordinates of the unit hydrograph
may be rounded off to the nearest whole time interval or to the nearest
time increment.
5.
Rainfall Patterns: The rainfall patterns shall be used in accordance
with the modeling technique selected.
6.
Snyder's Method: For Snyder's synthetic unit hydrograph
method, the loss rates in determining the runoff/hydrograph shall
be an initial loss of 0.5 inch and a uniform loss of 0.08 inch per
hour for the subsequent hours once the initial losses are satisfied.
7.
Review of Calculations: All calculations for detention facilities
shall be submitted for review by the City. The submittal shall include
hydrographs for both existing and developed conditions, detention
facility stage-area-volume relationships, outlet structure details,
and a stage versus time analysis through the facility.
8.
Identification of Floodplain and Detention Areas: Floodplain areas
and detention facility locations shall be identified at the preliminary
plat stage to illustrate how these areas will be managed during and
after construction.
9.
Backwater Information: If a tract of land under development has a
floodplain area within its boundary, the information that must be
furnished either with the preliminary plat or before the final plat
is submitted shall include both a backwater analysis on the existing
drainage system, and backwater analysis on the proposed drainage system.
10.
Detention Facilities: Detention facilities shall be located in areas
approved by the City. Each facility shall incorporate methods to minimize
erosion and other maintenance reducing designs.
11.
Additional Detention Storage: Additional detention storage, in excess
of the required storage for a specific drainage area, can be provided
to satisfy the detention requirements for a tract of land downstream
of the detention facility, providing the detention facility with additional
capacity is constructed prior to the development of the downstream
tract.
12.
Dry Detention Facilities: All detention facilities shall be designed
"dry" unless a special written maintenance agreement has been approved
by the City.
13.
Encouragement of Facilities: A minimum number of detention facilities
is encouraged for each development. Regional detention facilities
are encouraged for phased or cooperative development in a drainage
basin.
14.
Distribution of Facilities: If runoff has a natural tendency to drain
in several directions for a given development tract of land where
detention is required, then detention storage shall be provided for
the bigger drainage area. Additionally, detention storage may be provided,
at the same facility, to satisfy detention requirements for a separate
drainage area on the same development, provided that:
15.
Watershed Modification: If a tract of land being developed is located
in more than one watershed, grading work to divert flows from one
watershed to another will not be permitted and compensatory storage
will not be permitted in one watershed for that required in another.
16.
Detention Facility Criteria:
a.
All dikes and spillways on detention facilities shall have typical
cross sections shown on the plans.
b.
Side slopes on detention facilities shall not be steeper than three
to one (horizontal:vertical).
c.
Detention facilities shall be provided with a low flow channel from
the inlet to the outlet structure to transmit low flows and the low
flow channel shall be approved by the City.
d.
The detention area shall be identified as a separate platted area;
as appropriate, it may consist of one or more platted lots, a separate
block, or it may be identified as a reserve area.
e.
Provision for the detention facility shall appear among the plat's
restrictive covenants, or applicable law.
f.
In the event the detention facility, as a result of drainage improvements,
becomes unnecessary, the facility by action of the City council may
be vacated as provided for in the covenants or applicable law.
g.
An accessway at least 20 feet wide shall be provided to any detention
area. Access may be provided by frontage on a dedicated public street
or by an access easement from a dedicated public street to the detention
area. The access road shall have a maximum grade of 10%.
h.
If the detention facility is approved by the City to serve areas
outside the subdivision in which it is located, such additional areas
shall be specifically identified in the provision for detention.
i.
The maintenance responsibility for on site detention facilities shall
remain with the private sector and appropriate covenants shall be
obtained to secure such maintenance.
j.
Any dam or berm constructed shall be designed by a registered professional
engineer.
k.
All detention dams or dikes shall be constructed as earth filled
and nonoverflow type dams. Embankment slopes shall not be steeper
than three to one (3:1). Spillways shall be constructed to pass the
100-year flood event. The structure shall contain the 500-year flood
event with a minimum of one foot of freeboard on the earth dam structure.
l.
All earth slopes and areas subject to erosion, such as, adjacent
to trickle channels, inlet structures, and outlet structures, shall
be slab sodded with Bermuda sod or protected with other erosion control
measures. All other earth surfaces, with the area designated for detention
facility site, shall have an established growth of Bermuda grass.
All grass covered areas shall be fertilized, watered and in an established
growing condition prior to completion and approval of the detention
facility.
D.
Additional Requirements:
1.
Drainage Structures: All cross street drainage structures will be
designed in accordance with ODOT standard designs.
2.
Overflow Structures: Overflow structures shall be paved from the
back of curb to the low flow line of the channel, in accordance with
City of Tahlequah standard construction specifications.
3.
Trickle Channels: Trickle channels shall be constructed of Portland
cement concrete not less than six inches thick.
4.
Concrete Lining: Concrete lining of drainage channels shall include
the entire channel and one foot above the high water elevation. When
the lining is designed to be constructed with separate sides and bottom,
the design shall include the requirement for the bottom to be placed
last and it shall cover a minimum of four inches of the sides.
5.
Energy Dissipators: Energy dissipators shall be added to all outfalls
where velocities will cause erosion of the natural channel.
6.
Drainage Pipes: All drainage pipes in noncohesive soils shall have
either joint bands or omniflex or approved equal seals. Where the
storm drain is within 15 feet of a structure, the City may require
wrapping of joints with a nonwoven geotextile fabric such as SUPAC.
7.
Side Slopes: Side slopes for grass lined channels shall be three
to one or flatter. Side slopes for concrete lined channels shall be
one to one (1:1) or flatter for concrete placed against an existing
slope or vertical or flatter where the side wall is formed.
8.
Vegetative Cover: All drainage facilities shall have perennial vegetative
cover established that will check erosion.
[Ord. 1020-2003, 10-10-2003]
A.
Public Water Supply: A "public water supply" is defined as an entity
permitted by the state department of environmental quality to provide
potable water to facilities other than the facilities owned by that
entity.
B.
Accessible Public Water Supply: Where a public water supply approved
by the City is reasonably accessible, each lot within the subdivision
shall be provided with a connection thereto.
C.
Nonaccessible Public Water Supply: In a proposed subdivision, pending
accessibility of a public water supply, the subdivider may be required
to construct wells on each lot, or construct a private water supply
system or attach to a rural water district in such a manner that an
adequate supply of potable water will be available to every lot in
the subdivision at the time improvements are erected thereon. The
water supply plans shall be subject to approval by the Oklahoma department
of environmental quality (DEQ) and by the City. The water supply system
shall be subject to inspection by the City during construction.
D.
Minimum Design Criteria for all Public and Private Water Supply Systems:
1.
Water Distribution Lines: All water distribution lines shall meet
the minimum criteria set forth by state department of environmental
quality regulations regarding standards for public water supply facilities.
2.
Line Sizing:
a.
Hydraulic Analysis: All water distribution lines shall be sized utilizing
a hydraulic analysis based on flow demand and pressure requirements.
The system shall be designed to maintain a minimum pressure of 25
pounds per square inch at ground level at all points in the distribution
system under all flow conditions.
b.
Minimum Sizing:
(1)
Water mains constructed on section lines shall be not less than
12 inches in diameter, or such other size as may be approved by Tahlequah
public works authority.
(2)
Water mains constructed on half section lines shall be not less
than eight inches in diameter, or such other size as may be approved
by Tahlequah public works authority.
(3)
Water mains in residential areas shall not be less than six
inches in diameter, except those located in culs-de-sac as further
provided in this chapter.
(4)
Water mains in commercial, office, and industrial may be eight
inches in diameter if cross connecting lines are less than 600 feet
apart. Otherwise the minimum line size shall not be less than 10 inches
in diameter.
(5)
Two inch lines may be used in culs-de-sac for distances not
over 300 feet.
(6)
Minimum permanent line size is four inches in diameter, except
culs-de-sac and loop lines, subject to TPWA modification and approval.
3.
Looped Systems:
a.
All water lines used for service shall be looped to provide circulation,
if required by the Tahlequah public works authority.
b.
A main line that terminates at a location which will be extended
in the future, shall have a fire hydrant at the end of the line. This
fire hydrant may be moved to a more appropriate location when the
line is extended.
c.
All lines in culs-de-sac shall be looped with at least two inch lines.
d.
Lines used exclusively for fire hydrants may be, but are not required
to be, looped.
4.
Fire Hydrants:
a.
Hydrants shall not be installed on lines under six inches in diameter.
b.
A valve shall be installed between the main and the hydrant.
c.
Hydrants shall be connected to the main with pipe no less than six
inches in diameter, and shall be located on the property line between
two lots and one foot behind the right of way line in a utility easement
five feet deep and five feet wide in each lot for a total width of
10 feet.
d.
Residential area spacing shall not exceed 600, feet or as may be
required by the City.
e.
Commercial and industrial area spacing shall not exceed 300 feet.
5.
Valves:
a.
Air Relief/Vacuum Relief/Blow Off Valves: These types of valves shall
be installed on all lines 12 inches and larger as required by the
design. These types of valves shall be used on smaller lines only
with the prior approval of the Tahlequah public works authority.
b.
Water Valves:
(1)
Valves shall be located at not less than one mile intervals
on twenty-four inch or larger lines, not less than 1/2 mile intervals
on lines of 12 inches to 24 inches, inclusive, and not less than 1/4
mile intervals on eight to twelve inch lines.
(2)
Valves shall be located at street intersections in readily accessible
positions.
(3)
All distribution branching from larger mains shall be valved.
(4)
Valves shall be arranged so that each block can be isolated
in case of a line break.
(5)
Valve location shall be marked on curbs.
6.
Protection of Iron Pipe, Fittings, and Valves: All buried iron pipe,
fittings, and valves shall be polywrapped.
7.
Service Crossings:
a.
All service crossings shall be installed by the developer, or TPWA
if applicable, and shall be placed on lot lines in two inch PVC casing,
or such other size as may be required by TPWA.
b.
Single house services will be 3/4 inch PVC minimum, or such other
alternate size and materials as may be required or acceptable to TPWA.
c.
Two house services will be one inch PVC, or such other alternate
size and materials as may be required or acceptable to TPWA.
d.
Taps in RE zoned subdivisions will be one inch PVC for each house,
or as may be further required by TPWA.
e.
All service crossing requirements are subject to approval and possible
modification of TPWA.
8.
Blocking: All tees, bends, plugs, and hydrants shall be provided
with reaction blocking, tie rods, or joints designed to prevent movement.
9.
Pipe in Conduit: All pipe in conduit shall be provided with restrained
joints.
E.
Materials: As specified in the City of Tahlequah standard construction
specifications shall be used for water distribution lines.
F.
Disinfection: All new mains shall be disinfected by TPWA in accordance
with AWWA C651. Safe bacteriological samples shall be obtained in
two consecutive days before that portion of the line or system may
be used.
G.
Acceptance: The City may accept for maintenance any water lines connected
to its water system constructed within or outside of the City, after
the prescribed tests and inspections.
I.
Excess Line Capacity: The City, by reimbursing the owner for the
increase in cost by payback contract or otherwise, may require lines
larger than required by this article.
[Ord. 1020-2003, 10-10-2003]
A.
Public Sanitary Sewer System Accessible: Where a public sanitary
sewer is reasonably accessible, each lot within the subdivided area
shall be provided with a connection thereto. All connections shall
be subject to the approval of the TPWA in accordance with the regulations
of the Oklahoma state department of environmental quality.
B.
Connection to Public Sewers: Where a public sanitary sewer system
is not reasonably accessible but where plans for the installation
of sanitary sewers in the vicinity of the subdivision have been prepared
and approved by the DEQ, the owner shall install sewers in conformity
with such plans. Where immediate connection is not possible and until
such connection with the sewer system in the basin can be made, the
use of private sewage treatment facilities may be permitted, provided
such disposal facilities are installed and maintained in accordance
with the regulations and requirements of the City and the DEQ.
C.
Public Sewer Unavailable: Where no sewers are accessible and no plans for a sewer system have been prepared and approved, the owner of unplatted land shall either plan and install a sewer collection and disposal system in accordance with the requirements of Subsection B of this section, or an individual disposal device may be installed for the single residence on the unplatted land; provided that no individual disposal device shall be permitted unless the lot to be so served has a minimum width of 100 feet and a lot area of not less than 22,500 square feet. The DEQ, with the concurring approval of the City council, may modify these lot area requirements in relation to soil conditions and other pertinent facts and findings on any particular tract. Each such individual device and system shall be constructed and maintained in accordance with the regulations and requirements of the City, county health department and the Oklahoma state DEQ.
D.
Required Capacity:
1.
The City will require all developers constructing sewerage systems
within the City limits to construct the system with adequate capacity,
as determined by the City, to serve the entire drainage area upstream
from the point of consideration. The capacity shall include sewer
lines, lift stations and force mains, where applicable. The minimum
size of the sewer lines and lift stations shall be in accordance with
the following tabulation:
|
Drainage Area
|
Sewer Line Size
|
Pump Station Capacity
|
|---|---|---|
|
Less than 154 acres
|
8 inches
|
*
|
|
155 to 238 acres
|
10 inches
|
0.76 mgd
|
|
239 to 540 acres
|
12 inches
|
1.08 mgd
|
|
541 to 807 acres
|
15 inches
|
1.62 mgd
|
|
808 to 1,174 acres
|
18 inches
|
2.35 mgd
|
|
1,175 to 1,617 acres
|
21 inches
|
3.24 mgd
|
|
1,618 to 2,065 acres
|
24 inches
|
4.13 mgd
|
|
2,066 to 2,828 acres
|
27 inches
|
5.65 mgd
|
|
2,829 to 3,745 acres
|
30 inches
|
7.49 mgd
|
|
3,746 to 6,090 acres
|
36 inches
|
12.18 mgd
|
|
6,091 to 9,189 acres
|
42 inches
|
18.38 mgd
|
|
9,190 to 13,118 acres
|
48 inches
|
26.24 mgd
|
|
13,119 to 17,962 acres
|
54 inches
|
35.92 mgd
|
|
17,963 to 23,790 acres
|
60 inches
|
47.58 mgd
|
|
23,791 to 30,675 acres
|
66 inches
|
61.35 mgd
|
|
Notes:
| |
|
*
|
Capacity determined by actual area served and approved by the
City.
|
2.
No public sewer line shall be less than eight inches in diameter.
This requirement does not apply to "house sewers" defined as lines
from a single house or a single connection to a lateral sewer.
3.
The City will require any sewers so situated as to subsequently serve
an entire drainage area to be constructed with a capacity and at such
depths as to permit future extensions thereto throughout the entire
natural contributing drainage area without subsequently exceeding
the capacity available.
E.
Connection Requirements: All sewers being developed as part of the
subdivision of land shall be connected to public sewers within the
drainage area in which the development is located, and the subdivider
shall provide public sewer easements for all off site construction
which may be necessary to accomplish this connection.
F.
Minimum Design Criteria:
1.
System Criteria: All sanitary sewer systems shall meet the criteria
set forth by state department of environmental quality regulations
regarding standards for water pollution control facilities.
2.
Location of Lines: To the maximum extent possible sanitary sewer
lines will be located in the back yard and side yard easements. Sanitary
sewers may not be placed in front yard easements without prior approval
by the City.
3.
Manholes: Manholes shall be cast in place or precast and shall be
located not more than 400 feet apart.
4.
Manhole Rings: Manhole rings and covers in streets shall be of the
sealing bolt down type.
5.
Protection of Iron Pipe, Fittings, And Valves: All buried sanitary
sewers containing iron pipe, fittings, and valves shall be polywrapped.
6.
Sanitary Sewers in Floodplains:
a.
Creek Channels: When sanitary sewers are located in creek channels
or below the ground water table, PVC pipe will be used to the maximum
extent possible.
b.
Manhole Rings: Manhole rings and covers in floodplains shall be of
the sealing bolt down type.
c.
Manhole Markers: Manhole markers shall be installed in unimproved
floodplains on trunk sewers. The marker shall consist of a three-inch
diameter galvanized steel post with cover cap at least seven feet
long. The post shall be set with a minimum two feet of the post in
concrete and at minimum five feet exposed above finished ground elevation.
The post shall be set 15 feet from the center of the manhole on the
side opposite from the nearest drainage feature. To the maximum extent
possible, the marking post shall be set in a true north/south or east/west
direction from the manhole.
7.
Sanitary Sewer Taps: All lateral sewers will be designed with taps
installed during construction of the lateral. The tap shall be installed
by placing a tee sized for the lateral with a four inch opening in
the line and stubbing the four-inch line to within four feet of the
finished ground surface. The four-inch line shall be constructed of
schedule 40 PVC and shall have a glued joint cap affixed to the upper
end. A metal coupon shall be buried with the cap to allow location
with a metal detector. Plastic marking tape shall be tied to the four-inch
line and left exposed on the surface. The tee shall be located at
the first joint at least five feet upstream from the downstream property
line. The exact location shall be noted on the as built plans as a
distance in feet from the nearest manhole. This shall be in accordance
with the City of Tahlequah standard drawing for sanitary sewer taps.
In special cases and with the prior approval of the chief building
inspector the building contractor may install a second tap on the
lot and not use the installed tap.
8.
Backflow Preventers: When the designed finished floor elevation of
a structure is less than one foot above the top of ring elevation
of the upstream manhole, a backflow preventer must be installed on
the structure. This requirement must be shown on the sanitary sewer
plans, in a table that identifies each lot that requires a backflow
preventer.
G.
Lift Stations: Lift stations must include the following:
H.
Submittals:
1.
City Submittals: Sanitary sewer system plans including, as a minimum,
plan sheets, profile sheets, backflow preventer table, and standard
details.
2.
DEQ Submittals: Three sets of City approved plans, an engineer's
report for DEQ, request for DEQ construction permits, and payment
to DEQ for review and permit costs are required.
I.
Excess Line Capacity: The City, by reimbursing the owner for the
difference in cost, may require larger diameter lines than required
by this article.
[Ord. 1020-2003, 10-10-2003]
A.
General: During development of a subdivision, the owner will ensure
that proper erosion control measures are taken. Erosion control measures
shall ensure that runoff from the construction site is free of excessive
silt and does not impact downstream drainage structures.
B.
Design Criteria:
1.
The Oklahoma department of transportation standards for erosion control
shall serve as the minimum standard for erosion control plans. Each
owner or his engineer shall establish the erosion control plan for
the subdivision being developed.
2.
For construction on sites that are over five (5) acres, an NPDES
permit is required.
[Ord. 1020-2003, 10-10-2003; amended by Ord. 1126-2008, 4-7-2008]
A.
Driveways: Driveways in the public right of way shall be constructed
of Portland cement concrete which meets the requirements for streets
or as specified by the street department. Driveways in the public
right of way shall not be less than six inches in thickness and shall
have a turn radius of not less than 10 feet. The driveway shall start
at the elevation of the gutter of the street and be designed to divert
stormwater to the street. Removal of existing curb for driveway shall
be by saw cut method. Use of mountable curbs to start driveways is
prohibited, except in mobile home parks.
B.
Building Pads: Fill areas for buildings and structures shall be compacted
as subgrade in lifts with a maximum thickness of eight inches.
C.
Utility Adjustment: All utilities that are designed to be at ground
level shall be adjusted to the appropriate level when the grades are
altered during construction.
D.
Landscape: All landscaped strips, parkways and screening areas dedicated
to the public shall be graded, seeded and planted in an appropriate
manner by the owner.
E.
Street Signs: The owner shall submit a list of street signs required
at the time of final platting. Upon completion of the paving of the
street, signs shall be installed by the City of Tahlequah street department.
F.
Fences:
1.
Residential developments that back up to an arterial, collector,
or highway shall be screened with a solid opaque fence/screen that
is a minimum of six feet high.
2.
Multi-family development, mobile home parks, and industrial developments
which adjoin an arterial, collector, or highway shall be screened
with a solid opaque fence/screen that is a minimum of six feet high.
3.
Commercial and office development fencing requirements shall be imposed
at the time of the site plan review.
4.
Fences will not be permitted in stormwater drainage easements, established
floodplains, sight triangles, or ingress and egress locations; provided
that the City council may approve fences in floodplains which are
so designed that no impediment to the flow will occur.
G.
High Pressure Pipeline Markers: When a lot is located within 500
feet of a high pressure pipeline, which transports combustible materials,
a marker will be placed in the curb in front of the lot. The marker
shall be cast from yellow brass and mounted in concrete as specified
in the City of Tahlequah standard construction specifications.
H.
Lighting:
1.
General: TPWA will provide for adequate lighting of public streets
within the proposed subdivision.
2.
Types of Lights: Lights shall be installed by TPWA and conform to
the standard types accepted for maintenance by Tahlequah public works
authority (TPWA). Decorative lights must be approved by the City and
TPWA prior to installation.
I.
Reflectors At Fire Hydrant Locations: An embedded blue reflector
shall be installed in the curb face at all fire hydrant locations.
The size, type, and nature must be approved by the Tahlequah street
department.
[Ord. 1020-2003, 10-10-2003; amended by Ord. 1126-2008, 4-7-2008; Ord. 1150-2009, 9-21-2009]
|
Table 7.1 - Street Minimum Design Standards
| |||||
|---|---|---|---|---|---|
|
Residential
|
Collector
| ||||
|
Description
|
Large Lot
|
Typical
|
Residential
|
Commercial
|
Arterial
|
|
Street design criteria:
| |||||
|
Right of way width
|
60'
|
50'
|
60'
|
80'
|
100'
|
|
Paving width (no parking)
|
24'
|
28'
|
36'
|
39'
|
52'
|
|
Number of lanes
|
2
|
2
|
2
|
3
|
4
|
|
Design speed
|
25
|
25
|
35
|
35
|
45 - 55
|
|
Minimum CL radius
|
150'
|
150'
|
250'
|
400'
|
950'
|
|
Parking
|
None
|
1 side
|
1 side
|
None
|
None
|
|
Vertical clearance
|
15.5'
|
15.5'
|
15.5'
|
17.5'
|
17.5'
|
|
Maximum grade percent
|
8%
|
8%
|
8%
|
6%
|
5%
|
|
Minimum grade percent
|
0.5%
|
0.5%
|
0.5%
|
0.5%
|
0.7%
|
|
Paving design criteria:
| |||||
|
Asphalt surface option1:
| |||||
|
Type 'B' mix (ins)
|
1 1/2"
|
1 1/2"
|
2"
|
2"
|
2"
|
|
Type 'A' mix (ins)
|
2 1/2"
|
2 1/2"
|
4"
|
6"
|
6"
|
|
Type 'A' agg. base (ins)
|
6"
|
8"
|
8"
|
8"
|
10"
|
|
Separator fabric
|
Yes
|
Yes
|
Yes
|
Yes
|
Yes
|
|
Stabilized subgrade (ins)
|
6"
|
6"
|
6"
|
6"
|
6"
|
|
Concrete surface option1,2:
| |||||
|
Concrete surface (ins)
|
n/a
|
n/a
|
6"
|
8"
|
8"
|
|
Type 'A' agg. base (ins)
|
4"
|
6"
|
6"
| ||
|
Stabilized subgrade (ins)
|
6"
|
6"
|
6"
| ||
|
Subgrade modification3:
| |||||
|
PI < 15
|
None
|
None
|
None
|
None
|
None
|
|
PI between 15 and 29
|
Fly ash
|
Fly ash
|
Fly ash
|
Fly ash
|
Fly ash
|
|
PI > 30
|
Lime4
|
Lime4
|
Lime4
|
Lime4
|
Lime4
|
|
Notes:
| |
|
1.
|
Refer to the minimum street standard drawings for more detail.
|
|
2.
|
The minimum concrete strength shall be 3,500 psi.
|
|
3.
|
Liquid limit: The lowest moisture content at which soil tends
to flow when disturbed slightly. The change from plastic to liquid
is expressed in percentage of water by weight to the weight of dry
soil.
|
|
Plastic limit: The lowest percentage of water that will allow
rolling a sample to 1/8 inch diameter without crumbling. It is given
in terms of percentage of water by weight to the dry weight of soil.
| |
|
Plasticity index (PI): The difference between the plastic and
liquid limits.
| |
|
4.
|
A full paving design using lime stabilization shall be done
by a registered engineer and approved by the City engineer.
|
|
FIGURES[1]
|
[1]
Editor's Note: The figures are included as an attachment to this chapter.
