Kanab, Utah Ordinance
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Design StandardsSection 2 Design Standards |
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SECTION II
DESIGN STANDARDS
2-1 GENERAL
This section defines design requirements for improvements in the Kanab City. It is not the intent of these specifications to restrict professional judgement, but rather to serve as a guide and to establish consistency in design.
2-2 STREET DESIGN
All streets in the Kanab City shall be designed structurally to conform to Section 4, Roadway Construction of these specifications. Streets shall conform to City Specifications for grades, right-of-way, pavement, curb, gutter, and sidewalk dimensions as shown in Table 3.1 and in the Standard Construction Drawings Details. Streets shall be designed to provide adequate stopping and sight distance, degree of curve, and super elevation in accordance with AASHTO Design Standards.
All streets shall be designed to conform to the standards and technical design requirements contained within this sub-section AASHTO, a policy on geometric design of highways and streets, shall be used as a supplement to these guidelines. In cases of conflict, a determination shall be made by the City Engineer, which determinations shall be final. These requirements may apply as required by sub-ordinance.
2.2.1 STREET CROSS-SECTION STANDARDS; Requirements for the Street cross-section configurations are shown in Table 31. These requirements are based on traffic capacity, design speed, projected traffic, system continuity and overall safety.
All new, developments shall use street cross-sections with fifty feet (50) or more of right-of-way. Access to multi-family or commercial developments, shall use street cross-sections with sixty (60) feet or more of right-of-way.
Alternate road cross-sections incorporating the use of a planting strip may be permitted, if applicable safety and traffic standards are met and approved by the City Engineer.
2.2.2 ROADWAY NETWORK DESIGN. New roadway networks shall be designed in accordance with the general planning concepts, guidelines, and objectives provided within this sub-section.
The "Quality of Life’ for residential occupants shall be a primary concern when designing a residential roadway network.
An emphasis on proper street hierarchy should be adhered to, namely local streets should access residential collectors; residential collectors should access mahor collectors; mayor collectors should access minor arterials etc.
An emphasis on access management should provide control of the location, design, and operation of all driveways, median openings, and street connections to a roadway.
Roadways should be designed in a curve a linear method in order to reduce or eliminate long straight stretches of residential roadways which encourage speeding and cut through traffic.
Substantial increases in average daily traffic, due to development of adjacent property an established streets not originally designed to accommodate such increases should be avoided.
Drainage methods should concentrate on meeting the drainage needs while not impeding the movement of traffic. (See drainage guidelines).
Roads should be designed to lie within existing topographic features without causing unnecessary cuts and fills.
A reduction in the use of cul-de-sacs should be emphasized in order to provide greater traffic circulation and less volume on collector roads. Circulation is of the up most importance, long blocks and excessive dead end streets should be avoided.
Stopping sight distance should be considered at all intersections and curves to ensure the safety of the public, in accordance with AASF-ITO standards.
Pedestrians and bicycle traffic should be considered in the planning and design of all developed streets.
2.2.3 IMPROVEMENT REQUIREMENTS. All improvements including, but not limited to the following, shall be constructed in accordance with the standard specifications and drawings unless otherwise approved.
22.3.1 Curb, Gutter and Sidewalk. Required curb, gutter and sidewalk shall be constructed.
2.23.2 Driveways. Driveways shall be constructed in approved locations.
2.23.3 Pavement. All streets public or private, shall be surfaced to grade, with asphalt concrete pavement, to the required minimum width and thickness in accordance with these specifications.
2.2.3.4 Street lighting. Street lighting shall be provided on all streets. The construction on public streets shall be in accordance with the standard drawings and these specifications. Standard Public street lights may be installed on private streets upon agreement with the City and the local power agency when applicable.
2.2.3.5 Cross Cutters- No cross gutters shall be allowed across major collector or major and minor arterial streets. On commercial and industrial streets, cross gutters are generally not allowed and require approval by the City Engineer for their use. The City Engineer may prohibit construction of cross gutters on any street deemed necessary.
2.2.3.6 Handicap Ramps- When new construction occurs handicap ramps shall be constructed at all street intersections, unless otherwise approved in accordance with the standard drawings. In addition, when a project occurs where existing improvements are in place, handicap ramps shall be upgraded to meet current standards.
2.2.3.7 Roadway Medians. Medians on public roadways shall be approved by the City Engineer. Design and construction shall be In accordance with applicable standards.
2.2.3.8 Minimum Access. Proposed developments shall have only the required number of accesses to adequately address the needs of the development and only at approved locations. Too many access points or access on major routes hinder the safety and efficient travel of vehicles using these routes. In addition, too few accesses can stifle circulation and unnecessarily concentrate traffic at selected locations.
2.2.3.9 Drainage. Adequate drainage facilities shall be installed to properly conduct runoff from the roadway. Sub-drains and surface drainage facilities shall be designed in accordance with the approved drainage study. Cross gutters shell be used sparingly to maintain the public’s driving comfort and in accordance with these specifications.
2.2.3.10 Traffic Control Devices. Appropriate traffic control devices and street signs, as required by the City Engineer, shall be installed in accordance with the MUTCO.
2.2.3.11 Pavement Marking. Appropriate pavement markings, as required by the City shall be installed In accordance with the MUTCD.
2.3.12 Street Trees and Landscaping. Street trees and land-scaping shall be required as approved by the Planning Commission.
2.2.3.13 Other improvements. The above required improvements are not all inclusive. Other improvements needed to complete the development in accordance with current engineering and planning standard practice may be required by the City Engineer.
2.2.4 TECHNICAL DESIGN REQUIREMENTS.
The following requirements apply to public and private streets.
2.2.4.1 Street Grades.
A. All steet grades shall have a maximum grade as shown in
Table 2.1
B. A request to increase the maximum street grades shown in request to increase the maximum street shown in Table 2.1 may be considered upon submittal of a request and information justifying such a request to the City engineer. Request for approval must be based upon and in accordance with the latest edition of AASHTOS "A Policy on Geometric Design o Highways and Streets" guidelines. Any approvals for increased grades must be consistent with access requirements of fire apparatus as defined by the Firs Department. The City Engineer’s decision will be final. Cost of construction will not be justification for approval.
2.2.4.2 Intersections.
A. Wherever possible, all Street intersections should intersect at ninety degree angles.
B. In the event an acute angle intersection is proposed, the City Engineer may require mitigation by realigning to achieve a ninety degree intersection if no other reasonable option for realignment exists, a skew may be allowed up to a maximum of 15 degrees from 90 degrees. Other design approaches to mitigate the skewed angle my be required by the City engineer.
C. Proper combination of horizontal vertical alignment should be obtained by engineering study and consideration of the general guidelines listed in AASHTO (Section titled; Combination of Horizontal and Vertical Alignment, 1990 edition).
D. Intersections should not be located on the interior of, or ear, sharp curves. Intersections should be located a sufficient distance from all curves to provide proper sight distance for vehicles on the intersecting road or driveway and on the through road.
E. New intersections with mor than four "legs" are generally not permitted. For arterial access, only four-leg intersections, intersections and modern roundabouts are permitted. When designing local road networks, "V and "L" intersections are desired. The "L" intersection (knuckle) will only be permitted when the street length, in either direction from the angle point, is three hundred-fifty feet (350’), or less. Four-leg intersections on local road networks are generally discouraged. Where determined that a four-leg intersection is necessary, approval from the City Engineer shall be obtained prior to final design of the local road network. Exceptions to these requirements may be granted by the City Engineer on a case by case basis. The developer’s engineer must provide acceptable compelling Traffic Engineering analysis justification before deviations will be granted.
F. When designing local road networks, block lengths without an intervening connector street shall not exceed eight hundred feet (800’) in length unless previous approval has been obtained from the City Engineer. Cul-de-sacs are not considered an intervening connecting street.
G. New access locations created by development shall be unified whenever possible to create the fewest number of access paints onto arterials or major collectors. Cross use agreements shall be required where necessary.
H. Access to corner lots should be from the lesser-classified road at the greatest distance possible from the intersection, and should not be less than the distances shown below. This distance is measured from the PC of the corner curve. A 25’ radius is considered the minimum where the existing radius is less than 25’.
Table 3.2
ACCESS DISTANCE FROM CORNER IN FEET
Facility type Upstream Downstream
Residential Acces 50** 50**
Local Residential 50** 50**
Residential Standard 50** 50**
Residential Collector 100 75
Major Collector 175 150
Minor Arterial* 200 185
Major Arterial* 250 230
All access points shall he approved by the City Engineer. Distances shown may be increased as required by the City Engineer on a case-by-case basis. Exceptions can only be approved by the City Engineer upon submittal of proper traffic justification.
* * Distance shown is preferred.
I. The intersection of two local roads should be designed to operate with minimal traffic control devices. For example, do not design an intersection to operate with a four-way stop or signal control.
J. Direct access will not be allowed for parking, loading or driveway areas that require backing maneuvers onto major collector or higher order streets. This requirement shall apply to commercial and industrial use regardless of the order or classification of street.
K. Residential and commercial developments are generally required to provide at least two improved accesses to the development depending upon the forecasted traffic volumes. Adjacent developments may be required to combine or share driveway access to public roadways. The access shall be of proper widths to accommodate the calculated traffic volumes and expected vehicle types when the area is fully developed and shall be in accordance with the Zoning Ordinance. Projected traffic volumes shall be calculated using the criteria outlined within the Traffic Impact Study requirements of these specifications.
2.2.4.3 Intersection Spacing.
A. Street intersections shall be spaced far enough apart so that the existing and projected traffic stopped to make left turns at one intersection does not interfere with traffic movements at the adjacent intersection and to not hinder the capacity or safety of the roadway. When a Street intersects a low volume residential street, the minimum distance is 150 feet. When a street intersects a minor or major collector street, the minimum distance is 250 feet. Minimum distance measurements arc centerline-to-centerline The minimum spacing requirement on arterials shall be as determined by the City Engineer. Locations shall be based upon a number of items such as projected volumes, turning and stacking distances, intersection spacing, traffic progression, etc. Generally the minimum distance will be 650 feet for arterials and 1/4 mile for major arterials, The City Engineer shall review and give final approval to any intersection requests on arterials.
2.2.4.4 Maximum Design Volume
A. The maximum design volume shown on Table 3.1 shall be used unless otherwise approved by the City Engineer. A request to increase these volumes may be submitted for consideration to the City Engineer. This request shall include all necessary and required information including support and justification from the Traffic impact Study.
Conditions which must be considered when reviewing a request for and increase in maximum design volume include hillsides, safety, parking, traffic studies, access requirements etc.
2.2.4.5 Cul-de-Sac Streets
A. Such streets shall not exceed six hundred (625’) feet in length as measured from center of cross street to center of cul-de-sac. The turnaround pavement radius shall not be less than forty-two and one-half feet (42 ½') (50feet at property line).
Commercial pavement radii shall be no less than forty-seven and one-half feet (47 ½") (55 feet at property line). No road shall be ended without a properly designed cul-de-sac turnaround unless otherwise approved by the City Engineer .
Major collectors and higher order roads shall not be permanently dead-ended.
2.2.4.6 Sidewalks
A. Sidewalk shall be required in all residential and commercial developments. See Table 3.1.
B. For developments which are within hillside areas, see the City of Kanab Hillside Ordinance.
C. Sidewalks in areas of high pedestrian traffic may require greater width as delineated by the City Engineer.
2.2.4.7 Curb and Gutter
A. All public or private streets shall use curb and gutter of the type shown in standard drawings unless otherwise approved by the City Engineer. In large subdivisions, in rural or agricultural settings, the curb and gutter may be eliminated (although the use of the rural curb is recommended) unless required for drainage or Street continuity. When eliminated, roadside drainage and shoulder shall be as shown in standard drawings.
2.2.4.8 Planter Strips
A. Planter strip areas in road right-of-way must be landscaped with at least fifty percent (50%). by area, of live vegetation.
B. Xeriscape landscaping must be approved by City’s representative.
C. Planter strips shall not be filled with concrete or other hard surfaces.
D. Special drainage requirements may be imposed by City’s Representative to protect pavement and curb and gutter from damage due to irrigation of planter strips.
2.2.4.9 Design Speed
A. The design of geometric features such as horizontal and vertical alignment will depend on the design speed selected for each street. The design speed is primarily determined by the street function and classification, and is the maximum speed for safe and comfortable operation of a vehicle. The use of design speeds other than those listed below must be approved by the City Engineer who may decide that the speed provided in this sub-section be changed to that which is reasonable and prudent under the conditions and having due regard to the actual and potential hazards.
DESIGN SPEED
Classification Design
Residential Access 25
Local Residential 25
Local Standard 25
Residential Collector 30
Major Collector 35-40
Minor Arterial 40-45
Major Arterial Varies- (45 mm.)
Commercial Local 30
Industrial Local 35
Variance of design speeds on residential collectors or higher order roads may be granted by the City engineer to no greater (or less) than five MPH increments when conditions warrant. Variances will not be granted for shourt segments of roads, but for entire contiguous stretches so that consistency and driver expectancy are maintained.
2.2.410 Clear Sight Distance at Intersections
A. At intersections adequate, clear sight distance should be provided to permit drivers entering the higher order streets from a driveway or STOP-controlled intersection to see approaching traffic from a long enough distance to allow them to decide when to safely enter the higher order Street and complete their turning maneuvers ina dvance of approaching traffic. Clear sight distance, for both left and right turning vehicles, should be in accordance with AASHTO guidelines and generally as follows:
Through Street Sight*
Design Speed Distance
25 290
30 375
35 465
40 575
45 710
50 840
55 980
* Sight distances should be adjusted with cross road grades
2.2.4.11 Vertical Alignment
A. Vertical curves shall be provided in all changes in grade where the algebraic difference Is greater than one (1).
B. Longitudinal street grades shall not be less than one-half (1/2%) unless adequate alternative street drainage is provided, nor more than fifteen percent (15%), unless specifically approved by the City Engineer.
C. Vertical curve stopping sight distance design shall utilize criteria recommended by the latest edition of AASHTO. K-values shall be noted on all design drawings.
D. Minimum cross slope from street crown shall be two percent (2%) and the maximum four percent (4%) unless otherwise approved by the City Engineer.
E. Vertical alignment with the intersection is also of special nature, and design alternatives may be required. As a guideline, the approach area where vehicles stop while waiting to enter an intersection should not exceed five percent (5%) from the gutter line of the street being intersected for a distance of fifty (50) feet, though a range of fifty (50) to one hundred (100) feet is more desirable. This applies to all intersections, except those where both intersecting streets are minor or major collectors. In this situation, the landing area for a residential and major collector which is controlled by a STOP or YIELD sign should be designed for a grade of three percent (3%) for a distance of one hundred feet. Any other major intersection streets shall be approved by the City Engineer.
2.24.12 Safe Stopping Sight Distance
A. The minimum sight distance (length of roadway visible to the driver) to be provided for through traffic traveling at, or near, the design speed to stop before reaching a object In its path shall comply with the requirements set forth below (AASHTO guidelines):
Design Speed Required Distance
25 150
30 200
35 250
40 325
45 400
50 475
55 550
2.2.4.13 Horizontal Curves
A. The recommended minimum centerline radius for horizontal curves are outlined below.
Design Speed Curve Radius in Feet
25 MPH 185
30 MPH 310
35MPH 419
40 MPH 628
45 MPH 730
50 MPH 926
*For residential streets use 150.
2.24.13 Horizontal Curves
A. Generally, with design speeds less than thirty five miles per hour unless otherwise approved by the City Engineer.
B. Maximum Supervelvation for urban roads shall be 4 percent (4%) unless otherwise approved by the City engineer.
C. The use of Superelevation shall require prior approval from the City Engineer.
2.2.4.15 Deceleration Lanes
A. Deceleration lanes may be required on streets in conjunction with driveways and/or intersections adjacent to a proposed development. They are specifically required when all of the following factors are determined to apply:
B. 5,000 vehicles per day are using or are projected to use, the street;
C. The 85th percentile traffic speed on the street is thirty- five miles per hour or greater; or forty miles per hour for a two lane (one lane each direction) roadway: and
D. Filly vehicles or more making right turns into the driveway or street during a one-hour peak period.
The lane lengths cor a deceleration lane shall be determined on a case-by-case basis and must receive prior approval of the City Engineer. In addition to the above guidelines, deceleration lanes may be required in connection with the results of a Traffic Impact Study or by the City engineer
2.2.4.16 Driveway Profiles
The slope of a driveway can dramatically influence its operation. Usage by large vehicles can have a tremendous effect on operations if slopes are severe. The profile, or grade, of a driveway should be designed to provide a comfortable and safe transition for those using the facility, and to accommodate the storm water drainage system of the roadway.
Required treatments of driveway grades are shown below. In commercial use, while eight percent (8%) should be the maximum allowable initial grade, maximum grades of three percent (3%) are preferable for high-volume driveways and six percent (6%) for low-volume driveways.
For driveways that require steeper grades an engineered design is recommended.
Driveway Typeand Adjacent Street Classification Maximum
Grade
Low Volume Driveway**on Local Street* 15%
Low Volume Driveway** on Collector Street 10%
Low Volume Drive** on Arterial Street 5%
High Volume Driveway *** on Any Street 5%
* For single family residential homes these values apply to only the initial loft, of the driveway beyone the sidewalk or right-ot-way whichever applies.
** Low Volume Driveway - defined as a driveway with less than 100 vehicles in the peak hour in the peak direction.
*** High volume driveway defined as a driveway with more than 100 vehicles in the peak hour in the peak direction.
The above requirements apply only to driveways that adjoin public streets and are recommended for those adjoining private streets.
For grade changes greater than 12%, a vertical curve of at least 10 ft. should be used to connect the tangents.
2.2.4.17 Alignment and Continuity- Off-Site
A. Normally, off-site pavement construction requires asphalt concrete paving to the right-of-way centerline and in some cases beyond. When asphalt pavement is existing, the developers engineer shell submit to the City Engineer sufficient information prepared by the Engineer to indicate vertical and horizontal alignments are maintained and adequate drainage is provided for. The developer may be required to replace all, or any portion of existing roadway, in a manner that two-way traffic can be maintained without the use of potentially hazardous alignment transitions (vertical or horizontal) and in a manner to ensure that adequate drainage is provided for. As a minimum, there shall be twenty-five feet of paving to accommodate through traffic. Required parking and shoulders are not included in the 25 feet.
When off-site pavement construction consists of improvement to the right-of-way centerline (approximately), leading and trailing transition tapers shall be placed at each end of the improvements. Horizontal transition tapers shall be designed and constructed based upon the roadway speed and in accordance with the taper requirements in the MUTCD and applicable AASHTO guidelines unless otherwise approved by the City Engineer.
B. When paving for partial street construction, the edges of the pavement are to be protected by placing a minimum two feet of aggregate base material beyond the edge of pavement matching the pavement grade.
C. Wherever partial street construction is required, grades shall be set for the future curb line and approved by the City’s Representative. The future grades shall be compatible with the curb and centerline grades for the partial street construction. It may be necessary to design the roadway for a minimum of two hundred (200) feet to as much as one thousand (1000) feet beyond the development to ensure a future match.
D. Where a street abruptly ends or transitions, proper signage according to the MUTCD shall be required, Safe transitions into existing elevations shall be required where new roads transition into existing surfaces, i.e. gravel or natural surface.
2.2.4.18 PAVEMENT STRUCTURAL DESIGN
The structural details shown on the standard drawings are minimum requirements. The actual structural section for each roadway shall be designed by accepted Engineering design methods for flexible pavement (i.e. AASHTO, UDOT or CALTRANS). Required subgrade soil properties shall be obtained from an on-site geotechnical investigation. Required traffic information for design shall be approved by the City Engineer.
The geotechnical investigation shall be conducted by the Geotechnical Engineer. The investigation shall include a thorough exploration and sampling program of the sub grade to determine the nature and engineering properties of the on-site soils within the roadway construction area, for new construction and reconstruction projects, the minimum sampling and testing requirements are as follows.
Excavate test holes to a minimum depth of five feet below sub grade. There shall be three test holes for the first one thousand (1000) feet and one for every eight hundred (800) feet thereafter or as sail type varies.
Calculate "R" values using AASHTO T 190-93 or ASTM D2844-69 (1975) using exudation pressure of 300 PSI (2070 Kpa) corrected to 2.50 inches (63.50 mm) specimen. Calculate CBR’ values using AASFHTO T 193-93 three point using T 1 80 (Method D) for mold compaction with exceptions as listed in 5.1.1 through 5.1.3 of Test Method T193-93.
Minimum Testing Frequency for "B" or CBR" values shall be as follows:
Two tests with at least one test per significant soil type for roadway lengths of one foot to one thousand feet.
Three tests with at least one test per significant soil type for roadway lengths of one thousand feet to five thousand feet.
Four tests with at least one test per significant soil type for roadway lengths of five thousand feet to sixteen thousand feet.
Two tests per five thousand feet of roadway with at least one per significant soil type for any roadway over sixteen thousand feet,
Conduct sieve analysis using either AASHTO T27.91 or ASTM C136-95. Conduct a sand equivalent test to determine the presence or absence of plastic fine material using either AASHTO T176-86(1993) 4.3.2 alternate method No, 2, prewet 4.3.3 mechanical shaker or ASTM D2419-91 9.4.2 Procedure B, 11.6.1 mechanical shaker. Either method shall use distilled or demineralized water for the working solution.
One test for each stratum of each test hole, ! Calculate density in place using the drive-cylinder method ASTM P2937-83 or nuclear method ASTM D2922- 93. Two tests per test hole.
! Calculate resistively and pH using test methods MSF- ITO T-288-91 and AASHTO T-289-91.
One test for each corrugated metal pipe culvert location, 1 Test for soluble salts using Kanab Standard Test Method 82297-96 at one-third of the number of test hole locations.
1 Expansion index of soils shall be determined using the ASTM 04829-88 test method. This test shall be conducted whenever potentially expansive soils are encountered in a test hole.
The above schedule represents minimum sampling and tasting requirements. The Registered Professional Engineer responsible for directing and controlling the geotechnical investigation shall analyze each prefect to determine actual sample locations frequency and testing program beyond the minimums given above.
The above testing and design requirements may be waived by the City’s Representative providing a prior development has already performed the above testing, design and construction on the first half of the roadway in the same location, In this case the new development shall match the existing road section.
2.2.4.19 CURB SIDE MAIL BOXES.
All roadside mall boxes should be installed in accordance with applicable postal standards in the following locations:. In areas where the sidewalk is next to the curb, install boxes behind the sidewalk so as to not encroach into the sidewalk; in areas where a planter strip is provided, mail boxes may be installed within the strip, provided no part extends into the sidewalk or beyond the back of the curb; in rural areas where no barrier curb is installed, a minimum clear zone of ten feet from the traveled way should be provided.
2.2.4.20 SIGNS AND PAVEMENT MARKINGS.
All street name and traffic control signs and pavement markings required on the street system within a development or as a result of the development, shall be installed at the developer’s expense in accordance with the standard drawings and MUTCD standards. A signing plan should be submitted with the engineering drawings, however, additional signing and traffic control may be added to the project as determined by the Citys Representative.
2.2.4.21 UNDERGROUND WATER.
When underground water in or adjacent to the site is encountered by geotechnical investigation or during the construction work, the City’s Representative and the Project Engineer shall be notified immediately. The Project Engineer shall cause the necessary studies to be made and the required mitigation work to be installed. Do not ignore the situation.
2-3 DRAINAGE SYSTEM DESIGN
All subdivisions in the Kanab City shall be designed to accommodate rainfall and underground spring runoff.
2-3.1 SPRING CONTROL. Where in the determination of the City Engineer spring control is necessary, the Owner shall provide an adequate pipe system to eliminate the nuisance of the overland flow.
2-3.2 FLOOD CONTROL. Before altering the natural terrain all developers shall consult with the City Engineer or Geologist to determine the flood control measures necessary in their project area.
A flood control system shall be designed and approved as part of the construction plans. Flood water may be conveyed in pipes major washes, designated floodway easements, or dedicated city streets.
Table 1
STREET DESIGN STANDARDS
Copy of Table in the City Office
*Curb & Gutter Drawing No. XV-202A
Note 1. Area of high water flow may require larger curb and gutter capacity.
Note 2. Sidewalk widths for commercial areas will be determined on a case by case basis according to each individual site and the surrounding area.
2. All occupied buildings shall be constructed outside floodway limits and two feet above the 100 year flood stage.
3. Where an underground pipe system is required, it shall be designed to carry a 10-year return frequency. Major hydraulic structures shall be designed to carry a 25-year return frequency.
4. Streets shall not be inverted to carry flood-water without sufficient justification.
5. When designing, the Engineer shall give proper consideration to adjacent properties. The drainage basin up0stream shall be assumed fully developed in conformance to the current land use master plan. The impact of said runoff on downstream properties shall also be considered in design including acquisition of easement or agreements where necessary.
2-4 SANITARY SEWER DESIGN.
2-4-1 DESIGN FLOWS. All sanitary sewers and appurtenances shall be designed to carry the design flows from all contiguous or adjacent areas which may, within a reasonable period in the future, be tributary thereto.
2.4.1 DESIGN FLOWS. AU sanitary sewers and appurtenances shall be designed to carry the design flows from all contiguous or adjacent areas which may, within a reasonable period in the future, be tributary thereto.
Sanitary sewers must be designed to carry the peak discharge and to transport suspended material so that deposits in the sewer are precluded.
New sewer systems shall be designed on the basis of an average daily per capita flow of not less than 140 gallons per day. This figure is assumed to provide for normal infiltration, but an additional allowance should be made where conditions are unfavorable. To provide for peak loads sanitary sewers should be designed to carry, when full, not less than the following:
Laterals and Sub Mains 400 gal. per capita/day
Mains/ Trunks and Outfafls 250 gal. per capita/day
The following sewage flow parameters shall be used as a general guideline for minimum estimated flows generated from non-residential and use:
Residential Areas 1250 gal/acre/day
Commercial Areas 1000 gal/acre/day
Infiltration-inflow Allowance 500 gal/acre/day
All sewers shall be designed and constructed with hydraulic slopes sufficient to give mean velocities, when flowing full, of not less than 2.0 feet per second, based on Manning’s formula, using a valve for "N" of 0.013. The following shall be the minimum slopes to be provided:
Manho!es shall be installed at the end of each line, at all changes in grade, size or alignment; at all intersections; and at distances not greater than 400 feet apart for sewers fifteen inches in diameter or less, and not greater than 450 feet apart for sewers eighteen inches or more above the manhole invert. Floor troughs shall be furnished for all sewers entering manholes.
All manholes shall conform to the detailed dimensions, construction details, and materials as shown on the drawing entitled "Standard Manholes’ provided in the Appendix Drawings lVa-lVc. Manholes shall withstand tests as detailed in section 9-6.6.
2-4.4 SERVICE CONNECTIONS. Service connections to any public sanitary sewer shall be made only to a tee installed at the time of the sewer main installation or by machine tap and approved saddle appropriate to the main line sewer material. All connections and service lines must be water tight. Clean-outs shall be made with sanitary tee.
Under no circumstances shall roof drains, foundation drains, storm drains or sub-drains be connected to the sanitary sewer system.
All easements must be at least fifteen feet in width and graded so that every manhole will be accessible to maintenance equipment.
2-5 WATER SYSTEM DESIGN
2-5.1 DESIGN FLOW. All water main and appurtenances shall be designed to provide for all contiguous or adjacent areas which may, within a reasonable period in the future, be tributary thereto. Contiguous or adjacent areas are to be included in the design.
Water mains and looping must be designed to provide a minimum residual pressure of 20 psi under maximum day demand conditions with a fire flow of 1500 g.p.m. at any combination of two hydrants in the area and or must meet requirements of the insurance service office. A minimum of 35 psi residual pressure must be maintained under normal peak hour conditions without fire flow.
The system must be looped and valved, such that a break in any one length of main will put no more than 600 feet of main nor more than two flre hydrants out of service while maintaining adequate minimum service in the remainder of the water system once the break is isolated.
High density residential, commercial or industrial areas wfll require special investigation to determine flow requirements. Existing and future static pressure and flow information used in the design must be obtained from or approved by the City Engineer.
2-5.2 MINIMUM SIZE AND DEPTH. The minimum depth of cover for water mains shaft be three feet below the final grade or the street. Where final grades have not been established mains shall be installed to a depth great enough to insure three feet of cover below future grade based on the best information available. The minimum size water line shall generally be six inches in diameter. Some 4-inch diameter lines may be used in single family residential areas where the distance between connecting mains is 450 feet or less and for short dead-end runs.
Valves generally shall be located at street intersections in line with an extension of property line. Fire hydrants shall be spaced and located as follows:
(1) At each intersection, generally on alternate sides of the street.
(2) In residential areas, fire hydrant spacing shall be no greater than 500 feet from a hydrant via a public access to the property being served.
(3) In multiple family, industrial, business or commercial areas, fire hydrant spacing shall not be greater than is allowed by the Uniform Fire Code.
(4) Generally, hydrants should be located in line with extensions of the property line when located mid~block.
(5) Hydrants shall be placed about five feet from the curb, with a five-foot elliptical radius of clearance adjacent obstacles and with the lowest water outlet not less than eighteen inches or more than thirty inches from the final ground elevation.
(6) All hydrant installation must be on dedicated easements or public right-of-way and are to be owned and maintained by the Kanab City Utilities Department.
2-5.3 MISCELLANEOUS DESIGN CRITERIA.
(1) All public water mains shall be installed in an easement at least fifteen feet in width (7 1/2 feet each side of center line) or in public right-of-way with access for maintenance vehicles.
(2) Dead-end mains shall be avoided wherever possible and shall not exceed 600 feet. Hydrants shall be located at the end of dead-end mains for flushing purposes as well as for fire protection.
(3) Each building shall be served by a separate line and meter; however, in some situations, a common tap and service line from the main to a manifold with two curb stops and boxes may be installed to serve two adjacent properties.
(4) All service line taps shall be machine tapped at the time of the water main installation. Service ines must be installed prior to testing and acceptance of the water main.
(5) Water mains shall be laid at east ten feet horizontally from any existing or proposed sewer main. The distance shall be measured edge to edge.
(6) When a water main crosses over a sewer main, the water main main shall be laid at such an elevation that the bottom of the water main is at least eighteen inches above the top of the sewer. When the water main cannot be as high as eighteen inches above the sewer, the sewer shall be constructed of material with pressure conduit standards.
(7) The city will require a megalug retainer gland system be used on all mechanical. These shall meet Uni-B-13 for PVC and be ULJFM approved through twelve feet for both ductile iron and PVC. The restraint mechanism shall consist of individually activated gripping surfaces to maximize restraint capability. Twist -off nuts, sized the same as the tee-head bolts, shall be used to insure proper activating of restraining devices. The gland shall be manufactured of ductile iron conforming to ASTM A536-8O. The retainer-gland shall have a pressure rating equal to that of the pipe on which it is used through fourteen feet with minimum safety factor of 2:1. Gland shall be Megalug by EBM Iron, Inc. Or approved equal. They type of model retainer and amount for each connector is shown on Restraining System Details of the addendum.
(8) Air release vacuum assemblies and blowoff valves shall be provided on all mains arger than twelve inches where needed to prevent damage due to air accumulations.
(9) Detectable underground utility marking tape shall be placed over all underground utilities that are undetectable according to the following specifications and color code. It shall be placed one foot below grade.
1. SPECIFICATION:
Tape shall consist of a minimum of five mils overall thickness with a solid aluminum foil core. Construction shall be two mils clear film, reverse print laminated to aluminum foil two mils clear film, making the film permanently printed.
TEST DATA
Thickness ASTMD 2105 5.0 Mils
Tensile Strength ASTMD 882 35 lbs/inch (15,000psi)
Elongation ASTMD 882-75B 80%
Bond Strength Boiling Water 5 hours w/o peel
Adhesives Morton 548 or Equiv.
Bottom Layer Virgin FE
Top Layer Virgin Pet
Foil Industry Standard
Message Repeat Varies per legend
Inks AXL II
Flexibility ASTM 671-76 Pliable hand
Printability ASTM 2578 45 Dynes
COLOR CODE
Blue Water & Associated lines
Brown Force mains & Associated lines
Orange Telecommunication lines
Purple Reclaimed water lines
Yellow Gas & Associated lines
For all buried electric cables that are detectable a bright red warning tape made of light weight but rugged polyethylene, to resist high or low ph conditions, shall be instafled one foot below grade.
2-6 POWER SYSTEM DESIGN
All power systems in the Kanab City shall be designed according to the Kanab Power Department Electric Service Regulations, Power Department Ordinances, Underground Power Construction Standards and Specifications, REA Bulletin 50-3 Standard D-804 Standard D-804, and Electric Transmission Specifications and Drawings 34.Ky through 69KV