240.1             Standard Specifications.        All street and storm drainage construction shall meet the requirements of the City of Sedalia Street and Sewer Drainage Specifications and Standards and all subsequent revisions.






240.2               Asphalt Surfaced Roadways.

Newly constructed asphalt roadways allowed by these specifications shall meet the following standard specifications:


Local/Residential     -    4" Compacted Base Rock

4" Bituminous Base

2" Type C Asphaltic Concrete


Arterial & Collector -   4" Compacted Base Rock

6" Bituminous Base

2" Type C Asphaltic Concrete


Commercial -               6" Compacted Base Rock

                                                            8" Bituminous Base

            2" Type C Asphaltic Concrete


                         *Thickness is final lift thickness after compaction.


At the owner/developer option and with approval of the County Commission, concrete paved streets/roads meeting the following specifications will be allowed:


Local/ Residential     - 6" Portland Cement on Compacted Sub-Grade


Arterial & Collector  - 7" Portland Cement on Compacted Sub-Grade


Commercial -              4" Compacted Base Rock

 8" Portland Cement


Geometric Requirements of Section 230 shall supply.

240.2.1            Asphalt Surfaced Roadway.      Asphalt roadways constructed without curbs as allowed by these specifications shall meet the standard specifications with the following exceptions:


Concrete curbs shall be omitted.

Base material shall extend a minimum of 2' - 0" beyond the edge if the asphaltic surface.


240.2.2            Granular Surfaced Roadway.    (Where allowed by the County Commission)


24' Surface width

4' Shoulder (not surfaced)

2:1 In-Slopes (minimum)

3:1 Back Slope (minimum)

18" v-bottom ditch (minimum depth)

Roadway crown 3/8" – 1/2" per ft.


BASE             (Minimum requirements).          Subgrade shall consist of suitable construction material, free of organic or    other undesirable material, properly compacted to 95% of the Standard Proctor density. Any required testing will be the responsibility of the contractor with test results to be submitted to the Road/Bridge Department for review. Unsuitable sub grade material shall be removed and replaced as necessary. 1 1/2' - 2" sized rock shall be incorporated into and compacted as part of the base as necessary.

Application Rate for base rock will be approximately 800 ton/mile for 24' width roadways. Application Rates for other roadway widths shall be adjusted accordingly.


Surface (Minimum requirements)


1st Application

            1 1/2" minus rock = 1200 ton/mile for 24' width


The above quantity of aggregate surfacing shall be distributed and spread uniformly over the prepared sub grade prior to placing the 2nd application surface course.


2nd Application

            1" - 1 1/4" minus rock = 600 ton/mile for 24' width


Surface shall be graded and profiled to meet the requirements of typical roadway section.


Copies of rock tickets or other acceptable proof of rock quantities shall be submitted to the Pettis County Road & Bridge Department. Acceptance of base construction and surface course may be based on visual inspection by the department at the discretion of the Road & Bridge Superintendent.


240.2.3              Storm Drainage & Drainage Structures. All storm drainage shall generally be carried in enclosed storm sewers or Open channels subject to the following criteria and consistent with other County Regulations or requirements.  Storm water quantities for open channels or drainage structures serving a drainage: area of less than 200 acres shall be calculated using the rational method, Q=CIA. Storm water quantities serving drainage areas of greater than 200 acres shall be calculated using "Technique for Estimating the Magnitude and Frequency of Missouri Floods". The Manning Equation shall be used for sizing of open channels, culvert pipes, or other similar drainage structures.


          Design Flood Return Frequencies


Q10 - All enclosed structures in residential areas.


                        Q25 - Commercial property, arterial or collector street culverts, and open channel (earth) slopes.


Q50 - Open paved drainage channels.


The engineer shall have detailed design, computations available to support the design and may be required to submit them or review them with the Superintendent of the Pettis County Road & Bridge Department.


Minimum Pipe Size - The minimum size culvert pipe shall be 12 inches in diameter except under roadways where 18 inches in diameter shall be minimum.


Materials Allowed (Culverts/Storm Drains) - Reinforced Concrete Pipe (RCP), Corrugated Metal Pipe (CMP) - annular riveted or helically corrugated meeting minimum gage requirements, Corrugated Polyethylene (PE) Pipe (corrugated or corrugated with smooth interior wall). RCP and PE shall not be allowed under or adjacent to granular surfaced roadways. All pipes shall be used and installed in conformance with manufacturer specifications and guidelines.


Length of Pipe - All drainage pipes shall be of sufficient length such that pipe flow discharges beyond the toe of any fill and onto natural or stabilized ground.


Velocity - All storm drainage pipes, culverts, and open paved channels shall be designed so as to maintain a minimum velocity of flow of 3 fps and a maximum velocity of 15 fps when flowing full. All open channels (earth channels) shall have a gradient to keep the velocity within 1.5 - 4.0 fps depending on existing soil conditions. The developer may be required to line a channel if it is necessary to attain ultimate design capacity or to stabilize the embankments. Consideration shall be given to design and construction of discharge energy dissipaters to prevent erosion and scouring along down stream properties.


Cover Depth - The minimum allowable fill or cover for structures under roadways shall be one foot or a Minimum clearance of six inches from top of structures to the bottom of pavement base, except for box culverts designed to carry traffic on the top slab. Structural protection, such as special bedding, shall be provided where adequate cover cannot be determined on the basis of structural strength of pipe and design loads.


Special considerations may be made by the Road/Bridge Department for culverts under private entrance.


240.2.4                        Roadway Cuts (Utilities & others).




Roadway cuts in existing asphalt and concrete streets shall be repaired as per Pettis County Street Specifications and Standards. Utility cuts in granular surfaced roadways shall be repaired in a similar manner as above with a granular surface.


All underground water line installations within the road right-of-way shall have a minimum cover of 42 inches. All other underground installations shall have minimum cover of 30 inches. Direct burial underground telephone or TV cable placed parallel with the roadway shall have a minimum cover of 24 inches.


Roadway ditches, culverts, and other devices used to carry surface run-off shall be kept open, free and clear at all times. Construction signing shall be as required and consistent with the Manual on Uniform Traffic Control Devices (MUTCD). All disturbed areas shall be seeded and mulched to the satisfaction of the Road and Bridge Department. All work shall be performed expediently and in a workmanlike manner. Person (s) receiving permit shall be responsible for correcting any deficient repairs for a period of ninety (90) days from the completion of the work or the permit deadline, whichever is longer.


240.2.5            Driveway Entrances/Culverts.


General Information.     A driveway construction permit must be obtained from the Road and Bridge Department prior to constructing any driveway entrance (temporary or permanent). Driveway culverts shall be located so as to conform with the existing ditch line (s) or as directed by the County Road & Bridge Superintendent.  Driveway culvert pipe sizes must be approved by a representative of the Road & Bridge Department prior to installation. All driveway culvert pipes shall be a minimum 12" diameter, 20 ft. in length. Culvert pipes greater than 30 ft. in length will be a minimum 15" diameter.


All driveways shall be constructed in such a manner as to not direct drainage onto the roadway.


Culverts not meeting the specifications and/or causing drainage problems will be removed as necessary to correct the drainage problems. Costs of new culvert installations shall be borne entirely by the property owner.


Geometrics - Entrance onto Curb/Gutter Streets


Driveway locations shall meet the geometric requirements as shown on Illustrations 10R, 11R (2 pages as attached), adopted from the City of Sedalia Street and Storm Sewer Drainage Specifications and Standards.          


Installation of Driveway Culverts


It is the responsibility of the permit holder to install driveway culverts to meet these specifications. The Road and Bridge Department will not install any driveway culvert unless removed by Pettis County Highway Department for improvement.


After installation of the culvert is complete the Road & Bridge Superintendent or his representative shall be notified for a final inspection to ensure compliance with these specifications.


Culverts not meeting these specifications and/or causing drainage problems will be removed as necessary to correct the drainage.                                                                                       


When major road improvements (not normal maintenance) are performed by the County, the County shall be responsible for upgrading driveway entrances and drainage improvements to meet these specifications.




Corrugated metal pipe (CMP or CSP) with an aluminized or galvanized coating or plastic (PE) pipe with a corrugated outside and smooth interior will be permissible for use on County roads. Rock used for cover shall have sufficient fines to bind the rock together.


All driveways shall be constructed in such a manner as to not direct drainage onto the roadway.


Culverts not meeting the specifications and/or causing drainage problems will be removed as necessary to correct the drainage problems. Costs of new culvert installations shall be borne entirely by the property owner.


240.2.6                 Seeding & Mulching.        All unpaved or unsurfaced areas within road rights-of­-way which have been disturbed during grading, construction, or utility operations shall be fertilized and seeded to minimize erosion in those areas. Mulching is required on areas where slopes, soil type, excessive drainage or other conditions indicate additional protection is necessary.


The area to be seeded shall have a uniform surface free from rills, washes and depressions. Seeding shall be done before the proposed seedbed becomes eroded, crusted over or dried out and shall not be done when the ground is frozen or covered with snow. Seed shall be uniformly applied at a rate which will insure a dense growth to control erosion. If proper growth is not obtained as a result of the initial seeding additional applications of seed will be required until satisfactory results are obtained.


The Road & Bridge Superintendent may waive this requirement if the developer has provided adequate erosion control by some other means.


240.2.7            BRIDGE STANDARDS


1.         All new bridges will meet these minimum standards regardless of the source of funding, except as specified.


2.         Clear bridge roadway width will be a minimum of 22 feet unless the daily traffic count, approach road width, speed or a combination of these dictate the width to be greater.


3.         Minimum design loading for all new bridges shall be HS 20.


4.         All new bridges shall have safety tailings.


5.         Hydraulic design shall provide for low beam steel to be above the following flood elevations or fuse plugs shall be provided where more economical: 50 year flood for major rivers, 25 year flood for large streams, 10 year flood for small streams.


6.         Type of construction material will be steel or concrete beams with concrete floor, as designed by a licensed professional engineer.


7.         Exceptions to these minimum standards are:

a. Bridges being routinely repaired

b. Bridges that serve less than 5 households

c. Bridges providing limited access to agricultural fields or serving a dead end road.


8.         All bridges shall be designed by a competent licensed professional engineer.


240.2.8            INSPECTION AND TESTING


It is the sole responsibility of developers and/or contractors to schedule inspections with the Road & Bridge Superintendent.  Failure to do so may result in work not being accepted by Pettis County.  It is also the responsibility of the developer and/or contractor to ensure that all materials and workmanship conform to these specifications.  If at any time the Road & Bridge Superintendent feels minimum construction standards are not being met, he may require that an independent testing lab be retained to ensure adequate quality control.  The testing lab will be reimbursed by the developer and/or contractor.  Testing will be as required by the Missouri Standard Specifications for Highway Construction, 1996.