CHAPTER 1 - GENERAL INFORMATION
 

I.                PURPOSE:

The purpose of these guidelines is to inform Engineers, Planners and others concerned with subdivision design, of the basic procedures and requirements for construction plans for public facilities in subdivisions. These requirements are for use as guidelines only, and are not to be construed as a waiver by the CITY of LIVINGSTON of the right to require a more stringent or lenient design as conditions warrant.

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II.                DESIGNS:

All construction plans for subdivision improvements are to be prepared under the direction and supervision of a qualified Texas Registered Professional Engineer and such plans shall bear the seal and signature of that engineer.

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III.                CONSTRUCTION PLANS:

The following chapters outline the detailed requirements for the preparation of the construction plans for water, sanitary sewer, paving and drainage. These various plans may be combined into one complete set, as long as the clarity and usefulness of the drawings are not diminished.

A.                Submittal: Two complete sets of construction plans and specifications shall be submitted to the CITY prior to construction start on any subdivision. The CITY recommends the plans be completed and submitted at the time the preliminary plat is submitted to the CITY for consideration. Certain engineering decisions will affect the information placed on the preliminary plat such as the location of flood plains, utility easements, drainage easements and similar information. To wait until the preliminary plat is approved by the CITY could result in later amendments in the preliminary plat.

B.            Content: Completed plans shall include the following sheets:

1.             Title sheet showing names of subdivision, DEVELOPER, engineer, date, location map and any other pertinent information. It should also provide a space for signature of approval from the CITY.

2.                Subdivision preliminary plat as submitted.

3.             Overall water and sanitary sewer layout sheet showing street layout, lots and lot dimensions, curve data, and any other pertinent information necessary for surveying all lots and streets. This may be a modified print of the subdivision final plat.

4.             Drainage area map and drainage computation sheet showing contours at two foot intervals for the entire drainage basin of all structures planned for the subdivision and flood plains shown on the plat. Where two foot contour intervals are not available, five foot contour intervals shall be used.

5.             Plan-profile sheets showing all improvements in accordance with Chapter Two and Three.

6.             Detail sheets for special construction and CITY of LIVINGSTON standard detail sheets.

C.                Approval: Approval of the construction plans by the CITY is a prerequisite for construction start and eventual final plat approval by the CITY Council.

D.                Approved Construction Plans: Prior to commencing any construction, two prints of the approved subdivision construction plans shall be distributed to the CITY.

E.             "As Built" or "Record Drawings": Following construction completion, the DEVELOPER shall furnish to the CITY a record set of prints labeled that these drawings reflect the original design and field changes incorporated into the work. The drawings shall be professionally drawn and noted neatly. "Red lines" or pencil mark-up drawings are not acceptable. The CITY may elect to withhold building permits or utility connections until these drawings are submitted.

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IV.                CONTRACTOR PROCUREMENT: 

The DEVELOPER may secure contractors by whatever means (sealed bids, price quotes, force account, etc.) that may be deemed appropriate by the DEVELOPER, and the CITY of LIVINGSTON is not a party to the contract. When the CITY of LIVINGSTON is to participate in the cost of the improvements, in accordance with the CITY's cost sharing policy, and the CITY's portion of the cost is 30% of the total costs, or greater, the contractor must be secured by competitive sealed bids on plans and specifications furnished by the DEVELOPER and which bid is advertised by the CITY in keeping with public law and opened in a public bid opening at CITY HALL. The award of a contract, which contract will be between the DEVELOPER and the CONTRACTOR based on this bid may be to any contractor but the limits of the CITY's participation financially will be determined by the CITY on the basis of the lowest qualified bid irrespective of the bidder receiving the contract. The CITY shall have the right to refuse to participate, to require rebidding, or otherwise limit participation if, in the sole opinion of the CITY, the bids are not representative of local costs, that the bids were unbalanced, or that the bids were the result of any illegal activities between bidders, DEVELOPER, or suppliers.

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V.                INSPECTION:

An inspector for the CITY of LIVINGSTON may inspect any or all construction of the improvements described herein and the DEVELOPER shall guarantee access thereto. No work of any nature, except clearing and roadway excavation, shall begin without authorization of the inspector. The contractor shall cooperate with the inspector in coordinating construction and inspections, and shall notify the inspector so that he may be present to inspect construction. .Failure to notify the inspector properly may result in the CITY of LIVINGSTON not accepting that work. The contractor would then be required to remove and reconstruct the improvements. The inspector shall not have the authority to approve defective or substandard work and his acceptance of improvements will not constitute any waiver of the contractor's responsibility in adhering to the construction plans and specifications, nor the designing engineer's responsibility for the inspection of the construction of his design. The CITY, in providing an inspector or testing on the project, is in no way accepting responsibility for the progress of the work, the methods of construction employed, or making any acceptance of the work either in part or in whole. Failure of the Inspector or any other CITY staff or agents to detect defects in the work shall not be deemed to waive the responsibilities of others to design, build and maintain facilities in accordance with CITY regulations and state and federal law.

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CHAPTER 2

PAVING AND DRAINAGE IMPROVEMENTS
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I.                GENERAL:

The purpose of these guidelines is to guide the engineer in design and preparation of plans and specifications for the construction of public paving and drainage improvements. All paving and drainage improvements shall be designed and constructed in accordance with standard details of the CITY of LIVINGSTON. Drainage facilities shall be designed using the "Storm Drainage Design Standards" and all subsequent amendments. Materials and construction methods for paving and drainage work (technical specifications) shall conform to "Texas Department of Transportation, 1993 Standard Specifications for Construction of Highways, Streets and Bridges", except where specifically superseded in this publication. Where any questions arise as to the interpretation of the standards of design, the decision of the CITY will be final.

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II.                ROADWAY DESIGN:

A.                Roadway Pavement Section Design: The CITY of LIVINGSTON does not have a typical or standard pavement section, therefore, this section presents the method for the thickness design of roadway pavements. It contains the design requirements for various street widths and traffic conditions, various subgrade support soils, and various types of pavement materials. Pavement design options are based on a combination of the above variables.

Step 1 - Determine the structural support of the roadway's existing subgrade. The subgrade strength is defined by having a California Bearing Ratio Test (CBR) performed in accordance with ASTM Method D 1883-73 (Standard Test Method for Bearing Ratio of Laboratory - Compacted Soils) by a geotechnical and construction materials testing lab.

Location of borings to obtain soil samples are to be placed along the proposed roadway to provide a representative view of the existing subgrade. Laboratory tests are to be performed on these representative soil samples to determine natural moisture content, liquid and plastic limits, and percent passing the No. 200 sieve. These tests are to be performed in accordance with ASTM Methods D 2216, D 4318, and D 422, respectively, Additional CBR tests are to be performed where above lab tests on soil samples of the existing subgrade reveal variations in the subgrade soil according to the "Unified Soil Classification". Unified Soil Classifications are to be determined using procedures in accordance with ASTM Method D 2487. Additional CBR tests are to be performed on soil samples where roadway grades produce cuts into varying subgrade soils.

The existing subgrade shall always be able to provide a stable working platform when the soil is compacted to a density of 95% of standard proctor at optimum moisture content according to ASTM Method D 698. All organic and unstable material is to be removed during construction and replaced with select fill.

Step 2 - Identify the class of the street to be built. Street classifications are determined by the Master Street Plan designation, and street width. Choose the street type which matches the design roadway's attributes.

Step 3 - Determine the total thickness of the pavement section for each type of pavement design. Three pavement design tables are provided, (see tables II-A-2, II-A-3 & II-A-4); one for flexible base pavement, one for full-depth hot mix asphaltic concrete pavement, and one for concrete pavement. Each design table is divided into street classification columns and subgrade CBR% rows. Using the street class identified in Step 2, follow this column down until it intersects the subgrade CBR% row determined in Step 1. This number represents the total thickness of pavement section, in inches, to be used.

Step 4 - Determine the thickness of base. The minimum surface thickness is found at the bottom of each street class column. To obtain the thickness of base, subtract the surface thickness from the total thickness of the pavement section. On roadways that have an existing subgrade CBR% greater than 12, step four often provides the most economical design and the design process could be stopped, (see Example Problem II-A-1), however, for roadways that have subgrade CBR% less than 12, the design process should continue to provide an economical design.

Step 5 - Select a suitable subbase material if the process is continued. Subbase material can be the existing subgrade treated with lime or cement, or a select fill material, such as iron ore topsoil. The subbase material is sampled and the subbase strength is defined by having a CBR test performed.

Step 6 - Determine the new thickness of base and surfacing. Taking into account the subbase CBRI% value and using the pavement design table again, follow the same street class column down until it intersects the subbase CBRG% determined in Step 5. This number represents the total thickness, in inches, of base and surfacing. The base thickness is found by subtracting the surface thickness from the total thickness of base and surfacing.

Step 7 - Determine the thickness of the subbase material selected in Step 5. This is found by subtracting the total thickness of base and surfacing in Step 6 from the total thickness of the pavement section in Step 3. However, the minimum thickness of a subbase material is six inches.

Step 8 - Determine the overall pavement section design. Add the surface thickness and base thickness found in Step 6 to the subbase thickness found in Step 7. (See Example Problem II-A-2)

To determine the most economical and efficient roadway pavement design, the above process should be performed using each pavement design table, varying the subbase materials, and then applying current construction costs.

Step 9 - Design submittal. Submit to the CITY for approval, on the forms provided (see form II-A-9), the roadway pavement section designs performed and the roadway pavement design recommended. Also, submit the results of the CBR test performed by a geotechnical and construction materials testing lab.

 

TABLE II – A – 2,           FLEXIBLE BASE PAVEMENT DESIGN,                DESIGN PERIOD - 20 YEARS

TABLE II – A – 3,         FULL DEPTH HOT MIX PAVEMENT DESIGN,         DESIGN PERIOD = 20 YEARS

TABLE II – A – 4,              CONCRETE PAVEMENT DESIGN,                   DESIGN PERIOD =  20 YEARS

EXAMPLE PROBLEM II - A - 1

Required:                 Determine a pavement section for a collector street in a commercial area.

Solution A: FLEXIBLE BASE PAVEMENT SECTION

Step 1 - From testing the roadway's existing subgrade, a CBR of 12% was obtained.

Step 2 - From Table 11 - A - 1, the street classification was determined to be a 40' F-F commercial street.

Step 3 - From Table II - A - 2, "Flexible Base Pavement Design", the total thickness of the pavement section was determined to be 11 ".

Step 4 -The thickness of base without a subbase is found by subtracting the minimum surface from the total thickness; 11" - 2" = 9". The design process could stop here with an overall pavement section design of 2" HMAC Surface on 9" Flexible Base. However, a treated subgrade may produce a more economical design.

Step 5 - The existing subgrade is treated with lime, (say 6%) and testing shows the new subbase material has a CBR of 20%.

Step 6 - From Table 11- A - 2, the new total thickness of base and surfacing is 9". The new thickness of base with a subbase is found by subtracting the minimum surface from the new total thickness of base and surface; 9" - 2" = 7".

Step 7 - The subbase thickness is found by subtracting Step 6 from Step 3; 11" - 9" = 2". However, minimum subbase thickness is 6".

Step 8 - The overall pavement section design is found by adding Step 6 to Step 7; 2" HMAC Surface on 7" Flexible Base on 6" Lime Treated Subbase.

Solution B: FULL DEPTH HMAC PAVEMENT SECTION

Step 1 - From testing the roadway's existing subgrade, a CBR of 12% was obtained.

Step 2 - From Table II - A - 1, the street classification was determined to be a 40' F-F commercial street.

Step 3 - From Table 11 - A - 3, "Full Depth HMAC Pavement Design", the total thickness of the pavement section was determined to be 7.5".

Step 4 - The thickness of base without a subbase is found by subtracting the minimum surface from the total thickness; 7.5" - 2" = 5.5". The design process could stop here with an overall pavement section design of 2" HMAC Surface on 5.5" HMAC Base.

Solution C: CONCRETE PAVEMENT SECTION

Step 1 - From testing the roadway's existing subgrade, a CBR of 12% was obtained.

Step 2 - From Table II - A - 1, the street classification was determined to be a 40' F-F commercial street.

Step 3 - From Table II - A - 4, "Concrete Pavement Design", the total thickness of the pavement section was determined to be 7". The design process could stop here with an overall pavement section design of 7" Concrete Pavement on untreated subgrade.

 

EXAMPLE PROBLEM II - A - 2

Required: Determine a pavement section for a local street in a residential subdivision.

Solution A: FLEXIBLE BASE PAVEMENT SECTION

Step 1 - From testing the roadway's existing subgrade, a CBR of 3% was obtained.

Step 2 - From Table II - A - 1, the street classification was determined to be a 32' F-F residential street.

Step 3 - From Table 11- A - 2, "Flexible Base Pavement Design", the total thickness of the pavement section was determined to be 24".

Step 4 - The thickness of base without a subbase is found by subtracting the minimum surface from the total thickness; 24" - 2 = 22". A base thickness of 22" is excessive, and the design process should continue to find a more economical design.

Step 5 - The existing subgrade is treated with lime,(say 6%) and testing shows the new subbase material has a CBR of 9%.

Step 6 - From Table II - A - 2, the new total thickness of base and surface is 12". The new thickness of base with a subbase is found by subtracting the minimum surface from the new total thickness of base and surface; 12" - 2" = 10".

Step 7 - The subbase thickness is found by subtracting Step 6 from Step 3; 24" - 12" = 12".

Step 8 - The overall pavement section design is found by adding Step 6 to Step 7; 2" HMAC Surface on 10" Flexible Base on 12" Lime Treated Subbase.

 

Solution B: FULL DEPTH HMAC PAVEMENT SECTION:

Step 1 - From testing the roadway's existing subgrade, a CBR of 3% was obtained.

Step 2 - From Table 11 - A - 1, the street classification was determined to be a 32' F-F residential street.

Step 3 - From Table 11- A - 3, "Full Depth HMAC Pavement Design", the total thickness of the pavement section was determined to be 10.5".

Step 4 - The thickness of base without a subbase is found by subtracting the minimum surface from the total thickness; 10.5" - 1.5 = 9.0".

Step 5 - The existing subgrade is treated with lime,(say 6%) and testing shows the new subbase material has a CBR of 9%.

Step 6 - From Table II - A - 2, the new total thickness of base and surface is 7". The new thickness of base with a subbase is found by subtracting the minimum surface from the new total thickness of base and surface; 7"-l.5"=5.5".

Step 7 - The subbase thickness is found by subtracting Step 6 from Step 3; 10.5" - 7" = 3.5", however, minimum subbase thickness is 6".

Step 8 - The overall pavement section design is found by adding Step 6 to Step 7; 1.5" HMAC Surface on 5.5" Flexible Base on 6" Lime Treated Subbase.

Solution C: CONCRETE PAVEMENT DESIGN:

Step 1 - From testing the roadway's existing subgrade, a CBR of 3% was obtained.

Step 2 - From Table II - A - 1, the street classification was determined to be a 32' F-F residential street.

Step 3 - From Table II - A - 4, "Concrete Pavement Design", the total thickness of the pavement section was determined to be 7".

Step 4 - The design process could stop here with an overall pavement section design of 7" Concrete Pavement on untreated subgrade. However, a treated subgrade may produce a more economical design.

Step 5 - The existing subgrade is treated with lime,(say 6%) and testing shows the new subbase material has a CBR of 9%.

Step 6 - From Table II - A - 4, the new total thickness of pavement is 6".

Step 7 - The subbase thickness is found by subtracting Step 6 from Step 3; 7" - 6" = 1 ", however, minimum subbase thickness is 6".

Step 8 - The overall pavement section design is found by adding Step 6 to Step 7; 6" Concrete Pavement on 6" lime treated subbase.

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FORM II - A - 9
CITY OF LIVINGSTON
ROADWAY PAVEMENT SECTION DESIGN

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Top of curb grades shall be set low enough below the adjacent land to facilitate proper drainage from the residential lot to the street.

Curb separation shall not exceed crown height except in situations of super elevated curves or divided roadways. Divided roadways shall have a straight cross slope downward from median to outside curb rather than a parabolic crown on each lane. Divided roadways shall not be designed, unless approved by CITY.

D.            Street Alignment: Street alignment design shall consider not only the best use of the land, but also traffic safety. The maximum degree of horizontal curvature for an arterial shall be 7.0 degrees. The maximum degree of curvature on a collector shall be 22.9 degrees (minimum radius shall be 250 feet). The horizontal curvature on commercial or residential streets shall be designed so as to eliminate sharp reverse curves that are hazardous. The minimum tangent length between reverse curves shall be 50 feet. All horizontal curve lengths, degree of curvature, curve super elevations and other elements of traffic safety must be approved by the CITY during the approval of the subdivision plans.

E.                Intersections: All intersections should intersect at an angle of 90 degrees. When not practical, the angle of intersection will not be less than 70 degrees.

When intersecting a street in a horizontal or vertical curve, adequate sight distance must be provided.

Curb returns at intersections on residential streets shall have a radius of 20 feet measured to the face of curb.

At the intersections of collectors & collectors, collectors & arterials, and arterials & arterials, the radius will be 30 feet measured to the face of curb, unless otherwise approved by the CITY. A larger radius may be required by the CITY to accommodate traffic movement.

F.             Curb and Gutter: Concrete curb and gutter is required on all streets constructed within the CITY of LIVINGSTON and its Extraterritorial Jurisdiction, except in subdivisions with all lots 2.0 acres and greater in size. All curb and gutter will be designed in accordance with CITY of LIVINGSTON "Standard Details".

G.            Concrete Headers: Concrete headers shall be installed at the termination of all asphalt pavements, unless otherwise approved by the CITY.

H.            Concrete Valley Gutters: Where water runoff conditions dictate, the CITY may require certain valley gutters crossing streets or intersections within the subdivision to be constructed of reinforced concrete to prevent asphalt pavement deterioration.

I.                Subsurface Drainage: Ground water is prevalent in LIVINGSTON and its surrounding Extraterritorial Jurisdiction. The consulting engineer will design and provide for the construction of underdrain systems in the construction plans. Even if the consulting engineer provides no underdrain, the CITY may require the installation of underdrain at DEVELOPER's expense should field conditions warrant.

J.             Erosion Control: In the construction plans, the design engineer shall include plans for erosion control during construction and permanent erosion control.

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III.           PAVING PLANS:

A.            Paving plans shall be prepared on nominal 24"x36" plan profile sheets, or plan sheets with separate profile sheets. Profiles shall have grid increments of less than one inch. Drafting medium, lettering, layout, etc., are all optional except to the extent required herein.

B.            The plan shall be drawn to a scale of not more than fifty feet to the inch (1 "=50') for new sheets or not more than 20 feet to the inch (I"=20') for the reconstruction of existing streets and shall include but not be limited to the following list:

1 .             Right of way, easements, and street pavement widths

2.                Stationing of proposed street from left to right on sheet and stationing of intersecting streets.

3.             Angles and stations of intersections

4.             Street names

5.                Horizontal curve data

6.             Existing topographic features such as utility poles, fire hydrants, culverts, inlets, lakes, watercourses, etc.

7.             North arrow

8.             Graphic scale

9.             Lot lines, lot numbers, subdivision lines and CITY limit lines

10.           Curb radii, and special curb grade points such as end of radius returns and mid-points and top of inlet, etc.

11.           Underground utilities located as accurately as possible

12.           Location of soil borings

13.           Limits of significant cut or fill

14.           Directional arrows showing direction of drainage in gutters

15.           Crown transition in intersections

16.           Special notes

17.           Engineer's seal and signature

C.            The profile shall be drawn to a scale to match the plan horizontally and not more than five feet to the inch (I"=5') vertically and shall include but not be limited to the following list:

1.             Existing ground profiles along the centerline and each right of way line.

2.                Proposed top of curb profile line and existing top of curb line where curb has previously been built. If the new street does not have curb and gutter, proposed top of pavement profile along centerline and flowline of ditches on both sides.

3.             Vertical curve data including the curve length, vertical point of intersection station and elevation, high point or low point station and elevation. Percent grades shall be shown on all tangents.

4.             Top of curb grades shall be shown at not more than 50 foot intervals in tangents and 25 foot intervals in vertical curves. The PC, PT and PI shall be shown in profile with station and elevation.

5.                Benchmark (National Geodetic Survey Datum, formerly U.S          Coast and Geodetic Survey Datum) description and elevation on each sheet with temporary bench marks set at intervals of not more than 300 feet. Refer to the CITY benchmark used.

6.                    Proposed and/or existing storm sewer, sanitary sewer, water, electrical, gas and telephone lines.

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IV.                DRAINAGE DESIGN

A.            The criteria for drainage design shall be "Texas Hydraulic Design Standards" prepared by the Bridge Division of the Texas Department of Transportation except where superseded by these guidelines.

(1)            Drainage facility needs caused by the development or use of property must be identified and provided for in appropriate stages of development. During the platting process, the flood hazard areas shall be identified and drainage easements dedicated to the public on the final plat. The objectives of drainage planning and facilities is two-fold: (a) to protect the uses of the platted property and the safety of the citizens of LIVINGSTON who use the platted property in the future, and (b) to prevent development and usage of the platted property from adversely affecting others. The owners and DEVELOPERS of property have the duty to control: (a) rainfall runoff originating on the platted property; (b) the drainage systems flowing through the platted property; and © water courses along the boundaries of the platted property.

(2)           Drainage improvements required for tracts impacted by drainage systems having a contributing watershed area of less than one square mile or which are upstream from the LIMIT OF DETAILED STUDY as shown on the "Flood Boundary Floodway Map of the CITY of LIVINGSTON" prepared by the Federal Insurance Administration and subsequent map revisions thereto, shall be provided in accordance with these design guidelines. Water conveyances shall consist of reinforced concrete pipe culverts or reinforced concrete box culverts placed underground, or improved open channels. An improved open channel is one in which the channel bottom and sides are lined with reinforced portland cement concrete or other structurally sound material approved by the CITY to the depth that will convey the 25-year frequency flood or greater.

These permanent improvements shall be constructed in drainage easements dedicated to the public. When the construction is approved by the CITY, the CITY of LIVINGSTON will assume maintenance of the portion of such improvements that are within the CITY limits of the CITY of LIVINGSTON. Exceptions to the minimum standards may be granted by the CITY when such improvements are not warranted.

(3)           For drainage improvements required for a tract impacted by drainage systems having a contributing watershed area one square mile, or rg eater the following strategies for controlling drainage, erosion and flooding apply. A tract will be considered to be impacted when part of the property lies within the flood plain of a stream or watershed area one square mile or greater, or where the bed or banks of such a stream touches or crosses part of the tract. One of the following strategies may be selected by the DEVELOPER so long as the strategy can be demonstrated to function without adversely impacting property located either upstream or downstream from the subject tract.

(a)           The stream may be left in its natural state with minor improvements and no development within its floodplain. Minor improvements include the removal of dead trees, discarded debris and obstructions that would hinder the conveyance of water. The entire floodplain shall be platted and dedicated to the CITY as a floodway easement. The CITY will generally maintain the easement in the same condition as when conveyed provided when the easement is within the CITY limits of the CITY of LIVINGSTON.

(b)           The floodplain fringe may be reclaimed for use as long as the floodway is protected and the 100 year flood elevation is not raised more than one foot. This method of development may require erosion control to offset changes in the stream regimen caused by development of the property and drainage improvements in accordance with Section V, Paragraph 7, Environmental Considerations. The floodway will be platted as a floodway easement. The floodway easement will be maintained by the CITY of LIVINGSTON when it is within the CITY limits of the CITY of LIVINGSTON.

(c)           The stream may be reconstructed or relocated to accommodate development. The new channel shall be sufficient to convey the 100 year flood. The design will include erosion control such as seeding, sodding, channel lining, or a combination of these. The new channel shall be platted in a floodway easement. The channel will be maintained by the CITY of LIVINGSTON if it is within the CITY limits of the CITY of LIVINGSTON.

B.            All pipe used in the storm sewer system shall be reinforced concrete pipe and conform to ASTM C-76 unless otherwise approved by the CITY. Minimum pipe size shall be 18 inches inside diameter for storm sewer systems to be dedicated to and maintained by the CITY. All storm sewer pipe shall be placed in a drainage easement except where pipe is carrying storm water runoff solely from one property that likely will not be subdivided or where approved by CITY.

C.            All inlets shall conform to CITY of LIVINGSTON standard details.

D.                Proposed storm sewer systems may be connected into existing systems as long as the proposed combined discharge will not exceed the capacity of the existing system. Additional drainage areas shall not be directed into a watershed from another watershed.

E.             Storm sewers should discharge into natural streams or into other storm sewers. No new unimproved channels may be constructed to carry storm water runoff, although existing channels may be improved and realigned.

F.                Reinforced concrete bridges, box culverts, headwalls, wingwalls, piers and bents shall conform to Texas State Department of Highways and Public Transportation standard details for such structures. Headwalls or wingwalls are required on all culverts and on the discharge point of storm sewer pipe. Energy dissipating devices such as concrete or rock riprap, splash basins, baffles and other structures to minimize erosion shall be incorporated into design of storm drainage facilities.

G.            Any development within a designated 100 year floodplain must be permitted through the CITY. To develop property within a designated 100 year floodplain, the DEVELOPER must submit documentation to the CITY that proves the development of the lot will not encroach into the 100 year floodway.

If channel modifications are to be done to recover land in the floodplain, the DEVELOPER must submit documentation to the CITY to send to FEMA that proves the proposed modifications will revise the floodplain accordingly. The CITY will request a Conditional Letter of Map Revision (Conditional LOMR). This Conditional LOMR must be received prior to approval of channel modifications. Upon completion of channel modifications, documentation must be submitted to the CITY to send to FEMA showing that modifications have been completed and the CITY will request a LOMR which actually revises the floodplain maps. All fees charged by FEMA or other agencies for the review and issuance of approvals will be paid by the DEVELOPER.

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V.                DRAINAGE PLANS:

A.            Drainage plans shall be prepared on nominal 24" x36" plan profile or plan with separate profile sheets. Profiles shall have grid increments of less than one inch. Drafting medium, lettering, layout, etc., are all optional except to the extent required herein.

B.            An overall drainage area contour map with 2 foot contour intervals of the subdivision shall be shown divided into sub-basins for each structure or floodplain. Each sub-basin shall be marked with an identifying number or letter, and the acreage. Run-off computations, curb inlet design computations, and storm sewer design computations shall all be shown in a tabular format in the construction plans.

C.            The plan shall be drawn to a scale of not more than fifty feet to the inch (1 "=50') and shall include but not be limited to the following list:

1.             Location of all proposed or existing inlets, pipe, culverts, manholes, headwalls and wingwalls.

2.             Location of all channels and streams to be filled, improved, or used as discharge points for the system.

3.             Curve data, angle points, or other survey data necessary to install the storm sewer facilities or to locate the facilities and easements after installation.

4.             Location of all underground utilities or pipelines which might conflict with the storm sewer, culvert, or channel.

5.             Typical cross sections for improved earthen or concrete lined channels.

6.             North arrow, graphic scale, subdivision lines, lot lines, easement lines, street names.

7.                Proposed street paving width, right of way width, or easement width.

8.             Base line (centerline) showing stationing.

9.             Special notes.

10.                Minimum finished floor elevation for each lot within or adjacent to a 100 year floodplain or drainage easement.

D.            The profile shall be drawn to a scale of not more than fifty feet to the inch (1 "=50') horizontally and not more than five feet to the inch (I "=5') vertically. Drainage profiles shall include but not be limited to the following list:

1.             Existing surface profile above centerline of storm sewer pipe, culverts, and existing high bank and flowline profiles for open drainage channels.

2.                Proposed drainage structures with flowline (invert) elevation at not more than fifty foot intervals.

3.                Proposed top of curb profile.

4.                Elevations of pipelines or underground utility crossings.

5.             Vertical curve data for flowline including the curve length and the vertical point of intersection station and elevation.

6.                Benchmark (National Geodetic Survey Datum, formerly U.S. Coast and Geodetic Survey Datum) description and elevation.

7.             Water surface profile for the "one hundred year flood" for open channels within the subdivision and hydraulic grade line for storm sewer pipe.

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REFERENCES

Reference For Table II - A - 2

1.             National Crushed Stone Association's "Flexible Pavement Design Guide for Highways" April 1975

2.             National Crushed Stone Association's "Design Guide For Streets Featuring Crushed Stone Bases" June 1975

3.             U. S. Army Engineers' Manual TM 5-822-5" 1965

4.             U. S. Department of the Navy, Naval Facilities Engineering Command's "Civil Engineering-Pavements" Design Manual 5.4 NAVFAC DM-5.4 October 1979 Revised September 1985.

Reference For Table II - A - 3

1.             The Asphalt Institute's Manual Series No. 1 (MS-1) "Thickness Design - Full Depth Asphalt Pavement Structures For Highways And Streets" Revised Eighth Edition August 1970 & September 1981.

Reference For Table II - A - 4 

1.             Portland Cement Association's "Design Of Concrete Pavement For CITY Streets" IS184P 1974

2.             Portland Cement Association's "Thickness Design For Concrete Highways And Street Pavements" EB 109.01 P 1984

3.             U. S. Department Of The Navy, Naval Facilities Engineering Command's "Civil Engineering-Pavements" Design Manual 5.4 NAVFAC DM-5.4 October 1979 Revised September 1985

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CHAPTER THREE

WATER AND SANITARY SEWER IMPROVEMENTS

I.                GENERAL:

All water and sewer lines constructed within the CITY of LIVINGSTON shall be designed and constructed in accordance with the most current guidelines as promulgated by the Texas Department of Health, the Texas Natural Resource Conservation Commission (TNRCC), Texas Insurance Commission, American Water Works Association (AWWA), United States Health Service, and the Environmental Protection Agency (EPA). The design and construction shall also comply with the requirements of applicable CITY of LIVINGSTON standard specifications. The design and construction shall also be in compliance with the most current CITY Master Plan and in agreement with the LIVINGSTON service codes and current policies of the CITY of LIVINGSTON.

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II.            WATER LINE DESIGN:

A.                Location: Water mains shall be constructed in a dedicated street, alley, or an easement to the CITY of LIVINGSTON which shall be filed in the public records. Water mains shall be located in the north one-third and west one-third of street rights of way except where otherwise approved by the CITY.

(1)           Minimum cover for 6 and 8 inch water pipe shall be 36 inches below finished subgrade.

(2)           Water lines shall be laid higher in elevation than sewer lines, where possible.

B.                Minimum Size: The minimum inside diameter size requirement for water lines is 6 inches. Exceptions may be granted in special circumstances such as cul-de-sacs.

C.            Looping: All lines shall be looped except, where lines will enter a future subdivision, then a dead end will be allowed. The maximum length of looped 6 inch water lines shall be 3,000 feet. The maximum length of unlooped 6 inch water lines shall be 1,500 feet. A standard fire hydrant shall be installed at any dead end line, except where other suitable means of flushing can be provided. Any dead end line proposed for future extension shall have a gate valve installed on the line and a minimum of one 18 foot joint of pipe past the valve. The end of the line shall be plugged and blocked with concrete to prevent line and valve blow-off. Construction of water lines shall extend to the boundaries of the development.

D.            Design Criteria: The water lines shall be designed to carry a minimum of 750 gallons per minute while maintaining a minimum of 20 pounds per square inch gauge pressure at any connection. The CITY of LIVINGSTON's pressure plane datum varies depending on the part of town and the engineer must determine the data plane for his project. The maximum head loss allowable is 10 feet per thousand feet of pipe flowing a minimum of 750 gpm in residential areas. In commercial areas, the minimum flow shall be 1,500 gallons per minute and in mercantile or industrial areas, 3,000 gallons per minute. Shopping centers with 10 acres or more shall be considered mercantile areas. Assuming a pipe flow coefficient of C=140, based on the William and Hazen Formula, at the maximum head loss, the available flows are shown in the following table:

E.             Soil Tests: For use of any iron pipe, cast iron or ductile, the soil corrosivity shall be determined in accordance with the procedures outlined in ANSI/AWWA C105/A21.5 "Polyethylene Encasement for Ductile Iron-Pipe for Water and Other Liquids", Appendix A. The earth resistivity and soil analysis shall be performed in the line of the proposed water main and to a depth equal to the installed pipeline depth.

Locations of the earth resistivity and soil tests shall be placed along the proposed pipeline to provide a representative view of the existing subsurface conditions. A point accumulation of 10 or greater indicates corrosive soil conditions and pipeline corrosion protection shall be required.

Corrosive soil conditions in isolated areas of development shall require polyethylene encasement of ferrous pipes. Corrosive soil conditions in the general overall development may require the engineer to recommend alternate materials for construction of water pipelines, subject to approval of the CITY.

F.             Fire Hydrants:

(1)           In residential areas, fire hydrants shall be spaced at least every 500 feet or closer to provide a maximum distance of 500 feet from any point to the nearest fire hydrant. In commercial areas, fire hydrants shall be spaced at least every 300 feet or closer to provide a maximum distance of 300 feet from any point to the nearest fire hydrant.

(2)           Each fire hydrant shall be positively restrained with bridle rods and retaining glands and concrete blocking.

(3)           Fire hydrants shall be equipped with Pentagon operating nuts.

(4)           Each fire hydrant shall have an individual 6 inch gate valve to allow the fire hydrant to be shut off for service.

G.                Materials for Water Lines: Allowable materials for water lines are shown in the following list:

1.             Ductile Iron Pipe Cl 21 or better, cement lined and coal tar epoxy coated

2.             Concrete Cylinder Pipe (C 303)

3.                          PVC water pipe, DR 18, C-900 (4"-12") or C-903 (14"-24" diameters.)

H.            Valves:

(1)                Each branch line shall be valved.

(2)                Main lines shall be valved at least every 1000 feet.

(3)                The maximum distance between valves shall be 1500 feet.

(4)                Valves shall be located in intersection where possible. Where valves are located in other than paved areas they shall be furnished with a 24" square concrete valve blockout matching the surface of the ground.

I.              House Connections:

(1)           A 1 inch copper tubing service line shall be installed at a point three feet behind curb at each lot generally 5'-0" to the right of the center of the lot when facing the lot. (The sewer service will generally be to the center of the lot).

(2)           Each service line shall have a 1 inch corporation cock on the main line, and a 1 inch meter stop at the end of the service.

(3)           Each service line shall be permanently marked with a "W" on the curb where service line crosses curb, and a 1/2 inch diameter by 3 foot steel rod driven at the meter stop, with 6 inches of the rod left exposed.

(4)           2-inch magnetic tape shall be installed directly above the water service pipe from the main to the meter stop.

J.             Plans and Specifications:

(1)                Preliminary Plan For Water Service:

(a)           The DEVELOPER shall submit with the master plan plat, a preliminary plan for water service showing the proposed location and sizes of water lines, prepared, signed, and sealed by a Registered Professional Engineer. The plan shall include location of lots, minimum finished floor elevations, streets, water lines, sewer lines, valves, and fire hydrants along with the design calculations for the size of the lines.

(b)           On the preliminary plan for water service, the coverage of the area fire hydrants shall be shown. For residential areas, this preliminary plan shall have a circle scribed around each fire hydrant 500 foot radius. For commercial areas, this preliminary plan shall have a circle scribed around each fire hydrant 300 foot radius. Every part of every lot platted in the unit shall be covered within these radii.

(c)           The preliminary plans will be on a scale of not more than one hundred feet to the inch (1" = 100').

(2)                Construction Plans:

(a)           The DEVELOPER shall submit prior to construction, the proposed plans, specifications, and contract documents complete, prepared, signed and sealed by a Registered Professional Engineer. The CITY will review for approval the plans and specifications. After the review the DEVELOPER shall include into the plans and specifications any additions or corrections required.

(b)           The construction plans shall include a location map showing location of proposed water lines, valves, and fire hydrants. The map may be on the same scale as the preliminary plan for water service. The construction plans shall include plan and profile sheets showing the location of all water lines, valves, and fire hydrants.

(c)           Plan Section: The plan shall be prepared on 24" x 36" plan profile sheets or plan sheets with separate profile sheets. The plan section of the plan and profile shall show the streets and side streets, easements, lot lines, culverts, driveways (where possible), sewer lines, gas lines, power lines and poles, water lines, telephone lines and television cable lines. The plan shall also indicate where house service lines are to be installed. The plan shall show all valves, fire hydrants and any branch line connections, and concrete blocking. Plan shall be drawn to scale of not more than fifty feet to the inch (I" = 50').

(d)           Profile Section: Profiles are required for water lines 12-inch larger. The profile shall be drawn to a scale of not more than fifty feet to the inch (1" = 50') horizontally and not more than five feet to the inch (1" = 5') vertically. The profile section shall show the grade of the water lines, the existing ground line, and the proposed ground line where it is different from the existing. All Bench Mark and profile elevations shall be tied to the National Geodetic Survey Datum (formerly The U. S. Coastal & Geodetic Survey Datum). Assumed datums will not be allowed. The profile shall show all storm sewers and sanitary sewers crossing the construction alignment of the proposed water line. The grades for water lines 12 inches diameter and larger shall be set and staked in the ground for construction by the DEVELOPER's engineer and the contractor shall lay them as close as possible to the proposed grades. Grade stakes and profiles for water lines smaller than 12 inch diameter are not required, however, the engineer may include grades in the profile at his option.

Water lines shall not be laid to a grade less than 0.2 percent. A 1 inch corporation cock shall be installed at each low spot and each high spot in the water line on lines smaller than 12 inches. There shall be a temporary I inch copper tubing and I inch meter stop installed at each of these cocks for blowing off air and for testing the lines. After testing, these lines shall be removed. A 6 inch diameter blow-off line is required at each low spot of lines 12 inches and larger and an adequately sized combination vacuum breaker/ air release valve is required at each high point in lines 12 inches and larger.

(e)           Standard Details: The construction plans shall also include a sheet showing standard valve, fire hydrants, bedding and other pipe laying details. The CITY will furnish the details upon request.

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III.                SANITARY SEWER LINE DESIGN:

A.                Location: Sanitary sewer mains shall be constructed in a dedicated street, alley, or an easement to the CITY of LIVINGSTON which shall be filed in the public records. Sanitary sewer mains shall be installed in the south one-third and east one-third of street rights of way except where otherwise approved by the CITY.

A center line description of any off-site easement required across private property , or state or federal lands, for outfall, interceptor, approach or lateral lines to be constructed in conjunction with said project shall be furnished with the final plans and specifications for sanitary sewer mains. Center line descriptions shall be prepared by a Registered Public Land Surveyor.

(1)           Sewers shall be laid in a straight alignment with uniform grade between manholes.

(2)           The minimum cover for sewer lines shall normally be five feet with a minimum clearance of one foot below established flow line of creeks and drainage ways.

(3)           Sewer lines shall be at a lower elevation than any water line at crossings, and shall have one 18 foot joint of ductile iron pipe centered at the water line with the sewer pipe joints 9 feet each side of the water lines.

(4)           All PVC sanitary sewers shall have a Class C embedment but sanitary sewer lines installed 14' deep or more shall require Class "B-1" embedment.

B.                Minimum Size: The minimum nominal inside diameter size requirement for gravity sanitary sewer lines is 6 inches.

C.                Grade: Size and minimum grade requirements are shown in the following table:

 

These grade requirements are in accordance with the present State of Texas TNRCC Standards (TAC 317). If the State standards are changed in the future, the above requirements shall be changed to comply with the then present State of Texas requirements. The minimum velocity in a sewer line is 2 fps, and maximum allowable velocity is 15 fps. Where velocities greater than 10 feet per second are attained, special provision shall be made to protect against erosion by velocity, and displacement by shock.

D.            Design Criteria:

(1)           Design Flows: In residential development, gravity sewers shall be designed to carry an average daily flow of 140 gallons per capita per day based on 3.3 persons per single family unit. The line shall be designed to carry a peak flow of 4.0 times the average daily flow for 6 inch lines, and 2.5 times average daily flow for lines 8 inches and larger when flowing 100% full but not surcharged hydraulically. For developments other than residential, the DEVELOPER's engineer shall use the recommended design flows as promulgated by the Texas Department of Health or TNRCC, unless the CITY of LIVINGSTON has data to require greater design flows.

(2)           Lift Stations and Pressure Lines: In general, the CITY of LIVINGSTON will not permit the construction of lift stations and pressure lines, unless it is impossible to connect to a gravity system. If a lift station is required, complete design, including site work, an all weather access, etc. shall be included in the plans and specifications. At the option of the CITY of LIVINGSTON, the design may include service to an area, in addition to the property being developed, with the CITY of LIVINGSTON participating in the excess capacity cost. The lift station shall be designed in compliance with current state and federal requirements and shall have dual electrical supply from at least two different power substations, a stand-by generator OR a two hour capacity for storage of sewage at the peak flow described in Paragraph D (1) above. The minimum lift station capacity shall be 50 gallons per minute and each shall have at least two pumps. The minimum size for a pressure line shall be 3 inches. Lift stations may be either self-priming or submersible. Wet wells shall be concrete pre-cast or cast-in-place. Either sonic type controls or probe contacts shall be used for water level control in the wet well. Float systems are not acceptable. Lift stations shall be furnished with the following minimum equipment:

1.             Phase loss monitors for each phase of electrical supply.

2.                Lightning arrestors.

3.             Area lighting within the lift station site.

4.                Aluminum or stainless steel access hatchways for submersible stations and cast iron manhole rings and covers for self-priming stations.

5.             Stainless steel or fiberglass pump guide rails (submersible stations).

6.             Painted concrete wet well interiors and roofs with high build acrylic or epoxy coatings resistant to hydrogen sulfide attack.

7.             Exposed hardware, ferrous pipe and fittings shall be coal tar epoxy coated in the wet well.

8.             Hand-off-auto controls for each pump with starters, automatic pump alternators and non-resettable pump run time meters, all in a NEMA 3R or better stainless steel panel. Cube relays or solid state controllers are optional.

9.             Auto-dialer wired for inputs for at least high wet well level and loss of commercial power. The dialer shall be wired to local telephone service provider. It shall have a non-synthesized voice output and storage locations for up to eight emergency telephone numbers.

E.             Soil Tests: For use of ferrous pipes the soil corrosivity shall be determined in accordance with the procedures outlined in ANSI/AWWA C105/A21.5 "Polyethylene Encasement for Ductile Iron Pipe for Water and Other Liquids". The earth resistivity and soil tests shall be placed along the proposed pipeline at points of crossing water lines with proposed sanitary sewer lines, and to a depth equal to the installed pipeline, to provide a representative view of existing subsurface conditions. A point accumulation of 10 or greater indicates corrosive soil conditions and pipeline corrosion protection shall be required.

F.                Allowable Materials:

(1)           The materials for sewer line construction shall be as specified in CITY of LIVINGSTON standard specifications.

(2)           Gravity lines 6 to 12 inches in diameter size shall be ASTM D-3034 SDR 35 PVC or vitrified clay pipe with premolded gaskets.

(3)           Gravity lines 15 inches in diameter size and larger shall be vitrified clay pipe with premolded gaskets, concrete C-14 or C-76 pipe constructed using 75 percent limestone aggregate and rubber O-ring gasket, or cement lined, tar coated ductile iron pipe.

(4)           When sewers cross water lines, one full joint (I 8-foot or longer) of pressure rated sewer pipe, PVC or Ductile Iron, shall be centered over the crossing.

(5)           Aerial or underwater creek crossings, shallow lines, and lines laid in areas with high water table shall be constructed with ductile iron pipe, and shall be encased in concrete where unsuitable soil conditions necessitate encasement. The CITY may require concrete encasement at its discretion.

G.                Manholes: Manholes shall be designed and built in accordance with CITY of LIVINGSTON standard specifications.

(1)                Manholes shall be placed at points of changes in alignment, grade, or size of sewer. Manholes shall also be placed at all intersections of sewers and the end of all sewer lines that will be extended at a later date.

(2)           Manhole spacing shall be a maximum of 600 feet for 6 inch and 8 inch sewer lines.

(3)           The minimum inside diameter of a manhole shall be 4 feet.

H.                Cleanouts: Cleanouts may be used in lieu of manholes at the end of sewers which are not to be extended in the future. Where cleanouts are not located in pavement, they shall be encased in a 24" square concrete block at the surface.

I.             House Connections:

(1)           A minimum 4 inch service line shall be installed to the property line of each lot generally at the center of the front lot line with the water 5'-0" to the right when facing the lot. Service lines shall be terminated at the property line and plugged with a water tight sealing plug for later extension by the plumber.

(2)           Each service line shall have a "Y" fitting or a service saddle installed in the main sewer line for each house service. Breaking out and cementing in of house services shall not be allowed.

(3)           Each service line shall be permanently marked with a "S" on the curb where the service line crosses the curb, with a '/2 inch diameter x 3 foot steel rod driven at the end of the service line.

(4)           2-inch magnetic tape shall be installed directly above the sewer service pipe from the main to the end of the service.

(5)           The end of the service line shall be at least 4 feet deep at the curb and shall be deep enough to allow a I foot per 100 foot drop in the service line from the proposed house sewer service entry to the service stub out, plus an adequate depth for the house plumbing.

J.             Plans and Specifications:

(1)                Preliminary Plan:

(a)           The DEVELOPER shall submit with the master plan plat, a preliminary service plan showing the proposed location and size of sewer lines prepared, signed, and sealed by a Registered Professional Engineer. The plan shall include location of lots, minimum finished floor elevations, streets, sewer lines, manholes, cleanouts, and water lines along with the design calculations for the size of lines.

(b)           The preliminary service plan will be on a scale of not more than one hundred feet to the inch (1" = 100').

(2)                Construction Plans:

(a)           The DEVELOPER must submit prior to beginning construction of utilities within or extensions to the subdivision the proposed plans, specifications, and contract documents complete, prepared, signed and sealed by a Registered Professional Engineer. The CITY will review for approval the plans and specifications. After the review, the DEVELOPER will include into the plans and specifications any additions or corrections required.

(b)           The construction plans shall include a location map showing location of proposed sewer lines, manholes, cleanouts, and water lines. This map may be on the same scale as the preliminary service plan. The construction plans shall include plan and profile sheets showing the location of all sewer lines and manholes.

(c)           Plan Section: The plan shall be prepared on 24" x 36" plan profile sheets or plan sheets with separate profile sheets. The plan section of the plan and profile shall show the streets and side streets, easements, lot lines, culverts, driveways (where possible), gas lines, power lines and poles, sewer lines, water lines, telephone lines, and television cable lines. The plan shall also indicate where house service lines are to be installed. The plans shall show all manholes, cleanouts, ductile iron pipe, and branch line connections, and concrete encasement. The plan shall be drawn to a scale of not more than fifty feet to the inch (I " = 50').

(d)           Profile Section: Profile shall be drawn to a scale of not more than fifty feet to the inch (I" = 50') horizontally and not more than five feet to the inch (1 " = 5') vertically. The profile section shall show the grade of the sewer lines, the existing surface line, and proposed surface line where it is different from the existing. All Bench Mark and profile elevations shall be tied to the National Geodetic Survey Datum. (Formerly the U. S. Coastal & Geodetic Survey Datum). Assumed datums will not be allowed. The profile shall show all storm sewers and water lines crossing the construction alignment of the proposed sewer line. The grades for sewer mains shall be set by the DEVELOPER's engineer and the contractor shall lay them as close as possible to the proposed grades. Grade stakes and grade lines are required for all sewer mains.

(e)           Standard Details: The construction plans shall also include a sheet showing standard manholes, cleanouts, and other pipe laying details. The CITY will furnish copies of these details upon request.

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BIBLIOGRAPHY

"'RULES AND REGULATIONS FOR PUBLIC WATER SYSTEM"

Texas Natural Resource Conservation Commission
P.O. Box 13087
Austin, Texas 75711

"DESIGN CRITERIA FOR PUBLIC SEWAGE SYSTEMS"

Texas Natural Resource Conservation Commission
P.O. Box 13087
Austin, Texas 75711

"AWWA STANDARDS"

American Waterworks Association
6666 W. Quincy Avenue
Denver, Colorado 80235

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