A. 
This following document contains the various construction criteria, techniques, and details which are the minimum requirements of the City of North Richland Hills for public facilities. This data is primarily intended for the use of the developer and his engineer to enable the applicant to provide the proper design for the public facilities associated with a proposed development. This criteria is not intended as an exhaustive list of the construction techniques available. In the event that specific circumstances dictate additional requirements, it shall be the responsibility of the developer's engineer to provide the necessary details for construction to be approved by the public works department.
B. 
This design criteria and details may be modified by administrative action of the city and subsequent resolution by the city council at such times as may be appropriate in keeping with the most up-to-date construction techniques and specifications.
C. 
All water, sanitary sewer, street and drainage installations shall be in accordance with the current city standards and specifications.
D. 
All variance requests from the design criteria contained within this design manual that do not conflict with other ordinances, or designs which require approval from the public works director must be submitted in writing to the public works department. It will be at the discretion of the public works director or his/her designee to approve any design variances.
E. 
The City of North Richland Hills adopted a city image study in 2001 which addresses various design criteria not explicitly discussed within this design manual. During the plan review process all design elements will be reviewed to ensure the proposed development incorporates the criteria set forth in the city image study. A copy of the study can be obtained from the city upon request.
A. 
Construction plan submittal format.
All construction plans for proposed public water, sanitary sewer, street, drainage, and traffic control devices shall be submitted in the designated format:
1. 
Cover sheet. Containing the project title, legal property description, city name, vicinity map, public works signature block, sheet index, and submitting client information. The project title and legal description shall also be placed vertically along the right border in small print. The submitting client information shall contain the owner, engineer, and surveyor's name, address, and telephone number.
2. 
Plat. Copy of current plat bound with plans. The signed plat shall be bound with the as-built drawings.
3. 
Site plan. Showing the location and width of all existing and proposed street and driveway approaches and median openings, noting the back-of-curb radii, all building footprints, location of proposed water, sanitary sewer, and drainage systems, proposed landscaping and parking layout, existing and proposed easements, limits of 100-year floodplain, lot lines, sidewalks, and street lights.
4. 
Drainage layout. Containing a drainage area map and calculations with all existing contours, existing and proposed storm drains, and/or other drainage facilities. The drainage area map shall extend at least 200 feet beyond the limits of the drainage areas affecting the site in all directions. Plan and profile sheets shall be submitted for all storm drains, flumes, and channels. Stationing shall be generally left to right and with stationing beginning at the downstream end for all storm drains, flumes, and channels. Appropriate hydraulic grade line or water surface profile shall be plotted with all drainage design. Capacity, design discharge, velocity, velocity head shall be noted on each segment of drainage facility in the profile whenever one or more of these parameters change.
5. 
Utility plan. Showing the location and size of all existing and proposed water and sanitary sewer lines with adjacent existing or proposed top of curb grades. Provide the location of all existing and proposed fire hydrants adjacent to the site including the maximum coverage radius of each as outlined in later sections of this design manual. Plan and profile sheets shall be submitted for all sanitary sewer lines and for water lines 12 inches in diameter and larger. Stationing shall be generally left to right and with stationing beginning at the downstream end for all sanitary sewer lines.
6. 
Grading plan. Showing a topographical map of the subdivision which shows existing and proposed elevations and drainage patterns, and any watercourses. The plan must also include proposed flow arrows, cross sections, spot elevations, and finished floor elevations for properties adjacent to the floodplain, drainage easements, or other locations as determined by the public works department.
7. 
Erosion control plan. Showing a layout of development, storm drain inlets, storm drain manholes, drainage channels, detention/retention facilities, five-foot contours, construction entrance, and other erosion control measures in accordance with the City of North Richland Hills' Texas Pollutant Discharge Elimination System (TPDES) General permit TXR040000.
8. 
Mailbox and street light plan. Showing a layout of the subdivision including all lots, lot numbers, sidewalks, curbs, curb ramps, curb inlets, storm drain manholes, water meters, fire hydrants, sanitary sewer manholes, clean-outs, street lights and mailboxes. The plan shall not include pipes, trees, centerlines, baselines, contours, culverts, services, street markings or construction notes.
9. 
Detail sheet. Showing all details for improvements which are to become public.
B. 
General construction plan requirements.
All construction plans shall meet the following requirements:
1. 
Plans are to be designed, signed, sealed, and dated by a professional civil engineer registered in the State of Texas.
2. 
Horizontal scale shall be one inch equals 50 feet (one inch = 50 feet) or larger, i.e. one inch = 40 feet, vertical scale shall be one inch equals five feet or larger.
3. 
Plan and profile sheets shall be 22 inches wide by 34 inches long.
4. 
Stationing shall be included on the plan view as well as the profile for all roads, water, sanitary sewer, storm drain and channel sheets. Elevations shall be calculated and provided in all profiles as indicated below.
a. 
Straight grade. Provide elevations at a maximum interval of 100 feet.
b. 
Vertical curve. Provide elevations at the beginning and ending points and at a maximum interval of 25 feet in between.
5. 
The developer shall furnish all easements and right-of-way (ROW) necessary for construction of electrical, gas, cable TV, and telephone service to the proposed subdivision.
6. 
Construction plans will be reviewed by the public works department and signed after all comments have been resolved. Construction must start within one year following the public works signature. Plans for projects which have not started construction within this time period must be submitted to the public works department for a new review.
(Resolution 2007-012, adopted 2/26/2007)
A. 
Water system extensions.
1. 
Water systems shall be of sufficient size to furnish adequate domestic service, to provide adequate fire protection to all lots, and to conform to the city's current master water distribution system plan. Public water mains adjacent to federal, state, or county roadways shall be constructed outside the rights-of-way in a separate easement dedicated by separate instrument, not by plat.
2. 
All tee intersections of public water mains shall include at least two gate valves. All four-way intersections of public water mains shall include at least three gate valves. Four-way intersections shall be constructed of two tees. Cross fittings are not permitted.
3. 
The minimum size water main in single-family residential areas shall be six inches in diameter.
4. 
The minimum size water main in all other areas shall be eight inches in diameter. Larger diameter mains will be necessary if water demand or fire flow requirements so dictate. A fire flow analysis may be required by the public works director if deemed necessary to determine adequate proposed water main sizes.
5. 
Minimum depth of cover over all water mains smaller than ten inches in diameter shall be three feet. Minimum depth of cover for water mains ten inches and larger shall be 3.5 feet.
6. 
Where water mains are to be installed in rights-of-way having roads constructed without curb and gutter, a plan and profile sheet shall be submitted with the construction plans showing the proposed water main profile, the existing street grades, and the preliminary future top-of-curb grades for at least 300 feet either side of the boundary of the proposed subdivision.
7. 
The minimum horizontal separation between any water main and a storm drain facility shall be equal to 2.5 feet or half the depth of the water line, whichever is greater. Water and sanitary sewer mains shall be separated in accordance with the requirements of the Texas Commission on Environmental Quality (Chapter 317).
8. 
The minimum easement width for a water main shall be 7.5 feet on each side of the pipe, for a total of 15 feet.
9. 
Residential water services shall not normally be directly connected to water mains 16 inches in diameter or greater. Smaller diameter, parallel water mains are required for the connection of such water services.
10. 
All water services shall be placed at the lot line, between lots, where possible and all water meters shall be located in city rights-of-way or inside a waterline easement, unless approved otherwise by the public works department.
11. 
When a building sprinkler system is required, a separate fire line shall be required with a double detector check valve and vault that shall be located outside the building in a water line easement or right-of-way, immediately adjacent to the water main.
B. 
Required water main extensions.
1. 
All water mains constructed within a proposed subdivision shall be extended to the perimeter of the proposed subdivision to allow for future extension of the water system into adjacent properties.
2. 
Sufficient water mains shall be constructed to minimize the length of pipe required to service fire hydrants or detector check vaults. Fire hydrants shall be served by no more than 150 feet of fire hydrant supply line.
3. 
Connections to existing water mains shall be performed with tapping sleeves and valves unless otherwise specified. Tapping sleeve shall be JCM Industries JCM432, JCM462 or an approved equal.
C. 
Fire hydrants.
1. 
At a minimum, the fire hydrant spacing must be designed to met all requirements of the current fire code.
2. 
In all single-family subdivisions, fire hydrant spacing shall be designed such that all lots within the proposed subdivision are within 500 feet radial distance of a fire hydrant.
3. 
In all other subdivisions, fire hydrant spacing shall be designed such that the entire subdivision is within 300 feet radial distance of a fire hydrant.
4. 
Fire hydrants located on the opposite side of a major collector or arterial street, (i.e., roadway width greater than 40 feet or as identified on the master thoroughfare plan), from a development shall not be considered when determining adequate fire hydrant coverage for a development.
5. 
Dead end water mains shall always end with a fire hydrant or a blow-off hydrant.
6. 
Fire hydrants shall be supplied by not less than a six-inch diameter main installed on a looped system or by not less than an eight-inch diameter main if the system is not looped or the fire hydrant is installed on a dead end main exceeding 300 feet in length. Dead end mains shall not exceed 600 feet in length for main sizes under ten-inch in diameter.
D. 
Materials and workmanship.
All materials and workmanship incorporated in water system extensions shall be in accordance with the currently adopted city construction specifications.
(Resolution 2007-012, adopted 2/26/2007)
A. 
General sewerage system extensions.
1. 
All subdivisions developed subsequent to this ordinance must be served by city sanitary sewer collection, treatment and disposal systems approved by the public works department. Each lot must be provided with an individual service.
2. 
Sanitary sewer facilities shall be provided to adequately service each lot or tract of the subdivision, and shall conform to the city's current master sanitary sewer system plan.
3. 
No sanitary sewer main shall be less than six inches in diameter. All sewers shall be designed with consideration for serving the full drainage area subject to collection by the sewer in question. Exceptions to this requirement may be made only upon the approval of the public works director.
4. 
All sanitary sewer mains constructed within a proposed subdivision shall be extended to the perimeter of the proposed subdivision to allow for future extension of the sanitary sewer system into adjacent properties.
5. 
The minimum easement width for a sanitary sewer main shall be 7.5 feet on each side of the pipe, for a total of 15 feet.
6. 
The population density shall be based on 3.5 persons per single-family unit, but shall not be less than 9.5 persons per acre. The contributing sewage flow shall be determined on the basis of an average flow of 120 gallons per person per day. Outfall sewers and collector sewers shall be designed on the basis of Harmon's Formula for peaking factor.
Peaking Factor  =  
14
(4 + P1/2)
Where:
P = Population expressed in thousands.
B. 
Sanitary sewer improvements design criteria.
1. 
All services shall be placed at the center of each lot unless instructed otherwise by the public works department. Service lines shall not be connected directly to manholes unless approved by the public works director. The maximum depth for all sewer services shall be ten feet. If the existing or proposed sewer main is deeper than ten feet, a parallel sewer will be required to be constructed at a depth less than ten feet.
2. 
Vertical curves in sanitary sewer mains will not be allowed.
3. 
Manhole spacing shall not exceed 500 feet.
4. 
Sewer mains which require more than an 18 inch difference in flow lines must be accommodated with a five-foot diameter manhole with an internal drop.
5. 
All sanitary sewer mains shall end at a manhole. Cleanouts will not be allowed.
6. 
Four foot diameter manholes will be required as sampling ports on all automotive repair, food handling facilities, and any other industry deemed to discharge "abnormal sewage" as defined by Chapter 78 "Utilities", Article IV "Sanitary Sewer System," section 78-211 of the City Charter and Code of General Ordinances. The manhole must be located between the public sewer main and the grease trap.
7. 
If a new sanitary sewer main is to be constructed adjacent to an existing street, the profile will need to include the existing top of curb grades.
8. 
All sanitary sewers constructed adjacent to federal, state or county roadways shall be constructed outside the ROW in a separate easement dedicated by separate instrument, not by plat.
9. 
The minimum horizontal separation between any sanitary sewer main and a storm drain facility shall be equal to 2.5 feet or half the depth of the sanitary sewer, whichever is greater.
10. 
All sanitary sewer lines are to have one 13 foot minimum joint centered below water main crossings.
11. 
Sewer services six inches and larger will require a connection into a manhole at the main.
12. 
Minimum and maximum grades allowed for pipe size:
Pipe Size (inches)
Interior Diameter
Minimum Slope in %
Maximum Slope in %
6
0.5
12.35
8
.33
8.40
10
.25
6.23
12
.20
4.88
15
.15
3.62
18
.11
2.83
21
.09
2.30
24
.08
1.93
27
.06
1.65
30
.055
1.43
36
.045
1.12
39
.04
1.01
C. 
Lift stations or separate treatment facilities.
The provisions for lift stations or separate treatment facilities will not be permitted unless, in the opinion of the public works director or designee, there is no feasible alternative which can provide the necessary service to the proposed subdivision.
D. 
Connections.
No connection shall be made to any sanitary sewer within the city which will permit the entrance of surface water or waste which has other than domestic sewage characteristics without the specific authorization of the city council.
E. 
Alternate sewage systems.
Where public sanitary sewerage systems are not within 300 feet of the plat, alternate sewerage systems may be approved only if all of the following conditions are met:
1. 
The proposed subdivision consists of three lots or less.
2. 
The existing city sanitary sewer system is not and cannot feasibly, in the opinion of the public works department, be made available to the area of development.
3. 
Percolation tests run by an independent testing laboratory are submitted to both the city and the Tarrant County Health Department with results showing that a septic tank and absorption field can be developed in accordance with state and county criteria to provide adequate disposal of the sewage. Where septic tank installations are permitted in lieu of a sanitary sewerage system, the plat must include dedicated sanitary sewer easements not less than 20 feet in width adjacent to all lots to facilitate the future installation of a sewerage system. Dedication of such easement shall prohibit fencing or other obstructions that would interfere with the future installation of sanitary sewers.
4. 
Installation of individual septic tanks shall be in accordance with the rules and regulations issued by the Tarrant County Health Department.
5. 
A copy of the Tarrant County approved permit shall be submitted to the city prior to beginning construction of the system.
F. 
Materials and workmanship.
All materials and workmanship incorporated in sanitary sewer system extensions shall be in accordance with the currently adopted city construction specifications.
1. 
All proposed sanitary sewer lines shall use SDR-35 sewer pipe, unless the line is deeper than ten-feet, then SDR-26 sewer pipe shall be used.
2. 
Post-construction television inspection of sanitary sewer:
a. 
General.
After construction all sections of sanitary sewer mains shall have a television inspection performed. Work shall consist of furnishing all labor, material and equipment necessary for inspection of the sewer mains by means of closed circuit television. Satisfactory precautions shall be taken to protect the sewer mains from damage that might be inflicted by the improper use of cleaning equipment.
b. 
Television inspection equipment.
The television camera used for the inspection shall be one specifically designed and constructed for such inspection. The television camera and its lighting shall be suitable to allow a clear picture of the entire periphery of the pipe. The camera, television monitor, and other components of the video system shall be capable of producing picture quality to the satisfaction of the public works department and if unsatisfactory, equipment shall be removed and revideotaped with proper equipment.
c. 
Execution.
(1) 
Television inspection.
(a) 
The cameras shall be moved through the line in either direction at a moderate rate, stopping when necessary to permit proper documentation of any sewer service taps. In no case will the television camera be pulled at a speed greater than 30 feet per minute. Manual winches, power winches, TV cable, and powered rewinds or other devices that do not obstruct the camera view or interfere with proper documentation shall be used to move the camera through the sewer main.
(b) 
When manually operated winches are used to pull the television camera through the main, telephones or other suitable means of communication shall be set up between the two points or manholes.
(c) 
The cost of retrieving the TV camera under all circumstances, when it becomes lodged during inspection shall be incidental to TV inspection.
(d) 
The item shall also include all costs of installing and maintaining any bypass pumping required to provide reliable, regular sanitary sewer service to the area residents. All bypass pumping shall be incidental to the project.
3. 
Vacuum testing of sanitary sewer manholes:
a. 
General.
This item shall govern the vacuum testing of all newly constructed sanitary sewer manholes.
b. 
Execution.
(1) 
Testing procedure.
(a) 
Manholes shall be tested with all connections in place. Lift holes shall be plugged and all drop connections and gas sealing connections shall be installed prior to testing.
(b) 
The sanitary sewer mains entering the manhole shall be plugged and braced to prevent the plugs from being drawn into the manhole. The plugs shall be installed in the mains beyond the drop connections, gas sealing connections, etc. The test head shall be placed inside the frame at the top of the manhole and inflated in accordance with the manufacturer's recommendations. A vacuum of ten inches of mercury shall be drawn and the vacuum pump will be turned off. With the valve closed, the level of vacuum shall be read after the required test time. The required test time shall be determined from the table below in accordance with ASTM C1244-93.
MINIMUM TIME REQUIRED FOR VACUUM DROP OF 1" Hg
(10"Hg-9"Hg) (SEC)
Depth of MH (ft.)
48-Inch Dia. Manhole
60-Inch Dia. Manhole
0 to 16
40 sec.
52 sec.
18
45 sec.
59 sec.
20
50 sec.
65 sec.
22
55 sec.
72 sec.
24
59 sec.
78 sec.
26
64 sec.
85 sec.
28
69 sec.
91 sec.
30
74 sec.
98 sec.
For each additional 2
5 sec.
5 sec.
(2) 
Acceptance.
The manhole shall be considered acceptable if the drop in the level of vacuum is less than one inch of mercury after the required test time. Any manhole which fails to pass the initial test must be repaired with a suitable material and retested. The material and method used to repair the manhole shall be approved by the public works department.
(Resolution 2007-012, adopted 2/26/2007)
A. 
Streets required.
All streets constructed within the city shall be required to be constructed with curbs and gutters. The required widths of all streets within the city shall be determined by the "functional classification" of the streets as contained in the most current revision of the master thoroughfare plan of the City of North Richland Hills.
B. 
Street design criteria.
1. 
The applicant for rezoning, preliminary plat and final plat is required to submit a "Trip Generation Data Form" completed by a licensed professional engineer with experience in transportation engineering. The trip generation estimates will be based on the latest data contained within the Institute of Transportation Engineers' (ITE) Trip Generation Manual. The only applicants which will not be required to submit the "Trip Generation Data Form" will be single-family residential developments of ten lots or less and duplex residential developments of five duplex units or less. The trip generation form will be submitted with the initial application forms. The public works department will review the form and will determine if a traffic impact analysis (TIA) will be required. The public works department will consider the number of trips, the classification of adjacent streets, the proposed development type, and other pertinent information when making a determination of the need for a TIA. A TIA will be required automatically from the developer of a piece of property when the development is expected to generate 1,000 vehicle trips or more per day or an additional 100 vehicle trips or more in the peak direction (inbound or outbound) during the site's peak traffic hour or if the development is located along a principle arterial. The city may also require a TIA at any stage of development whether it meets this criteria or not if the city finds that special circumstances exist requiring a TIA. For the purposes of conducting a TIA, a level of service "C" is the minimum acceptable design service. Additional guidance for the TIA can be found in the City of North Richland Hills Building and Land Use Regulations, Chapter 94 Administration, Article II, Traffic Impact Analysis, Sec. 94-31. Trip Generation Data Form.
2. 
Traffic control devices shall be defined as all signs, signals, markings, and other devices used to regulate, warn, or guide traffic, placed on, over, or adjacent to a street, highway, pedestrian facility, or bikeway by the authority of the City of North Richland Hills.
Any traffic control device design or application shall be considered to be in the public domain and shall be designed and/or installed in accordance with the latest version of the Texas Manual on Uniform Traffic Control Devices or as directed by the public works department.
3. 
All streets within or abutting the proposed subdivision shall be paved, with curbs and gutters installed, in accordance with the city's standards and specifications. All paving shall be to the width specified on the master thoroughfare plan and shall be constructed under the inspection of the public works department. The construction costs of all street improvements shall be borne by the developer unless participation by the city has been approved by city council prior to the beginning of construction. This approval will be accomplished by a "city/developer agreement."
4. 
Underground city owned utilities required in the subdivision shall be placed under or across all streets after the rough grades are made, but prior to the paving being placed. Paving operations will not be allowed to start until the utility work is complete. Open cutting pavement to install new utilities is not allowed. The contractor must bore the utility under the existing street and use ⅜-inch steel encasement pipe that is at a minimum Class 51 steel. Spacers shall be used to center the utility pipe in the encasement pipe and the encasement pipe shall be grouted at the ends.
5. 
Street grades shall be designed such that excessive sand deposition from too low a water velocity or pavement scouring from too high a velocity is avoided. The minimum street grade permitted shall be 0.65 percent. The minimum gutter line grade in all cul-de-sacs or "knuckles" shall be 0.75 percent. The maximum street grade shall not exceed 8.0 percent. Any deviation from this range of permissible grades shall require written approval of the public works director.
6. 
Standard roadway widths from face-of-curb to face-of-curb shall be according to the following table:
STANDARD PAVEMENT WIDTHS
Street Type
Number of Traffic Lanes
Lane Width
(Feet)
Median Width
(Feet)
R.O.W. Width
(Feet)
R2U
2
15
-
50
C2U
2
20
-
60
C4U
4
12
-
68
M4U
4
12
-
70
M5U
5
12
-
80
M4D
4
12
18
90
M6D
6
12
18
110
P6D
6
12
18
110
7. 
The minimum classified width of a proposed street shall be enlarged under the following conditions.
a. 
Adjacent to commercial or multifamily land uses where, in the opinion of the public works department, additional width is necessary for proper access and circulation.
b. 
Where, in the opinion of the city or in the opinion of the developer, with the concurrence of the city, the aesthetic value achieved from extra width is dictated by special conditions.
8. 
The proposed streets shall be located in the center of the right-of-way to allow both parkways to be the same width. The final grade of all parkways, existing and proposed, shall be one-fourth inch per foot from the top of curb to the property line. All parkways shall drain to the street.
9. 
All cul-de-sacs shall be installed with a 48-foot radius to the face of curb in a 58-foot radius ROW.
10. 
Standard reinforced concrete curb height and width is six inches with a 24-inch integral gutter section measured from the face of the curb. Any deviation from this section will require the approval of the public works director.
11. 
The minimum pavement and subgrade thickness for the various street widths shall be as indicated in the standard details.
12. 
Minimum horizontal curvature radii for design of street centerlines shall be as follows:
Arterial
800 feet
Collector
400 feet
Residential
200 feet
All street intersections shall be constructed to form a 90 degree angle.
13. 
In order to maintain an adequate sight distance, the minimum "K" values for the computation of vertical curves in the formula L=KA, where L is the length of the vertical curve in feet, and A is the algebraic difference of the street grades in percent are listed below:
Design Speed
MPH
Crest Vertical Curve
"K" Value
Sag Vertical Curve
"K" Value
30
28
35
40
60
60
50
110
90
14. 
The minimum radius for curb returns at intersections shall be 20 feet to the face of curb.
15. 
A tangent of at least 100 feet long shall be introduced between reverse curves on arterial and collector streets.
16. 
At all street intersections there shall be provided a minimum ten-foot by ten-foot corner clip sidewalk and utility easement.
17. 
A minimum 15 foot x 70 foot sight and visibility easement is required at intersections on all collector/arterial streets. No obstructions will be permitted within the sight visibility easement which interferes with a clear line of sight at elevations between 30 inches and nine feet above the average curb grade. In situations where street intersections are proposed within a curve, sight visibility easements shall be designed to meet AASHTO standards.
18. 
Reinforced concrete valley gutters shall be required at all asphalt street intersections where gutter flowlines cross another street or at low points where water flow crosses the street.
19. 
Median openings shall be spaced a minimum of 600 feet center-to-center or 500 feet curb-to-curb, whichever is greater.
20. 
All new curb cuts must meet the commercial/industrial driveway spacing requirements as defined in driveway standards, section 2d or as approved by the public works department. All curb cuts located on the Texas Department of Transportation (TxDOT) right-of-way must also conform to the TxDOT Access Management Policy.
21. 
There are areas within the city where soil conditions necessitate additional quantities of lime and/or subgrade redesign. The design engineer shall coordinate with the public works department in this scenario to determine the extent of geotechnical analysis required. The public works staff shall determine the number of samples that the geotechnical engineer will need to submit.
22. 
All new public streets shall be constructed of concrete pavement in accordance with the standard details. Existing asphalt streets may be reconstructed with asphalt pavement if approved by the public works department.
C. 
Sidewalks.
1. 
Sidewalks shall be constructed of four-inch thick, 3,000 psi compressive strength concrete reinforced with #3 steel bars laid on maximum of 18 inch centers each way.
2. 
Sidewalks shall be a minimum of four feet in width. The sidewalk shall be located on the city parkway adjacent to the private property line. Sidewalks shall be graded at ¼ inch per foot such that the sidewalk at the property line shall be no greater than 2½ inches higher than the top of curb on a typical ten foot parkway. If the sidewalks are approved by the public works department to be located adjacent to the curb, the sidewalks shall be a minimum of five feet in width.
D. 
Driveway standards.
1. 
Residential driveway approaches.
a. 
Residential driveway approaches shall be constructed of five-inch thick 3,000 psi compressive strength concrete reinforced with #3 steel bars on 18 inch centers each way. The driveway shall begin at the street curb and extend to the property line or to a point ten feet from the face of the curb whichever is greater. The drive approach shall be constructed such that the height of the drive approach at the property ROW, with a normal ten-foot parkway, shall be 2½ inches higher than the top of the curb. The contractor shall not sawcut and/or remove or excavate within four feet of the existing curb more than 48 hours prior to the actual removal of the curb and construction of the driveway entrance. This is to prevent water from ponding against the back of the existing curb lines and undermining the subgrade.
b. 
Width of driveway approaches: Residential driveway approaches shall not be less than 12 feet in width nor more than 20 feet wide measured at the property line. Specific variance to this criteria may be requested by the property owner. Any variance granted based on a specific design submittal must have the approval of the public works department.
c. 
Radius: Residential driveways shall be constructed with the return curbs having a rolled face disappearing at the sidewalk and joining the street curb with a minimum five-foot radius and a maximum ten-foot radius.
d. 
Provision for joint approaches: Driveway approaches shall be located entirely within the frontage of the premises they serve except that joint, or cooperative, driveways with adjoining property holders may be permitted and may be required by the public works director. When the joint drive approach is proposed by the developer, the request must be made by all the interested parties and all property owners involved. The design of the joint driveway facilities must be submitted with the request to be approved by the public works director.
e. 
Residential driveway approaches at street intersections: The drive approach on corner lots must be located to approximately line up with the side of the house or garage that is farthest from the intersection, or the drive approach edge farthest from the street intersection must be within three feet of the far side of the house or garage.
Only drive approaches in accordance with the above criteria will be allowed onto residential streets or the minor street at a street intersection. If both streets are residentially classified, a circular drive will be allowed on a corner lot if one of its two approaches meets the above location criteria. The other drive approach can have its near side no closer than 15 feet to the property corner closest to the intersection. If both streets have the same classification, other than residential per the currently adopted city master thoroughfare plan, the public works director shall make the determination as to which street access will be allowed. The city may require a traffic impact analysis (TIA) be provided to justify a property owner's request.
2. 
Commercial/industrial driveway approaches.
a. 
Commercial and industrial driveway approaches shall be constructed of six-inch thick, 3,000 psi compressive strength concrete reinforced with #4 steel bars on 18 inch centers each way. The driveway shall begin at the curb of the street and extend to the property line or to a point ten feet from the face of the curb, whichever is greater. The drive approach shall be constructed such that the height of the drive approach at the property line shall be 2½ inches higher than the top of curb at the street.
b. 
Width of driveway approach: The width of any commercial or industrial driveway approach shall not be less than 20 feet nor more than 35 feet measured along the property line. Specific variance to this criteria may be requested by the developer. Any variance granted based upon a specific design submittal must have the approval of the public works director.
c. 
Radius: Commercial and industrial driveways shall be constructed with the return curbs having a rolled face disappearing at the sidewalk and joining the street curb with a minimum ten foot radius and a maximum 30 foot radius.
d. 
Allowable spacing for driveway approaches: On streets classified as collector streets, the minimum centerline spacing between driveways shall be at least 300 feet. On streets classified as arterials, minimum spacing shall be at least 500 feet. This spacing criteria shall be applied irrespective of the number of individual properties located within the intervening distance. Deviation from this criteria may be requested by the developer. Any deviation granted will be based on a specific design submittal and must have the approval of the public works director. Before any deviation can be considered, it must be justified with a traffic impact analysis (TIA) approved by the public works department.
e. 
Provision for joint approaches: Driveway approaches shall be located entirely within the frontage of the premises and shall be located no closer than ten feet from each side property line except that joint, or cooperative, drive approaches with adjoining property holders may be permitted in order to conform to the provisions of paragraph d above. Any request for joint drive access must be by agreement of all parties involved and a specific plan submittal must be included for approval of the public works director. Both properties will be required to dedicate public ingress and egress easements to cover the approach and joint access area.
f. 
Approaches on properties other than residential: The leading edge of driveway for the corner lot, if allowed, must be located a minimum of 100 feet from the point of intersection of the curb lines of both streets.
g. 
Angle of driveway approach: The angle of the driveway approach with the curb line shall be 90 degrees.
h. 
Sidewalk to be removed: Where a driveway approach is to be built, the sidewalk shall be removed and the entire area replaced as a driveway. The drive approach shall extend to the property line.
3. 
Driveways crossing bar ditches.
a. 
The minimum culvert pipe size shall be 18 inch diameter and only reinforced concrete pipe (RCP) may be used. The ends of all culvert pipe shall be cut at a 6:1 slope. Culvert pipe must be protected by headwalls, approved by public works.
b. 
Radius: Driveways shall be constructed with the return curbs joining the edge of pavement at the street with a minimum ten-foot radius.
c. 
The maximum slope from the edge of driveway to the top of the culvert pipe shall be 6:1. The sloped area around the end of the culvert pipe shall be sodded or hydromulched to resist erosion.
d. 
The minimum cross slope on the drive shall be one-eight inch per foot. The minimum longitudinal slope between the edge of pavement at the street and the valley over the culvert pipe shall be one-fourth inch per foot.
e. 
Future maintenance of the drive approach and culvert pipe is the responsibility of the property owner.
f. 
During the drive approach installation, all ditch grading upstream and downstream of the proposed driveway culvert is the responsibility of the property owner.
4. 
General.
a. 
Driveway approaches at pedestrian crossings: Driveway approaches shall not be located in street intersections or at established pedestrian crossings.
b. 
Driveway approaches at obstructions: Driveways shall be kept at a minimum of five feet away from obstructions such as street light posts, fire hydrants, traffic signals, etc.
c. 
Driveway approach not to be obstructed: Driveway approaches shall not be constructed or designed for parking of vehicles or for use as angle parking.
d. 
Accumulative width of approaches: Driveway approaches shall not occupy more than 40 percent of the frontage of a lot or tract.
(Resolution 2007-012, adopted 2/26/2007)
A. 
General.
1. 
The criteria herein provided shall govern the design of storm drainage improvements within the City of North Richland Hills. Improvements shall include streets, alleys, storm sewers, channels, culverts, bridges, swales, and any other facilities through which stormwater flows. All drainage improvements shall be constructed in accordance with city specifications and be in dedicated right-of-way (ROW) or drainage easement. The developer shall provide all the necessary easement and ROW required for drainage structures, including storm sewers and open channels with access ramps. Easement width for storm sewer pipe shall not be less than 15 feet, and easement width for open channels shall be at least 25 feet wider than the top of the channel with 20 feet on one side to serve as an access way for maintenance purposes.
2. 
The developer shall be required to install at his own expense all storm sewers and drainage structures. This policy is applicable to all required drainage facilities including the channel improvements on the main channels and tributaries of Mackey, Calloway, Walkers Branch, Little Bear and Mesquite Branch Creeks, but excepting the main channel of Big Fossil Creek. The developer shall be responsible for excavation and channel liner improvements based on the fully urbanized 100-year frequency discharge for the channel. Any channel work necessary in the Little Bear Creek Corridor shall comply with the Little Bear Creek Corridor Ordinance.
3. 
A floodplain development permit is required for any proposed development within the FEMA designated special flood hazard area (SFHA). Development is defined as "any man-made change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations or storage of equipment or materials." Such development is subject to:
(a) 
All provisions of the latest flood damage prevention ordinance.
(b) 
All federal laws and regulations which govern the National Flood Insurance Program (44 CFR).
B. 
Basis of design.
1. 
Rational method: The method of calculation for storm runoff for drainage areas less than 750 acres will be the rational method. The method is expressed by the following equation:
Q = CIA
Where:
Q
=
storm discharge at the design point in cubic feet per second.
C
=
runoff coefficient representing the ratio of peak runoff to the rainfall.
I
=
average rainfall intensity for the time of concentration at the design point in inches per hour. (See Technical Paper No. 40.)
A
=
area contributing runoff to the point of design in acres.
2. 
Unit hydrograph method:
Peak discharges for drainage areas exceeding 750 acres shall be determined by using the unit hydrograph method. The unit hydrograph for this method shall be developed by using the criteria as outlined in "Flood-Hydrograph Analysis and Computation", U.S. Army Corps of Engineers, Engineering and Design Manuals, EM 110-2-1405, Washington D.C. dated August 31, 1959. Typically a unit period of 15 minutes should be used for the determination of the unit hydrograph.
In lieu of this procedure, there are several public domain micro-computer programs available which will provide satisfactory results. If the developer elects to use a computer program, he should obtain prior approval from the public works director or his designated representative.
3. 
Runoff coefficient:
Storm drainage improvements shall be designed based on the drainage areas being fully developed. The zoning as shown on the current city zoning maps or the city's master land use plan, whichever is more restrictive, shall determine the particular coefficient value selected. The table below indicates the runoff coefficients for the different land uses.
RUNOFF COEFFICIENT "C"
Single-family zoning districts
0.55
Duplex zoning districts
0.60
Townhome districts
0.65
Multifamily districts
0.75
Commercial districts
0.90
Industrial districts
0.85
School, church, and institutional districts
0.65
Parks and agricultural district
0.30
4. 
Time of concentration:
The time of concentration shall be defined as the time required for a drop of water to flow from the upper limits of a drainage area to the point of concentration. Times of concentration shall be calculated for all inlets, pipe junctions, and other critical design points in the proposed storm sewer systems. The following minimum inlet times of concentration may be used in place of calculated times. When calculating inlet times, consider overland flow channelized at such time as the distance traveled exceeds 100 feet.
TABLE V-2
Minimum Inlet Time of Concentration
Type of Area
Minimum of Inlet Time
Business and commercial
10 minutes
Industrial
10 minutes
Multifamily
10 minutes
Residential
15 minutes
Parks and open spaces
20 minutes
5. 
Rainfall intensity-duration-frequency:
The rainfall intensity-duration-frequency compiled in Technical Paper No. 40 by the U.S. Weather Bureau, Department of Commerce shall be utilized in computing rainfall intensity.
6. 
Design storm frequency:
Storm frequency to be used in design shall be as shown in the following table:
TABLE V-3
Design Storm Frequency
Type of Facility
Minimum Design Frequency
Storm sewers
5 years
Streets
5 years
Culverts, bridges, channels, underpasses, and creeks
100 years
A storm sewer shall be designed to pick up flow from the street when the runoff from a five-year frequency storm exceeds the capacity of the street to its top of curb, or the spread of water on a collector street does not leave one traffic lane dry, or the spread of water on a arterial street does not leave two traffic lanes dry, whichever is more restrictive. The combined capacity of the street and ROW and/or drainage easements and the storm sewer pipe shall be adequate to safely convey the runoff from a 100-year frequency storm.
7. 
Flow in streets:
Street capacity shall be determined by utilizing Manning's equation:
Q = A x 1.486/n x R2/3 x S1/2
Where:
Q
=
discharge in cubic feet per second
n
=
Manning's roughness coefficient, use 0.016 for pavement and gutters
A
=
cross sectional area of flow in square feet
R
=
hydraulic radius in feet
S
=
street or gutter slope in feet per foot
For parabolic crown streets, the cross slope shall be represented by the following formula:
All discharge of runoff from street to an open channel shall be in a flume or through an inlet with adjoining pipe and headwall.
8. 
Storm drain inlets:
The capacity of a depressed curb inlet on grade will be based on the following equation:
q1  = 0.7 
1
   (H1)5/2 - (H2)5/2
H1 - H2
Where:
q1
=
discharge into inlet per foot of inlet opening in c.f.s./ft. (maximum allowable is 1.0 c.f.s./ft.)
H1
=
a + yo
H2
=
a = gutter depression in feet
Yo
=
depth of flow in approach gutter in feet
The capacity of low point or drop inlets will be (maximum allowable is 2.0 c.f.s./ft) determined based on the broadcrested weir formula:
q1 = 3.0 (H1)3/2
9. 
Storm sewer systems.
Storm sewers shall be designed using the continuity equation and Manning's equation.
Q
=
AV and
Q
=
1.486/n AR2/3 Sf1/2
Q
=
discharge in cubic feet per second
A
=
cross sectional flow area normal to pipe in square feet
V
=
mean velocity of flow in feet per second
n
=
Manning's roughness coefficient
R
=
hydraulic radius in feet
Sf
=
friction slope in feet per foot
The coefficient of roughness to be used in design shall be as shown below:
Pipe Material
 
Reinforced concrete
 
Pipe
0.013
Flumes
0.015
Streets
0.016
Corrugated metal pipe
 
Annular, unpaved with bituminous coating
0.024
Annular, 25 percent paved with bituminous coating
0.021
Annular, 100 percent paved with bituminous coating
0.013
Helical, unpaved with bituminous coating
0.014 - 0.26*
Helical, 100 percent paved with bituminous coating
0.013
Thermoplastic pipe
0.010 - 0.13*
Notes:
* To be determined by diameter and size of corrugations.
Storm sewer pipes shall be designed so that the mean velocity of flow is equal to or greater than 2.5 feet per second and equal to or less than 15 feet per second. Pipes may be designed on a horizontal radius provided that the minimum centerline radius is equal to 30 pipe diameters and the cumulative degree of curvature does not exceed 60 degrees between points of entry. Pipes shall not be designed with vertical curves. The minimum pipe size is 24 inches in diameter. If a lateral does not exceed 50 feet, an 18-inch diameter pipe may be used.
The appropriate hydraulic grade line shall be plotted for all storm drainage design. The elevation of the hydraulic grade line shall in no case be closer to the gutter flow line than 1.5 foot.
The head loss for each structure shall be computed as:
V22
-
Kj
V12
=
hj
2g
2g
Where:
V2
=
outflow velocity
V1
=
inflow velocity
g
=
32.2 ft./sec2
Kj
=
head loss coefficient
hj
=
head loss (minimum = 0.2 ft.)
Head loss coefficients (Kj)
Manhole or inlet in line
0.50
Manhole or inlet with lateral
0.25
Lateral only
0.75
Enlargements or contractions
0.30
hj for beginning inlet is
1.25V22
2g
Points of entry into the main storm drain shall be provided at least every 500 feet.
10. 
Open channels: When the runoff exceeds the capacity of a 72-inch diameter concrete pipe or equivalent cross sectional pipe area (i.e., 2-51 inch diameter concrete pipe), the discharge may be carried in an open channel. Open channels shall be designed to carry the 100-year frequency storm runoff from a fully urbanized watershed with one foot of freeboard. All open channels will be earthen and incorporate the design features of the City of North Richland Hills' City Image Study including but not limited to reinforced concrete pilot channels, maximum 5:1 side slopes, terracing, landscaping, and low retaining walls. All open channels shall have a minimum bottom width of eight feet.
a. 
Full concrete lining:
Concrete lined channel will not be allowed in the City of North Richland Hills unless written approval is received from the public works director. If approval is granted, the public works department will establish the design standards.
b. 
Partial concrete liner:
Partial concrete lined channels will not be allowed in the City of North Richland Hills unless written approval is received from the public works director. If approval is granted the public works department will establish the design standards.
c. 
Earthen channels:
Earthen channels shall be constructed at locations approved by the public works department.
(1) 
The following stipulations shall be met:
(a) 
The velocity of flow will not exceed six feet per second.
(b) 
The design features outlined in the City of North Richland Hills' City Image Study shall be incorporated into the design of all open channels. Alternative designs that meet the intent of the city image study may be submitted for review by the public works director.
(c) 
Adequate design features are provided to protect outside slopes in channel curves.
(d) 
Sufficient energy dissipation is designed and constructed at all locations where concrete lining meets earthen slopes and bottoms.
(e) 
Sufficient easements are dedicated to provide protection of adjacent properties or facilities. 6.
(f) 
Drainage easements are dedicated to encompass the area below the elevation of the water surface profile of a fully urbanized 100-year frequency storm, plus one foot of freeboard and any additional area necessary to provide access for maintenance, but not less than 60 feet in width.
(g) 
Arrangements have been made for perpetual maintenance of the channel by the adjacent property owners or a Home Owners Association (HOA).
(h) 
That, in the judgment of the public works director, the appropriate use of the neighboring property or the health and safety of persons affected will not be substantially injured.
(i) 
Fences shall not be placed closer than ten feet from the top of the earthen channel. A minimum ten-foot erosion control easement shall be dedicated to the city on both sides of the channel.
(2) 
Earthen channels shall be terraced with side slopes not steeper than five feet horizontal to one foot vertical. A reinforced concrete pilot channel not less than five feet in width shall be constructed to a minimum grade of 1.0 percent. (If no concrete pilot channel is constructed the minimum grade of an earthen channel shall be a minimum of 1.5 percent.) The side slopes shall be smooth, free of rocks, and contain a minimum of six inches of top soil. The pilot channel shall be constructed as approved by the public works department. The easement width for an earthen channel shall extend at least 15 feet beyond one side of the channel and ten feet beyond the other side and shall not be cross-fenced. The top of bank areas shall remain open for maintenance purposes.
(3) 
After proposed earthen side slopes are cut, slopes shall receive six inches of topsoil, hydro mulch, and a soil retention blanket. The furnishing and placing of topsoil shall conform to the Texas Department of Transportation (TxDOT) Specification Item 160. The furnishing and placing of hydro mulch shall meet the requirements of the latest version of the North Central Texas Council of Governments' (NCTCOG) Standard Specifications for Public Works Construction, currently Items 2.02.4 "Fertilizer" and 202.6.4.4 "Hydraulic Mulching". The soil retention blanket will be American Excelsior Hi-Velocity Curlex or equal as approved by the public works director. The soil retention blanket will be furnished and placed in accordance with the manufacturer's recommendation. In no instance shall the placement method per the manufacturer's recommendations be less than that required in TxDOT Specification Item 169.
(4) 
The water surface profile (hydraulic grade line) for the 100-year frequency storm shall be shown. Maximum permissible mean velocities for the 100-year frequency discharge shall be six feet per second.
(5) 
Special consideration should be given to outlet structures on channels where the structures meet earthen banks.
(6) 
One reinforced concrete access ramp shall be provided at all intersections of every open channel with a public street. Access ramps shall be a minimum of 12 feet wide with a maximum slope of 16 percent. The ramps shall be designed to meet the intent of the city image study.
d. 
Detention ponds:
Detention ponds shall be designed in accordance with Chapter 102, "Floods and Stormwater Management," Article III "Stormwater Management", Division 2 "Design", of the North Richland Hills Building & Land Use Regulations.
11. 
Bridges and culverts:
All bridges and culverts shall be designed in accordance with the current edition of the "Hydraulic Manual" prepared by the Texas Department of Transportation, Bridge Division. The fully urbanized 100-year frequency storm hydraulic grade line shall be plotted. All culverts shall have headwalls and wingwalls upstream and downstream. All culverts shall pass the fully urbanized 100-year frequency storm runoff without allowing runoff to pass over the road. All bridges shall have channel bottom and slopes concrete lined. The low point on the bridge structure shall be at least one foot above the fully urbanized 100-year frequency storm water surface.
12. 
Lot grading:
The minimum and maximum lot grades are 1.5 percent (1.5'V: 100'H) and 25 percent (1'V:4'H), respectively. Diverting or impounding the natural flow of surface waters, which results in damages to the property of another by the overflow of the water diverted or impounded, shall not be permitted.
a. 
Fences (private and public screening) shall be constructed such that blockage of surface water flow does not occur. This includes the requirement that erosive conditions shall not be created around, under or near a fence structure.
b. 
Unless drainage improvements are in a dedicated right-of-way or drainage easement as approved and accepted by the public works director or his authorized agent, all such drainage improvements shall remain the responsibility of the owner for safety and maintenance and shall be considered private drainage facilities.
c. 
Residential lot grading shall be conducted in a manner which will not allow runoff to cross more than two lots (including the lot on which the drainage originates) before it enters a street or drainage easement. If this is not possible, then a drainage easement must be provided and any necessary facilities shall be constructed and installed by the developer.
d. 
When more than two residential lots are graded to drain across each other, a concrete flume will be required to carry storm water runoff. The flume shall be designed to carry the 100-year frequency storm runoff assuming a fully urbanized watershed. Flumes shall be constructed of five-inch thick, 3,000 psi compressive strength concrete reinforced with #3 steel bars 18 inches on center. The flume shall have a minimum three-foot width with six inch curbs. The flume shall be placed in a permanent drainage easement at least ten foot in width with a minimum of 18 inches of easement on each side of the flume. No fencing will be permitted that encroaches or crosses the flume.
e. 
Commercial lot grading will be conducted in a manner which will take all runoff to the adjacent streets or drainage easements. No lot area will drain onto adjacent properties without approval of the public works director.
f. 
Commercial or institutional land use with a runoff coefficient higher than 0.55 (as in the case of schools, churches, and municipal facilities) which does not require actual commercial zoning shall be subject to the above commercial lot grading policy.
g. 
Finished floor elevations shall be set a minimum of one foot above the top of curb at the centerline of the lot or 1.5 feet above the 100-year frequency stormwater surface elevation, whichever is higher.
h. 
All lots that have a minimum finish floor requirement due to the presence of flood plain or other factors must have FEMA elevation certifications prepared and submitted by a licensed professional surveyor for review and acceptance by the city's floodplain administrator on two separate occasions during the construction process. An elevation certificate must be prepared, submitted, and accepted prior to the slab being poured and a second elevation certificate must be prepared, submitted, and accepted prior to issuance of the certificate of occupancy. Elevation certificate information may be found on FEMA's website (www.fema.gov).
13. 
Off-site drainage:
In respect to offsite drainage, the following provisions shall apply:
a. 
The developer shall be responsible for all runoff from property upstream of his proposed development as though it were all fully developed. Runoff coefficients utilized to design drainage systems for the properties involved shall use the current zoning and/or the future use of the property as shown in the future land use plan, whichever is the most intensive use.
b. 
Effect of the development's drainage design on downstream properties and adjacent properties shall be given proper consideration. Water concentrated in streets, pipes, drains, culverts, and channels will be moved to a recognized watercourse without damage to intervening structures or undue spreading across intervening land.
(1) 
A "recognized watercourse" shall herein be defined as either an open channel with hydraulic characteristics which provide capacity for at least a ten-year frequency storm after ultimate development of its watershed, or an underground storm drain with capacity for at least a five-year frequency storm plus overland relief sufficient to safely discharge up to a combined ten-year frequency flow (based on ultimate watershed development) without damage to adjacent property. Such ten-year capacity shall extend at least 100 feet downstream from the point of discharge or from the developer's property line, whichever is the greater distance. Typical examples of such "recognized watercourses" are the main channels of Mackey, Calloway Branch, Walkers Branch, Big Fossil, Little Bear, and Mesquite Branch Creeks, or those tributary creeks, streams, channels, or underground storm drains which meet the hydraulic capacity requirements of a "recognized watercourse". Bar ditches are not considered "recognized watercourses."
(2) 
The developer is responsible for constructing all offsite channelization or underground storm drain with overland relief required to discharge concentrated storm water from the low end of his development to the recognized watercourse, and also to obtain all the necessary easements from intervening land owners. Calculations will be required to show that connecting offsite drainage ways are capable of handling any increase in runoff due to development, concentration, or diversion for at least the ten-year storm frequency.
(3) 
Any drainage easements necessary due to the developer's alteration of existing concentrated discharge locations (i.e., existing creeks, channels, or storm sewers) shall be acquired by the developer at no cost to the city.
c. 
Where the preliminary drainage analysis by the developer indicates that additional runoff from the developing property will overload downstream drainage facilities and result in hazardous conditions, the city may withhold approval of the development until appropriate provisions have been made. These provisions shall include any drainage studies or plans necessary to indicate the offsite drainage problem will be corrected by offsite drainage construction.
d. 
When required, the developer will furnish to the city, a "hold harmless agreement" and a "release of liability" indemnifying the City of North Richland Hills from any liabilities due to damages caused to the downstream property owner by the discharge of storm drainage water from the said development.
C. 
Preliminary drainage analysis guidelines.
The purpose of a preliminary drainage analysis is to determine the need for drainage facilities and drainage easements either within the proposed development or offsite. These guidelines shall be used as the minimum for a preliminary plat. When requested by the public works department, a preliminary drainage analysis shall be submitted with a replat or short form plat. The preliminary drainage analysis shall consist of the following items:
1. 
A topographical map drawn at a scale of one inch = 200 feet and depicting the watershed which drains to and across the subdivision. The map must include the subdivision and an area extending for 200 feet in all directions from the proposed subdivision as a minimum. The map must also include contour lines at one or two foot vertical intervals. Data from the city topo maps will be acceptable where available. Data from USGS Quad sheets will be acceptable only where city topo maps are not available.
The map shall indicate any offsite or adjoining areas outside the limits of the area being platted which are relevant to onsite drainage. Show any proposed or existing drainage and utility easements, water bodies, streams, and railroads, parks, cemeteries, and drainage ditches. Show location of existing utilities including gas and petroleum lines, electric, telephone and TV cable. Also, the location of any existing structures located within the area being proposed for subdivision.
The datum for all topography shall be that of the United States Coast and Geodetic Survey or the City of North Richland Hills GIS datum. The preliminary analysis shall be sealed by a registered professional engineer licensed by the State of Texas.
2. 
Calculation of the drainage areas, time of concentration, and storm water runoff rate for the five-, ten-, 25- and 100-year frequency storms.
3. 
Identification of special flood hazard areas as defined by the flood damage ordinance and as located by the current flood insurance rate map.
D. 
Drainage study guidelines.
A drainage study is required when it has been determined that the area being developed will require stormwater drainage facilities or drainage easements either within the development or offsite. The following criteria shall be used for the engineer to prepare a drainage study.
1. 
The study shall analyze the effect of the subdivision on existing downstream drainage facilities. The study shall be sufficient to verify compliance with the criteria contained in subsection B, paragraphs 6, 7, and 10 above.
2. 
The study shall include a topographical map as defined above in subsection C, "Preliminary Drainage Analysis Guidelines."
3. 
Delineation and calculation of drainage areas together with proposed flow arrows shall represent flow patterns from runoff after all proposed improvements have been installed. Surface water drainage patterns shall be shown for each and every lot in the proposed subdivision and for each lot adjacent to the proposed subdivision.
4. 
In addition to those calculations required by the preliminary drainage analysis, this study shall also include:
a. 
Hydraulic calculations to each lateral, manhole, inlet and outlet structure on the pipe. Head losses shall be calculated as described in subsection B.
b. 
Inlet calculations utilizing the minimum time of concentration for the zoning type which is contributing the largest "CA" to the inlet.
5. 
If any portion of the proposed subdivision or its offsite improvements (including pipes or ditches) fall within the limits of a Federal Emergency Management Agency (FEMA) floodplain, additional backwater calculations may be required. Additional calculations in the form of a conditional letter of map revision will be required if:
a. 
Any portion of the proposed subdivision is determined to be located within a FEMA Zone "A" floodplain; or
b. 
Any portion of the proposed subdivision is determined to be located within a FEMA Zone "AE" floodplain and the overall subdivision (including all phases) is five acres or larger; or
c. 
Any portion of the proposed improvements from a subdivision include dredging or filling within a FEMA designated floodway.
Backwater calculations shall comply with normally accepted standards as required by FEMA for application for a letter of map revision (LOMR). In addition, the calculations must begin with a previously defined base flood elevation (BFE). The calculations shall continue upstream through the project until the proposed BFE is within 0.01 feet of the existing BFE or the limits of the existing zone "A" have been reached.
A LOMR will be required prior to issuing building permits.
6. 
The drainage study shall be sealed by a registered professional engineer licensed by the State of Texas. The following certification shall be included on the study and signed and sealed.
I, __________, a Professional Engineer registered in the State of Texas, have prepared this drainage study in compliance with the latest published requirements and criteria of the City of North Richland Hills, and have verified that the topographic information used in this study is in compliance with said requirements and is otherwise suitable for developing this workable Plan of Drainage which can be implemented through proper subsequent detailed construction planning.
Signature __________, P.E., (Seal)
(Resolution 2007-012, adopted 2/26/2007)
A. 
Installation.
Street lights in all subdivisions shall be installed on approved metal poles.
1. 
Poles must be approved by a public electric utility holding a city franchise and the public works department.
2. 
Poles shall be contracted and paid for by the developer during the construction phase of a subdivision and before building permits are issued.
3. 
Poles not purchased through a public electric utility holding a city franchise, shall be certified in writing by an engineer to meet the specifications as required by a public electric utility holding a city franchise and the public works department.
B. 
Location.
The location of street lights shall be as follows:
1. 
At all intersections.
2. 
Where a new street intersects an existing street.
3. 
Where a block is 600 feet or longer, a street light shall be installed every 600 feet or mid-block, whichever is the shortest distance.
4. 
If more than one mid-block light is required, they shall be installed to create an equal balance of light throughout the entire length of the block.
5. 
If a cul-de-sac block is 300 feet or longer, a street light shall be installed in the end of the cul-de-sac.
6. 
Street lights shall be installed at any other location as may be directed by the public works director for the welfare and safety of the community.
C. 
Thoroughfare street lighting.
1. 
Street lights on thoroughfares shall be the following type.
a. 
Street Light:
•
400W MH lamp
•
Tempered glass lens
•
Mounted on 35-foot pole
•
Manufacturer: KIM 1A/RA252/400MH480/BL-P/SAL-TMI on a SAL35-64400/BL-P pole
•
Provide pole with the factory base cover. The factory finish pole is to match the fixture. The pole shall have one set of banner stanchions.
b. 
Street light (signal pole):
•
400W MH lamp
•
Tempered glass lens
•
Mounted on signal pole
•
Manufacturer: KIM 1A/RA252/400MH480/BL-P/SAL-TMI on a SAL35-64400/BL-P pole
•
Provide with swept arm with finish to match fixture and mounting bracket to match signal pole mounting boss.
c. 
Pedestrian light:
•
100W MH lamp
•
Tempered glass lens
•
Mounted on 12-foot pole
•
Manufacturer: KIM 1A/RA252/400MH480/BL-P/SAL-TMI on a SAL35-64400/BL-P pole
•
Provide pole with factory base cover. The factory finished pole should match the fixture.
2. 
The fixture voltage should be verified prior to ordering fixtures. Only specified fixtures or approved equals shall be provided. Provide black fixtures, poles, base covers, mounting arms and adaptors.
3. 
All designs must be approved by the public works department.
(Resolution 2007-012, adopted 2/26/2007)
A. 
Construction.
Masonry or concrete screening walls shall be constructed according to the following specifications.
1. 
Concrete foundations shall have a minimum compressive strength of 3,000 psi at 28 days. Compressive strength tests conducted by an independent testing laboratory shall be submitted to the city staff for confirmation. All testing costs shall be paid by the developer or his contractor.
2. 
Reinforcing steel shall be billet steel conforming to the requirements of ASTM A-615-GR.60.
3. 
Concrete for piers shall be placed within eight hours of drilling pier holes.
4. 
Brick masonry shall be as approved by the city.
5. 
Mortar shall be Type "S".
6. 
Construction shall be in accordance with the requirements of the "Recommended Practice for Engineered Brick Masonry" Brick Institute of America.
7. 
Use #9 Gauge 1¾ inch wide galvanized ladder wire to extend horizontal in wall panel on every course.
8. 
The wall shall be a minimum of six feet in height as measured from the nearest/adjacent sidewalk grade. No masonry or concrete screening wall or column shall exceed eight feet in height unless the wall is functioning as a retaining wall and is designed as such.
9. 
Unless it has been determined by the public works director that no drainage problems are anticipated, an opening designed to allow for stormwater drainage shall be provided. The opening shall be a uniform two inches high the full length between columns.
10. 
Prefabricated screening fences such as "brickcrete" or "woodcrete" may be substituted for on-site masonry construction, provided that the finish resembles typical masonry constructed fences. No ordinary concrete finishes or traditional smooth faced concrete block as a finish shall be allowed along collector or arterial streets. However, a concrete finish consisting of exposed aggregate shall be allowed.
11. 
A 12-inch wide concrete mow strip shall be centered under the wall.
12. 
Screening walls must be contained within a 2.5 foot screen wall easement.
13. 
Screening wall maintenance shall be the responsibility of the property owner or homeowners association.
14. 
All masonry or concrete screening walls shall be designed by a professional structural or civil engineer licensed in the State of Texas. Sealed plans shall be submitted to the city for review and permitting.
B. 
Location.
1. 
No masonry or concrete screening wall shall be located on public right-of-way.
2. 
Adequate sight visibility easements shall be provided at all street intersections.
3. 
The location and placement of a masonry or concrete screening wall shall be coordinated with the public works department to avoid conflicts with utility and drainage easements.
C. 
Plan approval.
1. 
Plans are to be designed, signed, sealed and dated by a professional civil engineer licensed in the State of Texas and furnished with the following information:
a. 
The title shall include the legal name of the property on which the wall is being constructed.
b. 
A plan view of the wall showing its location, limits, and stationing.
c. 
A profile of the wall including grades for the top of the concrete mow-strip, adjacent top of curb, sidewalk and finished floor of proposed and/or existing adjacent slabs.
d. 
Elevation view of a typical column.
e. 
Elevation view of the wall.
f. 
Mow-strip detail.
g. 
Drainage clearance under wall (uniform two inches).
h. 
Steel tensile strength.
i. 
Concrete compressive strength.
j. 
Wind load calculations.
(Resolution 2007-012, adopted 2/26/2007)
This section shall apply to all subdivisions which are proposed for development; are existing and require additional grading; or are single lot subdivisions (platted or unplatted) which are proposing excavation or fill.
A. 
Definitions.
1. 
Clear-cutting -
The removal of all trees or a significant majority of the trees within an area of land.
2. 
Conceptual grading plan -
A topographical map of the subdivision with sufficient perimeter area to provide a clear definition of the initial elevations, watercourses, and drainage patterns. In addition, the plan includes proposed flow arrows, cross-sections and spot elevations sufficient to control the magnitude of excavation and fill. The plan must be sealed and signed by a registered professional engineer licensed by the State of Texas.
3. 
Excavation -
The removal of turf, soil, rock or weeds such that the surface is six inches lower than the initial elevation.
4. 
Fill -
The deposition of rock, concrete, soil or sod such that the cumulative thickness of all materials is equivalent to six inches or greater.
5. 
Final grading plan -
A topographical map of the subdivision with sufficient perimeter area to provide a clear definition of the initial elevations, watercourses and drainage patterns. In addition, the plan includes one foot contours, spot elevations and flow arrows. The plan is in sufficient detail and scale to determine limits and depths of excavation or fill. The plan must be signed and sealed by a registered professional engineer licensed by the State of Texas.
6. 
Grading -
The movement of dirt, top soil, grass, native material, brush, trees, landscaping or other forms of surface material which will result in a long term difference of six inches or greater from the initial elevation.
7. 
Initial elevation -
The mean sea level elevation as it existed five years prior to the current date.
8. 
Multi-lot subdivision -
A division of any tract of land into two or more parcels.
9. 
Protected tree -
Any self supporting woody perennial plant which has a caliper of four inches or more when measured at a point of 4.5 feet above ground level and which normally attains an overall height of at least 15 feet at maturity, usually with one main stem or trunk and many branches. It may appear to have several stems or trunks as in several varieties of oaks.
10. 
Selective thinning -
Thinning should include selective clearing of undesirable trees to allow unrestricted growth of young vigorous trees, especially hardwoods. Fifty to 60 percent shade is more desirable and conducive to all activities. Dense shade is the least desirable. On densely wooded properties selective thinning may be used to accomplish a required tree survey on the property.
B. 
Unplatted multilot subdivision.
When a multilot subdivision has been proposed for platting and the final plat has been approved by the planning and zoning commission, but has not yet been approved by the city council, the following provisions shall govern the excavation and fill process.
1. 
A conceptual grading plan shall be submitted to the public works department. The plan will be reviewed for consistency with city ordinances and policies. If the concept is approved, a 30-day permit will be issued to allow grading to begin.
2. 
The process must be inspected by a public works department representative and all fill shall be tested for compaction.
3. 
Areas which fail the compaction tests shall be excavated, the material replaced (or new material imported, depending on moisture content) recompacted and retested.
4. 
Areas which have been filled without adequate compaction tests or without inspection by a city representative shall be considered as areas which have failed the compaction tests.
C. 
Platted multilot subdivision.
When a multilot subdivision has been platted in accordance with the existing subdivision ordinance and the plat has been filed with the county, the following provisions shall apply.
1. 
A final grading plan shall be submitted to the public works department. The plan will be reviewed for consistency with city ordinances and policies. If the plan is approved by the public works department, the applicant will be allowed to begin the excavation and fill process.
2. 
The process must be inspected by a city representative and all fill shall be tested for compaction.
3. 
Areas which fail the compaction tests shall be excavated, the material replaced (or new material imported, depending on moisture content) recompacted and retested.
4. 
Areas which have been filled without adequate compaction tests or without inspection by a city representative shall be considered as areas which have failed the compaction tests.
5. 
Areas of a multilot subdivision which are not graded at the same time as the rest of the subdivision will be required to comply with the provisions of a single-lot subdivision.
D. 
Single-lot subdivision.
All single lot subdivisions shall be required to obtain a grading and excavation permit as required by the current North Richland Hills Building Code. Note that a single-lot subdivision shall be considered multilot if the subject parcel and any adjacent parcels are owned by the same individual or entity.
E. 
Revised grading.
In all situations where the foot print of the building exceeds the pad shown on the approved grading plan, a revised plan shall be submitted to the public works department.
F. 
Testing.
All compaction shall be tested by an approved soil testing laboratory.
1. 
The testing facility must maintain a current permit with the public works department. A sample application is included in the Appendix.[1] The public works department may disallow any and all firms which cannot or refuse to meet the minimum criteria established in the application.
[1]
Editor’s note — The sample application is on file in the Public Works Department.
2. 
All fill must be compacted to 95 percent Standard Proctor Dry Density.
3. 
Samples shall be taken at the rate of one per six inch lift per 500 cubic yards of fill, or; one per lot, whichever is greater.
G. 
Slopes.
Slopes created by excavation or fill shall not exceed four horizontal to one vertical.
H. 
Tree preservation.
Chapter 114, Article II "Trees" of the North Richland Hills Building & Land Use Regulations contains complete criteria and regulations for tree preservation. This section only identifies applicability.
1. 
Tree preservation applies to real property as follows:
a. 
All vacant and undeveloped property.
b. 
All property to be redeveloped, including additions and alterations.
c. 
All easements and rights-of-way, except those included in a preliminary plat approved by the planning and zoning commission shall meet the terms and provisions of this article.
d. 
The yard areas of all developed property, excluding developed single-family residential property.
2. 
Protected trees.
a. 
A "protected tree" is any tree that has a trunk caliper of four inches or more, as measured 4.5 feet above natural grade level.
b. 
Protected trees shall not include the following species:
Black Willow - (Salix nigra)
Bois d'Arc (Maclura pomifera - female only)
Cottonwood - (Populus deltoids)
Chinaberry - (Melia azeoarach)
Hackberry - Celtis occidentalis laevigata)
Honeylocust - (Gleditsia triacanthos)
Mesquite - (Prosopis glandulosa)
Mulberry - (Morus alba)
Tree of Heaven - (Ailanthus altissima)
3. 
If the Tree Preservation Ordinance applies to a property, a tree survey shall be submitted with the construction plans. The tree survey shall identify protected and unprotected trees with their respective caliper and species, trees to be removed, and the means that the protected trees shall be replaced. Trees shall be replaced by new plantings or by payment into the Re-Forestation Fund in accordance with Ordinance No. 2422, Section 700.
I. 
Erosion control.
1. 
A separate two-year Erosion Control Maintenance Bond in the amount of 100 percent of the installation costs for the proposed erosion control measures must be provided prior to beginning any grading activities or construction of public infrastructure improvements.
2. 
Silt fences shall include wire mesh backing on the down stream side and be supported by steel posts.
3. 
A minimum of one roll width of Curlex matting (or approved equal) is to be placed at the back of curb following the parkway grading.
4. 
All areas disturbed during construction, including areas outside the construction boundary, are to be seeded, hydromulched, or sodded to re-establish vegetation.
J. 
Stormwater pollution prevention plan.
1. 
The Texas Commission on Environmental Quality (TCEQ) issued the Texas Construction Storm Water General Permit (CGP) that regulates the storm water discharge from construction sites one acre or larger. Stormwater discharge is defined in this document as discharge from construction activity including clearing, grading and excavation, and construction materials or equipment storage or maintenance, or other industrial storm water directly related to the construction process.
2. 
The CGP requirements set forth below apply to construction sites disturbing more than five acres:
a. 
Prepare stormwater pollution prevention plan (SWP3).
(1) 
Components of SWP3.
(a) 
Site description.
[1] 
Project type (e.g., office park), total acres disturbed.
[2] 
Runoff coefficient before and after project.
(b) 
Site plans.
[1] 
Drainage patterns.
[2] 
Location of borrow and fill areas.
[3] 
Location of equipment, material, chemical, waste, and fuel storage areas.
[4] 
Outfall locations (where runoff leaves property).
[5] 
Location of physical controls (retention ponds, field outlets, silt fence).
(c) 
Name of receiving water and city.
(d) 
Wetlands/endangered specifies/habitats.
(e) 
Historic registry properties affected.
(f) 
Description of erosion control/sediment controls to be installed and responsible party.
(g) 
Sequence of major construction phases, estimated and actual dates.
(h) 
Structural control maintenance - responsible parties.
(i) 
Identify non-stormwater discharge (e.g., landscape watering).
(j) 
Identify industrial stormwater discharges (e.g., dedicated concrete plant).
(k) 
Best management practices (BMPs) for material stockpiles, chemical storage, and waste disposal.
(l) 
Inspections.
[1] 
Designate individual(s) who will conduct inspections (must be qualified individual or other person under supervision of qualified individual).
[2] 
Inspection and corrective action summary forms/reports.
[3] 
Regularity of inspections (once per week or every two weeks and after 0.5 inch rain event).
[4] 
Copy of permit text.
b. 
Post sign at construction entrance.
(1) 
File notice of intent (NOI).
(a) 
Must be filed by operator with day to day authority to direct construction activities, to make changes to the design of the stormwater controls or to specify the BMPs to be implemented.
(b) 
The CGP requirements for construction sites between one - five acres or less than one acre but is part of a common plan of development disturbing one - five acres does not require filing the notice of intent.
c. 
Designate and identify qualified individual(s).
d. 
Implement SWP3.
(1) 
Implement all physical controls, BMPs, inspections, and control maintenance.
(a) 
Erosion/sediment controls.
[1] 
Flow diversion - dikes, swales, pipe slope drains, concrete flume.
[2] 
Surface flow management - silt fence, straw bale berm, soil retention blanket.
[3] 
Permanent drainage - storm sewer drain inlets, culverts, drain pipes.
[4] 
Sediment traps - retention pond, rip-rap barrier, filter fence.
[5] 
Source controls - vehicle tracking, stockpile berms, fuel storage/transfer, equipment maintenance, dust control, sanitary waste.
[6] 
Dewatering - sump pit, settling basin, lift station.
(2) 
Best management practices (BMPs).
(a) 
Vehicle tracking offsite.
[1] 
Dust suppression.
[2] 
Inspect vehicles prior to departure.
[3] 
Wash off vehicle in designated area.
[4] 
Collect wash water, discharge to sanitary sewer or trap in retention pond.
[5] 
Use large gravel at construction entrances and heavily traveled internal roads.
(b) 
Stockpile management.
[1] 
Keep pipe, rebar, parts and construction material stockpiles organized.
[2] 
Confine stockpiles or berms.
[3] 
Keep amount on site as small as reasonable possible.
(c) 
Controls maintenance.
[1] 
Inlet protection barriers free of silt buildup.
[2] 
Replace/clean gravel and rip-rap stone.
[3] 
Silt fence secure and free of buildup.
[4] 
Replace straw or sand bag berms.
[5] 
Repair soil blanket tears.
[6] 
Remove sediment buildup in retention pond, outfalls.
For a complete list of acceptable BMPs, refer to the latest version of the NCTCOG Reference Manual - Storm Water Quality Best Management Practices Manual for Construction Activities.
e. 
Update plan as necessary based on inspection findings and project changes.
(1) 
If modifications to stormwater management, erosion control, or BMPs are required, such changes must be implemented prior to the next anticipated storm event or as soon as possible. If needed, revisions to the SWP3 shall be made within seven calendar days after inspection.
f. 
File notice of termination when final stabilization is achieved or when operational control ceases.
(1) 
Stabilization practices include temporary vegetation, preserving existing vegetation, permanent landscaping, mulching, geotextiles, sodding, buffer strips, protection/preservation of trees, erosion control blankets/mats.
(2) 
Stabilization must be initiated not more than 14 days after construction activities cease or if activities are not planned to resume within 21 days.
(3) 
Initial stabilization must commence as soon as possible when adverse weather conditions persist beyond 14 days.
(4) 
Final stabilization is defined as at least 70 percent vegetative cover in all areas.
3. 
For sites disturbing between one and five acres, all CGP requirements apply, except filing a notice of intent (NOI).
4. 
A complete copy of this documentation (as required by the state) must be submitted either by the developer's engineer during plan approval or by the contractor after the construction plans are approved. This information must be submitted to the city prior to scheduling a pre-construction meeting. The city construction inspectors will make periodic reviews of the required maintenance schedules as outlined in the SWP3.
5. 
The erosion control standards described within this section are an outline of the state requirements set forth in the construction general permit issued by TCEQ. The engineer/contractor should contact TCEQ for the application and complete details of the CGP.
(Resolution 2007-012, adopted 2/26/2007)
Detail No.
Category
Description
1M-1
Misc.
General Notes, Sht. 1 of 3
1M-2
 
General Notes, Sht. 2 of 3
1M-3
 
General Notes, Sht. 3 of 3
2M
 
NRH Project Sign
3M
 
Trench Embedment and Backfill Details
1P
Paving
Residential Streets Hot Mix Asphalt Concrete Pavement
2P
 
Residential Streets Reinforced Concrete Pavement
3P
 
Collector Streets Hot Mix Asphalt Concrete Pavement
4P
 
Collector Streets Reinforced Concrete Pavement
5P
 
Arterial & Industrial Streets Hot Mix Asphalt Concrete Pavement
6P
 
Arterial & Industrial Streets Reinforced Concrete Pavement
7P
 
Pavement Marking Details
8P
 
Typical Left Turn Lanes
9P
 
Concrete Valley Details
10P-1
 
Curb Ramp Details I
10P-2
 
Curb Ramp Details II
10P-3
 
Curb Ramp Details III
10P-4
 
Curb Ramp Details IV
10P-5
 
Curb Ramp Details V
10P-6
 
Curb Ramp Details VI
11P
 
Residential Drive Details
12P
 
Commercial Drive Details
13P
 
Drive with Culvert Details
14P-1
 
Combination Rail Type C301
14P-2
 
Combination Rail Type C301
14P-3
 
Combination Rail Type C301
15P-1
 
Permanent Asphalt Pavement Replacement
15P-2
 
Temporary Asphalt Patch
1D
Drainage
Channel Liners
2D
 
Storm Drain Flood Limits
3D
 
Reinforced Concrete Channel Liner Details
4D
 
Concrete Pilot Channel
5D
 
Concrete Flume
6D
 
Concrete Channel Apron for S.D. with Vertical Headwall
7D
 
Concrete Channel Apron for S.D. with Sloping Headwall
8D
 
Concrete Collar Details
9D
 
Storm Drain Tap Detail
10D
 
Concrete Plug Details
11D
 
Drainage Standard Drop Inlet
12D-1
 
Standard 4-foot Square Storm Drain Manhole/Vault, Sht. 1 of 2
12D-2
 
Standard 4-foot Square Storm Drain Manhole/Vault, Sht. 2 of 2
13D-1
 
Standard 5-foot Square Storm Drain Manhole/Vault, Sht. 1 of 2
13D-2
 
Standard 5-foot Square Storm Drain Manhole/Vault, Sht. 2 of 2
14D-1
 
Standard 6-foot square Storm Drain Manhole/Vault, Sht. 1 of 2
14D-2
 
Standard 6-foot Square Storm Drain Manhole/Vault, Sht. 2 of 2
15D
 
Angled Storm Drain Manhole/Vault Detail
16D-1
 
Standard Curb Inlet, Detail No. 1
16D-2
 
Standard Curb Inlet, Detail No. 2
16D-3
 
Standard Curb Inlet, Detail No. 3
17D
 
Inlet Protection Block and Gravel
18D-1
 
Channel Access Ramp, Sht. 1 of 2
18D-2
 
Channel Access Ramp, Sht. 2 of 2
1W
Water
Valve and Thrust Block Details
2W
 
Detail of Valve Locations at Street Intersections
3W-1
 
Fire Hydrant Details
3W-2
 
Fire Hydrant and Water Meters
4W
 
Water Service Connection Details Single and Double
5W
 
Two inch Water Service
6W
 
Domestic 4-inch Meter Installation
7W
 
Irrigation 4-inch Meter Installation
8W
 
Detector Check Installation Details
9W
 
Blow-Off Hydrant
1S
 
Sewer Sanitary Sewer Manhole Details
2S
 
Precast Concrete Manhole Details
3S
 
Sanitary Sewer Drop Manhole Details
4S
 
Sewer Service Connection Details
(Resolution 2007-012, adopted 2/26/2007)