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Home My WebLink AboutCC 1985-04-02 Agendas 4.. ~"" , . . City of J\9rth Richland Hills, Texas March 27, 1985 PUBLIC NOTICE The City Council of the City of North Richland Hills, Texas, will conduct a work session April 2, 1985, 6:30 p.m., in the City Hall, 7301 Northeast Loop 820. ITEMS FOR CONSIDERATION: 1. Public Hearing-Community Development Block Grant Funds 2. Discussion of Master Drainage Study ·d1¿¿CW 0' anette Rewis-City Secretary ~~. """". 281-0041 · 7301 N, E. LOOP 820. p, 0, BOX 18609. NORTH RICHLAND HILLS, TEXAS 76118 SUMMARY STATEMENT FOR PUBLIC HEARING FOR TARRANT COUNTY COMMUNITY DEVELOPMENT BLOCK GRANT PROGRAM The Community Development Block Grant Program of Tarrant County is now in its Tenth year. For the eleventh program year, beginning in 1985, Tarrant County expects to receive about $2.66 million, to be allocated among the 32-city members of the Tarrant County Urban Consortium. The primary purpose of the Community Development Program is to upgrade low and moderate income neighborhoods. The following projects are examples of activi- ties which have been approved by the Department of Housing and Urban Development for federal funding: , 1. Public Works Projects Water system construction and improvements Streets, curbs and gutter construction and improvements Drainage improvements Sanitary sewer collection systems construction 2. Public Facilities Senior Citizens' Centers and Community Centers construction and repair Sidewalk wheelchair ramps 3. Recreation Parks construction, development and improvements Recreation facilities construction 4. Public Services Fire Hall construction and pumper truck purchase 5. Housing Housing rehabilitation Housing rental assistance payments Since 1975, the City of North Richland Hills has received approval for and implemented the following projects: 1. Big Fossil Creek Trunk Sewer. 2. Mackey Creek Channel Improvements from Onyx Drive South to Harmonson Road. The procedures, which Tarrant County Planning Department and our City will follow in drawing up a plan for projects over the next three (3) funding years include: 1. Needs and priorities will be assessed through a survey recently con- ducted by Tarrant County and through this public hearing. 2. Project plans will be developed by the City staff with citizen input provided at this public hearing. 3. Three-year plan projects will be ranked by a Community Development Subcommittee. 4. Approval of the proposed projects will be voted on by the Mayor's Council of Tarrant County. 5. The Work Program and application will be submitted to Tarrant County Commissioner's Court for their consideration and approval. 6. The application will be submitted to North Central Texas Council of Governments for A-95 review and comment. 7. The application will be submitted to the area HUD office for approval, revision or rejection. All citizens, groups and organizations of our City are welcome to participate and be represented in the formulation of the three year plan. The public hearing is open for public advice, comments, complaints, questions or presentation of alternative proposals. You can be of great service to your City and neighborhood by participating. The purpose of this public hearing is to establish the needs of this City and your neighborhoods. If you wish to present your views in writing, please obtain a questionnaire from the City Secretary, complete it and return it to her office as soon as possible. Your inputs will be considered in our formulating the City's improvement program for the next three years. The proposed projects will be discussed at the next regular Council meeting, Monday, April 8, 1985, at 7:00 P.M. At this time, if anyone wishes to offer any comments, questions, state- ments or complaints regarding the needs of this community, please come forward, state your name and address. - ,,' " ,/ QUESTIONNAIRE FOR CDBG CITIZEN PARTICIPATION r::::::::· ( ":::::;:!!J Your County Commissioner and City Council would like to find out what your community needs are. The information obtained from this questionnaire will be used to develop progr~s using Community Development Block Grant funds that Tarrant County will request from the Department of Housing and Urban Development. Da'te City Name of the s'treet where you live: Your interest and cooperation will help make your city and community a bet'ter place to live. Please put an "X" in the box that best answers the question of need. PROJECTS: 1-10ST ?\TEEDED NEED DONIT NEED Repair of houses CJ c:J CJ Street improvements CJ 0 [=:J Curbs and gutters CJ CJ CJ Sidewalks CJ c:J CJ -"",- ,,- Ston:: drains CJ CJ CJ ( Removal of architectural CJ CJ CJ barriers (Example: Ramps for the handicapped) . Senior centers CJ CJ CJ Flood and drainage improvements CJ CJ CJ (example: channel improvemem:s) Water and sewer CJ CJ CJ In my opinion, the most important single need of my co~~unity out of the above is: Other services my community needs are: (Please list them) My co¡;..'TIents (other things I would like to tell my County Com.~issioner and City Council) are: '. \._, Notices on community development public meetings are published in area ne~s?apers, citizens' cor:~ents and input are ~elcome. Please return this form to the city officials at the end of the public hearing, or address "Titten comments to: Tarrant County Planning Department 100 W. Weatherford Street Fort Korth, 'Texas 76102 ':~~ .,' Thank you for your participation! · KNOWL TON-E NGLlSH-FLOWERS, INC. CONSULTING ENGINEERS I Fort Worth- Dallas March 26, 1985 Mr. Dennis Horvath, Assistant City Manager City of North Richland Hills 7301 N.E. Loop 820 North Richland Hills, Texas 76118 RE: 3-224Ã CITY OF NORTH RICHLAND HILLS DRAIN GE MASTER PLAN SUBDIV. ORDIN. REVISIONS Based on our discussion with the City Council at the last regular meeting regarding proposed Subdivision Ordinance revisions, we have reworded the proposed changes accordingly. We would request that the following changes be presented to the Council for consideration of adoption. Please refer to Section 2-06, "Storm Drainage" in the Ordinance: , 1. The term "overland rel ief'l is not adequately defined in Section B .1. EXISTING WORDING: Streets and underground storm drains shall be designed to accomodate a 5-year frequency storm with adequate overland relief for the 25-year storm. Design of all bridges, culverts, underpasses, and open channels are to be based on the 100-year frequency. ADD THE FOLLOWING: Overland relief for the 25-year frequency storm shall be fully contained within the street right-of-way. Overland relief for the 100-year storm may be provided in the street right-of-way plus the yard area adjacent to the street right-of-way, and the lowest adjacent building finished floor elevation shall be at least 1.5 feet above the 100-year street overland relief flow elevation. Where storm drains are located outside dedicated street rights-of-way in dedicated easements, overland relief for the 100-year storm shall be provided within the drainage easement, and the lowest adjacent building finished floor elevation shall be at least 1.5 feet above the 100-year overland relief flow elevation. I( 2. Presently, the developer has the option to provide open channels if the calculated storm drain size exceeds 48-inch diameter. We would recommend that this size be increased. See Section B.7(a). 550 FIRST STATE BANK BLDG,. BEDFORD, TEXAS 76021.817/283-6211. METRO/267-3367 Dennis Horvath Subdivision Ordinance Criteria Revisions, continued EXISTING WORDING: Capacity of storm sewers and ditches shall be calculated by Manning's Formula as illustrated...In cases where 48-inch or smaller pipe will handle the design flow, pipe shall be used. In cases where 48-inch pipe is not adequate, the developer may use pipe or a lined open drainage channel. REPLACE WITH THE FOLLOWING: ...Capacity of storm sewers and ditches shall be calculated by Manning's Formula as illustrated... In cases where 60-inch or smaller pipe will handle the design flow, pipe shall be used based on 5-year design criteria and overland relief as described in Section B.I. above. In cases where a 60-inch pipe is not adequate, the developer may use pipe or a concrete lined open drainage ditch. Such drainage ditch shall be completely concrete lined and sized using fully urbanized lOa-year frequency criteria. If cover above the calculated pipe size is not available then hydraulically equivalent concrete box, elliptical or arch pipe may be used. Not more than 3 parallel conduits may be substituted for the single conduit. In the design of the street storm drain system, the elevation of the hydraulic gradient of the storm sewer shall be a minimum of 1.5 feet below the elevation of the adjacent street gutter. In any system, the junction of pipes of different diameter shall be made at inlets, junction boxes or manholes so that the crowns of the pipes are at the same elevation. 3. Presently, the developer is not required to concrete line any of the major channels. The following options will be provided on all major channels: (a) Full laO-Year Concrete Channel Liner, (b) Partial lOa-Year Concrete Channel Liner, (c) Earthen 100-Year Channel Improvements with Concrete Pilot Channel. (See Figure 1, attached). Based on these options, we would recommend the following modifications to Section B.7(b): EXISTING WORDING: The Developer shall be required to install at his own expense all storm sewers and drainage structures. This policy is applicable to all drainage facilities other than the main channels of Mackey, Calloway, Walker, Big Fossil, Little Bear, and Mesquite Branch Creeks. On these six water courses the developer shall be responsible for the excavation and improvements of the channel in an earthen condition in a manner approved by the City. After this improvement to proper section and slope in an earthen condition and a dedication of right-of-way to the City, the Developer shall be relieved from further maintenance responsibilities. REPLACE WITH THE FOLLOWING: The Developer shall be required to install at his own expense all storm sewers and drainage structures. ~ March 26, 1985 DRAINAGE MASTER PLAN Page 2 Dennis Horvath Subdivision Ordinance Criteria Revisions, continued This policy is applicable to all drainage facilities includin~ the main channels and tributaries of Mackey, Calloway, Walker, Little Bear and Mesquite Branch Creeks, but excepting Big Fossil Creek. The Developer shall be responsible for excavation and full concrete channel liner improvements based on the fully urbanized 100-year frequency discharge for the channel, unless otherwise approved by the City Council. EARTHEN CHANNELS (ONLY IF APPROVED BY CITY COUNCIL): Earth channels may be approved provided that the velocity of flow will not produce serious erosion; that sufficient easements are dedicated to provide protection of adjacent properties or facilities; that floodway 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 and maintenance, but not less than 60 feet in width; where arrangements have been made for perpetual maintenance by the adjacent property owners, and/or has been dedicated and accepted for City Park purposes; and where, in the jUdgement 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. Earth channels, when approved, shall be constructed with a trapezoidal shape and a minimum bottom width of 12 feet and side slopes no steeper than 3 feet horizontal to 1 foot vertical (4 to 1 preferred). A reinforced concrete pilot channel not less than 12-feet in width or, as determined by the Public Works Director, shall be constructed. The side slopes shall be smooth, free of rocks, and contain a minimum of 6-inches of top soil, and shall be seeded with Bermuda grass. Gobi blocks, rock rubble riprap, or other such similar materials, shall be placed a minimum of 4-feet along both sides of the pilot channel to a depth of at least 2 feet. Size and gradation of such material shall be determined based on peak discharge velocity requirements. The pilot channel shall be constructed as approved by the Public Works Department. The easement width for earthen channels shall extend at least 20-feet beyond the top of each channel bank. 4. If sufficient overland relief is not available above a 5-year storm drain, then the developer is required to upsize the storm drain based on 25-year criteria. We would recommend that Section B.8 be modified to include a wider range of design frequencies: EXISTING WORDING: Where storm sewers are designed an overland swale March 26, 1985 DRAINAGE MASTER PLAN Page 3 Dennis, Horvath Subdivision Ordinance Criteria Revisions, continued shall be provided to accommodate the excess runoff to be expected during the 25-year storm unless the storm sewer is enlarged to a 25-year frequency design. ~REPLACE WITH THE FOLLOWING: Storm sewers are to be designed for a ~ storm frequency of 5 years, (See Figure 2); however, the total capacity of the drainage facility including surface flow within limits of available street, front yard, right-of-way or drainage easements shall be equal to or greater than the runoff of a storm whose fully urbanized design frequency is 100 years. At such point within a storm sewer system that the capacity of the storm sewer designed for a storm frequency of 5 years, in addition to the surface flow capacity within available right-of-way or easements, is exceeded by the runoff from a storm whose fully urbanized design frequency is 100 years, then the storm sewer shall be increased in size and designed for a capacity of a higher return year, of 10, 25, 50, or 75 years, so that the right-of-way or easement section and the storm sewer has the combined capacity to provide for the runoff of a storm whose design frequency is 100 years. At such point within a storm drain system that the capacity of the storm sewer designed for a storm frequency of 75 years, in addition to the surface flow capacity within available right-of-way or easements is exceeded by the runoff from a storm whose design frequency is 100 years, or the required pipe size exceeds 60-inches in diameter, then storm drainage facilities shall be designed as an underground storm drain with fully urbanized 100-year capacity or designed as a completely concrete lined open channel with fully urbanized 100-year discharge capacity. 5. We would recommend that design details covering concrete lined channels be modified and amplified. Section B.14 should be replaced: EXISTING WORDING: All open ditches in all subdivisions that are used to carry surface runoff shall be lined across the entire areas of each subdivision being developed, except as otherwise determined by the City Council. Lining of drainage ditch floors is to be done with 6-inch thick or thicker concrete. Walls are to be lined with 4-inch thick concrete sloped not steeper than 1 foot vertically to 1.5 feet horizontally. All concrete slabs are to be reinforced with a minimum of 6 II X 6 II X 10 gauge X 10 gauge wire mesh, and provided with proper weep holes or other pressure relief measures. REPLACE WITH THE FOLLOWING: All open ditches in all subdivisions VV March 26, 1985 DRAINAGE MASTER PLAN Page 4 Denni~ Horvath Subdivision Ordinance Criteria Revisions, continued that are used to carry surface runoff across more than two lots shall be fully concrete lined across the entire areas of each subdivision being developed, except as otherwise determined by the City Council. Lining of drainage ditch floors is to be done with 6-inch thick or thicker, Class "A" 3,000 psi Portland Cement concrete. Walls are to be lined with 5-inch thick concrete sloped not steeper than 1 foot vertically to 1 foot horizontally. All concrete slabs are to be reinforced with a minimum of #3 reinforcing steel bars placed at most IS-inches on center each way, and provided with minimum 2-inch diameter weep holes with approved filter media placed at intervals no greater than 25-feet centers. One (1) foot wide concrete wings shall be provided at the top of each concrete side slope and pvc sleeves formed in the wings as required for constructing fencing along the top of the channel on each side. Vertical concrete retaining wall sections shall be designed with adequate footings and reinforcing steel to support all anticipated soil and water pressure loads acting on each side of the structure. In addition, retaining walls shall be designed to support at least a Highway Surcharge load unless otherwise approved by the Public Works Department. FULL CHANNEL LINER: The height of concrete channel liner shall be at least 1 foot above the fully urbainzed laO-year water surface profile. Such profile shall be determined by backwater calculations using the HEC-2 computer program or other approved modeling methods which take into account backwater effects from downstream bridges, culverts, and other obstructions. Sizing based only on normal depth calculations will not be approved unless it can be demonstrated that such downstream backwater effects can be safely ignored, or future downstream improvements are being made which will lower the controlling downstream elevation below normal depth as determined using the Mannings Equation. In cases where the top of channel liner must be constructed above natural ground level as required to fully contain the 100-year flow, and where construction of levees or berms are permitted, provision shall be made for draining the local runoff which ponds behind the levees after the water surface in the channel recedes. Finished floor elevations may be established at least 1.5 feet above the peak 100-year water surface which ponds behind the levees, if approved by the Publics Works Department. If levees are not approved by the Public Works Department then compacted earthen fill shall be placed along side the channel within the entire flood plain area as required to concrete line the channel to a height of 1 foot above the fully urbanized lOa-year water March 26, 1985 DRAINAGE MASTER PLAN Page 5 Dennis Horvath Subdivision Ordinance Criteria Revisions, continued surface elevation. Side slopes of the channel banks behind the concrete channel liner shall be no steeper than 5 foot horizontal to 1 foot vertical within the drainage channel easement, or for a distance of not less than 20-feet behind the top of channel. Side slopes beyond the 20-foot minimum shall be no steeper than 3 foot horizontal to 1 foot vertical unless concrete lined or covered with approved soil erosion protection materials. The easement width for earthen channels shall extend at least 40-feet beyond the top of each channel bank. PARTIAL LINER: If the 100-year fully channel contained water surface is above the natural ground line and levees are not approved or flood plain fill is not feasible, then the concrete channel liner shall be extended to the natural ground line along each side of the channel. In no case shall the concrete lined channel capacity provided be less than that required to convey the 25-year frequency discharge. Floodway easements shall be provided along the sides of the concrete lined channel sufficient to encompass all areas beneath the water surface elevation resulting from a fully urbanized 100-year discharge, plus such additional width easements as may be required to provide ingress and egress to allow maintenance and to protect adjacent property against erosion, caving-in of over-banks, etc., as determined and required by the Public Works Department. The Developer shall be responsible for furnishing complete cross-sections, grading plans, HEC-2 computer runs and all other documentation requested by the Public Works Department as required to justify less than full section concrete channel lining and to establish the limits of the 100-year overflow flood plain lines. Water surface profile calculations shall be based on backwater effects created by any existing bridge, culvert or other obstruction regardless of future downstream proposed improvements. {/ 6. Requirements covering channel access ramps and easement fencing should be added to Section B.15: EXISTING WORDING: In new subdivisions the developer shall provide all the necessary easement and right-of-way required for drainage structures, including storm sewers and open lined channels. Easement width for storm sewer pipe shall not be less than 10 feet, and easement width for open channels shall be at least 20 feet wider than the top of the channel, 15 feet of which shall be on one side to serve as access way for maintenance purposes. ~ ADD THE FOLLOWING: Concrete channel access ramps and access ~ easements shall be provided at all street crossings for Public Works L- March 26, 1985 DRAINAGE MASTER PLAN Page 6 þ" '. Dennis Horvath Subdivision Ordinance Criteria Revisions, continued maintenance vehicle access to the channel bottom. Access ramps shall be a minimum 12 feet wide with a maximum slope of 16-percent. If fencing is required, it shall be placed along the top of the concrete channel liner unless a sanitary sewer main or water line is located within an easement along the channel bank, in which case the fence shall be located on the easement line to permit unrestricted Public Works access to the utility line. 7. We would recommend that the following paragraph be added to the Subdivision Ordinance which covers drainage ditch requirements across subdivision lots designed to discharge small local runoff flows. ADD THE FOLLOWING PARAGRAPH (Section B.19): If drainage swales or flumes are constructed within a subdivision to discharge local surface runoff to a street or storm drain system, such swale or flume shall not be permitted to cross more than two (2) lots without dedication of a drainage easement. Fences shall not be constructed across any drainage easement which would obstruct flow. Alternates are provided in the Drainage Master Plan for either concrete of earthen channel improvements on the major streams located within North Richland Hills. All tributary channels are designed based on full IOO-year concrete channel liner improvements. Proper transition structures shall be provided on all major channels where concrete and earthen sections are connected to minimize damage and erosion potential created by changes in flow velocity. ~v / r Storm drain sizing calculations are based on 5-year frequency criteria with a note in the report stating that sizing of storm drains shown in the Master Plan assume that sufficient overland relief is available in accordance with Subdivision Ordinance requirements, and that upsizing will be required if such overland relief is found to be insufficient after more detailed field surveys are made and subsequent design is completed. March 26, 1985 DRAINAGE MASTER PLAN Page 7 .' , I ." " ~ Dennis Horvath Subdivision Ordinance Criteria Revisions, continued Please call if you have any questions. RI~ff~ RWA/ra Enclosures cc. Mr. Rodger N. Line, City Manager Mr. Gene Riddle, Director of Public Works Mr. Allen Bronstad, Assistant Director of Public Works Mr. Richard Royston, Director of Planning and Development March 26, 1985 DRAINAGE MASTER PLAN Page 8 .' f .' -,".. EXISTING lOO-YEAR FLOOD PLAIN MINIþtM EASEMENT WIDTH IF ACCESS RAMP TO CHANNEL BOTTOM IS PROVIDED (INCREASE EASEMENT ~-FEET IF RAMP NOT PROVIDED) IMPROVED lOO-YEAR FLOOD PLAIN FENCE ------_ _..:sz..__ I FT. -' 1.5' MIN. -1- IMPROVÈDIOO-Y:'; r, WA TER SURFACE:;:>' EXISTING CHANNEL SECTION BEFORE IMPROVEMENTS lEVEE ROPOSED CONCRETE CHANNEL LI NER FULL IOO-YEAR C.ONCRETE CHANNEL LINER IMPROVED lOO-YEAR FLOOD PLAIN (ADD ~FEET FOR EA~EMENT WIDTH) EXISTING IOO-YEAR {IMPROVED lOO-YEAR --':ATER~R:Eì_ ':'T~U~C~_ 1-4!-tWl. I I. 5' MIN. r ---;~~ATER-- .L~~-T l:m _S~CE (~ST)~ PROPOSED CONCRETE CHANNEL LINER (EXTEND LINER TO NATURAL GROUND -25 YEAR MIN. CAPACITY REQUIRED) EXISTING CHANNEL SECTION BEFORE IMPROVEMENTS PARTIAL IOO-YEAR CONCRETE CHANNEL LINER PROPOSED EARTHEN CHANNEL IMPROVED IOO-YEAR FLOOD PLAIN (ADD ~-FEET FOR EASEMENT WIDTH) --7------.2...-- EXISTING lOO-YEAR PILOT 1.5' MIN. WATER SURFACE CHANNEL I , - .....1L- ROCK RUBBLE EARTHEN CHANNEL WITH CONCRETE PILOT FIGURE 1 - " ... ·f ... . BUilDING SETBACK WIDTH IMPROVED lOO-YEAR FLOOD PLAIN (M4X. SPREAD) STREET RIGHT-OF-WAY HOUSE 25-YEAR FLOOD PLAIN (MAX. SPREAD) -------2-____ 1.5' MIN. 25-YEAR WATER SURFACE MINIMUM 5-YEAR DESIGN OVERSIZE AS REQUIRED (10, 25, 50, 75-YEAR) TO M4INTAIN 25 AND ¡OO-YEAR SPRE~D LIMITS SHOWN ABOVE UNDERGROUND STORM DRAIN CONOUIT (. STORM DRAIN IN STREET 25-YEAR WATER SURFACE (NOT MAJOR WATERCOURSE) r I , I I I I , IMPROVED lOO-YEAR FLOOD PLAIN liMITS lOO-YEAR WATER SURFACE 1.5' MIN. 12- \...O~~~F\ - L;j ., I I I I I PERMANENT DRAINAGE EASEMENT STREET F.F UNDERGROUND STORM DRAIN CONDUIT OVERSIZE AS REQUIRED (10, 25, 50, 75-YEAR) TO M4 I NTA I N 100- YEA R FLOOD PLAIN liMITS WITHIN EASEMENT (M4Y REPLACE PIPE WITH CONCRETE CHANNEL IF GREATER THAN OR EQUAL TO 50-INCH DIA.) OVERLAND RELI EF SWALE -- liNE WITH CONCRETE OR OTHER M4 TER IAl ,~PPROVED BY PUBLIC WORKS DEPT. STORM DRAIN IN EASEMENT FIGURE 2