A.4 - General Design Requirements.
A.4.1
Line Sizes. The developer's engineer is responsible for sizing all new waterlines within the development and submitting these sizing calculations to the City for acceptance. The minimum distribution system line size is six (6) inches, with the exception of short Cul-de-Sacs and parallel lines as indicated in Sections A.4.9 and A.5.2. Sizing of off-site waterlines shall conform to the Water Distribution System Master Plan, where applicable. In other instances, computer modeling is the preferred method for sizing water lines. At a minimum, the design engineer shall submit hand calculations justifying the size of the proposed waterlines. The following criteria, in addition to the requirements of TCEQ, are to be used in sizing new waterlines.
Design Parameters:
Hazen Williams Coefficient (PVC) 130 Hazen Williams Coefficient (DI or CSC) 100 Service Unit Equivalent (SUE) Single-family residential 1.0 Multi-family residential 0.66 The number of SUEs for commercial uses shall be based on the meter size calculated as being needed by the developer's engineer per Section A.5.8.
Fire flows shall conform to Insurance Standards Office (ISO) standards and the International Fire Code that the City is using according to Section 4-1. The City of Copperas Cove is currently classified by ISO/PPE as Class 2.
When the City determines that a waterline needs to be larger than required to facilitate future services in the area, the City may require that a waterline be oversized as determined by the Developer's Agreement.
The minimum sizes of service lines that shall be used are as follows:
Dwelling Units Minimum Line Size 1 ¾" 2 1½" 3—6 2" 7—11 4" 12—75 6" A.4.2
Pipe Material. The following table summarizes the acceptable pipe materials and their uses:
Pipe Material Use Pipe Size Classification Copper Tubing Service lines <2" Type K Polyethylene Service lines <2" SDR 9—200psi PVC Service lines 2"—3" Schedule 80 PVC Distribution, service lines 4"—12" C900 DR 14 Ductile Iron Fire hydrant lead, distribution 6" C115 CI 350 Ductile Iron Distribution line 8"—12" C115 CI 350 Ductile Iron Transmission line 16"—60" C151 CI 250 Concrete Steel Cylinder Transmission line 16"—60" C301 PVC Transmission line 14"—42" C905 DR 18 Pipe materials other than those identified in this section may be proposed, but shall meet appropriate American Water Works Association Standards (AWWA) and bare the National Science Foundation (NSF) approval for use in potable water systems. Acceptance of alternative pipe material is subject to Public Works Director and City Engineer approval.
When ductile iron pipe or fittings are used, they shall be lined on the inside with cement mortar in accordance with AWWA C104. All ductile iron pipe shall be wrapped with a minimum 8-mil thick polyethylene film conforming to AWWA C105. In highly corrosive soils, ductile iron pipe shall be double wrapped.
A.4.3
Embedment and Depth of Cover. Embedment material for water system construction shall conform to the City's standard details and the pipe manufacturer's recommendations, whichever is more conservative. The depth of cover to the top of the pipe shall be a minimum of three (3) feet below natural ground or the bottom of the flex base course where under pavement. If three (3) feet of cover is not achievable, a 2000 psi concrete trench cap at least 6 inches extending laterally 6 inches on both sides of the pipe zone onto undisturbed soil shall be installed. In rural areas and for pipes 16 inches in diameter and larger, the minimum depth of cover to the top of the pipe shall be four (4) feet. In no case will a minimum depth of cover of less than two (2) feet be allowed.
A.4.4
Fittings. When Ductile Iron or PVC pipe is used, the fittings for distribution and transmission mains shall be Ductile Iron, in conformance with AWWA C110. The pressure class shall be the same as the pipe with a minimum of Class 250. Concrete Steel Cylinder (CSC) fittings shall be allowed when CSC pipe is utilized. All fittings shall have either mechanical or flanged joints.
A.4.5
Pipe Joints. Push-on, mechanical, or flanged joints shall be allowable unless otherwise indicated in this chapter.
A.4.6
Thrust Restraint. The preferred method for thrust restraint is mechanically restrained joints. Concrete thrust blocking is acceptable with written notification to the City Engineer and Public Works Director. The restrained joint design shall conform to the following:
1.
Water line tees, bends, valves and fittings must be restrained against thrust forces to prevent movement or failure of the water line.
2.
The designer is responsible for providing, on the construction drawings, an adequate restraining system design for the waterline, including minimum length of restrained pipe required in each direction. Computer programs as distributed by EBAA Iron, Inc. and Certain TEED are available to calculate restrained joint requirements.
Concrete thrust blocks shall conform to the standard details. In the absence of City-approved standard details, the design engineer must provide thrust blocking details for approval.
A.4.7
Fire Hydrants. For residential zoned property or use, and as the property develops, fire hydrants shall be located at a maximum spacing of six hundred (600) feet as measured along the length of the roadway. No part of a residential structure shall be farther than five hundred (500) feet from the fire hydrant as measured by the route that a fire hose would be laid.
For non-residential zoned property or use, and as the property develops, fire hydrants shall be located at a maximum spacing of three hundred (300) feet as measured along the length of the roadway. No part of a non-residential structure shall be farther than five hundred (500) feet from the fire hydrant as measured by the route that a fire hose is laid.
Drain hydrants shall be located at all low points on transmission lines. Fire hydrants shall be located within the distances from public streets as shown in the Standard Details.
A.4.8
Looping. All pipelines, other than those in cul-de-sacs, should be connected to other distribution system pipelines so that all services may receive feed from two directions for system redundancy. Exceptions to this requirement will require approval from the Public Works Director in consultation with the City Engineer.
If it is necessary to install water lines between lots to meet flow requirements, no service taps will be installed on such water lines and a valve will be located on each end to allow isolation of such water lines without service interruption.
A.4.9
Cul-de-Sacs. If a fire hydrant is not required in a cul-de-sac due to distance requirements as outlined in E.4.7, a 2-inch blow off valve should be located behind the curb at the end of the line and in such a manner to allow drainage to an appropriate location.
A.4.10
Trench Safety. In accordance with state law, whenever trench excavation exceeds a depth of five feet trench safety systems that meet current federal standards of the Occupational Safety and Health Administration (OSHA) shall be provided.
(Ord. No. 2016-61, § 1(Exh. A), 10-13-16)