· piping design layout training lesson 6 underground page 5 of 25 15/30/2002 rev 0 8.3.1...

PIPING DESIGN LAYOUT TRAININGLESSON 6

UNDERGROUNDPage 1 of 25

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8. UNDERGROUND

8.1 PREFACE

This lesson will cover the procedures required for underground studies. Two things to keep in mind;first, use Fluor standards as a guide, and second, the guidelines mentioned in this lesson may bedifferent than jobs you may have worked on in the past. Some clients have their own engineeringstandards.

8.1.1 Lesson Objectives

Lessons provide self-directed piping layout training to designers who have basic piping design skills.Training material can be applied to manual or electronic applications. Lesson objectives are:

• To know the types of underground systems.

• To know how to make underground studies avoiding major mistakes and costly changes.

• To familiarize you with Fluor standards. (Fluor standards are a guide. The standards used onyour contract may differ.)

8.1.2 Lesson Study Plan

Take the time to familiarize yourself with the lesson sections. The following information will be requiredto support your self-study:

• Your copy of the Reference Data Book (R.D.B.)• Fluor Technical Practices. The following Technical Practices support this lesson:

000.210.1150000.210.1160000.210.1200000.210.1210000.210.1211000.250.2040

If you have layout questions concerning this lesson your immediate supervisor is available to assistyou. If you have general questions about the lesson contact Piping Staff Group.

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8.1.3 Study Aids

Videos on Piping Design Layout Practices supplement your training. It is suggested that you view thesevideos prior to starting the layout training. You may check out a copy of the videos from the KnowledgeCentre (Library).

8.1.4 Proficiency Testing

You will be tested on your comprehension of this lesson. Proficiency testing will be scheduled three tofour times a year. Piping Staff will notify you of the upcoming testing schedule.

• Questions are manual fill-in, True-False and short essay (bring a pencil).• The test should take approximately one hour.• You may use your layout training Reference Data Book and material from previous layout training

lessons during the test.• The test facilitator will review your test results with you at a later date.• Test results will be given to Piping Staff.

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8.2 TECHNICAL DUTIES OF LAYOUT PERSON

Develops the following specifications, in accordance with contract requirements and TechnicalPractices 000.250.1938 and 000.250.1939.

• Gravity sewers - design, layout and testing

• Plant and unit firewater systems. Prepares fire protection system layouts and data and attendsmeetings pertaining to it.

• Advises general piping supervisor as to the need for any additional specifications relating tounderground piping by Civil.

• Reviews piping material specifications and recommends additions, deletions or changes based ondesign requirements. Initiates action for the development of purchase descriptions for anyunderground items that are normally not covered in the piping material specifications.

• Develops and/or directs the development of the underground piping standard details, consistentwith contract and material requirements.

• Develops and/or directs the development of unit underground layouts and insures they reflect thejob philosophy. Assembles data and calculations relating to the sizing of the unit sewer systems.

• Maintains underground workbooks: collections of vital data relating to the design of U/G systems.

• Coordinates underground piping with other groups and establishes a two-way flow of information.

• Represents general piping in meetings with vendor, clients, engineering and other internal groups.

8.2.1 Underground Systems Work Book

It is the responsibility of the underground layout person to develop and maintain an undergroundsystems work book that contains:• Schedules• Narrative underground specifications.• Applicable sections of codes having jurisdiction.

• Piping material information and specifications.• Process data (P&ID's, flow conditions, quantities and temperature).• Job instructions and design memos relating to underground piping.• Calculations and sketches.• Notes on interface meetings.• Questions and answers.

The above contents are considered minimum and other topics may be added as necessary

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8.2.2 Prerequisites to Start Underground Piping Layout and Design

ITEM SOURCE

1. Meteorological Data, Rainfall, Frost Depth Basic Jobsite Questionnaire 2. Existing Obstructions Client Via Project Manager 3. Sewer Systems, Segregation Process Engineer 4. Soil Conditions Structural Engineer 5. Paving Structural Engineer 6. Clients Design Requirements Project Manager 7. Federal, State and Local Codes Project Manager

Additional Information 8. Schedule Piping Supervisor *9. Approved Plot Plan(s) Piping Supervisor

10.00 P&ID's Piping Supervisor +11 Preliminary Foundation Design Sketches Structural Engineer

12. Process Drainage Rates, Temperaturesand Intermittent or Continuous

Process Engineer

13. Piping Materials Specifications Piping Materials Engineer 14. Fire System Capacity (in spec.) Process Engineer 15. Site Preparation Drawings Structural Engineer 16. Decision on Location of Cooling Water

System (above or below ground)Project

* May not be available at start of layout (use best available info).+ Discuss approximate size with Structural Engineer.

8.3 UNDERGROUND PIPING MATERIALS

Purpose

The purpose of this guide material is to provide the designer with information relating to some of themore commonly used underground pipe and fittings.

Scope

The list that follows is for information only and gives the A.S.T.M. or A.W.W.A. specification reference,size range, and normal use for each type. For additional information the designer should refer to thespecifications or manufacturer's catalogs that are listed. The designer needs to work with the materialengineer for material selection on the project.

Selection of Pipe

Selection of pipe for underground service depends upon pressure, temperature, commodity, durability,cost, availability, and client requirements.

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8.3.1 Vitrified Clay Pipe

Vitrified clay pipe (standard and extra strength, A.S.T.M. C-700) is used for gravity pipinghandling surface drainage and process drainage when this piping is not under concrete pavingor buildings. It is also used for sanitary sewage to within 5 feet of an outside wall of a buildingwhere there is no paving and for acid sewers with acid proof cement joints.

It is available in extra strength in the following sizes: 4"-6"-8"-10"-12"-15"-18"-21"-24"-27"-30"-33"- 36". Joint lengths vary per manufacturer, but are approx. in 2' or 3' lengths in sizes up to12" and 3' to 5' lengths in sizes 15" through 36". (Catalogs: Cantex, Interpace)

8.3.2 Cast Iron Soil Pipe

Cast iron soil pipe (A.S.T.M. A-74) is used for gravity piping handling surface drainage, processdrainage or sanitary sewage under concrete paving or buildings. It is available in 2"-3"-4"-5"-6"-8"-10" -12"-15" sizes. Joint lengths available in 5' & 10' lengths. (Catalogues: Tyler, Cal-Alabama, Rich Manufacturing).

8.3.3 Cast Iron Water or Pressure Pipe

Cast iron water pipe (A.W.W.A. C-106, 108 & 110) is used for pressure or sewer systems wherelong runs with few branches are required. Pipe & A.W.W.A. fittings are available in sizes 2"through 48". Joint lengths vary from 12' to 18' depending upon the manufacturer. (Catalogs:U.S. Pipe, Mead Pipe.)

8.3.4 Asbestos Cement Pipe (Transite Pipe) (Reference only no longer used)

Asbestos cement pipe (A.W.W.A. C-400) in conjunction with cast iron fittings was used forpressurized water service. It had the advantage of lower installed cost than most other pipingmaterials, but would not be used in congested areas where it is susceptible to damage.Available sizes were 4"-6"-8"-10"-12"-14"-16"-18"-20"-24"-30"-36" in pressure classes 100, 150and 200. (Catalogs: Johns-Mansville, Certain-teed.)

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FIGURE 8-1

FIGURE 8-2

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8.4 DESIGN CONSIDERATIONS

8.4.1 Settlement

The following list identifies problems created by differential settlement together withrecommended solutions. The degree of the problem should be determined by discussions withthe Structural Engineer and a review of the soil report.

Sewer lines connected to manholes -- differential settling of the manhole and the sewer sometimesbreaks the sewer pipe. A pipe joint just outside the manhole lessens this danger. If the soil conditionsare unstable or a high water table could leach sand bedding out from under the pipe a second jointwithin three feet of the first should be provided. In these situations cast iron pipe should be used inplace of vitrified clay pipe. The joints must be flexible such as a compression joint, mechanical joint, oreven a lead joint is considered flexible.

Differential settlement involving cooling water branch lines between large cooling water headers, whichcould settle and exchangers on piled foundation which may not, could over stress the piping. Thisproblem can be remedied by locating the headers so that the branch lines are at least 10 feet long andproviding flexible connectors (Dresser, Smith-Blair, etc.) at either end of the branch for steel pipe, or byusing mechanical joints for cast iron pipe.

For other types of settlement problems these methods just described should provide a remedy.

Unstable bedding -- when the bottom of the trench is not sufficiently stable or firm, to prevent vertical orlateral displacement of the pipe after installation a non-yielding foundation must be designed.

8.4.2 Crushed rock

The simplest supplementary foundation is to excavate native soil below grade of bedding material andreplace with a layer of broken stone, crushed rock, or other coarse aggregate that may produce thedesired stability under conditions where the instability is only slight.

8.4.3 Encasement

Under conditions where an extremely unstable area is to be crossed, and that area represents a veryshort length of line, it is possible to reinforce the pipe by full concrete encasement and adequatereinforcing steel to produce a rigid beam.

8.4.4 Piling

In some instances, lines must be constructed for considerable distances in areas generally subject tosubsidence, and consideration should be given to constructing them on a timber platform or reinforcedconcrete cradle supported by piping. Supports should be adequate to sustain the weight of the fullsewer and backfill.

The details and requirements for the above should be worked out in conjunction with the StructuralEngineer based on the recommendations of the soil report.

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8.4.5 Angle of Repose

Underground lines installed below adjacent foundations should not undermine the 45o angle of reposeof the foundation (See Figure # 8-3). Where there is no obvious solution consult with the StructuralEngineer to see if the actual conditions permit a steeper angle. It may also be possible to brace thetrench if equipment has been set, and to protect the pipe against loads by encasement.

FIGURE # 8-3

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8.4.6 Breakage

Precautions must be taken to prevent breakage of pipe due to construction and maintenanceequipment traffic.

Depth of cover for protection against surface loads is covered in another section.

Guard posts are provided to protect the above ground features of the firewater system.

Cleanouts in vitrified clay systems are subject to breakage, particularly in offsite areas. Wherecleanouts are thus exposed, protective structures similar to those for the firewater system, as well asconcrete cradles, must be detailed. Notes on offsite drawings should state, "INSTALLATION OFCLEANOUTS SHOULD NOT BE COMPLETED UNTIL PROTECTION SHOWN ON DETAILDRAWING CAN BE PROVIDED".

Use Cast Iron adjacent to manhole to avoid breakage caused by differential settlement of loss ofbedding in high water table (See Figure #8-4).

FIGURE # 8-4

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8.4.7 Stub-Ups

Stub-ups are used to connect underground lines carrying water, steam, air process liquids and the likewith above ground facilities. Flanged and welded underground lines should terminate 18 inches abovehigh point finish surface with a flame cut end. The above ground spool should indicate bevel end orface of flange at 12" above H.P.F.S. (See Figure #8-5). This will permit field fit-up.

Cathodic protection may be required depending on the soil conditions.

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8.5 SYSTEM SAFETY CONSIDERATIONS

8.5.1 Purpose of Seals

Seals play a vital role in maintaining safe operation of a process plant sewer system. Undernormal conditions, sewers are only partially filled because flow rates are designed for storm orfirewater quantities. The large vapor spaces in process plant sewers will frequently containflammable vapors. Liquid seals form vapor barriers and prevent flame fronts or explosions fromrunning the full length of the sewer system. Without a sealed sewer system, a fire in one areacould ignite vapors in a catch basin, which could flash through the sewer to initiate a fire atsome other location.

Seals also prevent the release of vapors or gases to the atmosphere at grade level where theycould create a hazard or contribute fuel to a fire.

8.5.2 Location of Seals

Catch Basins

Catch basins discharging to any sewers that have the possibility of containing flammable orhydrocarbon vapors are isolated from the lateral by one of the following:

(a) Providing an outlet seal at the line where it leaves the catch basin (See Figure # 8-6a).

(b) Routing the outlet line to a manhole or adjacent catch basin and providing an inlet seal atthe point of entry (Figure # 8-6b).

Manholes

Laterals leaving a unit are isolated from main or trunk sewers by providing manholes at junction pointsand routing the lateral into the manhole at a sealed inlet (Figure # 8-6b).

The plant main sewer may be sectionalized by providing sealed inlets at those manholes that wouldenable isolation of major process area groups, storage areas, treatment areas, marine terminals, etc.Baffle type manholes serve this purpose on larger sewer runs (Figure # 8-6c).

Drains and Funnels

Groups of drain funnels in fairly close proximity, say up to 30' apart, are connected to a single branchline which is isolated from the rest of the system by running it to a catch basin or manhole and providingan inlet seal at the point of entry.

Generally funnels serving pumps are isolated from the other funnels on the branch by providing arunning trap between the pump funnels (Figure # 8-6d).

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Where a sewer system must handle toxic or extremely hazardous material, each funnel is provided witha "P" trap type seal (See Fig # 8-6e), and the branch line is connected to the lateral at an inlet sealedmanhole.

Where a funnel is located close, say within 10' of the catch basin it is connected to, an inlet seal is notrequired, since a fire can travel above ground as easily as through the sewer.

8.5.3 Types of Seals

FIGURE # 8-6

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8.5.4 Venting

Sewers in general are designed for gravity flow. In a sealed system (i.e. without vents), a rise in waterlevel would reduce the vapor space and cause an increase in pressure. This would reduce the designcapacity of the sewer. Therefore vents are necessary to prevent vapor lock and to release vapors to asafe location.

Vents serve to prevent rapid pressure buildup in the sewer should hot commodities or water enter thesewer and vaporize any liquid hydrocarbons present.

8.5.5 Location of Vents

Vents are provided at every manhole where the inlet line is liquid sealed so as to prevent venting to thenext upstream manhole.

The highest manhole in a system is provided with a vent.

Both chambers of a baffle sealed manhole are provided with vents.

See the design specification for additional information.

8.6 ON-SITE UNDERGROUND LAYOUT

The purpose of this guide material is to provide the layout designer with instructions and a standardizedapproach to the layout of the Underground Piping Systems within a unit.

Scope

This instruction covers the step by step development of the underground systems layout and points outcritical items with respect to the design.

General

Specifications covering the layout and design of sewer and firewater systems are normally prepared foreach contract. These specifications must be carefully followed as they provide the basis for design.

8.6.1 Drainage Areas

In process or operating areas, the distance a liquid spill must travel across the pavement to a catchbasin should be kept to a minimum. Concrete paved areas are subdivide into drainage areas, normally3600 sq. ft. (See contract specifications.) Each drainage area is bounded by a high perimeter anddrains to a catch basin located at a low point. Figure 8-7.

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See Figure 8-7.

8.6.2 Drainage Area Sizing Guide

Figure #8-8 may be used as a guide to make a quick evaluation of the minimum and maximumdrainage area sizes and catch basin locations based on maintaining required paving slopes at variousdrops in paving from high to low point.

Drainage areas are based on two considerations: The elevation difference between high and lowpoints, and the prevention of fire flow and process spills flowing between adjacent areas. Ideally, adrainage area should be about 50 to 60 feet square, draining to a catch basin at or near the center.Equipment requiring curbed areas shall be noted on the P&ID's or defined in the job specifications.w

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FIGURE # 8-8

8.6.3 Guidelines

Locate the high point of paving: at perimeter of concrete paving or edge of road.

at edge of buildings

along major access ways around heater areas, to direct spillageaway from heater and other equipment.

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When locating catch basins give consideration to the following:

• locate near center of drainage area if possible.

• do not locate under equipment or piping manifolds.

• do not locate at building entrances or ladder and stairway landings.

• keep at least five feet clear of equipment work areas, such as alongside of pumps.

8.6.4 Preliminary Work

In order to avoid design and construction problems resulting from interferences the following items areshown on the layout.

• Existing concrete obstructions (foundations, sumps, etc.).

• Existing underground electrical ducts and piping systems.

Foundations of columns, heaters, pumps, structures and pipe supports should be indicated based onwhatever information the Structural Engineer can provide (or your best guess). Foundation depths andthickness have an important bearing on the routing of underground piping (structural engineering. willadvise).

8.6.5 Paving and Surface Drainage

Perimeter of concrete paving to encompass all equipment within unit area. Paving perimeter isnormally five feet beyond the furthest projecting equipment. In the interest of economy this outer limitmay be staggered to suit groups of equipment which do not project as far. (Keeping the jogs to aminimum.) Drainage outside the perimeter of the concrete paving is by Civil.

NOTE: Job specifications may dictate that certain equipment groups handling gases or liquidsthat vaporize at ambient temperatures may not require concrete paving.

Types and characteristics of paving (verify with your Civil/Structural Eng.)

• Concrete, 6" thick Process liquid spills truck traffic.• Concrete, 4" thick Process liquid spills, no truck traffic.• Asphalt, 3" thick Primary roads.• Asphalt, 2" thick Secondary roads, general paving and parking areas.• Crushed rock - 3" deep General area cover.• Concrete sidewalks - 4" thick 3'- 0" wide, raised 1" above adjacent finished surface.

Paving slope - Minimum 1/8"/ft.

Maximum 1/2"/ft.

Verify with your Civil/Structural engineer

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8.6.6 Types of Catch Basins

Figure 8-9 illustrates four basic types of catch basins and drain boxes.

• Concrete box per job standards, precast or poured-in-place are used as area drains and sealboxes in combined sewer (storm and process water). Liquid level in box should be at orbelow frost line.

• Concrete pipe may be used for perimeter areas where only a single outlet is required.

• Dry box type catch basins, are used as area drains for heater drainage areas in order toremove all hydrocarbon liquids from the area promptly in event of a tube break. Do not locatedry boxes under burners. The downstream end of the dry box outlet line shall be keptseparate from other heaters or equipment areas and sealed in a catch basin or manhole.(Generally located 50' or more from the shell of the fired equip.)

• Cast Iron - [Not shown] used as area drain only generally in separate storm sewer. Not usedin cold climates where they could be subject to freezing. Not used in crushed rock areas.

Figure 8-9

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8.6.7 Drawings

Process area underground layouts are normally done on a brownline of the plot plan at a scale of 1" =20' or 1" = 10'. The initial layout is in the form of a transposition with sufficient information shown toenable a reasonably accurate material takeoff. The final layout and design is handled as a part of thedevelopment of the underground piping drawings. Figure 8-10 shows a portion of an underground plandrawing.

Figure 8-10

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8.6.8 Sewer System Piping

The unit collection headers for storm, process or combined sewers (laterals) are usually located underthe pipeway area for convenience in connecting catch basins and drain funnels on both sides ofpipeway. If the electrical power duct system is also located in this area, the layout designers from bothgroups should work closely to establish easements. Laterals are installed below frost line.

Normally the slope of the longest path governs the inverts in the system and the depth of the sewer atthe start, or high end.

Sewer laterals leaving process units are sealed at manholes on the plant sewer mains. Sealing andventing philosophy for sewers containing hydrocarbon or flammable vapors is shown on Fig. 8.6a andFig. 8-6b, and in the section on Manholes in this document.

Sublaterals are routed from the catch basins and/or branches to the laterals. The connection at thelateral may be at a WYE branch or at a manhole. In a sewer collecting process drainage, manholesmay be located along the lateral to serve as seal boxes for the incoming branches.

Pump and equipment process drains discharge into drain funnels. A 6" minimum size opening for alldrain funnels is preferred. Where a 6" opening does not provide sufficient area to accommodatemultiple drains a larger opening is provided.

Drain funnel requirements are indicated on the P&ID's. Approximate locations are shown on the initiallayout. Exact locations are set later by the above ground piping layout. Groups of funnels in fairlyclose proximity, say 30' apart, are connected to a single branch line which is run to a catch basin,manhole or seal box.

Each drain, sublateral or lateral shall be accessible for rodding out by providing either a cleanout orcatch basin at its upper terminus.

Limitations for the use of cleanouts are defined in the job specifications.

Indicate line class, size, and slope for laterals, sublaterals, and branches. Indicate invert elevation forstart and termination of unit lateral. Use line sizing criteria provided in conjunction with Sewer SizingChart, or job specification.

NOTE:It will be necessary for the Layout Designer to consult with the Process Engineer to determine thesource, nature and quantity of each process waste stream discharging to the sewer. A permanentrecord of this information should be maintained for future reference.

To facilitate construction, maintain a constant slope over long runs, change line sizes as required, andmaintain common invert elevations for adjacent parallel lines.

Sanitary sewers within buildings are designed by the Plumbing Section of the Architectural Group to apoint five (5) feet outside of the building, at this point you will be given the design information, e.g.,fixture units being served, gpm and velocity. Sanitary sewer minimum size is 4". Minimum slope to be1/8" per foot.

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8.6.9 Manhole and Catchbasin Piping Elevations

Use Figure # 8-11 and the formulas that follow to calculate and set the elevations of manholes andcatchbasins.

FIGURE # 8-11Where:

x = horizontal distance from inside face of wall to intersection of invert (or B.O.P.)lines at 22½o bend. (feet)

y = difference in invert (or B.O.P.) elevations between points 2 and 3.

w = sum of:= difference in inlet and outlet line size (D2-D1) (feet)= minimum liquid seal = .5 feet= D1 x cos 22.5o

(W is tabulated in Table 1 & 2., for lines at 22½o only.)

s = slope of inlet line (feet/foot)

E = inside diameter or inside face to face of walls for manhole orcatch basin (feet)

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Procedure

Calculate invert elevation (or B.O.P. for steel pipe fabrication) at point 1 or 1a.

Deduct "W" which yields invert elevation (or B.O.P.) of seal pipe at point 2.

Calculate X and Y using equations 1 and 2 that yield invert (or BOP) and location of point 3.

When seal pipe enters box at an angle other than 22.5o use the natural tangent of that angle inplace of 0.4142 in equations 1 and 2.

Dimension "W" must be calculated in the above situation using D1 x cos of the angle used, fordimension (c).

Dimension "W" is the sum of (b), (c), and (d) when inlet line is a branch run at a higher elevationthan the normal flow line of the system.

DO NOT USE THESE TABLES IF THE LINE ENTERS AT AN ANGLE OTHER THAN 22.5o.TABLE 1

DIMENSION "W" (FEET)BASED ON INVERT EL. FOR C.I. OR CLAY PIPE

OUTLET PIPE SIZE4" 6" 8" 10" 12" 14" 15" 16" 18" 20" 24"

4" 0.81 0.97 1.14 1.31 1.47 1.64 1.72 1.81 1.97 2.14 2.476" 0.96 1.13 1.30 1.46 1.63 1.71 1.78 1.95 2.13 2.468" 1.12 1.28 1.45 1.61 1.70 1.78 1.95 2.12 2.45

10" 1.27 1.44 1.60 1.69 1.77 1.94 2.10 2.4412" 1.42 1.59 1.67 1.76 1.92 2.09 2.4214" 1.58 1.66 1.74 1.91 2.08 2.4115" 1.65 1.74 1.90 2.07 2.4016" 1.73 1.90 2.06 2.4018" 1.89 2.05 2.3920" 2.04 2.3724" 2.35

TABLE 2DIMENSION "W" (FEET)

BASED ON B.O.P. FOR STEEL PIPEOUTLET PIPE SIZE

4" 6" 8" 10" 12" 14" 16" 18" 20" 24"4" 0.85 1.02 1.19 1.37 1.53 1.64 1.80 1.97 2.14 2.476" 1.01 1.18 1.35 1.52 1.62 1.79 1.96 2.12 2.468" 1.16 1.34 1.51 1.61 1.78 1.95 2.11 2.45

10" 1.33 1.49 1.60 1.76 1.93 2.10 2.4312" 1.48 1.59 1.75 1.92 2.09 2.4214" 1.58 1.74 1.91 2.08 2.4116" 1.73 1.90 2.07 2.4018" 1.89 2.05 2.3920" 2.04 2.3724" 2.35

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8.6.10 Sewer Sizing Guide

• Purpose

The intent of this instruction is to provide the designer with an organized approach to sizingsewer lines, and to promote a better understanding of the hydraulics involved in sewer design.

• Design Basis

The general requirements for the plant sewer systems are outlined in the design specification. Linesizing is based on the expected flows in the line plus a safety factor for storm water flows. Thedesign specification should provide the following:

• Rainfall intensity (inches/hour)

• Maximum fire water flow based on pumping capacity, and fire protection facilities. (spraysystems, monitors, etc.)

• Definition of waste water system.

8.6.11 Sewer Layout

The Civil Group is responsible for the sewer system layout.

• Generally inverts for the mains can be set by determining which "path" is the longest. Howeverthis must be analyzed since shorter paths at steeper slopes may govern.

• On a large plant several trial designs may be required to determine the most advantageousrouting.

8.6.12 Sewer Sizing Calculation Sheet

The Sewer Sizing Calculation Sheet may be utilized to provide a permanent record of the hydraulicdesign of the principal sewer systems. It is used during the layout and design phase to keep track ofcalculations.

The intent is to use the form for unit laterals, sublaterals and branches. (See design specification fordefinitions)

Using the chart is actually a "step by step" automatic way to size the system. The notes that followserve as instructions.

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SEWER SIZING CALCULATION SHEETLine No. _________________________ Layout Dwg No. ______________________

System No. __________________________ Contract No. ______________________

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18FROM TO SQ. FT. SQ. FT. STORM STORM PROCESS FIRE DESIGN SEWER VELOSITY SLOPE LENGTH INVERT I.E. I.E. ELEV. APPROX.

MK. MK. PAVED UNPAVED RUNOFF RUNOFF DRANAGE WATER FLOW DIA. (FT./SEC.) (FT./FT.) (FT.) DROP UPPER LOWER GROUND COVER (GPM) (GPM) (GPM) (GPM) (IN.) (IN.) (12X13) (FT.) (FT.) UPPER 17-(15+10)

INCREMENT TOTAL 6+7 or 7+8

NOTES:1. STORM RUNOFF BASED ON THE RAINFALL INTENITY OF ______"/HOUR2. FACTOR OF IMPERVIOUSNESS FOR UNPAVED AREAS = _______3. FIREWATER FLOW IS BASED ON ________GPM PER CATCH BASIN4. LINE SIZE CHANGES ALONG A RUN SHOULD BE REFLECTED - COLUMN 14 BY AN APPROXIMATE INCREASE IN THE INVERT DROP

z

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Using the Sewer Sizing Calculation Sheet

• On a copy of the sewer layout, assign identifying letters to each junction where flow isincreased, breaking the sewer into individual segments or runs to be separately sized on thechart.

• Column 1: List the identifying letter for the upstream end of the first run. (The first lineshould be used for the first run in the system.)

• Column 2: List the identifying letter at the downstream end of the same run.

• Column 3: Enter the square footage of the paved area with runoff to the junction pointdesignated in column 1 of the same line.

• Column 4: Enter the square footage of unpaved areas.

• Column 5: Calculate and list the storm runoff based on areas listed in columns 3 and 4,using appropriate formulas in the design specification.

• Column 6: List the total cumulative runoff for run by adding runoff in column 5 to that listed incolumn 6, in the preceding line.

• Column 7: List the total cumulative process drainage to the point listed in column 1.

• Column 8: List the total cumulative firewater flow, based on requirements in the designspecification.

• Column 9: List the design flow, the total of columns 6 + 7 or 7 + 8 whichever is greater.

• Column 10, 11 and 12: Select and enter the pipe size, flow velocity and line sloperespectively, using the Pipe Flow Chart in 000.210.1160, Attachment 2, in the PipingEngineering Design Guide, Vol. 2. In the larger sizes there is a range in choices for anygiven flow. Selections are a matter of judgement, but consider the following:

� Velocities of 3 to 4 ft. per sec. are preferred.

� Use lesser slopes where limited by elevations at the terminus of the system, orwhere excavation is difficult and/or excessive.

� Use steeper slopes where terrain gradient permits.

• Column 13: Enter the length of run in feet and decimals of a foot between the pointsdesignated in columns 1 and 2. (For example: 242.25').

• Column 14: Multiply col. 12 x col. 13 to calculate the invert drop in decimals of a foot, andenter the result. If there is a size change in the run, add half the difference in nom. pipesize.

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• Column 15: The highest invert elevation at the start of a system should be based onthe cover requirements and length of the branches serving the junction point listed. Insubsequent runs if the line size is larger than in the preceding section, the invertshould drop accordingly.

• Column 16: The lowest invert elevation, at the end of the system. Calculate bydeducting the value in column 14 from that in column 15.

• Column 17 and 18: Self-explanatory, used for reference only.

Remember to add the required information in notes: 1, 2 & 3.

8.6.13 Utility Water Systems

Cooling water supply and return headers, if underground, are routed approximately five (5) to ten (10)feet from the exchanger channel end connections to keep branches short yet still permit for someadjustment. If there is a choice it is preferable to keep the main headers out from under concretepaved areas.

Where frost is not a factor the trench depth for the cooling water headers should be kept to a minimum.As a general rule 3'-0" cover is adequate protection for truck loading for steel lines 24" and smaller inunpaved areas. Greater cover may be required for larger sizes and/or other piping materials. Underconcrete paving one (1) foot cover may be adequate. (See Civil/Structural Eng.)

Branch lines from the cooling water headers to the exchangers are taken off the bottom quadrant of theheader if clearance above will not permit adequate cover. Short branch piping may be routed in thefrost zone and supply and return need not be at the same B.O.P.

Provide a minimum clearance of eighteen (18) inches between cooling water supply and return headers(24" for lines 30" and larger) to prevent heat transfer.

Utility water headers are located under the pipeway area in order to keep branches to the utility stationsat pipe support columns short.

Potable water piping within buildings is designed by the Plumbing Section of the Architectural Group toa point five (5) feet outside of the building.

If practical the potable water header and sewer laterals and/or mains shall not be less than ten (10) feetapart horizontally. If the requirement cannot be met, the water header shall be placed on a solid shelfand at all points shall be at least twelve (12) inches above the top of the sewer line at it's highest point.

Locate unit block valves at plot limits. Protect from maintenance vehicles with guard posts.

In freezing climates all utility water headers shall have their top of pipe at or below the frost line.(Firewater shall be 1'-0" below frostline.)

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8.6.14 Firewater System

Hydrants are located along plant roads or unit perimeters, so that a fire at any location in the processunit can be approached from two directions by men handling fire hoses connected to the hydrants.

The hose coverage area is based on a nozzle with a 1 1/8" tip connected to 250 feet of hose. Abrownline of the plot plan should be marked-up to show monitor and hydrant locations as well as theircoverage arcs. The Fire Protection Engineer, a plant Fire Marshall, and local Fire Authorities reviewthis document. (Several onionskin circles with 250' radius positioned on the plot can assist indetermining the best hydrant locations.)

Hydrants or monitors should not be located where they will conflict with exchanger tube pull or othermaintenance activities. Hydrants or monitor locations that might interfere with construction erectionactivities should be noted to "install after equipment has been erected."

Monitors and hose reels are located to protect specific hazards as outlined in the job specifications.

Water spray systems, when required are designed in accordance with the National Fire Specification,N.F.P.A. #15. Stub and valve location is also covered by this standard.

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PURPOSEThis practice provides guidelines for overall storm drainage design for a project site andapplies to projects being performed by the Civil Discipline that require storm drainagedesign.

Information contained herein should be used by the Civil Engineer as a guide. Many designcriteria, data, charts are available in text books, handbooks, manuals, but some of them areshown here. The Design Engineer should stay up to date on materials, specifications, anddesign criteria.

Each project will have its own set of situations to be analyzed and addressed with the bestengineering concept. Good engineering judgment and most economical solutions should beutilized.

For complicated projects, obtain appropriate reference publication and design storm drainagesystem as specified in the publication. For very large projects, computer programs areavailable where time and cost saving is justified. Even for smaller systems, simple computerprograms are available which provide quick and accurate results.

SCOPEThis practice utilizes many design criteria, data, charts, textbooks, handbooks, and manualsavailable for storm drainage design.

This practice contains types of commonly used hydrology analysis, hydrology design criteria,the rational method to determine storm water runoff from a drainage area, hydraulic designof open channel and closed storm sewers, storage basins, and design of culverts.

APPLICATIONEach engineer or designer performing storm drainage design should utilize this guideline oneach project. It is the overall responsibility of the Lead Engineer to ensure that this practiceis used for storm drainage design on projects.

GENERALCONSIDERATIONS

Comprehensive storm drainage design includes more than determination of runoff quantitiesand the layout of a collection or conveyance system to dispose of the runoff. Integral to thedesign is the consideration of erosion control and its impact on adjacent properties. Thedesign of the storm drainage system should be prepared in conjunction with the gradingdesign since the grading directly influences the type and design of drainage systememployed. It is necessary that the drainage philosophy be established before the gradingdesign is prepared.

The impact of increased/decreased runoff from the project site to adjacent properties must beconsidered. Further development within the watershed must also be considered. Stormwatermanagement is integral to the drainage system design. It is becoming more commonplace

Practice 670 210 1150Publication Date 20Sep95

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for local/state authorities to require stormwater management programs in the form ofretention/detention ponds. The rate of runoff is frequently controlled by statute.

Implementation OfStorm DrainagePractice

Implementation of storm drainage practice includes the following:Data collectionDefine existing watershedDefine/develop drainage philosophy for siteDevelop proposed layout of systemPrepare calculations for systemDesign stormwater management facilities, if required

Data CollectionReview local/state statutes.- Erosion Control- Stormwater ManagementEstablish/determine requirements for permit applications.- Plan Requirements- CalculationsObtain most recent topographic plans of watershed.- Use USGS to establish general location and define total watershed.- Use city/county topographic plans for preliminary design in absence of more

accurate data.- Obtain topographic survey prepared at suitable accuracy for final design.Obtain rainfall data.- Obtain latest rainfall data from appropriate governmental agency (weather bureau).

Define ExistingWatershed

Delineate watersheds on topographic plans.Calculate existing runoff (Q10, Q25, Q50, and Q100) as required.- Onto site- From site

Define/Develop Design Philosophy For Site

Consider method of collecting runoff.- Sheet flow versus series of drainage inlets- Ditches versus underground piping system


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Establish design criteria.

Develop ProposedLayout Of System

Prepare conceptual grading and drainage plan.Delineate drainage area for each inlet or section of ditch.

Note!!! For conceptual design, space inlets based on 1 inlet per 10,000 sf.

Prepare CalculationsFor System

Design collection system for design storm frequency.Refine grading plans and adjust layout of storm drainage.- Check ponding at inlets. Check capacity of grates.- Consider special inlets with high capacity grates.- Check ditch flow for depth and velocity. Consider need for erosion netting, sod, or

rip rap/energy dissipaters. Use available charts for design of open channels.- Check pipe flow for cleansing/scouring velocity and depth of flow.- Determine inlet and outlet losses for manholes and culverts.Pay special attention to details for proper drainage at the following:- Intersections of roadways- Truck docks- Building entrances- Rail docks/yards- Pedestrian crossings- Roof drainage discharge points- Parking lots

Design StormwaterManagement Facilities

Code search- Check state/local/federal requirements.Prepare calculations/drawings for the following:- Erosion control- Retention/detention basins- Outflow structures- Emergency spillways- Earth dams


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HYDROLOGYANALYSIS

Technical Release 55(TR-55)

Technical Release 55, Urban Hydrology for Small Watersheds, presents simplifiedprocedures to calculate storm runoff volume, peak rate of discharge, hydrographs, andstorage volumes required for floodwater reservoirs. These procedures are applicable in smallwatersheds, especially urbanizing watersheds, in the United States.

The model described in TR-55 begins with a rainfall amount uniformly imposed on thewatershed over a specified time distribution. Mass rainfall is converted to mass runoff byusing a runoff CN (curve number). CN is based on soils, plant cover, amount of imperviousareas, interception, and surface storage. Runoff is then transformed into a hydrograph byusing unit hydrograph theory and routing procedures that depend on runoff travel timethrough segments of the watershed.

Use peak discharge method for up to 2,000 acres of drainage area. Use tabular method forup to 20 square miles of drainage area.

In TR-20, the use of TC (Time of Concentration) permits this method for any size watershedwithin the scope of the curves or tables, while in TR-55, the procedure is limited to ahomogeneous watershed. The approximate storage routing curves are generalizationsderived from TR-20 routings.

Use TR-20 if the watershed is very complex or a higher degree of accuracy is required.

Use TR-20 if TT (travel time) is greater than 3 hours and time of concentration TC is greaterthan 2 hours and a drainage area of individual subareas differ by a factor of 5 or more.

Refer to Civil Engineering software, quick TR-55, and TR-20 for computer application.

Synthetic UnitHydrograph Method(Chapter 16, Pages16-1 To 16-26)

Over the past 2 decades, the federal, state, county, and local agencies have made numeroushydrologic investigations of drainage basins using synthetic unit hydrograph methodology.The synthetic unit hydrograph method should be used on larger drainage areas.

Rational MethodThe rational method is 1 of the most widely used techniques for estimating peak runoffs, andis applicable to most of the drainage problems encountered on Fluor Daniel projects.

The rational formula is Q = CIA

where

Q = Peak runoff, cfs

C = Coefficient of runoff, the rate of direct runoff to rainfall


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I = Rainfall intensity, inches per hour, corresponding to the time of concentration

A = Tributary area, acres

The rational method is commonly used for determining peak discharge from relatively smalldrainage areas up to 200 acres.

HYDROLOGY DESIGN CRITERIA

Normally, design for a storm frequency of 10 years for projects, unless otherwise specified bythe client.

Check for storm frequency of 50 years to estimate the consequences of flooding the site.

For major structures such as culvert under public highway, use a storm frequency of 50years.

Design major flood control channels and major lift stations for a storm frequency of 100years.

Stormwater runoff from tank farms is normally not included in the design. Stormwater isimpounded within the dikes and released after the peak stormwater runoff has passed.

Design containment storage within containment areas for a storm frequency of 10 years,24-hour storm for projects, unless otherwise specified by the client.

Ponding at inlets should be less than 3 inches for a frequency of 25 years storm.

RATIONAL METHOD

Rational FormulaThe rational formula is Q = CIA. On a topographic plan of the drainage area, draw thedrainage system and block off the subareas draining into the system.

Determine A, the area of each subarea in acres.

Coefficient Of RunoffThe coefficient of runoff is intended to account for the many factors which influence peakflow rate. The coefficient of runoff primarily depends on the rainfall intensity, soil type andcover, percentage of impervious area, and antecedent moisture condition.

Determine the coefficient of runoff C, for appropriate class of ground surface from thefollowing table. If more than 1 class of ground surfaces fall in 1 tributary drainage area, usea composite coefficient of runoff value.


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Coefficient of Runoff C

Roofs 1.00Pavements

Concrete 1.00Asphalt 1.00

Oiled Compacted Soil 0.80Compacted Gravel 0.70Compacted Impervious Soil 0.60Natural Bare Soil 0.60Uncompacted Gravel 0.50Compacted Sand Soil 0.40Natural Soil, Grass Cover 0.40Uncompacted Soil 0.20Lawns 0.20

Composite coefficient of runoff C:

A1C1 + A2C2 + A3C3 + −−−−AnCnA1 + A2 + A3 + An

where

A1 A2 A3 ---- An = Areas in acres of different class of surfacesC1 C2 C3 ---- Cn = Corresponding coefficient of runoff

Time Of Concentration

If rain were to fall continuously at a constant rate and be uniformly distributed over animpervious surface, the rate of runoff from that surface would reach a maximum rateequivalent to the rate of rainfall. The time required to reach the maximum or equilibriumrunoff rate is defined as the time of concentration.

The time of concentration depends upon the length of the flow path, the slope, soil cover,and the type of development.

Determine the initial time of concentration using the nomograph on Attachment 01.

Use a minimum time of concentration of 5 minutes for paved areas and a minimum time ofconcentration of 10 minutes for unpaved areas.

PrecipitationThe various precipitation amounts during specified time periods at recording stations areanalyzed using common models of probability distributions.

A number of alternative statistical distributions such as Log Pearson Type III, Pearson TypeIII, Two-Parameter Lognormal, Three-Parameter Lognormal, and Weibull, Type I, ExtremeValue are used in flood hazard analysis.


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Intensity DurationCurves

Use the intensity duration curves available from federal, state, county or local agencies forthe project location. If such curves are not available, construct these curves using WeatherBureau Technical Paper Number 40 (Continental United States); 42 (Puerto Rico andVirginia Islands); 43 (Hawaiian Islands); 47 and 52 (Alaska); or NOAA Atlas, Precipitation- Frequency Atlas of the United States, published by the National Weather Service.

For constructing the curves, given only 1 or 2 points, use the following conversion factorsbased on 30 minutes as 1.00:

Duration inMinutes Factor

Duration inMinutes Factor

5 2.22 40 0.80

10 1.71 50 0.70

15 1.44 60 0.60

20 1.25 90 0.50

30 1.00 120 0.40

To go from 1 curve to another, use the following factors based on the 50 year maximumrainfall as 1.000:

1 year 0.428 25 years 0.898

2 years 0.455 50 years 1.000

5 years 0.659 100 years 1.108

10 years 0.762

Rainfall intensity duration curves for more than 100 years can be constructed using rainfalldata for periods of 2, 5, 10, 25, 50, and 100 years; and time periods of 20 minutes, 60minutes, 2 hours, 3 hours, 6 hours, 12 hours; and 24 hours using the following formula:

_ _Xji = Xi + Kj Si Xi

where

j = Return period in yearsi = Specific storm duration in minutes, hours or daysXji = Precipitation in inches for return period j and duration iXi = Mean maximum annual storm for duration iKj = Frequency factor (in standard deviations) for a return period of j yearsSi = Standard deviation of maximum annual storm for duration i

For more detailed procedures using this formula, refer to "Analysis of Data," Pages 7 to 25 ofRainfall Depth Duration Frequency for California, Department of Water Resources, State ofCalifornia, November 1982.

A sample set of curves is shown in the sample problems in this practice.


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Using the initial time of concentration, determine "I" intensity of rainfall in inches per hourfrom the intensity duration curve for the plant's geographical location using the proper yearlyrainfall frequency.

Compute Q = CIA.

Refer to sample problems in this practice.

Travel TimeDetermine the size of the channel or pipe required to carry Q on the slope of the drain.Determine the velocity of flow.

Measure the length of flow to the point of inflow of the next subarea downstream. Computethe time of flow for this reach and add it to the initial time of concentration for the first areato determine a new time of concentration.

Calculate Q for second subarea, using the new time of concentration and continue in similarfashion until a junction with a lateral channel is reached.

Start at the upper end of the lateral and carry its Q to the junction with the main channel.

Storm Runoff AtJunction

Compute the Q at the junction.

Tributary area with longertime of concentration

Tributary area with shortertime of concentration

QA QB

TA TB

IA IB

Peak Q cfs (cubic feet per second), time of concentration in minutes, rainfall intensity ininches/hour.

If TA = TB then Qp = QA + QB TP = TA = TB

If QA > QB then Qp = QA + QB IAIB

TP = TA

If QA< QB then Qp = QB + QAIBIA

TP = TB

Qp = Peak Q at junctionTp = Peak time of concentration at junction

If more than 2 tributary areas are contributing at 1 junction, combine 2 areas at a time andproceed similarly until tributary areas are combined.


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DITCHES ANDCHANNELS

CapacityThe capacity of ditches and channels will be calculated using the Manning's equation:

Q = 1.486n r2/3s1/2A

where:

Q = Capacity in cfsA = Cross sectional area of flow in square feet

r = Hydraulic radius = in feetArea of flow

Wetted perimeters = Slope of energy grade line in foot per footn = Roughness coefficient

Values of roughness coefficient n for ditches and channelsLined ditches and channelsn = 0.014 for poured concreten = 0.016 for shotcrete (gunite)n = 0.014 for asphaltn = 0.035 for medium weight rip rapn = 0.025 for crushed rockn = 0.030 for grassUnlined ditches and channelsn = 0.020 for very fine sand, silt or loamn = 0.025 for sand and graveln = 0.030 for coarse gravel

Values of n for other surfaces can be found in Session 7, Pages 7-17 of King and Brater,Handbook of Hydraulics, McGraw-Hill Book Company, New York; and Chapter 5, Pages110 to 113 of Chow, Ven Te, Open-Channel Hydraulics, McGraw-Hill Book Company, NewYork, 1959.

Ditches and channels should be designed with the top of the walls at or below the adjacentground to allow interception of surface flows.

The minimum velocity of flow should be 2.0 feet per second in order to prevent the settlingof solids, if there is possibility of solids flowing in the ditches and channels.

Velocities in unlined ditches and channels must be limited to prevent cutting or erosion ofthe ditch or channel bottom or sides. Permissible channel velocities for various types of soilcan be found in Session 7, Pages 7-19 of King and Brater, Handbook of Hydraulics,McGraw-Hill Book Company, New York; and Chapter 7, Page 165 of Chow, Ven Te,Open-Channel Hydraulics, McGraw-Hill Book Company, New York, 1959. If the meanvelocity exceeds that permissible for that particular kind of soil, the channel should beprotected with some type of lining.

Freeboard or additional wall heights are to be added above the calculated water surface.

For ditches and channels with capacities to 50 cfs, add 1.0 feet.


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For ditches and channels with capacities from 50 cfs to 200 cfs, add 1.5 feet.

For ditches and channels with more than 200 cfs capacities, refer to Chapter 7, Pages 159and 160, of Chow, Ven Te, Open-Channel Hydraulics, McGraw-Hill Book Company, NewYork, 1959.

For curved alignments, add freeboards above the superelevated water surface.

It is desirable to provide a depth greater than critical. If not possible, an energy dissipatormay be required at the end of the ditch section.

LiningsDitches and channels with a flow velocity that exceeds permissible velocity will be lined.

Lining of ditches and channels will be poured concrete, gunite, asphalt, crushed rock, riprap,or other type of slope protection.

For design procedure of riprap design, refer to Chapter 3, Pages III-137 to III-150 ofVirginia Erosion and Sediment Control Handbook, Virginia Department of Conservationand Recreation Division of Soil and Water Conservation, 1980.

GRAVITY STORMSEWER SYSTEM

CapacityThe capacity of a gravity storm sewer system will be calculated using the Manning'sequation. Refer to sections covering Ditches and Channels in this practice.

Closed storm sewers should be deigned to flow full for the design storm, unless otherwisespecified by the Client.

The gravity storm sewer system will be designed in such a manner that at the maximumdesign flow, the water level in the most remote catch basin of the system or subsystem is aminimum of 6 inches below top of grating. The controlling elevation at a junction of a main,lateral, or sublateral for calculating the hydraulic gradeline upstream will be the hydraulicgrade elevation of the main or lateral at the point or the soffit elevation of the pipe,whichever is greater.

Values of Manning's n for closed sewers are as follows:

Pipe Material n

Polyvinyl chloride pipe 0.010Steel 0.011Ductile iron 0.013Cast iron 0.013Cement lined pipe 0.015Concrete pipe 0.013Vitrified clay pipe 0.013Fiberglass reinforced plastic 0.010Corrugated metal pipe 0.024


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The preferred slope for sewer lines will be approximately 0.01 foot (1/8 of an inch) per foot.The minimum slope will be approximately 0.005 foot (1/16 of an inch) per foot but may bedecreased, if necessary, provided the required minimum velocity is maintained to avoiddisposition of solids.

The minimum pipe size for branch lines will be 4-inch diameter and 8-inch diameter forcatch basin outlet pipes.

The minimum velocity for closed storm sewers should be 2.0 feet per second to prevent thesettling of solids.

For concrete sewers where high velocity flow is continuous and grit erosion is expected to bea problem, use a maximum velocity of about 10 feet per second.

The alignment chart in Attachment 02 can be used for the solution of Manning's equation forcircular pipes flowing full.

The graph in Attachment 03 is used for the solution of problems involving sewers flowingonly partly filled. The following procedure is used for finding the hydraulic elements of thepipes.

Compute the ratio of q/Q for each line.Find the ratio of h/D and v/V.From the ratio h/D, calculate h.From the ratio v/V, calculate v.

q = Actual flow, cfsQ = Quantity if pipe flowing full, cfsh = Actual depth of flow, feetD = Inside diameter of pipe, feetv = Actual velocity, fps (feet per second)V = Velocity if pipe were flowing full, fps

LossesManhole losses will be calculated from the following:

hmh = 0.05 v

2

2gto0.75

v

2

2g

depending upon the inlet and outlet pipe size, elevation and design.

Bend losses will be calculated from the following equations:

hb = Kb v

2

2g

where

Kb = 2.0

δ90

where δ = Central angle of bend in degrees.

Bend losses should be included for closed conduits; those flowing partially full as well asthose flowing full.


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CULVERTSDrainage culverts are normally corrugated metal pipe, reinforced concrete pipe, or reinforcedconcrete box as necessary to meet the requirements for stormwater drainage flow, truckloads, and depth of fill above the culvert.

Culverts under roads will be designed to support the earth pressures on the culvert and themaximum wheel load that will be imposed over it through its design life, plus the applicableimpact, as defined in AASHTO (American Association of State Highway and TrafficOfficials) Standard specifications for Highway Bridges. In the absence of construction ormaintenance vehicles with a greater wheel load, the culvert will be designed to support awheel load of 16,000 pounds (HS-20 loading). Minimum cover over culverts will be12-inches for circular corrugated metal pipe, and 18-inches for reinforced concrete pipe, andcorrugated metal pipe arches.

The minimum size of culvert will be 12-inch diameter for lengths of 30 feet or less and18-inch diameter for lengths over 30 feet.

Where installation of multiple culverts is required, the minimum clear distance betweenpipes will be as follows:

Pipe Diameter Minimum Clear Distance

12 inch to 24 inch27 inch to 72 inch78 inch to 120 inch

12 inches1/2 diameter

36 inches

Culverts will have a slope that will provide a minimum velocity of 2.0 fps. Culverts will besized to pass the 10-year storm flow with unsubmerged inlet. However, the culvert will bechecked for the 50-year storm with ponding at the entrance not to exceed the top of the roadsubgrade.

In designing any culvert larger than a 36-inch diameter single-barrel pipe (for example, archand oval pipe, multiple-barrel culverts, concrete box), design features such as headwalls,endwalls, transition structures, and energy dissipators will be selected strictly on the basis ofculvert performance and be economically justified.

Procedure for determining culvert size:List the design data. Refer to sample problems in this practice.Estimate first trial size.Find headwater depth.

Inlet Control: Using Attachments 04, 05, or 06, determine HW/D using the appropriateentrance scale. Convert HW/D to HW (headwater) by multiplying by D (pipe diameter) infeet.

Outlet Control: Using Attachment 07, 08, or 09, determine H (head) in feet using theappropriate value for k(e) as given in the following table:


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Entrance Loss Coefficients

Type of EntranceCoefficient

k(e)

Concrete Pipe

Projecting from fill, socket end (groove end) 0.2

Projecting from fill, square cut end 0.5

Headwall or beadwall and wingwallsSocket end of pipe (groove end)Square endRound radius (radius - 1/2 D)

0.20.50.2

End section conforming to fill slope 0.5

Corrugated Metal Pipe

Projecting from fill (no beadwall) 0.9

Headwall or beadwall and wingwalls, square edge 0.5

Beveled to conform to fill slope 0.7

Flared end section (available from manufacturer) 0.5

Beadwall, rounded edge 0.1

Solve for HW in the following equation:

HW = H + ho − SoL

For TW (tailwater) elevation equal to or greater than the top of the culvert at the outlet, setho equal to TW.

For TW elevation less than the top of the culvert at the outlet, use the following equation orTW, whichever is greater, where dc, the critical depth in feet, is determined fromAttachment 10 or 11.

ho = dc + D2

Compare the headwaters for both inlet and outlet control. The higher headwater governsand indicates the flow existing under the given conditions for the trial size selected.

Select culvert size which keeps headwater depth below allowable limit.

STORMWATERDETENTION ANDRETENTION BASINS

Flood ControlDetention Basin

The primary function of the flood control detention basin is to store the storm runoff duringpeak flood and reduce the peak discharge.


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The flood control detention basin is generally the least expensive and most reliable measure.It can be designed to fit a wide variety of sites and can accommodate multiple outletspillways to control multifrequency outflow.

Measures other than flood control detention basins may be preferred in some locations. Anydevice selected, however, should be assessed as to its function, maintenance needs, andimpact.

Design flood control detention basins for 50 years storm frequency.

For flood control detention basin storage volume requirement calculations procedure, for upto 2,000 acres of drainage area, refer to Chapter 6 Storage Volume for Detention Basins,Pages 6-1 to 6-11 of Urban Hydrology for Small Watersheds, TR-55, United StatesDepartment of Agriculture, Soil Conservation Service, January 1975, or use local drainagemanual, if available.

Stormwater RetentionBasin

Regulations require management of storm runoff from industrial plant sites so as not todischarge toxic or hazardous pollutants to receiving waters.

The purpose of stormwater retention basins is to store the stormwater during periods ofstorm runoff and release it at a lower rate to the treatment process.

Retention pond and storage basin capacities will be determined based on the totalaccumulated stormwater runoff from the design storm frequency for duration of 24 hours. Aminimum freeboard of 12 inches will be provided on top of water surface.

Lining for ponds and basins will be as recommended in the Geotechnical InvestigationReport or as required by process and environmental criteria for the project.

Sediment ControlBasin

Erosion and sediment control measures are required during construction to prevent surfacestorm water runoff pollution into stream channels and water bodies.

The sediment control basin is required to collect and store sediment or debris from affectedareas.

The sediment control basin collects and holds stormwater runoff to allow suspendedsediment to settle out.

Design sediment control basins for 10-year storm frequency, unless regulatory agenciesdictate otherwise.

The surface area of the sediment basin at the height of the rim of the riser pipe is calculatedby using the following formula:

A =KQVs


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where

A = Basin surface area square feetQ = Storm runoff cfsK = 1.2Vs = 0.00096 ft/sec settling velocity for a 0.02 millimeter particle size.

Particles greater than or equal to the 0.02 millimeter particle size are to be retained in thebasin.

The sediment storage volume is 75 cu yd per acre of disturbed construction area. Thesettling zone will be a minimum of 2 feet deep.

The combined capacities of the riser pipe and spillway are designed to be sufficient to passthe peak rate of storm runoff of a 10-year storm frequency.

The sediment control basin will need to be periodically cleaned out to restore the basin to itsoriginal designed volume capacity.

A concentric antivortex device and trash rack should be provided on top of the riser pipe.

A concrete base of sufficient weight to prevent flotation of the riser is attached to the riserpipe with a watertight connection.

Stone riprap protection should be provided on the spillway to reduce erosion of the spillwaydike.

A protection fence should be provided around the sediment control basin for safety.

The sediment control basin may be used after construction as a permanent stormwatermanagement basin.

For sediment control basin design requirements and procedure, refer to Chapter 3, PagesIII-59 to III-88 of Virginia Erosion and Sediment Control Handbook, Virginia Departmentof Conservation and Recreation Division of Soil and Water Conservation, 1980.

STORM DRAINAGESOFTWARE(AVAILABLEIN IRVINE)

1. Advanced Designer SeriesCivil SoftStorm PlusStorm Drain Analysis Program

Storm Plus is based on the original computer program F0515P and was developed inApril 1979. This program was written for use by the Los Angeles County Flood ControlDistrict or by its contractors on district projects.

This program computes and plots uniform and nonuniform steady flow water surfaceprofiles and pressure gradients in open channels or closed conduits with irregular orregular sections. The flow in a system may alternate between super critical, subcritical,or pressure flow in any sequence. The program will also analyze natural river channels


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although the principle use of the program is intended for determining profiles inimproved Flood Control Systems.

2. Haestad MethodsCivil Engineering SoftwareHEC-1Flood Hydrograph Package

This computer program was developed by HEC (The Hydrologic Engineering Center),Corp of Engineers, Department of the Army.

The HEC-1 model is designed to simulate the surface runoff response of a river basin toprecipitation by representing the basin as an interconnected system of hydrologic andhydraulic components.

Each component models an aspect of the precipitation runoff process with a portion ofthe basin, commonly referred to as a subbasin. A component may represent a surfacerunoff entity, a stream channel, or a reservoir. The result of the modeling process is thecomputation of stream flow hydrographs at desired locations in the river basin.

HEC-1 has several major capabilities which are used in the development of a watershedsimulation model and the analysis of flood control measures. The capabilities are thefollowing:

Automatic estimation of unit graph, interception/infiltration, and streamflowrouting parameters.Simulation of complex river basin runoff and streamflow.River basin simulation using a precipitation depth versus area function.Computation of modified frequency curves and expected annual damages.Simulation of flow through a reservoir and spillway for dam safety analysis.Simulation of dam breach hydrographs.Optimization of flood control system components.

3. Haestad MethodsCivil Engineering SoftwareHEC-2Water Surface Profiles

This computer program was developed by HEC, Corps of Engineers, Department of theArmy.

The HEC-2 computer program is intended for calculating water surface profiles forsteady, gradually varied flow in natural or manmade channels. Both subcritical andsupercritical flow profiles can be calculated. The effect of various obstructions such asbridges, culverts, weirs, and structures in the flood plain may be considered in thecomputations. The program is also designed for application in flood plain managementand flood insurance studies to evaluate floodway encroachments and to designate floodhazard zones. Also, capabilities are available for assessing the effect of channelimprovements and levels on water surface profiles.


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4. Haestad MethodsCivil Engineering SoftwareHEC-PlotPlotting Program for HEC-1 and HEC-2

HEC-Plot is an enhanced version of the Plot 2 Program of the US Army Corps ofEngineers, written by HEC.

Computer Program HEC-Plot was developed to provide a quick and simple graphicaldisplay of cross section data and computed results from HEC-1 and HEC-2. TheHEC-Plot Program provides the capability to plot cross section data, including thechanges to the section caused by the HEC-2 options that modify section data. HEC-2profiles and rating curves of the output variables, available on HAESTAD 95 or TAPE95, can be plotted. HEC-Plot also plots HEC-1 output hydrographs.

5. Haestad MethodsCivil Engineering SoftwareQuick HEC-12Drop Inlet Design and Analysis

Quick HEC-12 handles the following inlet types:CurbGrateCombination curb and grate4-inch bridge ScupperSlotted DrainGrate in trapezoidal ditch

Quick HEC-12 uses the manual procedure outlined by the Federal HighwayAdministration, Hydraulic Engineering circular Number 12, Drainage of Highwaypavements, March, 1984.

6. Haestad MethodsCivil Engineering SoftwarePOND-2Detention Pond Design and Analysis

POND-2 Computer Program is for detention pond design. It estimates detention storagerequirements, computes a volume rating table for any pond configuration, routeshydrographs for different return frequencies through alternative ponds and plots theresulting inflow and outflow hydrographs. POND-2 is completely compatible withLINK-2 and can automatically import inflow hydrographs from QUICK TR-55, TR-20,and HEC-1 computer files.

7. Haestad MethodsCivil Engineering SoftwareQuick TR-55Hydrology for small watersheds

Quick TR-55 Computer Program was developed based on the SCS TR-55 UrbanHydrology for small watersheds. The program can generate and plot hydrographs,compute peak discharges, and perform predeveloped and postdeveloped analysis.


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8. Haestad MethodsCivil Engineering SoftwareTR-20Project Formulation Hydrology

The TR-20 Computer Program is a single-event model which computes direct runoffresulting from any synthetic or natural rainstorm. It develops flood hydrographs fromrunoff and routes the flow through steam channels and reservoirs. The following majorCivil Engineering software programs from Haestad Methods are also available:

9. HECWRCFlood Flow Frequency

10. HMR52Probable Maximum Storm

11. WSP-2Water Surface Profiles

12. Hy-4-69Hydraulics of Bridge Waterways

13. WSPRO (Hy-7)Bridge Waterways Analysis Model

14. DAMS 2Structure Site Analysis

15. THYSYSCulverts Storm Sewer and Inlets

16. SWMMStorm Water Management Model

17. HEC-6Scour and Deposition

18. SEDIMOT IIHydrology and Sedimentology

19. HYDRAStorm and Sanitary Sewer Analysis SoftwarePITZER

HYDRA is one of the most practical programs available to analyze storm and sanitarysewer collection systems. It is structured to work well on both large municipal systemsand small tracks, with or without database files and without or within AutoCAD.

HYDRA allows the designer to generate storm flows by the Rational Method, a modifiedSCS Method (Soil Conservation Service) or by continuous simulation. The best methodto use depends upon the situation, available data, and the requirements of themunicipality.


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REFERENCESAASHTO (American Association of State Highway and Traffic Officials).

Analysis of Data, Pages 7 to 25 of Rainfall Depth Duration Frequency for California,Department of Water Resources, State of California, November 1982.

Bureau of Engineering Manual. Part G, Storm Drain Design. City of Los Angeles,Department of Public Works.

Capacity Charts For the Hydraulic Design of Highway Culverts. Hydraulic EngineeringCircular Number 10. Mar. 1965.

Chow, Ven Te. Handbook of Applied Hydrology. McGraw-Hill Book Company. 1964.

Chow, Ven Te. Open-Channel Hydraulics. McGraw-Hill Book Company. New York.1959.

Design and Construction of Sanitary and Storm Sewers. American Society of CivilEngineers. WPCF Manual of Practice Number 9. 1972.

Design Manual. Hydraulic. Los Angeles County Flood District.

Design Manual. Orange County Flood Control District.

Engineering Field Manual. United States Department of Agriculture. SCS. Washington,DC. 1989.

Estimating Probabilities of Extreme Floods: Methods and Recommended Research.National Research Council. Washington, DC. 1988.

Guide For Sediment Control on Construction Sites in North Carolina. United StatesDepartment of Agriculture. Soil Conservation Service, SCS. North Carolina. 1973.

Guidelines For Determining Flood Flow Frequency. Interagency Advisory Committee onWater Data, Bulletin #17b of the Hydrology Subcommittee, VA. 1982.

Gumbel, E. J. Statistics of Extremes. Columbia University Press. New York. 1958.

Hydraulic Charts For the Selection of Highway Culverts. Hydraulic Engineering CircularNumber 5. Dec 1965.

Hydraulic Design of Improved Inlets For Culverts. Hydraulic Engineering Circular Number13. Aug 1972.

Hydrology Manual. Los Angeles County Flood Control District.

Hydrology Manual. Orange County Flood Control District.

Hydrology Manual. Riverside County Flood Control and Water Conservation District.

King and Brater. Handbook of Hydraulics. McGraw-Hill Book Company. New York.

Kite, G. W. Frequency and Risk Analysis in Hydrology. Water Resource Publication.Littleton, CO. 1977.

Manual For Erosion and Sediment Control in Georgia. Georgia Soil and WaterConservation Committee. 1975.


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Manual of Standards For Erosion and Sediment Control Measures. Association of Bay AreaGovernments. Jun 1981.

Maryland Erosion and Sediment Control Handbook. United States Department ofAgriculture, SCS. College Park, MD. 1975.

National Engineering Handbook. Drainage of Agricultural Land. United States Departmentof Agriculture, SCS. Washington, DC. 1971.

National Engineering Handbook. Hydraulics. United States Department of Agriculture,SCS. Washington, DC. 1975.

National Engineering Handbook. Hydrology. United States Department of Agriculture.SCS (Soil Conservation Service). Washington, DC.

NOAA Atlas, Precipitation - Frequency Atlas of the United States, published by the NationalWeather Service.

Rainfall Depth Duration Frequency For California. Department of Water Resources. Stateof California. Nov 1982.

Urban Hydrology For Small Watersheds. TR-55. United States Department of Agriculture.Soil Conservation Service. Jan 1975.

Urban Runoff. Erosion and Sediment Control Handbook. United States Department ofAgriculture. Soil Conservation Service, SCS. St. Paul, MN. 1976.

Virginia Erosion and Sediment Control Handbook. Virginia Department of Conservationand Recreation Division of Soil and Water Conservation. 1980.

Water Resources Technical Publication. Research Report Number 24. United StatesDepartment of The Interior, Bureau of Reclamation.

Weather Bureau Technical PaperNumber 40Number 42Number 43Number 47Number 52

ATTACHMENTSAttachment 01:Overland Flow Time

Attachment 02:Alignment Chart For Manning Formula For Pipe Flow

Attachment 03:Relative Velocity And Flow In Circular Pipe For Any Depth Of Flow

Attachment 04:Headwater Depth For Concrete Pipe Culverts With Inlet Control


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Attachment 05:Headwater Depth For CM Pipe Culverts With Inlet Control

Attachment 06:Headwater Depth For CM Pipe Arch Culverts With Inlet Control

Attachment 07:Head For Concrete Pipe Culverts Flowing Full

Attachment 08:Head For Standard CM Pipe Culverts Flowing Full

Attachment 09:Head For Standard CM Pipe Arch Culverts Flowing Full

Attachment 10:Critical Depth Circular Pipe

Attachment 11:Critical Depth Standard CM Pipe Arch

Attachment 12:Form: 000.210.F8000: Rational Method Calculation Form

Attachment 13:Form: 000.210.F8001: Peak Q At The Junction Calculation Sheet

Attachment 14: (12Mar93)Form: 000.210.F5000: Datasheet - Culvert Design


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FLUOR DANIEL

FORM 000 210 F5000 (12Mar93)Page 1 of 1

DATASHEET - CULVERT DESIGN

Client Name:Project Name:Project Number:

DATE: REV.:

Culvert Station

Hydrology:

( Year Frequency), Q = cfs( Year Frequency), Q = cfs

Q = Design DischargeQ = Check Discharge

NOTES:

1. h =dc + D

2or TW, Whichever is Greater

2. HW = H + h - S L

DESIGN SELECTION

CommentsOutlet ControlInlet ControlQCulvert Identification

Entrance Material Size HW

D

HW(ft)

H h S L HW(ft)

(Note 2)

O

O O

O O

1

2

Elevation

AHW =

HeadwaterMaximum Allowable

Elevation

TW =

Elevation

(Note 1)

S =

L

O

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PURPOSEThis practice establishes the parameters of the various components involved in the design ofgravity and force main sanitary sewer systems.

Design of these systems will require compliance with regulations and standards of variousprivate and public agencies and applicable federal, state, county and city regulations. Thedesign data, dimensions, regulations and standards will reflect a considerable diversitybetween owner and government agencies.

The Civil Engineer must review these various regulations and standards and select theappropriate ones for the project. This technical practice should be used in conjunction withtextbooks and other publications on the subject, such as those listed in the references. Thedesign engineer should stay updated on materials, specifications, and design criteria.

SCOPEThis practice includes the following major sections:

SEWAGE FLOWRATESGRAVITY SEWER DESIGNMANHOLESPUMPING STATIONSSIPHONSHYDRAULIC DESIGNEXAMPLE PROBLEMREFERENCESATTACHMENTS

APPLICATIONThis practice provides guidelines for the design of sanitary sewers and applies to all projectsand work assignments being performed by Fluor Daniel Civil Discipline. The Lead CivilEngineer on a project is responsible for the use of these guidelines in designing sanitarysewer systems.

SEWAGE FLOWRATES

Domestic sewage quantities normally are to be computed on a contributing population basis,except as noted in subparagraph d and e on page 3-1 of Hydraulic Design of Sewers.

Subparagraph d (Industrial Waste Flows)

Such industries cannot be computed totally on a population or fixture unit basis.Industrial waste sewers and sanitary sewers will be designed for the peak industrial flowas determined for the particular industrial process or activity involved.


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Subparagraph e (Fixture Unit Flow) The size of building connections, including thosefrom theaters, restaurants, chapels, clubs and other such buildings, will, in all cases, belarge enough to discharge the flow computed on a fixture unit basis.

The population to be used in design depends upon the type of area which the sewerserves. If the area is entirely residential, the design population is based on fulloccupancy. If the area served is entirely industrial, the design population is the greatest

Average DailyPer Capita

Sewage quantities for different types of installations are shown on page 3-1 of HydraulicDesign of Sewers. The average daily flow will be computed by multiplying the resident andnonresident contribution populations by the appropriate per capita allowances and adding thetwo flows.

Nonresidents working 8 hour shifts will be allowed 30 gallons per capita per day.

FlowrateThe average hourly flowrate should be used when designing sewers to serve small areas ofthe installation where several buildings or a group of buildings are under consideration andwhere the majority of sewage is generated by nonresidents or other short term occupants.

The peak daily or diurnal flowrate is an important factor in sewer design, especially whenminimum velocities are to be provided on a daily basis. The peak diurnal flowrate will betaken as 1/2 of the extreme peak flowrate.

Extreme flowrates of flow occasionally and must be considered. Sewers will be designedwith adequate capacity to handle extreme peaks flowrates, ratios of extreme peak flowrates ataverage flow will be calculated with the use of the following

· piping design layout training lesson 6 underground page 5 of 25 15/30/2002 rev 0 8.3.1...

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