Design Charts for Open - Channel Flow HDS 3 August 1961

Design of Highway Drainage Channels
The design of a highway drainage channel to carry a given discharge is accomplished in two
parts. The first part of the design involves the computation of a channel section which will carry
the design discharge on the available slope. This chapter briefly discusses the principles of flow
in open channels and the use of the Manning equation for computing the channel capacity.
The second part of the design is the determination of the degree of protection required to
prevent erosion in the drainage channel. This can be done by computing the velocity in the
channel at the design discharge, using the Manning equation, and comparing the calculated
velocity with that permissible for the type of channel lining used. (Permissible velocities are
shown in Table 2 and Table 3.) A change in the type of channel lining will require a change in
channel size unless both linings have the same roughness coefficient.
Types of Flow
Flow in open channels is classified as steady or unsteady. The flow is said to be steady when
the rate of discharge is not varying with time. In this chapter, the flow will be assumed to be
steady at the discharge rate for which the channel is to be designed. Steady flow is further
classified as uniform when the channel cross section, roughness, and slope are constant; and
as nonuniform or varied when the channel properties vary from section to section.
Depth of flow and the mean velocity will be constant for steady flow in a uniform channel.
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HYDRAULICS IN CIVIL AND ENVIRONMENTAL ENGINEERNG

HYDRAULICS IN CIVIL AND ENVIRONMENTAL ENGINEERNG
This manual has been prepared for use in cojunction with the textbook
HYDRAULICS IN CIVIL AND ENVIRONMENTAL ENGINEERNG (4th editon).
The problems for solution in the book cover the material found in Chapters 1-11
The solutions manual is particularly inteded for use by course tutors.
It provides detailed method of solution for all of the problems in the 4th edition,
so that they can be integrated into the tutorial scheme for a hydraulics lecture programme.
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RIVER ENGINEERING FOR HIGHWAY ENCROACHMENTS

The purpose of this chapter is to lay the groundwork for application of the concepts of
open-channel flow, fluvial geomorphology, sediment transport, and river mechanics to the
design, maintenance, and environmental problems associated with highway crossings and
encroachments.
This manual is a basic reference for related Federal Highway Administration (FHWA) hydraulic
publications and National Highway Institute (NHI) Hydraulics Courses. Some of these
publications are: "Hydraulics of Bridge Waterways" (Bradley 1978), "Design of Riprap
Revetment" (Brown and Clyde 1989), "Evaluating Scour at Bridges" (Richardson and Davis
2001), "Stream Stability at Highway Structures" (Lagasse et al. 2001), "Bridge Scour and
Stream Instability Countermeasures - Experience, Selection and Design Guidance" (Lagasse
et al. 2001). Related NHI courses include:
(1) River Engineering for Highway Encroachments,
(2) Stream Stability and Scour at Highway Bridges, and
(3) Finite Element Surface Water
Modeling System (FESWMS).
Basic definitions of terms and notations adopted for use in this document have been presented
in the preceding section (Glossary) for rapid reference. Additionally, these important terms and
variables are defined and explained as they are encountered.
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Bridge Scour and Stream Instability Countermeasures: Experience, Selection, and Design Guidance-Third Edition Volume 2

In this volume design guidelines are provided for a variety of stream instability and bridge
scour countermeasures. Most of these countermeasures have been applied successfully on
a state or regional basis, but, in several cases, only limited design references are available in
published handbooks, manuals, or reports. No attempt has been made to include in this
document design guidelines for all the countermeasures listed or referenced in Volume 1.
Countermeasure design guidelines formerly presented in HEC-20 (spurs, guide banks, drop
structures) and in HEC-18 (riprap at abutments and piers) are now consolidated in this
document. Since many bridge scour and stream instability countermeasures require riprap
revetment as an integral component of the countermeasure, riprap revetment design
guidance is summarized in Design Guideline 4. An appropriate granular or geotextile filter is
essential for any countermeasure requiring a protective armor layer (e.g., riprap, articulating
concrete blocks, etc.). Filter design guidance is provided in Design Guideline 16.
Design Guideline 8 – Articulating Concrete Block Systems, Design Guideline 9 –
Grout-Filled Mattresses, and Design Guideline 10 – Gabion Mattresses each contain
two countermeasure applications: (1) bankline revetment or bed armor, and (2) pier
scour protection. Consequently, these three design guidelines appear in Section 2,
but are referenced in Section 3 with a page citation to the pier protection application.
A number of highway agencies provided specifications, procedures, or design guidelines for
bridge scour and stream instability countermeasures that have been used successfully
locally, but for which only limited design guidance is available outside the agency. Several of
these are presented as design guidelines for the consideration of and possible adaptation to
the needs of other highway agencies (see for example, Design Guideline 6, Wire Enclosed
Riprap Mattress, and Design Guideline 13, Grout/Cement Filled Bags). These specifications,
procedures, or guidelines have not been evaluated, tested, or endorsed by the authors of
this document or by the FHWA. They are presented here in the interests of information
transfer on countermeasures that may have application in another state or region.
Since publication of the Second Edition of HEC-23 in 2001, both the Transportation
Research Board through the NCHRP Program and FHWA have sponsored a number of
research projects to improve the state of practice in bridge scour and stream instability
countermeasure technology and provide definitive guidance to bridge owners in
countermeasure design. Among the projects that represent advances in countermeasure
technology that have been incorporated into the Design Guidelines are:
• NCHRP Report 544 - Environmentally Sensitive Channel and Bank Protection Measures
• NCHRP Report 568 - Riprap Design Criteria, Specifications, and Quality Control
• NCHRP Report 587 - Countermeasures to Protect Bridge Abutments from Scour
• NCHRP Report 593 - Countermeasures to Protect Bridge Piers from Scour
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Highway Hydrology Metric Version

Hydrology is often defined as the science that deals with the physical properties, occurrence, and
movement of water in the atmosphere, on the surface of, and in the outer crust of the earth. This
is an all-inclusive and somewhat controversial definition for there are individual bodies of science
dedicated to the study of various elements contained within this definition. Meteorology,
oceanography, geohydrology, among others, are typical. For the highway designer, the primary
focus is with the water that moves on the earth's surface and in particular that part which
ultimately crosses transportation arterials, i.e., highway stream crossings. A secondary interest is
to provide interior drainage for roadways, median areas, and interchanges.
Hydrologists have been studying the flow or runoff of water over land for many decades, and
some rather sophisticated theories have been proposed to describe the process. Unfortunately,
most of these attempts have been only partially successful not only because of the complexity of
the process and the many interactive factors involved, but also because of the stochastic nature
of rainfall, snowmelt, and other sources of water. Most of the factors and parameters that
influence surface runoff have been defined, but for many, complete functional descriptions of
their individual effects exist only in empirical form. Extensive field data, empirically determined
coefficients, and sound judgment and experience are required for their quantitative analysis.
By application of the principles and methods of modern hydrology, it is possible to obtain
solutions that are functionally acceptable and form the basis for the design of highway drainage
structures. It is the purpose of this manual to present some of these principles and techniques
and to explain their uses by illustrative examples. First, however, it is desirable to discuss some
of the basic hydrologic concepts that will be utilized throughout the manual and to discuss
hydrologic analysis as it relates to the highway stream crossing problem.
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Introduction to Highway Hydraulics

Highway hydraulic structures perform the vital function of conveying, diverting, or removing surface water from the highway right-of-way. They should be designed to be commensurate with risk, construction cost, importance of the road, economy of maintenance, and legal requirements. One type of drainage facility will rarely provide the most satisfactory drainage for all sections of a highway. Therefore, the designer should know and understand how different drainage facilities can be integrated to provide complete drainage control.
Drainage design covers many disciplines, of which two are hydrology and hydraulics. The determination of the quantity and frequency of runoff, surface and groundwater is a hydrologic problem. The design of structures with the proper capacity to divert water from the roadway, remove water from the roadway, and pass collected water under the roadway is a hydraulic problem.
This publication will briefly discuss hydrologic techniques with an emphasis on methods suitable to small drainage areas, since many components of highway drainage (e.g., storm drains, roadside ditches, etc.) service primarily small drainage areas. Fundamental hydraulic concepts are also briefly discussed, followed by open-channel flow principles and design applications of open-channel flow in highway drainage. Then, a parallel discussion of closed-conduit concepts and applications in highway drainage will be presented. The concluding sections include an introduction to energy dissipation, construction, maintenance, and economic issues. In all cases, detailed design criteria and standards are provided primarily by reference, since the objective of this document is to present a broad overview of all the components of highway drainage and to serve primarily as an "Introduction to Highway Hydraulics."
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Highway Hydrology

Hydrology is often defined as the science that addresses the physical properties, occurrence,
and movement of water in the atmosphere, on the surface of, and in the outer crust of the earth.
This is an all-inclusive and somewhat controversial definition as there are individual bodies of
science dedicated to the study of various elements contained within this definition. Meteorology,
oceanography, and geohydrology, among others, are typical. For the highway designer, the
primary focus of hydrology is the water that moves on the earth's surface and in particular that
part that ultimately crosses transportation arterials (i.e., highway stream crossings). A
secondary interest is to provide interior drainage for roadways, median areas, and interchanges.
Hydrologists have been studying the flow or runoff of water over land for many decades, and
some rather sophisticated theories have been proposed to describe the process. Unfortunately,
most of these attempts have been only partially successful, not only because of the complexity
of the process and the many interactive factors involved, but also because of the stochastic
nature of rainfall, snowmelt, and other sources of water. Hydrologists have defined most of the
factors and parameters that influence surface runoff. However, for many of these surface runoff
factors, complete functional descriptions of their individual effects exist only in empirical form.
Their qualitative analysis requires extensive field data, empirically determined coefficients, and
sound judgment and experience.
By application of the principles and methods of modern hydrology, it is possible to obtain
solutions that are functionally acceptable and form the basis for the design of highway drainage
structures. It is the purpose of this manual to present some of these principles and techniques
and to explain their uses by illustrative examples. First, however, it is desirable to discuss some
of the basic hydrologic concepts that will be utilized throughout the manual and to discuss
hydrologic analysis as it relates to the highway stream-crossing problem.
In highway engineering, the diversity of drainage problems is broad and includes the design of
pavements, bridges, culverts, siphons, and other cross drainage structures for channels varying
from small streams to large rivers. Stable open channels and stormwater collection,
conveyance, and detention systems must be designed for both urban and rural areas. It is often
necessary to evaluate the impacts that future land use, proposed flood control and water supply
projects, and other planned and projected changes will have on the design of the highway
crossing. On the other hand, the designer also has a responsibility to adequately assess flood
potentials and environmental impacts that planned highway and stream crossings may have on
the watershed.
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HIGHWAY STORMWATER PUMP STATION DESIGN

1.1 NEED FOR STORMWATER PUMP STATIONS
Stormwater pumping stations are necessary for the removal of stormwater from sections of
highway where gravity drainage is impossible or impractical. However, stormwater pumping
stations are expensive to operate and maintain and have a number of potential problems that
must be addressed. Therefore, the use of stormwater pumping stations is recommended only
where no other practicable alternative is available. Alternatives to pumping stations include
siphons, recharge basins, deep and long storm drain systems and tunnels.
1.2 INTENT OF MANUAL
This manual is intended primarily for highway drainage designers and others interested in the
hydraulic design of highway stormwater pump stations. Though some discussion relates to other
engineering disciplines and responsibilities, the information is basic and intended only to
enhance the hydraulic designer’s ability to accommodate other needs and communicate with
designers from other disciplines.
1.3 ORGANIZATION OF MANUAL
This manual is divided into fourteen chapters including this introduction. The general
organization can be classified as follows:
1. Identification and basic concepts (Chapters 2 and 3)
2. Design process (Chapter 4)
3. Design criteria, considerations, and procedures (Chapters 4 through 9)
4. Additional Information (Chapters 10 through 14, and appendices)
1.4 UNIT CONVENTION
The general convention employed in this manual is to present values and dimensions in
System Internationale (SI) units followed by English units in parentheses. Where practicable, the
manual provides equations with unit conversion factors. In this manner, only one equation
appears for a particular operation and the user must select the desired units and unit conversion
factor.
1.4.1 SI versus Metric
System Internationale (SI) units are very specific. Not all metric units are SI. For example,
linear measurements of millimeters and meters are metric and SI, whereas centimeters are metric
but not SI. This manual uses SI units except where noted to conform to industry standards.
1.4.2 Caution on Unit Usage
Most manufacturers in the US develop pumps and pumping equipment in English units. Few
present design data in SI units. The designer should take care when using and quoting units
because some variables that are seemingly dimensionless may have units. Some commonly used
coefficients have dimensions, which, in the strictest sense, should take on different values when
using SI units. These will be noted where appropriate throughout the text.
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Hydraulic Engineering Circular No. 22, Third Edition

URBAN DRAINAGE DESIGN MANUAL
This circular provides a comprehensive and practical guide for the design of storm drainage
systems associated with transportation facilities. Design guidance is provided for the design
of storm drainage systems which collect, convey, and discharge stormwater flowing within and
along the highway right-of-way. As such, this circular covers the design of most types of
highway drainage. Two exceptions to this are the design of cross-drainage facilities such as
culverts and bridges, and subsurface drainage design. Guidance for the design of crossdrainage
facilities is provided in HDS-1, Hydraulics of Bridge Waterways,(1) HDS-5, Hydraulic
Design of Highway Culverts,(2) as well as the AASHTO Highway Drainage Guidelines Volume
IV,(3) and Volume VII.(4) Subsurface drainage design is covered in detail in Highway
Subdrainage Design.(5)
Methods and procedures are given for the hydraulic design of storm drainage systems.
Design methods are presented for evaluating rainfall and runoff magnitude, pavement
drainage, gutter flow, inlet design, median and roadside ditch flow, structure design, and storm
drain piping. Procedures for the design of detention facilities and the review of storm water
pump stations are also presented, along with a review of urban water quality practices.
The reader is assumed to have an understanding of basic hydrologic and hydraulic principles.
Detailed coverage of these subjects is available in HDS-2, Hydrology,(6) HDS-4, Introduction
to Highway Hydraulics,(7) Design and Construction of Urban Stormwater Management
Systems,(8) as well as basic hydrology and hydraulic text books.
This document consists of nine additional chapters and four appendices. The nine chapters
cover System Planning, Urban Hydrologic Procedures, Pavement Drainage, Roadside and
Median Channels, Structures, Storm Drains, Stormwater Quantity Control Facilities, Pump
Stations, and Urban Water Quality Practices. Appendixes include: Appendix A, Design
Charts; Appendix B, Gutter Flow Relationship Development; Appendix C, Literature
Reference, and Appendix D, Blank Forms.
Several illustrative design examples are developed throughout the document. By following the
design examples, the reader is led through the design of a complete stormwater management
system. In the main body of the manual, all procedures are presented using hand
computations in both SI and English units.
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Tidal Hydrology, Hydraulics and Scour at Bridges

This manual draws extensively from the results of a Pooled Fund Project "Development of
Hydraulic Computer Models to Analyze Tidal and Coastal Stream Hydraulic Conditions at
Highway Structures." The authors gratefully acknowledge the special efforts of the lead
state, South Carolina Department of Transportation and William Hulbert (formerly SCDOT),
the Pooled Fund Project’s Technical Advisory Panel, and Johnny Morris (formerly FHWA) for
their support and guidance in completing the Pooled Fund Project.
The authors also wish to acknowledge the technical assistance, review, and guidance
provided by Larry Arneson and Joseph Krolak (FHWA), and Scott Douglass (University of
South Alabama) for their efforts in completing this First Edition of Hydraulic Engineering
Circular No. 25 – Tidal Hydrology, Hydraulics, and Scour at Bridges.
The purpose of this manual is to provide guidance on hydraulic analysis for bridges
over tidal waterways. This document includes descriptions of: (1) common physical features
that affect transportation projects in coastal areas, (2) tide causing astronomical and
hydrologic processes, (3) approaches for determining hydraulic conditions for bridges in tidal
waterways, (4) applying the hydraulic analysis results to provide scour estimates. This
document is not intended to provide guidance on coastal surge modeling (modeling that is
used to predict the magnitude of hurricane-produced storm surges based on direct simulation
of hurricane conditions). However, the information provided by other agencies (including
FEMA, NOAA, USACE, States Agencies) on surge conditions is used to estimate the
hydraulic conditions of tidally affected bridges.
By using the methods in this manual, better predictions of bridge hydraulics and scour
in tidal waterways will result. In many cases, simplified tidal hydraulic methods will provide
adequate results. However, when the simplified methods yield overly conservative results,
use of the recommended modeling approaches will provide more realistic predictions and
hydraulic variables and scour.
Location and hydraulic design studies for tidal bridges should be conducted in
accordance with 23 CFR 650A, when applicable. Since this document provides guidance on
the hydraulic analysis of bridges over tidal waterways, the methods described herein can
help assess potential impacts of proposed structures and encroachments on floodplains.
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Highways in the Coastal Environment

Hydraulic Engineering Circular No. 25
June 2008
A technical advisory panel oversaw the development of this document. Members of that panel
were Kevin Bodge, Billy Edge, Dave Henderson, Rick Renna, and J. Richard Weggel.
This is the second edition of HEC-25. This second edition is a new document with a new title.
The authors of the first edition, entitled “Tidal Hydrology, Hydraulics and Scour at Bridges,” were
L.W. Zevenbergen, P.F. Lagasse, and B.L. Edge. This second edition incorporates and
presents more comprehensive discussions of highways in the coastal environment.
A number of faculty and students at the University of South Alabama provided input into this
document including Qin “Jim” Chen, Lauren McNeill, Bret Webb, Caren Reid, Patrick Keith, Joel
Richards, and Jason Shaw.
The majority of this document was written by Scott L. Douglass, Professor of Civil Engineering
at the University of South Alabama. The project manager, Joe Krolak, FHWA Office of Bridge
Technology, provided some significant contributions.

The purpose of this HEC-25 document is to provide guidance for the analysis, planning, design
and operation of highways in the coastal environment (HICE). The focus is on roads and
bridges (highways) near the coast that are always, or occasionally during storms, influenced by
coastal tides and waves.
This document is intended to be a reference guidance document for Federal Highway
Administration (FHWA), State Departments of Transportation (SDOT), the American Association
of State Highway and Transportation Officials (AASHTO), consultants to these organizations,
and others.
This is nominally the second edition of HEC-25. The first edition was entitled “Tidal Hydrology,
Hydraulics and Scour at Bridges” and reflected results of a SDOT pooled fund study
investigating coastal scour. This second edition is a completely new document and incorporates
and presents more comprehensive discussions of the coastal environment.
Nationally, there are few transportation (and specifically highway related) documents that focus
on the coastal environment. The existing guidance most similar to this document is a Chapter of
the “Highway Drainage Guidelines” published by AASHTO.1 This HEC-25 HICE document
provides additional details on many of the topics discussed in those AASHTO guidelines.
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Junction Loss Experiments: Laboratory Report Publication No. FHWA-HRT-07-036

The junction loss study described in this report was conducted at the Federal Highway
Administration (FHWA) hydraulics laboratory. Between 1986 and 1992, Chang et al. conducted a
lab study of energy losses through junction access holes, using relatively large-scale (one-quarter
scale) physical models.(1) A preliminary method for determining such losses, based on early results
from that study, was published in the Federal Highway Administration’s (FHWA) Urban Drainage
Design Manual (Hydraulic Engineering Circular No. 22 (HEC 22)).(2) FHWA plans to update HEC
22 and further develop computer software for storm drain design. The need for consistent
technology in FHWA publications and software applications on this subject is urgent. To
accommodate that need and overcome some of the difficulties in estimating energy loss in access
holes, the FHWA’s Office of Bridge Technology initiated this study to validate Roger Kilgore’s
proposed method for computing access hole energy losses. This report will be of interest to
hydraulic engineers involved in storm drain design and to researchers involved in developing
improved storm drain design guidelines. It is being published as a Web document only.
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DESIGN FOR FISH PASSAGE AT ROADWAY STREAM CROSSINGS: SYNTHESIS REPORT

A waterway of perceptible extent that periodically or
continuously contains moving water. It has definite bed and banks, which serve
to confine the water and includes stream channels, secondary channels, and
braided channels. It is often determined by the “ordinary high water mark” which
means that line on the shore established by the fluctuations of water and
indicated by physical characteristics such as clear, natural line impressed on the
bank, shelving, changes in the character of soil, destruction of terrestrial
vegetation, the presence of litter and debris, or other appropriate means that
consider the characteristics of the surrounding areas.

This document is a design reference for the classification, assessment, design or
retrofit of a roadway-stream crossing to facilitate fish passage. It is the result of
a comprehensive literature review completed to categorize design procedures,
case histories, and culvert assessment techniques. No new recommendations
for a universal design procedure are made; rather, a compilation of design
options used in different geographic regions is included to allow the user to select
the most appropriate design method for their unique situation. A collection of
design examples and case histories is intended to add clarity to the design
methodology selection.
In order to provide stream reach connectivity for all wildlife, removal of road
barriers or the installation of a bridge spanning the floodplain are ideal; however,
this report presumes that a narrower, fish-friendly, installation is both permitted
and desirable for economical or logistical reasons. It is recognized that fish are
not the only animals requiring habitat connectivity for long-term population
viability, and future versions of this circular are intended to cover aquatic
organism passage (AOP) in more detail. This report is intended solely as a
reference for the design, retrofit, or replacement of a road stream crossing to
meet fish passage requirements.
The scope of this report is also limited to culvert installations. If the total culvert
span including all barrels and fill between barrels exceeds 6.1 m (20 ft), it is
called a bridge according to the Federal Highway Administration code
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Design of Roadside Channels with Flexible Linings

This manual addresses the design of small open channels called roadside channels that
are constructed as part of a highway drainage system. Roadside channels play an
important role in the highway drainage system as the initial conveyance for highway
runoff. Roadside channels are often included as part of the typical roadway section.
Therefore, the geometry of roadside channels depends on available right-of-way, flow
capacity requirements, and the alignment and profile of the highway. The procedures in
this manual may also be used for ancillary roadside drainage features such as
rundowns.
Roadside channels capture sheet flow from the highway pavement and backslope and
convey that runoff to larger channels or culverts within the drainage system. This initial
concentration of runoff may create hydraulic conditions that are erosive to the soil that
forms the channel boundary. To perform reliably, the roadside channel is often stabilized
against erosion by placing a protective lining over the soil. This manual presents a class
of channel linings called flexible linings that are well suited for construction of small
roadside channels.
This manual is presented in dual units. The SI (metric) units precede the customary
units (CU) when units are given. Design examples are provided in both systems of
units.
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PENGENDALIAN GERUSAN LOKAL DI PILAR DENGAN CHASING PENGAMAN

Peran sungai sebagai penunjang kebutuhan hidup sungguh tidak bisa
dipungkiri. Hal ini menyebabkan fungsi sungai sangat strategis sebagai penunjang
kebutuhan ekonomi. Akan tetapi masalah sungai dari dahulu sampai sekarang
masih hangat dibahas dalam kaitanya dengan keruntuhan jembatan akibat gerusan.
Gerusan yang terjadi umumnya diakibatkan oleh terhalangnya aliran oleh pilar itu
sendiri. Dalam pengujian gerusan pada pilar jembatan, peneliti mencoba suatu
model penanggulangan gerusan yang ada dengan chashing. Pemasangan chasing
ini bertujuan untuk mereduksi horse soe vortex yang menuju ke dasar saluran.
Adapun alat yang dipergunakan adalah satu set Recirculating Sediment
Flum dengan panjang 7 m. Bahan yang digunakan adalah pasir dengan spesifikasi
d50 0.39mm, debit aliran 3.64 l/d dengan kecepatan 0.1925m/detik, kecepatan
kritis 0.26 m/detik, tipe aliran adalah turbulen dan regime aliran sub kritis. Model
pengendalian gerusan berupa pipa PVC ukuran 32.95 mm pada pilar, dan 65 mm.
Kondisi aliran seragam permanen. Tinggi muka air yang digunakan 90 mm,
dengan dipasang pintu di ujung flum, untuk mengatur tinggi rendahnya muka air.
Pada tiap variasi ketinggian chasing dilakukan 1 kali uji. Pada tiap watu 1 menit
selama 10 menit dilakukan pengamatan kedalaman gerusan. Dilanjutkan 5 menit
selama 15 menit, 5 menit selama 30 menit, 10 menit selama 30 menit dan sisa
waktu yang ada diamati tiap 15 menit hingga tercapai keseimbangan.
Hasil penelitian menunjukkan bahwa dengan adanya chasing pada pilar,
terjadi gerusan maksimal di posisi samping pilar. Hal ini disebabkan karena
intensitas aliran di sebelah pilar sangat tinggi akibat penyempitan penampang
aliran dan pengaruh horse shoe vortek. Gerusan maksimal yang terjadi pada posisi
samping chasing dengan kedalaman 20 mm, pada penempatan chasing 4/9h.
Gerusan yang terjadi meningkat seiring peningkatan ketinggian pemasangan
chasing. Sedangkan saat pengujian dengan ketinggian chasing 0 cm terhadap
dasar saluran hanya terjadi gerusan sedalam 5mm pada posisi belakang pilar. Dari
hal ini menunjukkan bahwa pilar dengan pemasangan chasing 1/9 hingga 4/9,
terjadi gerusan yang cukup besar yaitu : pada pilar dengan chasing ketinggian
4/9h kedalaman gerusan mencapai 20 mm, pada pilar dengan pemasangan
ketinggian chasing 1/3 kedalaman gerusan 15 mm, kemudian pada chasing
dengan ketinggian 2/9h terjadi gerusan 13 mm, dan pada ketinggian chasing 1/9h
terdapat gerusan sebesar 11 mm. Sedangkan pada pilar dengan ketinggian chasing
0 cm tidak terjadi gerusan di depan, melainkan pemindahan gerusan dari samping
pilar ke belakang pilar.
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WATER SUPPLY, WATER TREATMENT

This manual, intended for planners and design engi-
neers, presents information on water quality stand-
ards and design criteria for water treatment processes.
This manual also establishes criteria to be followed in
determining the necessity for and the extent of treat-
ment, and on procedures applicable to the planning of
water treatment projects. This manual is applicable to
all elements of the Army and Air Force responsible for
the planning and design of military construction,
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