7509.11,80
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             FSH 7509.11 - DAMS MANAGEMENT HANDBOOK
                    WO AMENDMENT 7509.11-93-1
                        EFFECTIVE 8/5/93

                CHAPTER 80 - PLANNING AND DESIGN


Dams, channels, and other hydraulic structures on National Forest 
System lands must be planned and designed in accordance with 
accepted engineering practice.  Many sources of information on 
planning and design exist, including those published by the Army 
Corps of Engineers, the Bureau of Reclamation, and the Soil 
Conservation Service.  See section 08, References, in the Zero 
Code, FSM 7505, and FSM 7530 for additional references.

80.2 - Objective.  To complete an efficient and effective design 
for a safe dam, channel, or hydraulic structure.

81 - SCHEDULING.  To efficiently accomplish the design of a 
hydraulic structure or system of hydraulic structures, schedule 
the work in a manner that will allow the design to be developed 
and reviewed in an orderly progression.  The design process 
should begin with many alternatives and progress to the best 
alternative through a progressive refinement and evaluation of 
alternatives.

The design schedule may be divided into four main phases:

    1.  Phase I, feasibility study. 

    2.  Phase II, data collection and evaluation.

    3.  Phase III, preliminary design.

    4.  Phase IV, final design.

Although there is some overlapping of work in the various phases, 
the end of each phase provides a logical opportunity for 
effective review.  Complex projects may be further divided into 
subphases for control purposes.  Simple projects may not require 
separate review of each phase.  The scope of work normally done 
in each phase of design follows.

81.1 - Phase I, Feasibility Study.  In the planning stage, make a 
study to determine the feasibility of constructing the proposed 
hydraulic structure in the given watershed.  

The reports of a feasibility study may vary from brief reports to 
formal, comprehensive reports, depending on the type and class of 
project.  Watershed work plans developed for watershed protection 
and flood prevention projects under Public Law 566 are examples 
of formal feasibility studies.

Much of the information gathered in a feasibility study may be 
obtained from record searches; topographic, seismic, and geologic 
map studies; site reconnaissance; and watershed reconnaissance.  
However, such reconnaissance investigations usually must be 
supplemented by field surveys, hydrologic studies, economic 
studies, and surface and subsurface investigations.  

    1.  A feasibility study must be made in the detail required 
to determine, with reasonable assurance, that:

        a.  The benefits derived from the project will exceed the 
        cost of installation, operation, and maintenance.

        b.  The desired functional objectives of the project can 
        be attained.

        c.  The project is environmentally sound.

        d.  The project meets the intent of the Forest Plan.

        e.  The construction of the project is physically 
        practicable.

        f.  The administrative and hazard potential 
        classifications were considered.

    2.  The required scope and intensity of the study, surveys, 
and investigations vary with:

        a.  The complexity of the proposed structure or system of 
        structures.

        b.  The complexity of the site and the watershed with 
        respect to geology, hydrology, and so on.

        c.  The importance of the project in terms of size, type, 
        hazard potential, cost, or impact on other programs. 

81.2 - Phase II, Data Collection and Evaluation.  Collect 
sufficient basic data by means of surface reconnaissance, 
surveys, subsurface investigations, materials testing and 
hydrologic studies (FSM 2530) to furnish an adequate basis for 
design.  Ensure the data collected are sufficiently accurate to 
allow reasonable confidence in the assumptions and approximations 
that must be made to establish and apply design criteria.

To avoid duplication of effort, perform phase I surveys and 
investigations to the same standards prescribed for phase II 
surveys and investigations when it is cost effective to do so.  
If not, use the phase I data to reduce the cost of collecting the 
phase II data.

It is often necessary to obtain supplementary data after the 
design has progressed into phases III and IV.  When such needs 
arise the designer (or reviewer) should promptly notify the 
office concerned.

The scope and intensity of the data collection program varies 
with the size and complexity of the project, the complexity of 
the site and of the watershed, the hazard potentials, and the 
impact on other programs.  The designer or reviewer must evaluate 
all of the data and assess their suitability for use as a basis 
for design.  In making this evaluation, the designer, in 
collaboration with appropriate specialists, must be guided by 
published instructions and criteria, and by a general knowledge 
of good design practice.

Omissions, discrepancies, and inadequacies must be reported to 
the engineer responsible for data collection as soon as possible.  
Such reports should contain suggestions for supplementary 
investigations or other corrective actions to be taken to secure 
adequate data.

81.3 - Phase III, Preliminary Design.  Two or more preliminary 
designs may be made to allow for the selection of the best 
alternative for final design.

    1.  Each preliminary design alternative consists of selecting 
the general features of the structure including:

        a.  The structure type.

        b.  The general form and the arrangement of the elements 
        of the structure.

        c.  The types and locations of appurtenant mechanical 
        equipment.

        d.  The most practical power source, if applicable.

    2.  Each preliminary design alternative includes hydraulic 
features that define as a minimum:

        a.  The alignment, grades, and cross-sections of 
        channels.

        b.  The critical elevations, general dimensions,and 
        capacities of all water-control structures and equipment 
        in the system.

    3.  Each preliminary design includes structural dimensions 
that, as a minimum, allow preparation of reasonable estimates of 
quantities of materials. 

    4.  Each preliminary design includes prescriptions for 
reservoir clearing that, as a minimum, reflect recommendations in 
the environmental analysis and consider the effect of debris on 
spillway function. 

81.4 - Phase IV, Final Design.  The final design consists of:

    1.  Checking the adequacy of surveys and investigations and 
the accuracy of the selected preliminary design alternative.

    2.  Refining the elements of the preliminary design.

    3.  Completing the structural design.

    4.  Preparation of construction drawings, specifications, bid 
schedules, engineer's estimate of costs and construction 
schedule.

    5.  Review by the appropriate level of the organization or 
other agencies, if applicable.

    6.  Preparation of the final design summary.

    7.  Preparation of the operation and maintenance plans. (FSM 
7515).

82 - CHANNEL PLANNING, INVESTIGATION, AND DESIGN.  Channel work 
shall be performed by personnel having up-to-date skills and 
training appropriate for the work.  For modifications and changes 
to natural channels, up-to-date training is required in river 
mechanics, fluvial geomorphology, or related hydrologic areas of 
knowledge.  This is a rapidly advancing branch of science, but 
one that is not commonly taught in engineering schools.  For all 
channels, up-to-date training in channel hydraulics and earth 
work engineering are required.  

Contact the Forest Service Stream Systems Technology Center in 
Ft. Collins, Colorado, a unit of the Rocky Mountain Forest and 
Range Experiment Station for current state-of-the-art courses, 
handbooks, and publications on channels, sediment transport, and 
related topics.  Contact agencies such as the Soil Conservation 
Service and Bureau of Reclamation for current state-of-the-art 
information in channel hydraulics and earthwork engineering.

82.1 - Layout.  Align the channel to optimize economy of 
construction and operation and minimize environmental impacts.  
Design the channel to safely release excess flow where:

    1.  Natural flow is intercepted by the channel.

    2.  The channel grade decreases.

    3.  Sedimentation is likely to occur.

82.2 - Planning and Design.  Design linings, depth, width, and 
slope of channels so they are appropriate for the site conditions 
and design capacity.

83 - HAZARD CLASSIFICATION.  Assign a hazard classification in 
accordance with FSM 7511 and chapter 40 of this handbook.  The 
hazard classification will affect the degree of precision 
required in a design and the need for a conservative, low risk 
design.