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WATER RESOURCES DEPARTMENT









 

DIVISION 20
DAM SAFETY

690-020-0000
Purpose and Applicability
(1) The purpose of these rules is to implement
ORS 537.400(4) and ORS 540.350 through ORS 540.390 with actions that are intended
to ensure the safety of the dams insofar as dams may affect possible damage to life
or property. The Department is authorized to review design and specifications for
dam construction and modification, to conduct routine inspections, and to take enforcement
actions on dams that do not ensure the safety of life and property.
(2) These rules apply to dams
that are subject to ORS 540.350 through 540.390 and which exceed the height and
storage limits described in ORS 540.400.
(3) These rules do not apply
to:
(a) Dams that are less than
ten feet high or that store less than 3 million gallons (9.2 acre feet), except
for general guidance and permit requirements described in OAR 690-020-0029; or
(b) Water storage tanks or various
types of tanks that are part of water treatment facilities.
(4) The dam safety fee authorized
by ORS 536.050(2) shall be used to support the dam safety program as described in
OAR 690-020-0200.
(5) The State Engineer may delegate
dam safety duties to a dam safety engineer working for the Department for the purposes
of ORS 540.350 through 540.390.
Stat. Auth.: ORS 540.350 - 540.400,
536.050
Stats. Implemented: ORS 183,
540, 536
Hist.: WRD 12-1986, f. &
ef. 10-3-86; WRD 12-1994, f. & cert. ef. 11-7-94; Renumbered from 690-020-0021,
WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10; WRD 2-2015, f. & cert. ef. 3-17-15
690-020-0021 [Renumbered to 690-020-0000]
690-020-0022
Definitions
Unless the context requires otherwise,
the following definitions apply in OAR 690, division 20:
(1) “Abutment” means
a natural valley or canyon side against which the dam is built;
(2) “Acre-foot”
means the equivalent volume of one acre covered with one foot of water (325,900
gallons);
(3) “Annual Exceedance
Probability Flood” means the likelihood of specific flood flow being equaled
to or exceeded in any given year at that specific location, expressed as a percentage;
(4) “As-built drawing”
means an engineering drawing of a dam as it was actually constructed, noting all
differences between original design and actual constructed condition;
(5) “Conduit” means
a closed conveyance used to release water through a dam;
(6) “Core” means
a soil of low permeability within an embankment dam;
(7) “Cutoff Trench”
means a trench excavated beneath the dam foundation and backfilled with low permeability
material to retard water seepage;
(8) “Dam” means
a hydraulic structure built above the natural ground grade line that is used to
impound water. Dams include all appurtenant structures, and together are sometimes
referred to as “the works.” Dams include wastewater lagoons and other
hydraulic structures that store water, attenuate floods, and divert water into canals;
(9) “Dam Crest”
means the top of the dam;
(10) “Dam Height”
means the maximum height of the dam as measured at the maximum section along the
dam’s longitudinal axis;
(11) “Department”
means the Oregon Water Resources Department;
(12) “Director”
means the Director of the Oregon Water Resources Department;
(13) “Embankment”
means an engineered earth fill;
(14) “Emergency Action
Plan” (EAP) means a plan that assists the dam owner or operator and local
emergency manager perform actions that ensure the safety of people in the event
of a potential or actual dam failure or in the event of a sudden release of water;
(15) “Engineer of Record”
means the professional engineer registered in Oregon working for the dam owner to
design the dam to current safety standards and is responsible to oversee safe construction
of the dam;
(16) “Foundation”
means the ground surface upon which a dam is constructed;
(17) “Freeboard”
means the vertical distance between the high-water level in the reservoir and the
dam crest;
(18) “Gate” or “Valve”
means a permanent device for regulating water flow through the dam;
(19) “Hazard Rating”
means the rating established by the Department of the potential damage to life and
property downstream of a dam in the event of a dam failure;
(20) “High Hazard Rating”
means that if a dam were to fail, loss of human life would be expected;
(21) “Inflow Design Flood”
(IDF) means a volume and peak flood flow that the engineer of record will design
to safely pass over or through the spillway;
(22) “Low Hazard Rating”
means that if a dam were to fail, loss of life would be unlikely and damage to property
would not be extensive;
(23) “Pressurized Conduit”
means any pipe that penetrates into a dam that may have a gate, valve, or irrigation
pipe placed in the dam or at the outlet so that all or a portion of the pipe within
the dam is under hydrostatic pressure when the valve is closed;
(24) “Probable Maximum
Flood” (PMF) is the largest flood that could occur at a specific location,
determined by the most severe set of atmospheric, soil moisture and snowpack conditions
that are reasonably possible at that location;
(25) “Significant Hazard
Rating” means that if a dam were to fail, loss of life would be unlikely but
damage to property would be extensive;
(26) “Soil Filter”
means soil with a gradation designed to inhibit movement of adjacent, finer grained
soils;
(27) “Spillway”
means a structure constructed to bypass flood water and prevent water overtopping
the dam crest. Dams may have two or more spillways.
(28) “State Engineer”
means a registered professional engineer working for the Department, and may be
either the Director or a principal assistant working for the Director as described
in ORS 536.032.
(29) “Tank” means
a fully-enclosed (bottom and sides) hydraulic structure made from metal, reinforced
concrete, rigid fiberglass, or plastic that provides its own water-sealing and structural
stability.
(30) “Toe Drain”
is a drainage structure designed to collect and remove seepage water from the toe
of the dam and to discharge this water in a manner where it can be measured;
(31) “Zoned Embankment”
means an embankment dam with a core of low permeability materials, soil filter materials,
drainage and other materials placed to improve performance and safety of the dam.
Stat. Auth.: ORS 183 & 540
Stats. Implemented: ORS 183
& 540, 536
Hist.: WRD 12-1986, f. &
ef. 10-3-86; WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10; WRD 2-2015, f. & cert.
ef. 3-17-15
690-020-0023
Dam Safety Process Requirements for
Construction of Dams
(1) Dam safety requirements shall be based
on the hazard rating of the dam, in order to efficiently protect life and property.
(2) Any person, corporation,
association, firm, partnership, limited liability company, joint stock company,
unit of local government as defined in ORS 190.003, or State agency must, before
beginning any construction on a dam, secure the services of a qualified engineer
to design the dam and also to provide information on the dam as it was actually
constructed. This engineer shall be deemed the engineer of record for the purposes
of these rules.
(3) The engineer of record shall
design the dam and develop plans and specifications consistent with these rules.
(4) Prior to beginning construction
on any dam subject to these rules, written approval of dam designs, drawings and
specifications must be obtained from the State Engineer as described in OAR 690-020-0080.
(5) The engineer of record must
oversee construction of the dam consistent with rules governing administration of
dam construction in OAR 690-020-0065 to evaluate whether the dam is constructed
consistently with approved plans and specifications. Any essential design changes
must be described and justified in a letter sent to the State Engineer with the
“as-built” drawings.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 543
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0025
General Requirements
(1) The director may require any information or data in addition to that outlined herein which the director finds necessary for determining the safety of the p(1) The Director may require additional
information or data beyond that specified in these rules to determine the safety
of a proposed dam.
(2) The Director may include,
as part of any permit to construct a dam, limitations and conditions that pertain
to construction, operation, maintenance, and the protection of lives and property.
These limitations and conditions become, by reference, part of the water right certificate
and remain in effect throughout the life of the water right.
(3) Approved plans and specifications
for construction are, by reference, considered limitations and conditions placed
on the water right permit and water right certificate. The Director retains the
authority to place additional limitations and conditions on the water right relative
to operation and maintenance.
(4) Dams constructed or operated
in violation of limitations and conditions included in the water right permit or
certificate are subject to restricted use. The certificate affirms the applicant's
right to store water subject to the limitations and conditions therein.
(5) For new dams on stream channels,
an outlet conduit must be installed to permit drainage of all or most of the reservoir
and for passage of flow to downstream, instream and out of stream water right holders
or instream minimum releases unless the engineer of record provides another alternative
and demonstrates the safety and efficacy of this alternative to the State Engineer.
(6) The Department shall determine
water impoundment volumes in acre-feet as follows:
(a) For dams impounding water
for an authorized beneficial use, the impoundment volume indicated in the area-capacity
curve as measured from the bottom of the reservoir to the spillway crest. For dams
with multiple spillways, ‘spillway crest’ is referring to the crest
of the lower elevation spillway.
(b) For wastewater treatment
lagoons, the impoundment volume is that indicated in the wastewater lagoon plans
and specifications.
(c) For diversion or flood control
dams, the impoundment volume is that calculated at full reservoir at the dam highest
elevation spillway crest level.
(7) The State Engineer may approve
final designs, drawings and specifications for water storage reservoirs after a
water storage application and a draft final order for that application have been
issued by the Department.
(8) Any person, firm or private
or municipal corporation must provide to the State Engineer an evaluation of whether
the dam includes measures that make it readily adaptable to power generation for
any new dam over 25 feet high on a stream with average annual flow over 2 cubic
feet per second, unless exempted from this requirement as provided in ORS 540.350(3).
(9) For any dam rated high hazard,
the Department must review and approve an Emergency Action Plan prior to filling
the reservoir.
(10) For any dam rated high
or significant hazard, the Department must review and approve an operations and
maintenance manual prior to construction on the dam.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 543
Hist.: WRD 3, f. & ef.
2-18-77; WRD 12-1986, f. & ef. 10-3-86; WRD 12-1994, f. & cert. ef. 11-7-94;
WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10; WRD 2-2015, f. & cert. ef. 3-17-15
690-020-0029
Recommendations for Dams Under 10
Feet High or Storing less than 9.2 Acre-feet
(1) Persons constructing or designing dams
under ten feet high or storing less than 9.2 acre feet may be subject to requirements
for use of registered engineers as specified in ORS 672.002 through 672.091.
(2) The Department is authorized
to provide guidance for the construction of dams requiring a water right permit
but not requiring State Engineer review and approval of designs, plans and specifications.
(3) Potential dam owners are
advised that even small dams, should they fail, may cause injury to people and property.
Dam owners should consider designs and inundation analysis methods described in
OAR 690-020-0035 through 690-020-0065, 690-020-0100, and 690-020-0120.
(4) Persons proposing to build
a dam under 10 feet high or storing less than 9.2 acre-feet must comply with all
the requirements for a storage permit in ORS 537.409 and in OAR 690-020-0310.
Stat. Auth.: ORS 183 & 540
Stats. Implemented: ORS 183
& 540
Hist.: WRD 12-1986, f. &
ef. 10-3-86; WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10; WRD 2-2015, f. & cert.
ef. 3-17-15
690-020-0035
Minimum Engineering Design Requirements
(1) A design report or multiple design
reports must be submitted with the drawings and specifications by the engineer of
record for all new dam construction. Design reports may be completed by other engineers
registered to practice in Oregon.
(2) The design report(s) for
new dam construction must include the following elements:
(a) Site suitability evaluation
as provided in OAR 690-020-0036;
(b) Hydrology and inflow design
flood as provided in OAR 690-020-0037;
(c) Dam structure design (embankment,
concrete or other) as applicable and as provided in OAR 690-020-0038 – 690-020-0041;
(d) Spillway design as provided
in OAR 690-020-0042;
(e) Design for penetrating conduit(s)
as provided in OAR 690-020-0043; and
(f) Methods for determining
whether a dam is operating properly based on the hazard rating of the dam as provided
in OAR 690-020-0044 (monitoring and instrumentation).
(3) If multiple reports are
submitted, each must be stamped by the engineer who prepared the report and the
engineer of record must compile and understand reports for preparation of drawings
and specifications.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 3, f. & ef.
2-18-77; WRD 12-1986, f. & ef. 10-3-86; WRD 12-1994, f. & cert. ef. 11-7-94;
WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10; WRD 2-2015, f. & cert. ef. 3-17-15
690-020-0036
Site Suitability and/or Geotechnical
Evaluation
The design for new dam construction shall
characterize the soil and rock at and around the dam site and shall include the
following elements:
(1) A description of the general
and local geology and geomorphology at and around the dam and reservoir. Field investigation
by a geotechnical engineer and/or engineering geologist is required for all high
hazard dams and also for significant hazard dams where landslides, faults, dispersive
soils or liquefiable soils could reasonably be expected near the dam site. All such
features shall be shown on a map of the dam site, and described as necessary for
design of the dam. For dams on rock, mapping of discontinuities relevant to safety
of the dam and evaluation of the need for grouting is required.
(2) Subsurface investigation
to determine distribution of relevant earth materials. This investigation shall
include borings or test pits; identification of springs, seeps and groundwater encountered
at the dam site; and evaluation of the potential for landslides into the dam or
reservoir.
(a) All materials shall be logged
by the Unified Soil Classification System; blow counts (for borings only); and description
of samples taken for testing.
(b) Subsurface investigations
for High Hazard dams shall include drilling to a minimum depth 1.5 times the height
of the dam or at least 10 feet into bedrock, whichever is less.
(3) Soil and or rock evaluation
and testing of relevant materials. This evaluation may include: proctor compaction
testing from all borrow areas; estimation or testing the permeability of soils to
be used in dam construction; and an assessment for the presence of dispersive soils.
(a) An analysis of materials
in the foundation and proposed embankment shall be completed if materials are prone
to liquefaction or significant settlement.
(b) Where suitable materials
can be collected, strength tests shall be required for all high hazard dams, and
may be required by the State Engineer for significant hazard dams.
(c) Testing of dynamic soil
properties may be required for high hazard dams in areas with large ground acceleration
potential from earthquake loading.
(4) Borrow area locations. Areas
proposed for borrow shall be identified and shown on the drawings.
(5) Earthquake considerations.
Seismic site characterization is required for high hazard dams, and may be required
for significant hazard dams. A seismic site characterization shall include earthquake
sources, ground motion hazard, peak ground acceleration, and recommended ground
motions (time histories).
(6) Site preparation criteria.
The site evaluation shall recommend a depth of stripping unsuitable materials, and
also a minimum, and where necessary, maximum depth for the cutoff trench.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0037
Hydrology and Inflow Design Flood
The design shall characterize flow into
and through the reservoir and dam and shall include the following elements:
(1) A topographic map delineating
the drainage area contributing to the dam, with the drainage area size labeled in
square miles and showing the specific location of the proposed dam.
(2) For dams on stream channels,
the name of the stream where the dam is located, the name of the principal watershed,
and a determination of average annual inflow into reservoir and potential to fill
the reservoir.
(3) Dam failure inundation analysis
is required for any dam that might be high or significant hazard. The inundation
analysis shall comply with OAR 690-020-0120.
(4) The inflow design flood
that is the basis of hydraulic design for the dam shall be determined based on the
hazard rating of the dam.
(a) The inflow design flood
for a high hazard dam is the Probable Maximum Flood (PMF).
(b) The minimum inflow design
flood for a significant hazard dam is the 0.2 percent annual exceedance probability
flow.
(c) The minimum inflow design
flood for a low hazard dam is a 1.0 percent annual exceedance probability flow.
(d) The inflow design flood
for a lagoon or off channel reservoir is the maximum capacity of inflow pumps, ditches
plus the maximum local storm precipitation over the lagoon.
(e) For watersheds under 30
square miles, the engineer may consider just the 24-hour storm to help determine
the PMF, while for larger basins the engineer shall utilize at least a 72-hour storm
for calculating the PMF for a general storm.
(5) For a high hazard dam, the
engineer of record may also propose to determine an inflow design flood based on
a quantitative analysis of risk to people and property.
(6) Designs shall include a
description of all hydrologic parameters and the method used to determine the inflow
design flood hydrograph and the volume of the inflow design flood, which is to be
determined considering basin size and other factors as appropriate to the watershed
above the dam.
(7) The design report must include
the information used to develop the stage and storage capacity curve for the reservoir,
including the capacity with and without excavation for construction.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0038
Embankment Dam Structures
Designs for Embankment (soil and or rock)
dams shall include the following elements:
(1) A determination of embankment
stability and stable embankment slope angles.
(a) Embankment dams shall be
designed to have stable slopes during construction, and under all conditions of
reservoir operation.
(b) Standard slopes of 3:1 upstream
and 2:1 downstream may be used at the discretion of the engineer of record for low
and significant hazard dams as long as low strength materials are not used in the
embankment and conditions leading to elevated pore water pressures are not present.
(c) Dams that are rated high
hazard must be designed as zoned embankment dams and/or include a chimney drain
designed also as a filter.
(d) High hazard dams shall be
analyzed for static and seismic slope stability, and also for deformation analysis.
The State Engineer may require static and or seismic slope stability analysis for
significant hazard dams. At a minimum, seismic analysis shall be based on full reservoir
under steady state seepage conditions. Factors of safety shall be evaluated by slope
stability analyses using appropriate strength parameters based on laboratory or
insitu testing. For materials that can be reasonably tested either on site or in
a laboratory, soil strength values may not be based on assumptions and must be made
on strength testing of the appropriate soil or rock units.
(e) High Hazard dams shall be
designed for the maximum credible earthquake. If the State Engineer requires seismic
analysis of a significant hazard dam, deformation analysis shall be designed for
the 0.2 percent annual exceedance probability earthquake.
(f) Abrupt changes in depth
of compressible foundation material shall be identified and where present, the design
shall prevent significant differential settlement.
(2) Analysis of seepage and
leakage expected through the dam and design of measures to prevent internal erosion
and excess leakage.
(a) Steady state seepage and
internal drainage conditions beneath, around and through the dam shall be quantified
for all high hazard dams, and may be required by the State Engineer for significant
hazard dams.
(b) A core of low permeability
material protected by a soil filter is required for all high hazard dams. A core
and soil filter is required for any significant hazard dams where the engineer of
record or State Engineer determines piping could potentially occur. All core and
filter zones must be of a configuration with dimensions that can be readily constructed.
(c) Internal drains and/or soil
filters shall be used as needed to drain water and prevent internal erosion of the
dam. Toe drains shall be standard design practice for water storage facilities,
but not for most wastewater lagoons.
(d) Internal drain pipes to
collect and distribute seepage flows from internal filters and drains shall be comprised
of material that is non-corrodible, designed to carry the overburden load, and be
no smaller than 6 inches in diameter.
(3) A safe and accessible dam
crest.
(a) The dam crest shall be of
sufficient width to be accessible by equipment and vehicles for emergency operations
and maintenance, and shall have a road to allow crest access during periods when
the spillway is flowing.
(b) The crest shall have a camber
sufficient to maintain the design freeboard, based on the anticipated crest settlement,
and in no case shall the camber be less than 0.5 feet.
(c) Roads located on the dam
crest shall have appropriate surfacing to provide a stable base that resists rutting
and provides adequate traction for access and safety in wet conditions.
(d) The crest shall have adequate
cross slopes to prevent ponding.
(4) Measures to control wave
and surface erosion as needed.
(a) For reservoirs large enough
to generate significant waves, the design shall include a determination of minimum
freeboard based on expected waves. The design shall also include slope protection
for wave action if significant waves are likely.
(b) The downstream slope shall
be provided with a well maintained cover of non-woody vegetative cover, or a gravel
or rock surface, to prevent surface erosion. No woody vegetation shall be planted
on the dam during the life of the structure unless specifically designed by the
engineer of record, by demonstrating that cover plants will not affect critical
dam functions.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0039 [Renumbered to 690-020-0050]
690-020-0041
Concrete Dam Structures
Designs for concrete mass dams must be
prepared by a structural engineer and a geotechnical engineer and/or engineering
geologist. This rule does not apply to concrete flashboard dams. Designs for all
other concrete dams shall include the following elements:
(1) Concrete dams shall be specified
as gravity, arch, arch-gravity, or buttress. Gravity dams can be of conventional
mass concrete or roller compacted concrete.
(2) Dams shall be designed to
be stable during construction and under all conditions of reservoir operation.
(a) Headwater and tailwater
elevations pertinent to the design shall be described with respect to both static
and dynamic loading.
(b) Uplift pressure distributions
assumed for design shall be provided.
(c) When foundation drains are
used to reduce uplift, the assumed drain efficiency shall be indicated and permanent
access shall be provided at the project to inspect and maintain the drains.
(3) Sliding stability shall
be evaluated at lift joint surfaces, at the dam foundation interface, and at discontinuities
in the foundation materials beneath the dam and abutments.
(a) Factors of safety shall
be based on limit equilibrium methods.
(b) For earthquake loadings,
the critical acceleration (acceleration required to initiate sliding) may be less
than the peak ground acceleration of the design earthquake. In such cases a permanent
sliding displacement shall be determined in lieu of a sliding factor of safety.
(c) Overturning of the dam on
its foundation shall be evaluated for static and seismic loading.
(4) Seismic stability analysis
is required for certain concrete dams and shall demonstrate the dam can withstand
the design earthquake without loss of life or damage to property.
(a) High hazard dams shall be
designed for the maximum credible earthquake based on current information from the
US Geological Survey or a site specific seismic evaluation. A dynamic stress analysis
that considers the dynamic characteristics of the dam and the ground motions of
the design earthquake shall be provided for high hazard dams.
(b) Where the State Engineer
requires seismic analysis on significant hazard dams, they shall be designed for
the 0.2 percent annual probability of exceedance earthquake. The Department may
require a dynamic stress analysis for significant hazard dams.
(5) When foundation grouting
is needed, the design for the grout curtain and/or consolidation grouting of the
foundation shall be required.
(6) Specific properties of mass
concrete that can be important to design and construction include the compressive
strength (at 28 days and one-year), modulus of elasticity, Poison’s ratio,
shear strength, tensile strength, volume change during drying, thermal coefficient
of expansion, specific heat, thermal conductivity, permeability and durability.
(a) As a minimum for static
loadings, the assumed compressive and shear strengths for the parent concrete, lift
joint surfaces, and the dam-foundation contact shall be provided.
(b) In addition, tensile strength
assumptions for the aforementioned regions for dynamic loadings (seismic) shall
also be provided.
(c) Air entraining agents shall
be provided in the concrete mix to provide freeze-thaw protection and to improve
the workability of lean mass concrete mixes. The quantity of air entrained in mass
concrete shall be in the order of 5 percent.
(7) Mix design and construction
methods used to minimize cracking due to temperature gradients between interior
regions subject to heat of hydration effects and surfaces exposed to ambient temperatures
shall be specified. Treatment of lift joint surfaces to achieve desired shear and
tensile strengths shall be indicated. Treatment of contraction joints to prevent
leakage and/or to transfer load between adjacent monoliths shall be described.
(8) When reinforcing steel is
used, the strength properties of the reinforcement shall be provided and contract
drawings shall clearly indicate the size, location, spacing, and cover requirements.
(9) The minimum crest width
must be 15 feet unless otherwise approved. The dam crest and appurtenant structures
shall be accessible by equipment and vehicles for emergency operations and maintenance.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0042
Spillways
All dams must have a spillway. Spillway(s)
design shall include the following minimum elements:
(1) Utilization of inflow design
flood. Determination of inflow design flood as described in OAR 690-020-0037 is
required to determine the required spillway capacity.
(2) Hydraulic evaluation of
flow through control section. Flood flow through the control section must be calculated
and the minimum freeboard at the inflow design flood must be 1 foot for high hazard
dams and 2 feet for significant and low hazard dams.
(3) Optional low elevation spillway.
An interior spillway connected to the low level conduit may be used for low and
significant hazard dams, and for high hazard dams only with specific approval by
the State Engineer. The capacity of the low elevation spillway may be considered
in design of the overflow spillway.
(4) Stable spillway control
section. The spillway control section must be hydraulically and structurally stable
for the inflow design flood and have permanent features so that the control section
is identifiable for re-measurement of cross section during routine inspections.
(5) Spillway channel stability.
Spillways shall be designed to be structurally adequate and stable under all conditions
of reservoir operation. Spillway structures of high hazard dams shall be designed
for earthquake ground motions per OAR 690-020-0036.
(6) Reinforced concrete specifications.
Structural elements of reinforced concrete shall be designed for both strength and
serviceability. The 28 day strength of structural concrete shall be provided. The
strength properties of the reinforcing materials shall also be provided and contract
drawings shall clearly indicate the size, location, spacing, and cover requirements.
Treatment of construction joints and contraction/expansion joints shall be described
and special provisions for strength transfer and leakage prevention identified.
Air entrainment shall be provided in cast-in-place concrete if needed for freeze-thaw
protection, durability, and workability.
(7) Debris booms. For high and
significant hazard dams, debris or log booms may be required. Where required, they
shall be designed for the spillway approach where logs and other debris may block
or damage the spillway structure. The design shall specify the necessary anchor
capacity, and the design of the anchors.
(8) Gates and Flashboards. Detailed
drawings and specifications are required for spillway gate structures or flashboards,
if present on the proposed dam. Operations and maintenance manuals are required
for any dam with a gated spillway, or where flashboards or stop-logs are used in
the spillway.
(9) Energy dissipation. The
design of stilling basins for high hazard dams, and where required by the State
Engineer for significant hazard dams, shall be based on calculated hydraulic forces
and designed to dissipate energy from the inflow design flood.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0043
Penetrating Conduit (s) and Control
of Flow Through Conduits
All new dams on stream channels must have
a low level conduit. All other dams must have a low level conduit or other means
to safely drain the reservoir. The conduit and related control structures must be
designed to meet the following criteria:
(1) Ability to lower the reservoir.
The minimum diameter of the conduit should be determined through analysis of the
time required to drain the dam at average inflow.
(a) The conduits for high hazard
dams shall be capable of releasing the top five feet of the reservoir in five days.
(b) The conduits for significant
and low hazard dams must be able to release the top five feet of the reservoir in
ten days.
(c) All conduits must be of
sufficient size to allow passage of inflows as needed.
(d) In no case shall conduits
be smaller than 8 inches in diameter.
(2) Durable and water-tight
conduits. Conduits must be made of medium to heavy gage durable materials. Pipe
joints must be designed to seal and prevent leakage. Corrugated metal culverts are
only acceptable for low hazard dams, and only when the conduits are encased in concrete.
Encasement of conduits in concrete may be used to assist in the design of a durable
conduit and to reduce the potential for seepage and erosion adjacent to the conduit.
(a) Diaphragms using materials
designed as an effective soil filter are required for any conduits not designed
as encased in concrete, and are required regardless of encasement for all high hazard
dams.
(b) Seepage collars may not
be used in any dam.
(3) Control Mechanisms. The
design for the control mechanism must be sturdy, durable, allow for air venting
when needed, and allow manual operation to drain the reservoir if hydraulic or other
power controls are inoperable. Hydraulic controls must have redundancy if control
relies on any submerged hydraulic hoses. Intake structures for outlet works must
have trash racks unless the engineer of record shows trash racks are unnecessary,
or unsafe to construct due to conditions at the dam site. For high and significant
hazard dams, measures to prevent unauthorized use of the control mechanism must
be included in this design.
(4) Outlet structure. The outlet
structure must not be submerged when the inlet control gate or valve is fully closed.
The outlet structure must be designed to protect the conduit from mechanical damage
and convey water to the stream channel without channel erosion and cavitation near
the gate structure.
(5) Pressurized operation. Conduits
must be specified as suitable for pressurized operation if they are to be operated
with controls other than at the inlet of the conduit. Conduits for dams with pressurized
conduits shall have a guard gate installed at the upstream end of the conduit. Operations
and maintenance manuals are required for any dam designed for pressurized operation,
and the plans must include procedures for periodic inspections of the interior of
any pressurized pipes.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0044
Monitoring and Instrumentation
Designs must include methods for determining
if the dam is operating properly based on the hazard rating of the dam, and include:
(1) Staff gage near controls
for the conduit. The staff gage shall be clearly marked in feet and tenths of feet,
and extend to within one foot of the crest of the dam. Markings and numbers on the
gage rod shall be of sufficient size to be easily readable from the crest of the
dam.
(2) Multiple and easily accessible
outlets of all toe drains. Toe drains shall be designed to discharge into locations
where flows can be evaluated and monitored. Multiple discharge points are required
in order to isolate seepage to various sections of the dam and foundation. Discharge
points must be located where routine dam maintenance is not likely to damage the
drains.
(a) For high hazard dams, drains
must have a measuring weir or other device, and a basin for settling drainage water
so that internal erosion can be identified.
(b) Where drainage galleries
are provided for concrete dams, seepage measuring devices should be provided and
accessible for making the necessary readings.
(3) Unique Identification. All
instrumentation and exterior drains shall be labeled with a unique identifying marker
designed for durability and to withstand maintenance activities.
(4) All high hazard and where
required by the engineer of record or State Engineer, significant hazard dams shall
have the following instrumentation:
(a) Monuments that allow measurement
of the horizontal and vertical movements of the dam. Control or benchmark monuments
shall be placed in areas not subject to movement;
(b) Piezometers to allow monitoring
of the phreatic surface within the dam or for concrete dams, to determine uplift
pressures.
(c) Instrumentation to measure
strong ground motions for dams in locations where the peak ground acceleration in
the 0.2 percent annual probability of exceedance earthquake is greater than 0.4g.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0047
Geosynthetics
Geosynthetics shall not be used as the
sole element employed to perform an essential dam safety function. Redundant design
features are required whenever geosynthetics are used for essential dam safety functions.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0048
Modification of Standard Design Requirements
Exceptions to design standards may only
be obtained with written approval from the State Engineer. Where the engineer of
record requests design exceptions, the request must be in writing, be affixed with
the engineer of record’s professional stamp, and include a report describing
why design standards are inapplicable to the safety of the dam.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0050 [Renumbered to 690-020-0500]
690-020-0055
Design Drawings
The engineer of record shall submit applicable
drawings when the engineer believes the design is ready for review and approval
by the State Engineer.
(1) Drawings must accurately
portray the work to be accomplished and be of sufficient detail to clearly define
all features of the project. After all changes required by the State Engineer are
made, final design drawings must be neatly and accurately drawn to a scale sufficiently
large for the drawings to be readily interpreted.
(2) Drawings must be uncluttered
and easy to understand for determination of design compliance by the contractor,
the engineer of record, and the State Engineer.
(3) Drawings must be no larger
than 24” X 36”. Other acceptable sizes for drawings are 17" X 22" and
22" X 34". All drawings must have a graphic scale bar so that scale can be determined
after enlargement or reduction. Each sheet shall be numbered sequentially with the
first sheet being sheet number one along with the total number of sheets; e.g.,
1 of 6.
(4) Drawings shall include the
following information:
(a) An official dam name, which
must not have already been used for a dam as indicated in the Oregon dam safety
database. This unique name must be affixed on each drawing;
(b) The first drawing must include
a location map with the drainage basin, the dam and reservoir, streams within the
drainage area, and the location of the nearest access highway. This drawing must
include legal location of the dam (Section, Township and Range), and the location
of the survey reference point with latitude, longitude, elevation, and datum elevation
(NAVD1988);
(c) A contour map of the reservoir
site showing the legal location of the dam with a contour interval no greater than
5 feet. A plan of the dam should be superimposed on this map. If scale permits,
this drawing should show the location of the spillway(s), conduit inlet and outlet,
and the location, distance and direction to a government land corner or other permanent
survey marker;
(d) Area and storage capacity
curves and information on the hydrology of the proposed reservoir drainage area
in square miles;
(e) A profile of the dam site
at the center of the dam;
(f) A cross section of the dam
at maximum section;
(g) Plan view(s) of dam at maximum
section, and other sections as needed;
(h) Cross section(s) of dam,
including the maximum section with the official dam height;
(i) Spillway details, spillway
approach control discharge, and energy dissipation;
(j) Low level conduit details,
including diameter, material, encasement; and
(k)Slide gate or valve details
including the trash rack, control stem, pedestal and wheel, or other control details,
and air vent.
(5) Elevations must be clearly
labeled on applicable drawings and include the:
(a) Base of dam and official
height of dam;
(b) Dam crest;
(c) Spillway control section;
(d) Base of spillway discharge;
and
(e) Invert of the conduit at
both the inlet and outlet.
(6) All drawings must be dated
and have sufficient space for State Engineer’s approval stamp, at least 3”
x 3” near the lower right hand corner of the drawing.
(7) Drawings must be designated
as final design drawing or as-built drawings.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0060
Construction Specifications
All drawings for dams must be accompanied
by construction and material specifications that include the following:
(1) Construction conditions.
Specifications must include the construction period based on typical weather for
that location and in-stream work periods if applicable, and may include a process
for the engineer of record to modify the construction period.
(2) Clearing of the dam site
and reservoir. Specifications must include the area to be submerged by the new or
enlarged reservoir and specify that the submerged area shall be cleared of logs
and debris prior to filling the reservoir. The specifications must require that
the footprint of the dam shall be cleared of all soils containing organic materials,
and that this material may not be used for dam construction.
(3) Cutoff trench requirements.
Specifications must include the minimum trench depth, width at base of the trench,
and maximum side slope steepness. These specifications shall be based on the subsurface
investigations and direct that the cutoff trench may not be filled if it contains
standing water. A requirement not to begin filling the cutoff trench until approved
by engineer of record, and where specified, by State Engineer or Dam Safety Engineer,
must also be included in the specifications.
(4) Material specification standards.
The specifications shall include material and testing specifications for dam materials,
conduits, control structures, and other appurtenant structures, using an ASTM standard
methodology if available.
(5) Soil Compaction. The typical
compaction specification is 95 percent of standard proctor density, though the engineer
of record may use a different compaction standard. Specifications shall include
the types of acceptable compaction equipment, by material source if necessary. Specifications
shall also include maximum lift thickness. To reduce potential for leakage around
the conduit, specifications shall prohibit soil compaction dry of optimum moisture
content for materials placed immediately above or adjacent to the conduit. Specifications
must also include verification testing of soils, with representative samples selected
for testing by the engineer of record and not the contractor.
(6) Concrete placement. Specifications
shall include means to prevent separation of aggregate and cement, air entrainment
requirements if needed, methods for placement and vibration of concrete, required
minimum 28 day strength, slump, moisture and temperature requirements for curing.
Alkali reactive aggregate shall not be used in the concrete.
(7) Conduit specifications.
Specifications must include the material, diameter, and thickness of the conduit,
and the length of conduit required for the project. Methods for sealing joints must
be specific. Specifications must require that all materials from a manufacture are
certified to meet this test, or that the engineer of record has tested the materials
directly.
(8) Accepting and Rejecting
Materials. Specifications must include tolerances for acceptable departure from
material specifications and a process for rejection of defective materials or workmanship.
(9) Notification by the engineer
of record to the State Engineer of changed conditions critical to the safety or
operations of the dam. Specifications shall include State Engineer notification
if previously unidentified springs, slope movement or sand lenses are identified,
or if storm or other damage occurs during construction.
(10) The specifications must
require supervision by the engineer of record during construction and for inspection
by the Director or Director’s authorized representative at any time during
the construction period.
(11) The specifications must
also contain a provision to the effect that plans or specifications shall not be
altered or changed without the written approval of the State Engineer.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0065
Dam Construction
The Engineer of record shall submit plans
for administering the construction of the dam to the State Engineer for approval.
Construction plans must include the following:
(1) Construction of the dam
shall be observed and documented by the engineer of record and employees working
for the engineer of record as applicable.
(2) The engineer of record or
an inspector working for the engineer of record shall be on-site as needed for instructions
to the contractor, approval of initial excavation, acceptance of materials, and
general project administration.
(3) The dam owner shall cease
construction activity if the engineer of record is no longer employed or for any
reason cannot complete necessary construction administration activities. Construction
may resume when a new engineer of record is employed, the State Engineer has been
notified of the new engineer of record, and both engineers have discussed the project.
(4) The engineer of record shall
observe the construction of the dam. It is the engineer of record's responsibility
to make periodic inspections to evaluate whether the construction is proceeding
in accordance with the approved plans and specifications. The engineer of record
shall endeavor to prevent defects and deficiencies in the construction of the dam
and appurtenant structures, and shall disapprove or reject work identified that
fails to conform to the approved plans and specifications.
(5) The engineer of record shall
confirm foundation design assumptions once surface materials have been stripped
and the cutoff trench excavated. Changes in actual foundation conditions from assumptions
made in the initial site evaluation shall be communicated to the Department.
(6) The engineer of record shall
maintain a record of construction that shall include:
(a) Logs of construction inspections
whenever such inspections are made by the engineer or the engineer’s employee;
(b) All test results pertaining
to construction;
(c) Photographs; and
(d) Construction problems and
remedies.
(7) The engineer of record shall
complete as-built drawings and a final construction report, including statements
that the observations are either consistent or inconsistent with the design drawings
and specifications. If key elements of construction were not observed, the construction
report shall detail those specific elements that were not observed.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0070
Submittals and Notifications by the
Engineer of Record
(1) When necessary, the engineer of record
must include an inundation analysis that complies with OAR 690-020-0120 prior to
submitting the design report, plans and specifications, so that the Department can
determine the hazard rating of the dam.
(2) All final designs, drawings
and specifications submitted to the State Engineer for approval must be prepared
and stamped by a professional engineer licensed to practice in the State of Oregon.
The first page of the drawings, the specifications, and the construction administration
plan must be stamped by the engineer of record. All submitted materials must be
addressed directly to the State Engineer and labeled as a dam safety submission.
(3) Final drawings shall be
submitted on full size paper. The design reports and specifications must be submitted
as packaged 8.5 x 11 inch bound documents, with essential maps folded within.
(4) A schedule of construction
will be provided to the State Engineer prior to initiating construction of any significant
or high hazard dam.
(5) Prior to completion of the
cutoff trench and all stripping of foundation and embankments the engineer of record
shall notify the State Engineer to allow for State Engineer inspection of the excavation.
The required notice to the State Engineer is as follows:
(a) 48-hours for a low hazard
dam;
(b) 120-hours for a significant
hazard dam; and
(c) for high hazard dams, 240-hours
or the time specified in the approval, whichever is longer.
(6) Any changes made to the
designed location, height or width of the dam, or to materials used in dam construction
shall be reported in writing immediately to the State Engineer.
(7) If any slope instability
is observed during construction in the embankment or adjacent to the dam or into
reservoir, it shall immediately be reported to the State Engineer by phone.
(8) If for any reason the engineer
of record ceases construction administration work, the engineer of record must immediately
notify the State Engineer of the situation, by phone and in writing.
(9) For high hazard rated dams,
the final emergency action plan and any additional inundation analysis required
for the EAP as described in OAR 690-020-0400 must be submitted by the engineer of
record prior to or concurrent with submission of the as-built drawings and the project
completion report.
(10) The engineer of record
must submit as-built drawings and a project completion report. A project completion
report must include the following:
(a) As-built drawings, if possible
on the same sheet as the initial design drawings. As-built drawings shall be submitted
in the form of electronic copies of all applicable drawings;
(b) A completion report stating
either that the dam has been built according to the drawings with changes to improve
safety as documented in the as-built drawings, or that essential safety functions
are unknown;
(c) A list of the days the engineer
of record was on site, the number and location of material tests, and observations
of all changed conditions;
(d) Test results (compaction,
strength, permeability) must be summarized in the completion report;
(e) The completion report must
document the observations and decisions made and communicated to the contractor
or dam owner. Photographs of key stages of construction, including but not limited
to photographs of the cutoff trench, borrow pit development, trenching and placement
of the conduit, the spillway before and after placement of concrete; and
(f) The project completion report
shall be stamped by the engineer of record.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0080
Written Approval by State Engineer
(1) Prior to commencing construction activity,
all design reports, drawings of the dam and critical appurtenant structures, specifications,
and plans for construction administration must be approved by the State Engineer
as indicated by the State Engineer’s stamp and a written letter of approval
from the State Engineer.
(2) The State Engineer’s
approval of design plans and specifications shall be valid only for five years.
Upon request, written requests for time extensions may be granted in writing by
the State Engineer.
(3) The following activities
which involve the construction or operation of an existing permitted dam that may
impair the safety of the dam require State Engineer approval of engineered designs:
(a) Any changes that affect
storage capacity of the dam or increase dam height above that in the approved drawings
for the dam, including all dam rises other than adding fill to restore crest height
lost to settlement or erosion;
(b) Any changes to or near the
spillway that may affect spillway capacity or ability to pass flows safely;
(c) Installation of any valve
or gate on the downstream side of the dam;
(d) Removing and replacing or
otherwise excavating into or near the dam to place or replace any conduit or utility
in the dam;
(e) Replacement of the conduit
control structure;
(f) Installation of any valve
on the downstream side of the low level conduit, or directly connecting irrigation
pipe to the low level conduit;
(g) Repair of damage which has
already significantly weakened the dam;
(h) Any activity where at least
30 percent of fill material in the dam is impacted by that activity; and
(i) Any other change to the
dam that affects its safety as determined by the State Engineer.
(4) Prior written approval will
not be required for replacement or lining of toe drains, relining of conduits of
low hazard dams, and for specific actions required in a safety emergency. As-built
drawings may be sent to the State Engineer after completion of such projects to
show these projects have been completed in a safe manner.
(5) For pre-existing dams without
a valid storage permit, the State Engineer may approve plans and specifications
so that a permit may be issued only if the engineer of record provides the following:
(a) Drawings of the dam as it
exists during the engineer’s evaluation and survey of the dam. These drawings
should include all the critical features as described in OAR 690-020-0035, except
for those elements that cannot be evaluated such as the cutoff trench;
(b) Evaluation of any embankment
distress, including erosion, seepage or leakage;
(c) Condition and function of
the conduit and its controls, capacity and stability of the spillway;
(d) Any other safety information
needed as determined by the State Engineer;
(e) Designs as needed to bring
the dam up to the current standards based on the hazard classification of that dam;
(f) As improved drawings of
the dam showing that all necessary modifications have been made with a report from
the engineer describing the necessary work that was completed; and
(g) The source of all information
used to develop the as-improved drawings must be documented in a report submitted
by the engineer. This includes but is not limited to the engineer’s measurements,
engineer’s observations, a photographic record, and testimony of individuals.
(6) No newly constructed dam
may store water until final written approval of necessary plans, specifications
or other information is received from the Department.
(a) Final approval may be obtained
only after construction has been completed and as-built drawings and a satisfactory
project completion report have been submitted to and approved by the State Engineer.
(b) The State Engineer shall
notify the engineer of record and dam owner in writing when final documents have
been approved.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0100
Hazard Rating of Dams
(1) Dams shall be assigned a hazard rating
of high, significant, or low.
(2) The Department shall utilize
dam breach inundation analysis as a primary factor to determine the hazard rating
of dams as described in OAR 690-020-0120.
(3) Using the dam breach inundation
analysis described in OAR 690-020-0120, the Department shall make the final determination
of any hazard rating using the following criteria:
(a) An inundation depth of flowing
water of at least two feet over the finished floors of dwellings, other frequently
occupied buildings, or road surfaces where a vehicle is likely to be present establishes
a “high hazard” rating.
(b) Any inundation depth of
water over the floorboards of structural buildings establishes a “significant
hazard” rating.
(c) For other roads and vulnerable
utilities, an inundation depth of two feet or evidence of depth and velocity capable
of creating damage establishes a “significant hazard” rating.
(d) Wherever heavy recreational
or other frequent use occurs downstream a “high hazard” rating shall
be established to prevent probable loss of life. Such designation shall not depend
on the presence of downstream infrastructure.
(e) For water depths close to
those listed in the subsections (a) and (c), the Department may also consider water
velocity in its determination of hazard rating.
(4) The hazard rating of a dam
shall remain in effect until the rating is revised by the Department using the procedures
described in OAR 690-020-0120. A dam owner may request that the Department revise
a hazard rating. The owner must provide information in support of the request and
prepared by an engineer licensed in Oregon and familiar with hydraulic and hydrologic
calculations and using the procedures described in OAR 690-020-0120.
Stat. Auth.: ORS 183 & 540
Stats. Implemented: ORS 183
& 536, 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0120
Dam Breach Inundation Analysis
(1) A dam breach inundation analysis must
be submitted with the design for any new dam, except only for dams in a remote location
far enough from buildings, high use recreation sites or high use public roads so
that damage or fatalities from a dam breach would be very unlikely as determined
by the State Engineer.
(2) A dam breach inundation
analysis is required to change the hazard rating of an existing dam.
(3) The dam breach inundation
analysis must use a breach time based on dam materials and thickness and other factors
that would influence the time it would take for the dam to breach from internal
erosion, overtopping, or displacement.
(4) Any simplified and conservative
hydraulic model may be used to show that a dam should be rated low hazard. The State
Engineer may determine if the model was used appropriately and conservatively.
(5) Accepted and hydraulically
consistent models must be used to conduct the inundation analysis for significant
and high hazard dams, as these will be used in the event of an emergency at the
dam. Models developed by the US Army Corps of Engineers including HEC-RAS are the
preferred methods of analysis. Other models that use hydrodynamic equations checked
for minimum tolerances such as FLO 2D are also acceptable for conducting dam breach
inundation analysis. Information on the specific model used for analysis, dam breach
parameters and justification, and all assumptions made for the analysis must be
included in the documentation for the inundation analysis.
(6) Inundation analysis for
hazard rating of high and significant hazard dams must be conducted with the reservoir
at full pool and inflow equal to the 0.2 percent annual exceedance probability flood
flow. The analysis must show on a map areas inundated, areas inundated by greater
than 2 feet, and all frequently occupied structures.
(7) The following additional
information shall also be required for newly constructed or modified high hazard
rated dams.
(a) A sunny day and a PMF inflow
analysis as part of the emergency action plan.
(b) The inundation mapping must
include cross sections with depth and times to flood wave arrival, and must be extended
downstream to a location where no significant property damage exists.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0150
Routine Inspection of Dams
(1) The Department shall maintain a program
of inspecting dams and may conduct routine safety inspections of dams with an inspection
frequency based on the hazard rating of the dam and may specify modifications necessary
to insure the safety of the works to prevent possible damage to life or property.
(2) The frequency of inspections
may be based on the hazard classification of the dam. Inspections may occur as follows:
(a) Inspections for high hazard
dams may be scheduled on an annual basis;
(b) Inspections for significant
hazard dams may be scheduled every three years; and
(c) Inspections for low hazard
dams may be scheduled every six years.
(3) Expedited inspections may
be conducted if an urgent dam safety issue is identified or if there is a potential
change in hazard classification.
(4) Following an inspection,
the Department shall provide to dam owners a letter with the inspection observations
and recommendations that assist the dam owner to ensure the safety of the dam.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0200
Fees for Dams
(1) Dam owners subject to dam safety regulations
shall submit to the Department an annual fee on the basis established under ORS
536.050(2).
(2) Dam owners who fail to pay
an annual fee on or before six months after the billing date may be required to
pay a late fee of $100.
(3) If a dam owner fails to
pay the annual fee or late fee charged by the Department, the Department may, after
giving the dam owner notice by certified mail, place a lien on the real property
where the dam is located for the fees owed by the dam owner.
(4) Multiple large dams connected
together and separated only by embankments or other manmade materials (common with
sewage lagoons) will count as one dam for fee purposes.
(5) The Department may use the
dam safety fee to support dam safety inspections; conduct dam breach inundation
analysis for existing dams; help dam owners complete emergency action plans for
existing dams; conduct or support the technical analysis of the safety of specific
dams; and other actions as needed to support the dam safety program.
Stat. Auth.: ORS 536.050
Stats. Implemented: ORS 536.050
Hist.: WRD 7-2009, f. 12-7-09,
cert. ef. 1-1-10; WRD 2-2015, f. & cert. ef. 3-17-15
690-020-0250
Maintenance of Dams
(1) When inspecting dams to insure the
safety of the dam, the Department may consider whether the dam owner has conducted
routine maintenance on dams as follows:
(a) Whether brush and trees
have been removed and whether vegetation on the embankment or spillway has been
mowed;
(b) Whether burrowing animals
are controlled and animal burrows are filled;
(c) Whether surface erosion
is effectively controlled;
(d) Whether freeboard and adequate
crest width have been maintained;
(e) Whether the spillway is
functioning correctly and that its capacity has not been reduced;
(f) Whether mechanical equipment
has been properly cycled and lubricated;
(g) Whether cracked concrete
structures have been properly patched, sealed, caulked or replaced to prevent deterioration;
(h) Whether debris, rock, or
earth have been removed from outlet conduits, outlet channels or spillway channels;
(i) Whether worn or damaged
parts of conduits, outlet valves or controls are in need of repair or replacement;
(j) Any other condition or activity
that might affect safety of the dam.
(2) The Department may find
that a dam is not safe if large trees or large woody vegetation exists on the dam.
(3) Maintenance deficiencies
observed during periodic dam safety inspections shall be described in an inspection
letter provided to the dam owner.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0300
Modification of Dams Requiring Notification
and/or Approval
(1) The activities described in OAR 690-020-0080(3)
are considered such significant modification of the dam so as to constitute new
construction requiring approval of engineered designs prior to initiating these
activities.
(2) Any activity that will increase
the volume or rate of water released during failure requires a new inundation analysis
using methods described in OAR 690-020-0120 unless the dam is in a remote area with
no downstream development or high recreational use areas that might be affected
by a dam breach flood.
(3) Certain repairs that may
affect the safety of the dam require on site analysis by an engineer during the
actual repair process in order to determine the specific repairs needed. Prior approval
of drawings for these repairs will not be required, as conditions encountered on
site are likely to deviate from plans. Therefore, submission of an as-built drawing
by the engineer of record of the following repairs indicating the repairs have been
made correctly may be deemed as evidence of the safety of the dam:
(a) Slip lining of existing
conduits that does not involve excavation into the dam and does not result in a
significant reduction in the time required for the conduit to empty the reservoir;
(b) Replacement of toe drains;
and
(c) Any other such repairs as
determined by the State Engineer.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0350
Operations and Maintenance Plans
(1) As part of the plans submitted with
the design, the engineer of record shall provide to the Department operations and
maintenance plans for new significant and high hazard dams, and for any new dam
with a gate or flashboard as part of the spillway. The dam owner shall be responsible
for implementation of operations and maintenance plans, and compliance with these
may be reviewed during dam safety inspections.
(2) Operations and maintenance
plans may include but are not limited to:
(a) Procedures for operation
of all gates and valves;
(b) Specified frequency for
cycling of the slide gate and/or valves;
(c) The time of year flashboards
are allowed in the spillway;
(d) Removal of trees and shrubs,
and mowing other vegetation as needed;
(e) Routine inspections, including
evaluation of seepage flow, and visual identification of any turbid seepage;
(f) Water release plan in the
event of a flood forecast when reservoir is above a certain level; and
(g) Measurement frequency for
all monitoring instrumentation installed at the dam.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0400
Emergency Action Plans (EAP) and
Emergencies
(1) Draft Emergency Action Plans are required
prior to completion of new dam construction or modification as described in OAR
690-020-0300(1), and final EAP’s must be submitted prior to filling the reservoir.
The final emergency action plan must be reviewed and approved by the State Engineer.
EAPs for dams constructed after March 2015 must be updated at least once every two
years, including but not limited to ensuring all notification contacts are current.
(2) Dam owners are encouraged
to complete emergency action plans for their existing high hazard dams.
(3) An EAP shall contain, as
a minimum, the following key elements:
(a) Emergency condition detection;
(b) Emergency level determination;
(c) Notification and communication
lists applicable to each of the emergency levels;
(d) Expected actions to prevent
a dam failure incident or to help reduce the effects of a dam failure and facilitate
response to an emergency;
(e) Inundation mapping that
normally includes both a sunny day and a probable maximum flood failure; and
(f) Procedures for termination
of the emergency.
(4) Dam owners of high or significant
hazard dams shall immediately notify the State Engineer of potential or actual dam
failure situations.
(5) Dam owners shall notify
the State Engineer of any breach of any dam subject to these regulations.
(6) If the Department observes
evidence of a dam at risk of imminent failure and a risk to life or property, local
public safety officials shall be notified of the situation.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 2-2015, f. &
cert. ef. 3-17-15
690-020-0500
Enforcement
(1) When any dam is found to be in violation
of the terms and conditions of the water right permit or certificate, or directly
threatens life or property, or when any structure is found where lack of maintenance
or unauthorized alterations could lead to a direct threat to life or property, the
Department shall notify the owner in writing of the violation and the action necessary
and specified time allowed to bring the structure up to design, operation, or maintenance
standards.
(2) Failure by the owner to
perform the required action may result in proceedings for one or more of the following:
(a) Notice and opportunity for
a contested case hearing as provided for in ORS 540.350(5).
(b) Posting of the structure
to prevent storage or to limit operation until the owner has complied with the requested
action required to fulfill conditions of the permit or certificate.
(c) Instituting legal action
by the District Attorney or Attorney General to have the facility declared a public
nuisance.
(d) Issuance of an order to
prevent storage or to breach the embankment as provided for in ORS 540.370.
(e) Any other enforcement action
permitted by law.
(3) Engineering work that is
inconsistent with any rules in this Division may be referred to the Oregon State
Board of Examiners for Engineering and Land Surveying, for appropriate actions.
Stat. Auth.: ORS 540.350 - 540.400
Stats. Implemented: ORS 183,
536 & 540
Hist.: WRD 12-1986, f. &
ef. 10-3-86; Renumbered from 690-020-0039, WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10;
Renumbered from 690-020-0050, WRD 2-2015, f. & cert. ef. 3-17-15

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