Inspection Services
Owners are required to evaluate the safety of their dams and all appurtenant works, and to make
modifications, as needed, to reasonably secure safety to life and property.
Construction Inspections
Construction inspections are performed to verify that the field conditions encountered are
compatible with the conditions assumed in design and that the construction is proceeding in
accordance with the approved plans, specifications, and construction inspection plan.
Particular emphasis is placed on observing and documenting the construction of elements
which are critical to the safe performance of the facility. The frequency of DSO site
inspections depend on the size and complexity of the project.
WAC 173-175-200 Department Role in Construction Inspection.
Owner Conducted Annual Inspections - Owners are required to conduct annual surficial inspections
and submit a copy of the inspection checklist to the department within 30 days following the
inspection. Information to assist owners in performing these inspections can be found in Chapter 5 of
Part III, Dam Safety Guidelines.
Copies of inspection records must be provided to the DSO upon request. WAC 173-175-510 Inspection by Owner.
Typical inspection items
would include:
- Condition of the dam crest and upstream and downstream dam faces with particular
attention to settlement, cracking, slumps or other distress.
- Condition of the outlet works and spillways
noting any erosion damage.
- Testing of infrequently used valves, control works, and other hydraulic
mechanisms.
- Observation and measurement of seepage, noting location and concurrent reservoir water
level.
- Observation and recording of any conditions which are a change from previous inspections.
Periodic Inspections
Periodic inspections are conducted on existing dams that are located in areas where dam failure
and release of the reservoir contents could pose the potential for loss of life. The inspections
are intended to identify deficiencies, and to reasonably assure safe operation and confirm that
maintenance is being adequately performed.
Inspections are performed by the department
every 5 years for dams with high downstream hazard or significant hazard classifications.
(2009 legislation requires that significant hazard dams now be inspected
every 5 years; previously it was every ten years.)
The inspections are performed by professional
engineers from the DSO and involve:
- Review and analysis of available data on the design,
construction, operation, and maintenance of the dam and its appurtenances.
- Visual inspection of
the dam and its appurtenances.
- Evaluation of the safety of the dam and its appurtenances,
which may include assessment of the hydrologic and hydraulic capabilities, structural
stabilities, seismic stabilities, and any other condition which could constitute a hazard to the
integrity of the structure.
- Evaluation of the downstream hazard classification; evaluation of the
operation, maintenance, and inspection procedures employed by the owner and/or operator,
and
- Review of the emergency action plan for the dam including review and/or update of dam
breach inundation maps.
The department will prepare a comprehensive report of the findings,
which includes findings from the inspection, and any required remedial work to be performed.
WAC 173-175-705 Periodic Inspection by the Department.
Non-routine Inspections by the Department
- Non-routine Inspections by the Department
The department may perform non-routine inspections of dams with any downstream hazard classification, separate from the periodic inspection program.
WAC 173-175-725 Non-routine Inspections by Department.
- Non-routine Unpermitted Dam Inspections
Ecology has identified
hundreds of dams from publicly available aerial photos that weren’t
listed in Ecology’s dam inventory. Inspections of these dams are
underway. All dams found to be jurisdictional are being added to the
state’s dam inventory and will be inspected on a routine basis.
Inspection at Public Request
The department may inspect a dam if a complaint from the public is received.
WAC 173-175-735 Inspection at Public Request.
