Appendix D
Existing Raw Water Facilities Evaluation
Physical Condition of Existing Raw Water Supply Facilities
This section summarizes the physical condition of the City’s existing raw water supply and
conveyance facilities. The purpose is to identify problem areas; review potential
rehabilitation requirements; and make recommendations for related capital improvements.
The information included was obtained from past inspection reports; discussions with City
staff (i.e., operations and engineering); and field observation of existing facilities.
Spavinaw/Eucha Supply
Spavinaw Dam, Spillway, and Intake
The City of Tulsa completed the construction of the lower Spavinaw Reservoir in 1924.
Some modifications to this facility were made during the construction of the second
Spavinaw project. The major modifications included raising the earthen fill section of the
dam to meet probable maximum flood conditions, relocation of the low lift pump, and the
addition of a chlorine injection station.
As mandated by State of Oklahoma requirements, the City of Tulsa performs annual and 5year periodic inspections of the dam, spillway, and intake structure at Spavinaw. The most
recent periodic inspection for this facility was performed on October 15, 1999. A synopsis of
the inspection findings (i.e., condition of the dam and associated structures) was obtained
from the City of Tulsa, and is summarized herewith.
During the October 1999 inspection it was observed that no flow was occurring over the
spillway section of the dam. The overall condition of the reservoir was good. The concrete
spillway is in good shape considering its length of service. The spillway has numerous
spalled areas and some vegetation, but no major leaks. No reinforcing is exposed to
weather. The upstream slope of Spavinaw Dam is in good condition with adequate and
sound rip rap, free of vegetation and saplings. The historic leak at the south abutment of the
dam has shown no increase from the previous year. The leak is approximately 4 feet south
of the south abutment, and continues to be monitored. The leak that was identified in 1996
at a joint on the downstream side of the non-overflow section, approximately 40 feet north
of the north abutment, is still being monitored. There has been no change in flow since the
upstream joint was pressure grouted. Erosion is occurring on the downstream slope at the
south abutment. The erosion appears to be the result of the removal of trees. The erosion
will be monitored and acted upon, if necessary. Some minor vegetation has been reestablished in this area, but more vegetation is needed to help stop the erosion. Numerous
minor spalled areas on the face of the spillway were noted. There is no increase from what
has been reported in previous years.
Eucha Dam, Spillway, and Intake
The construction of Lake Eucha was completed in 1952. Except for periodic maintenance
this project has remained essentially unchanged since its original construction. The most
recent inspection performed at Eucha Dam was October 15, 1999. A synopsis of the
inspection findings was obtained from the City of Tulsa, and is summarized herewith.
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During the dam inspection, no water flow was occurring over the spillway section of the
dam. The overall condition of the reservoir was good. The concrete spillway is in good
shape. It was noted that the spillway section has numerous spalled areas and some
vegetation, but no major leaks. There were no signs of reinforcing being exposed to the
weather in the spalled areas. The upstream slopes of Eucha Dam are in good shape with
adequate and sound rip rap, free of vegetation and saplings. The historic seepage below the
south abutment of the dam continues and is monitored. Five of the 16 toe drains are flowing
clear, while one toe drain is damp. There is a deep erosion hole located approximately ten
feet downstream of the dam and one-third of the dam length, south of the right abutment,
cutting itself toward the toe of the spillway. This erosion continues to be monitored, and it
was noted that there is no apparent movement of the erosion since the inspection in October
1998. The tainter gates on the spillway show minimal leakage
A project to remove vegetation, repair spalled areas, clean and reseal joints, and inject grout
at the Spavinaw and Eucha facilities is currently underway. This rehabilitation project,
which was advertised for bid in October 1999, has been awarded for a total contract amount
of $225,000. The City’s budget for this project is $290,000. Recent findings from construction
activities on this project, as reported by City of Tulsa Engineering staff, have revealed that
the conditions at Eucha Dam may be worse than originally anticipated. It was reported that
the current project budget may only be sufficient for completing the necessary repairs at
Eucha Dam. It is likely that the City will need to budget an additional $250,000 to complete
the rehabilitation work at Spavinaw.
Spavinaw Flowlines
As mentioned previously, hydraulic testing performed in 1952 revealed that the combined
capacity of the Spavinaw flowline system was 70 mgd. Testing done in May 1955 indicated a
4 mgd reduction in system capacity. It was speculated that this loss was due to the growth
of a fresh water sponge on the inside walls of the pipe. The present day delivery capacity of
the two pipelines is estimated to be 65 mgd by gravity.
Although the reinforced concrete pipe used to construct the first Spavinaw flowline is now
over 75 years old, these portions of the line do not exhibit any signs of degradation.
Interviews with maintenance personnel confirm the outstanding service of this conductor.
Reports of occasional minor joint leaks, occurring at random locations, are most likely due
to seasonal water temperature changes, which cause thermal expansion and contraction of
the line.
The pipe sections of the newer second Spavinaw flowline, installed 50 years ago, exhibit the
same mechanical integrity as the earlier line. Occasional and random minor leaks at joints
have been the most serious maintenance issue.
The 1.9 mile long tunnel through the Tiawah Ridge has been the area of most concern and
the focus of the majority of maintenance efforts. The inlet and outlet sections of the tunnel
have historically been the source of leaks, and periodic maintenance of the concrete tunnel
liner has been the largest expense in maintaining the flowline system.
The Tiawah Tunnel was inspected by DM/URS in January of 2000. Review of the data
contained in the draft report dated March 16, 2000, shows no obvious locations of unusual
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degradation, and there were no recommendations for major repair. Lining maintenance
work was conducted following the inspection to address the holes discovered.
Test towers, valves and gates used to regulate the flow and control the system are in
working order. Periodic valve re-packing and stem lubrication have kept these components
functional.
The only major repair work recommended for the flowlines would be to remove the original
booster pump stations at PS No. 1 by Grand River station, PS No. 3 by Canyon Lake station
and PS No. 5 by Mohawk No. 1 station. These abandoned facilities have deteriorated to the
point where maintenance on leaking concrete flow structures and broken pipes is causing
increasing maintenance expense. The facilities should be totally removed and new sections
of concrete flowline installed. The improved hydraulic characteristics would allow a minor
improvement in the delivery capacity of the system, during both gravity and pumped
conditions.
Spavinaw Booster Pumping System
The pump stations on the Spavinaw Flowlines are operated approximately 40 to 50 days per
year, under current demand requirements. Operation of the pumping system commences
when a level of 608 feet is detected in the Yahola Reservoir. Once placed in operation, the
system runs continuously, at a flowrate of 92 to 93 mgd, until the reservoir reaches its high
level of 610 feet.
System flowrate is established by adjusting the Mohawk No. 1 and No. 2 pumps. These
electric motor driven, variable speed pumps, discharge directly into Yahola Reservoir, and
pull suction from Bird Creek discharge surge tank. Individual station controls, starting with
the Bird Creek station, govern pump speed and water flowrate by maintaining the hydraulic
level at the discharge of each station. Suction surge tank level is a control override to keep
from pulling air into the system. Under this control arrangement all the pump stations east
of the Mohawk pumps respond to increasing or decreasing flow through the Mohawk
pumps.
The original pneumatic control system has been updated under TMWA 92-11. The City has
installed an electronic Supervisory Control and Data Acquisition (SCADA) system in each
pumping station. The system is functionally complete and operates satisfactorily, with no
anticipated changes.
The two original Mohawk station pumps were replaced in 1995/96 under TMWA 92-11,
Contract No. 2. Equipment condition is satisfactory, with no currently anticipated
maintenance required.
The pump stations at Bird Creek, Canyon Lake and Woods were modified in 1996/97 under
TMWA 92-11, Contract No. 3. Modifications to the pump controls and station electrical
service were completed to allow remote SCADA control.
The Grand River pump station was also modified under TMWA 92-11, Contract No. 3. The
modifications were more extensive and involved replacement of the two, propane-fueled
engines, the pump rotating element, and engine/pump controls. Steel grating, platforms,
water and fuel piping, heating and ventilation ducts, and electrical system changes were
also completed during this renovation.
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The Grand River pump suction cans have valving that allows water from either Spavinaw
Reservoir or Lake Hudson to be drawn into the system. The current operating procedure
requires that these valves be fully opened, or completely shut, to select either Spavinaw, or
Hudson water at each pump. The individual discharge flow meters allow separate metering
of each pump, and therefore, source flow. The variable speed engine drive allows for
selectable flow rate from each source, up to the maximum flow of each pump. This feature is
important as the City evaluates its options to take more water from the Lake
Hudson/Grand River system.
During the last period of pumping from the Lake Hudson intake, in 1981, the Grand River
pumps had to be operated at very high speeds to obtain water flows in the 92 to 93 mgd
range. Since the rotating element replacement, this situation should be corrected. A test of
this pumping mode should be done to verify performance, and new pump curves plotted.
Yahola Reservoir
The original Mohawk Lake constructed in 1928, and subsequent expansions during the 1945
- 1948 period resulted in the existing Yahola Reservoir which is a terminal raw water storage
facility for the City of Tulsa’s Mohawk Water Treatment Plant. Yahola Reservoir has no
watershed drainage area to provide supplemental water inflow. All water into Yahola
Reservoir, other than rainfall directly onto the reservoir surface, is transported by conduit
flow. The existing reservoir covers approximately 420 acres, and has a volume capacity of
2 billion gallons. The top of the earthen embankment is at elevation 610 feet, and the earthen
embankment has a height of approximately 20 feet.
The last Yahola Reservoir inspection was performed on November 14, 1999, by City of Tulsa
employees. The City of Tulsa Dam Inspection Report, filed with the State of Oklahoma
Water Resources Board, is summarized as follows.
Upstream Slope.
1. The repair of the paved slopes and sealing of the construction joints continue to be in
good condition.
2. Most sink holes behind the construction joints at the top of the paved slopes have been
filled.
Downstream Slope.
1. The erosion between the two backwash lagoons along the access drive cited in previous
reports has been addressed. The east backwash lagoon was drained, backfilled, and
compacted. The west backwash lagoon remains as detention for stormwater runoff.
2. The tree line should be moved back 50 feet from the base of the slope.
3. Numerous rodent holes were apparent on the southwest and west sides of the reservoir.
The rodent holes will be filled, contained, and monitored.
4. There appears to be an area on the downstream slope at the northeast part of the
reservoir near the pedestrian steps where seepage may be developing. This area has
been monitored all year long and will continue to be monitored. There appears to be a
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correlation between the dampness of the area and the water level of the reservoir,
although no hard data exists to suggest the lake level at which the dampness occurs.
Oologah Supply
Oologah Dam, Spillway, and Intake
To comply with federal mandates, the Tulsa District USCOE performs annual inspections,
and 5-year periodic inspections of its dams. The last periodic inspection of Oologah Dam
was performed in October 1998. A synopsis of this inspection was obtained from the Tulsa
District. The condition of the dam and the associated applicable structures is summarized
herewith:
The embankment remains in overall very good condition. The upstream riprap is beginning
to show signs of minor weathering, primarily near the normal conservation pool level. No
significant displacement of the rock was observed. The crest is in very good condition. The
downstream slopes are in very good condition. The gate tower appeared to be in overall
very good condition, with no significant deterioration noted in the concrete surfaces. The
gated spillway remains in very good condition. All gates were inspected for structural
integrity and operational capability prior to the periodic inspection with only minor
maintenance items found. Significant erosion occurred to the right bank outlet channel
during 1995 releases. The unstable slope on the right bank outlet has been investigated and
a design for a repair is complete. The earthfill dike appeared to be in very good condition,
with no sloughing, significant erosion or settlement noted on the slopes or crest. None of the
project instrumentation revealed an unsafe condition regarding the stability of the dam.
Oologah Raw Water Pump Station
The current design of the Oologah Raw Water Pump Station includes four (three 2,000 hp
and one 1,750 hp) vertical turbine, electrical motor driven pumps. The three 2,000 hp pumps
are single speed, and the fourth, a 1,750 hp, has a dual speed motor, which allows it to
deliver 30 or 60 mgd, when operated alone. Normal operation of the station includes one
pump under continuous duty, with swing operation of a second pump.
The three original constant speed pumps are in good mechanical condition. The fourth
variable speed pump is currently in the process of being commissioned, and should be
available for duty during the summer of 2000.
The first Oologah flowline, installed in 1977, was routed to and from the Bird Creek
pumping station on the Spavinaw system. This cross connect between the systems was
designed to allow for the diversion of Oologah Reservoir water to the Mohawk Water
Treatment Plant, and Spavinaw Reservoir water to the A.B. Jewell Water Treatment Plant.
The cross connection piping at the Bird Creek pump station has been changed from the
original design, and currently only allows approximately 30 mgd to be delivered to the
Mohawk Treatment Plant from the Oologah system.
To improve system flexibility, it is recommended that the original Bird Creek piping
configuration be restored to allow a greater delivery capacity to Mohawk, in the event of a
catastrophic failure, or extended outage of the Tiawah Tunnel, and if required, delivery of
Spavinaw water to A.B. Jewell. The original piping configuration allowed flow from the
Oologah lines to the Spavinaw lines through a 66-inch cross connection, capable of
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delivering in excess of 100 mgd to Mohawk, or 60 mgd from Spavinaw to A.B. Jewell. The
revised piping restricts the flow to two 24-inch connections capable of 30 mgd, with delivery
from Oologah to Mohawk only.
Oologah Flowlines
The first flowline from the Oologah Reservoir to the A.B. Jewell Reservoir was installed in
1977. The second line was added in 1987. The original line consists of 16.5 miles of 42-inch
diameter concrete pipe, from the Oologah Raw Water Pump Station to the Bird Creek pump
station, and 7.5 miles of 66-inch diameter steel pipe from Bird Creek station to A.B. Jewell
Reservoir. The second line consists of 17.7 miles of 72-inch diameter concrete pipe from
Oologah, and 4.8 miles of 54-inch concrete pipe to A.B. Jewell. The two lines are cross-tied in
three locations.
Both flowlines operate only under pumping conditions since gravity flow is not possible,
due to the lower elevation of the Oologah Reservoir. Both lines are in good mechanical
condition, including valves and air eliminators.
A.B. Jewell Storage Reservoir
The A. B. Jewell Reservoir is a terminal raw water storage facility for the City of Tulsa’s A.
B. Jewell Water Treatment Plant. The A. B. Jewell Reservoir was constructed in 1972, and
has no watershed drainage area to provide supplemental water inflow. All water into
reservoir, other than rainfall directly onto the reservoir surface, is transported by conduit
flow. The existing reservoir covers approximately 225 acres, and has a volume capacity of
1.2 billion gallons. The top of the earthen embankment is at elevation 675 feet, and the
earthen embankment has a maximum height of approximately 55 feet.
The last A. B. Jewell Reservoir inspection was performed on November 14, 1999, by City of
Tulsa employees. The City of Tulsa Dam Inspection Report, filed with the State of
Oklahoma Water Resources Board, is summarized as follows.
Upstream Slope.
1. Sink holes behind the splash wall construction joints have been filled and replacement of
joint sealant by City forces has proven adequate.
Downstream Slope.
1. New panels and the sluice gate have controlled the seepage that previously occurred
along the west wall of the reservoir.
2. The minor sloughing on the west side of the reservoir shows no change from previous
years.
3. Minor sloughing has occurred on the north slope near the pedestrian steps. This
sloughing has not changed from last year, but will continue to be monitored.
4. The numerous rodent holes along the lower east slope near the double air relief valve
and on the lower north slope near the pedestrian steps have been controlled.
5. The sloughing on the west bank of the west downstream slope has shown no changes
from previous years, but will continue to be monitored.
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6. The downstream slopes are clear of vegetation.
System Vulnerabilities
Spavinaw Flowlines
The Problem. The major vulnerability in the Spavinaw raw water delivery system is the
Tiawah tunnel. In the event of a prolonged outage of this tunnel both Spavinaw and Grand
River water sources would be undeliverable to either water treatment plant, leaving the
Oologah Reservoir and delivery system to supply all the needs. Because the treatment
capacity of A.B. Jewell WTP is limited to 120 mgd, some delivery of this water would have
to be made to Mohawk.
The Solution. Current piping restrictions at the cross connection in the Bird Creek Pump
Station limit this delivery to 30 mgd. Reinstallation of the original 66-inch connection would
increase the Oologah flow capability to 100 mgd to Mohawk. The operation of the Oologah
flowlines, with high rate delivery to both Mohawk and A.B. Jewell, would require the
operation of all four Oologah pumps. Under this scenario, a hydraulic model of the system
predicts the total supply volume to the two reservoirs of 128 mgd.
The Problem. The concrete in the old Spavinaw Line No. 1 booster stations has deteriorated
significantly, to the point where a large section of flow conduit could blow out. This could
result in an extended period where the total Spavinaw flow would be limited to the second
flowline. Delivery rate would be limited to 42 mgd under gravity flow, and 60 mgd under
pumped conditions.
The Solution. The City should consider awarding a contract to remove these stations, under
a scheduled timeframe to allow the orderly replacement of the flowline at these locations.
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Physical Condition of Potential Raw Water Supply Facilities
Keystone Dam Safety Inspection Program. The Tulsa District COE performs annual
inspections and 5-year periodic inspections of its federal dams to comply with the federal
mandate for such inspections. The last periodic inspection and report completed for this
project was in November 1996. A synopsis of this inspection was obtained from the Tulsa
District for this report, and the condition of the dam and associated applicable structures is
summarized herewith.
The dam and all of its appurtenant structures remain in very good condition with no
breakdown or displacement observed. The crest remains in good condition with no
significant movements or subsidence identified. The downstream turf is well established
and is providing adequate protection against erosion. The spillway and powerhouse
structures are in overall good condition with no significant change observed in the hairline
cracking within the structures. Moderate deficiencies on the tainter gates were noted during
the structural integrity inspection. Corrosion, ranging from minor to significant, was
observed on the downstream structural members of the gates. Some secondary members on
isolated gates will require metal replacement, and an entire repainting of all the gates will be
necessary to retard further deterioration of their structural integrity. The stilling basin was
sounded and inspected by divers during fiscal year 1995 (FY95) and no significant change
was noted in the condition of the basin. None of the instrumentation data indicates an
unusual condition regarding the safety of the dam.
Fort Gibson Lake Dam Safety Inspection Program. The last periodic inspection for this
dam is dated August 1999. A synopsis of this inspection was obtained from the Tulsa
District for this report, and the condition of the dam and associated applicable structures is
summarized herewith.
Both embankment sections and wraparounds are in good overall condition. The riprap on
the upstream slopes has deteriorated somewhat since the last inspection, but provides
ample protection to the embankments. No significant erosion was noted on the
embankments or abutments. The spillway remains in overall good condition. The tainter
gate and sluice gate operational capability inspections and structural adequacy inspection
were scheduled to proceed with the dam safety inspection, but were delayed due to weather
and high pool conditions. Also the diving inspections of the powerhouse intake, tailrace and
spillway stilling basin were delayed until October 1999 due to required flood releases. No
significant deficiencies were found during any of the supplemental inspections. None of the
instrumentation performed at the project indicates a problem concerning safety of the
structures.
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Tenkiller Lake Dam Safety Inspection Program. A synopsis of the Periodic Inspection
of the Embankment, Dike, Spillway, Outlet Works and Powerhouse for Tenkiller Ferry Lake
was obtained from the Tulsa District of the Corps of Engineers. The last periodic inspection
report is dated August 1999, and is summarized herewith.
The embankment and dike remain in overall good condition. The riprap slope protection
has deteriorated somewhat since 1994. Stone weathering appeared to be more evident,
primarily on the left half of the main embankment, and is considered adequate protection,
but should be visually monitored for additional deterioration and displacement. The crest of
the embankment and dike remains in overall very good condition. The downstream slopes
were in good condition. Some heavy vegetation and woody growth still remains on the
downstream embankment and abutment. Some of the growth will be removed during the
auxiliary spillway construction. The outlet works structures were all in very good condition
with only minor maintenance needed. The stilling basin was not unwatered, but the
exposed portions appeared to be in good condition. The gated spillway remains in very
good condition and only minor maintenance items were noted. A new auxiliary spillway
construction is in progress. None of the project instrumentation revealed an unsafe
condition regarding the stability of the dam.
Lake Eufala Dam Safety Inspection Program. A synopsis of the Periodic Inspection of
the Embankment, Spillway, and Powerhouse for Eufaula Lake was obtained from the Tulsa
District of the Corps of Engineers. The last periodic inspection report is dated October 1996,
and is summarized herewith.
The Project remains in overall very good condition. The upstream riprap is in overall very
good condition. Some individual stones have significant signs of weathering, but no
meaningful movement of the stone was observed. The downstream turf is in very good
condition. The spillway structure remains in good condition with no noticeable change in
any of the cracking and seeps. During a separate inspection, the tainter gates showed
significant corrosion and metal loss was observed on any minor members on several gates.
No loss of structural integrity was found, but the gates will require metal replacement,
cleaning, and repainting within the next 3 years to assure safe conditions prevail. None of
the project instrumentation revealed an unusual condition regarding the safety of the dam.
Copan Lake Dam Safety Inspection Program. A synopsis of the Periodic Inspection of
the Embankment, Spillway, and Caney Levee for Copan Lake was obtained from the Tulsa
District of the Corps of Engineers. The last periodic inspection report is dated September
1996, and is summarized herewith.
The Project remains in overall very good condition. The upstream riprap was in very good
condition with no deterioration of individual stones. The 1 on 8 berm continues to be a
maintenance problem due to wave and surface related erosion. A modification to
incorporate stone protection on the berm may be needed in the future. The embankment
crest is in fair condition. The overbuilt slopes have deteriorated. The downstream slopes are
in very good condition. Minor deficiencies have been discovered in the toe drain system that
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will require remedial efforts to assure the continued operation of the drain. The spillway
structure remains in very good condition. Structural and operational inspections of the
tainter gates revealed only minor deficiencies. The Caney levee is in very good condition.
None of the instrumentation data indicates a problem concerning the safety of the dam or
appurtenant structures.
Hulah Lake Dam Safety Inspection Program. A synopsis of the periodic inspection of
the embankment, outlet works, spillway, and dike for Hulah Lake was obtained from the
Tulsa District of the USCOE. The last periodic inspection report for this facility is dated
September 1998, and is summarized herewith.
The embankment is in overall very good condition. The upstream riprap is generally in very
good condition. Some minor deterioration and benching was observed. Desiccation cracking
has developed along nearly the entire length of the downstream slope break. A small skin
slide at the crest was observed, with a length of approximately 200 feet, and with a
maximum depth of disturbed soil of 2 to 3 feet. Construction of repairs was scheduled to be
completed by the summer of 1999. The downstream slope is in very good condition. The
spillway is in overall good condition. Spalling on many of the exposed concrete surfaces
appears to have deteriorated since the 1993 inspection. The saddle dike located right of the
main embankment remains in excellent condition. None of the Project instrumentation
revealed an unsafe condition regarding the stability of the dam.
Kaw Lake Dam Safety Inspection Program. A synopsis of the periodic inspection of the
embankment and spillway for Kaw Lake was obtained from the Tulsa District of the Corps
of Engineers. The last periodic inspection report is dated April 1995, and is summarized
herewith. The next periodic inspection report is scheduled for April 2000.
The overall condition of the dam remains very good. The upstream riprap remains in very
good condition. No adverse effects of the record pool of May 14, 1993 were noted. The
downstream slopes remain in good condition with well-established turf. The problem of
burrowing animals on the embankment continues. The seepage area near the toe of the left
abutment still remains a maintenance problem. The spillway remains in very good
condition. The non-federal powerhouse was inspected and remains in overall good
condition. None of the instrumentation data indicates a problem regarding the safety of the
dam.
Skiatook Lake Dam Safety Inspection Program. A synopsis of the periodic inspection
of the embankment, outlet works, and spillway for Skiatook Lake was obtained from the
Tulsa District of the Corps of Engineers. The last periodic inspection report for this facility is
dated August 1998, and is summarized herewith.
The embankment remains in overall very good condition. The upstream slope protection
remains in very good condition with only some minor weathering noted. Some erosion
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holes were observed along and adjacent to the concrete-lined ditches at both abutments. The
crest is in overall good condition. The outlet works gate tower is in very good condition. The
long-term problem with the hydraulic system to the emergency gates has been remedied.
No debris or significant erosion was noted in the stilling basin. There is evidence of minor
movement in the soil material above the tunnel since the last inspection in 1993. The visual
condition of the spillway has not changed from previous inspections. Studies have
confirmed the spillway will fail due to the erodibility of the exposed rock materials.
Funding for design to modify the spillway is scheduled for FY99 and for plans and
specification preparation in FY 00. None of the instrumentation data indicates an unusual
problem regarding the safety of the dam.
Birch Lake Dam Safety Inspection Program. A synopsis of the periodic inspection of
the embankment, outlet works, and spillway for Birch Lake was obtained from the Tulsa
District of the USCOE. The last periodic inspection report is dated April 1995, and is
summarized herewith.
The overall condition of the embankment and outlet works remains very good. The
upstream riprap and downstream turf are providing adequate protection for the
embankment. The crest was in very good condition with no visual indication of sloughing
or excessive settlement. The gate tower and service bridge are in good condition. The stilling
basin was not dewatered, but was surveyed in June 1994 and was determined to be in good
condition. The outlet channel was in good condition. The emergency spillway was in very
good condition. Some concern over the erodibility of the surface and underlying soil/rock
materials in the spillway will require additional investigation. None of the instrumentation
data indicates a problem regarding the safety of the dam.
Grand Lake Dam Safety Inspection Program. The Federal Energy Regulatory
Commission requires that GRDA, as a non-Federal Licensee, performs 5-year periodic
inspections of its licensed hydropower project to comply with the Federal mandate for such
inspections. The last periodic inspection report, prepared by The Benham Holway Power
Group of Tulsa, Oklahoma, is dated 1995. A synopsis was obtained from The BenhamHolway Power Group inspection report, and the condition of the dam and associated
applicable structures is summarized herewith. The complete report is available from GRDA,
Benham-Holway Power Group, or FERC.
The condition of the Pensacola Dam is generally satisfactory and capable of operating safely.
Visually, the dam, spillways, and powerhouse are in excellent condition for structures that
are over 50 years old. Since the project concrete structures are founded on rock, there is no
visible evidence of any recent distress attributable to settlement. There is no visual evidence
of recent distress, which would indicate movement of the Project structures. Minor erosion
of rock has occurred in the main spillway channel downstream of the apron, and some
erosion has occurred along the footing of the right training wall. Continuing erosion can be
expected, and is not serious at this time. Erosion along the right wall should be inspected
after major spillway releases. The powerhouse is generally free from any serious cracking in
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the interior, as is the exterior of the powerhouse. The spillways, including the main spillway
gallery have only very minor cracking. The inside of the arches and the buttresses have a
number of minor cracks which are apparently in the same general condition that has been
reported for many years. The dam is in good condition, and shows very minimal evidence
of deterioration.
Lake Hudson Dam Safety Inspection Program. The Federal Energy Regulatory
Commission requires that GRDA, as a non-Federal Licensee, performs 5-year periodic
inspections of its licensed hydropower project to comply with the Federal mandate for such
inspections. The last periodic inspection report, prepared by The Benham-Holway Power
Group of Tulsa, Oklahoma, is dated 1995. A synopsis was obtained from The BenhamHolway Power Group inspection report, and the condition of the dam and associated
applicable structures is summarized herewith. The complete report is available from GRDA,
Benham-Holway Power Group, or FERC.
Generally, there is no visual evidence of settlement in the transition non-overflow monolith
between the powerhouse and spillway. The Kerr Dam embankment crest does not show
visual evidence of settlement. There are no visual indications of movements or
misalignments in either the Robert S. Kerr structures or the Salina Dike. There are
indications of localized sloughing in the left abutment limestone about 105 feet upstream of
the powerhouse abutment contact. There is no evidence of extensive instability, which
would affect the integrity of the powerhouse abutment contact. There is no visible
indications of erosion which would adversely affect the Project. Project seepage observed
during the inspection was minimal. Seepage observed at the Kerr embankment was
confined to the right abutment and appears to be the normal condition observed over the
years. There was no significant cracking noted in the Robert S. Kerr embankment or in the
Salina Dike. Exterior structural cracking is limited to structural shrinkage cracking of the
horizontal surfaces such as the powerhouse deck, spillway, and non-overflow decks. There
were no significant cracks noted in the spillway gallery.
Salina Pumped Storage Project Dam Safety Inspection Program. The Federal Energy
Regulatory Commission requires that GRDA, as a non-Federal Licensee, performs 5-year
periodic inspections of its licensed hydropower project to comply with the Federal mandate
for such inspections. The last periodic inspection report, prepared by The Benham Holway
Power Group of Tulsa, Oklahoma, is dated 1994. A synopsis was obtained from The
Benham- Holway Power Group inspection report, and the condition of the dam and
associated applicable structures is summarized herewith. The complete report is available
from GRDA, Benham-Holway Power Group, or FERC.
There has been no settlement of Project structures that can be detected by visual inspection.
Embankment movements, measured on two lines of settlement-alignment monuments
indicated that embankment settlement stopped several years ago at a maximum settlement
of 5 to 6 inches. No movement of the Project structures was detected by visual inspection,
except at the expansion joint between Unit No. 6 and office bays in the powerhouse. The
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movement is minimal, and appears to have occurred since the May 1989 inspection. Some
minor movement in the east forebay structure wingwall has been noted in previous
inspections. Chimney Rock Dam is remarkably free from erosion and no significant erosion
was seen. The north end and abutment of Chimney Rock Dam was carefully inspected for
seepage and wet areas. There is some seepage on the lower abutment side of the groin and
damp areas along the toe, the embankment slope is dry. Evidently the seepage control
blanket placed in 1989-1990 is performing as intended. There was no cracking observed in
the crest of Chimney Rock Dam. There are cracks in the east wing and retaining wall of the
forebay which were first observed in 1982. There were no visible indications of recent
movement on these cracks. There are several cracks in the powerhouse which are not new,
but there is some uncertainty as to whether or not they are moving. There is evidence of
corrosion on stoplogs at the powerhouse and forebay structure and in connection with
leakage in the powerhouse. There is visual evidence of corrosion on stoplogs at the
powerhouse and in connection with leakage in the powerhouse. There is minor evidence of
concrete deterioration n the crest of the forebay. There is no evidence of foundation
deterioration associated with Project structures, except that the south abutment seepage
may be associated with increasing opening or washing out of flow paths through the
abutment rock. This is not a serious concern at present, but will require continuing
monitoring.
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