-2- January 23, 2018

• Assess the existing condition of the outlet works and identify any dam safety concerns and need for future repairs by the City.

• Collect information to support evaluation of the hydraulic capacity of the outlet works and alternatives for repair of identified deficiencies.

The purposes of this memorandum are to present our inspection findings for use in future work phases and to support Project repair or rehabilitation decisions. The inspection documentation (videos and photographs) are provided for record purposes.

1.3 Background

Cerro Reservoir Dam (DAMID 620105) is a high-hazard dam with a 675 acre-foot (ac-ft) reservoir located in Montrose County, Colorado. The dam is owned and operated by the City. Project stakeholders include the City of Montrose, Project 7 Water Authority, Uncompahgre Valley Water Users Association, Colorado Division of Water Resources (also known as the SEO), Colorado Parks and Wildlife, and Bostwick Park Water Consrevancy District. The Project site location is shown on Figure 1. The reservoir consists of three earthen embankment dams: western embankment, southern embankment, and eastern embankment. The outlet works is located through the western embankment and the spillway is located on the left abutment of the eastern embankment. The outlet works includes low-level and mid-level intake pipes, an upstream brick manhole, hydraulic-actuated gate valves (inside manhole), 8-inch-diameter outlet pipeline, downstream gate valves, and an outfall structure that directs flow into the raw water pipeline for deliveries to the Project 7 water treatment plant. The reservoir was enlarged in 1953 and the outlet works was modified in conjunction with the enlargement. It is our understanding that the 1953 modifications included an approximately 10-foot vertical raise to the earth embankment, addition of upstream slope protection, and modifications to the outlet works including an approximately 5-foot riser section on the brick manhole, and possibly improvements to the downstream end of the outlet pipeline. The original Project drawings are dated 1953 and 1954 and are included in Attachment 1. The Project drawings appear to be as-builts; however, based on observations in the field and discussions with the City, the drawings are not up to date and do not reflect as-constructed conditions at the dam. The discrepancies with the Project drawings included intake structure details, location of the west inline gate valve on the outlet pipe, and differing pipe material installed on the downstream end of the outlet pipe circa 1953 (see notes in Section 4). RJH annotated the Project drawings to capture inspection findings that differed from drawing details. Additional project documentation can be found in past inspection documents. RJH was provided the 2017 SEO Engineer’s Inspection Report and the 1980 Phase 1 Inspection Report prepared by International Engineering Co., Inc. The 2017 inspection represents the annual SEO inspection in accordance with Section 37-87-107 of the Colorado Revised Statutes and provides a comprehensive inspection of Cerro Reservoir Dam and appurtenances. The 2017 inspection includes inspection remarks for the dam features, recommended maintenance and repairs, noted items requiring action by Owner to improve the safety of the dam, and safe storage level recommendations. The 1980 inspection is a Phase 1 investigation of the dam in accordance with the requirements of the National Dam Safety Program as authorized by the National Dam Inspection Act, Public Law 92-367. The

-3- January 23, 2018

1980 inspection is a general assessment of the structural integrity and operational adequacy of the dam and its appurtenant structures. 1.4 Personnel The following is a summary of key participants involved in this work: Korey J. Kadrmas, P.E. Project Manager/Lead Field Inspector Michael L. Graber, P.E. Senior Technical Advisor Ben Czaplewski Lead Diver – Inland Marine Services(1) Note: 1. Subconsultant to RJH

Section 2 Inspection Planning and Proposed Activities A kick-off meeting was held via conference call between the RJH team, the City, and the SEO to coordinate the outlet works inspection and address site logistics and operational considerations. The kick-off meeting topics included a discussion of the Project communication protocols (project member roles and responsibilities), inspection activities including diving and ROV camera, data collection goals, consideration of trouble shooting possibilities such as access issues, diver obstacles or anticipated deficiencies with the existing outlet works facilities, and schedule discussions. Coordination of survey activities was also discussed and field work was scheduled for after the outlet works inspection (see Section 3.3). The planned outlet works inspection activities included:

• Diver inspection of the submerged facilities such as the intake structures, manhole, water control equipment, etc. to assess existing condition and performance. Condition assessment included identifying deficiencies such as sedimentation, corrosion, concrete deterioration, and structural damage.

• Visual inspection of non-submerged, above-ground outlet works facilities such as valve turnout boxes and the outfall structure. RJH will also perform an informal inspection of the western dam embankment to identify any dam deficiencies associated with the outlet works.

• Perform a ROV camera inspection of the outlet works to identify deficiencies such as corrosion, tuberculation (pipe corrosion mounds resulting in reduction in pipe area), joint separation, cracks, or other pipe defects.

• Survey of key outlet works facilities to confirm and obtain location and elevation information.

Section 3 Inspection Documentation 3.1 Video Video recording files of all conduit inspections will be transmitted under a separate cover with files loaded on a computer external hard drive. The video file sizes are large and would be difficult to access via an online file transfer site.

-4- January 23, 2018

3.2 Photographs Photographs of the inspection are limited to non-submerged, above-ground outlet works features. RJH has included a folder of inspection photographs on the electronic Project data DVD in Attachment 2. 3.3 Survey Del-Mont Consultants, Inc. was retained by RJH to perform topographic and structural survey at and near the Cerro Reservoir Dam in support of this Project. Survey work included exposed outlet works site features, temporary buoys in the reservoir denoting locations of intake structures and manhole on the upstream slope, and establishing three survey control monument points at locations considered permanent for use in future surveys and construction control. The outlet works site features surveyed including, but not limited to, the hydraulic actuation control vault on the dam crest, valve turnout boxes downstream of the dam, and the outfall structure including building, top of concrete foundation, pipe invert, and any other significant feature as directed by the City. The survey control monument points consisted of #5 steel reinforcement bar with an aluminum cap stamped with the survey details. Survey data was established for the following datum: • HORIZONTAL: Local datum based on modified Colorado State Plane. • VERTICAL: NAVD 88 in accordance with the requirements of Geospatial Positioning Accuracy Standards “PART 4: Standards for Architecture, Engineering, Construction (A/E/C) and Facility Management Section 4 Outlet Works Inspection and Assessment 4.1 General Observed Conditions The outlet inspection was performed on October 10 and 11, 2017. Weather was generally cold (30ºF to 50ºF), partially sunny, and windy. The inspection was performed under submerged and unsubmerged (i.e., dewatered) conditions and included these outlet works facilities:

• Submerged facilities:

o Low-level intake – consists of a concrete intake structure, 12-inch-diameter cast iron pipe, and gate valve (immediately upstream of the manhole).

o Mid-level intake – consists of a concrete intake structure, 12-inch-diameter cast iron pipe, and gate valve (immediately upstream of the manhole).

o Brick manhole – manhole (varied 3-foot and 4-foot size) in the upstream embankment housing the outfall ends of the intake pipes and hydraulic-actuated gate valve on the upstream end of the outlet pipeline.

o Gate control stem box – consists of a concrete encasement box for the low-level and mid-level gate stem extension sleeves. The box is covered with a metal plate and the gate stem sleeves are capped. The box is located immediately downslope (east) and adjacent to the brick manhole.

-5- January 23, 2018

• Dewatered facilities:

o Outlet pipeline – consists of an 8-inch-diameter pipe comprised primarily of cast iron pipe with a short section on the downstream end of Transite (asbestos cement) and steel pipe.

o Gate valves – two buried inline gate valves are present on the downstream end of the outlet pipeline to regulate reservoir releases through the outlet works. Currently, the City is operating the west valve and the east valve may be inoperable but in the fully opened position.

o Outfall structure – consists of a brick building enclosure housing the outlet pipe outfall and the raw water diversion pipe inlet.

o Hydraulic controls system concrete enclosure – consists of an above-ground reinforced concrete enclosure on the dam crest housing the hydraulic actuation system equipment and controls. Most of the equipment has been abandoned or is missing.

• A plan view of the outlet works system and surveyed features are shown on Figure 2. Following is a summary of general observations from the outlet works inspection:

• Relative measurements of the dam and reservoir were taken to confirm elevations on the Project drawings. Following is a summary of these measurements:

o The reservoir water elevation was approximately 7 feet below the western dam crest and 2 feet below the principle spillway flowline elevation. There is no reservoir staff gauge to reference the water surface to an elevation.

o The spillway invert was approximately 5 feet below the eastern dam crest.

o The locations of the intake structures and brick manhole on the upstream slope were estimated using laser rangefinder binoculars and appeared to match the distances shown on the Project drawings.

o The depths of the intake structures were measured with the diver pneumofathometer hose and gage. The top of the mid-level and low-level structures were estimated to be about 30 and 38 feet deep, respectively. Those measurements generally correspond to the structure elevations on the Project drawings.

• The submerged low- and mid-level intake conduits and brick manhole were not dewatered and an underwater inspection and assessment were performed.

• A construction dive team from Inland Potable performed the underwater portion of the outlet works inspection and assessment. The divers were equipped with video cameras and lights attached to dive helmets and two-way audio communication between the submerged divers and the RJH staff located in the dive trailer on the dam crest. The divers received real time instructions and direction from RJH staff via two-way audio communication.

• The sequence of items inspected included the top of the brick manhole, mid-level intake, low-level intake, and inside of the brick manhole. The video inspection of these features can be found on the video titled “Cerro 10-10-17.”

• The intake structures were inspected by the divers; however, the intake conduits could not be inspected with the ROV camera because of significant sediment buildup at the entrances to the conduits.

-6- January 23, 2018

• Divers were able to enter the brick manhole once debris and inoperable steel hydraulic lines were moved. Access to the lower manhole section was difficult and restricted to the smallest diver. Also, movement inside the manhole was limited.

• The outlet pipe was dewatered and inspected with the ROV camera. The sequence of activities to dewater the outlet included:

o Confirmation that downstream valves are closed.

o A diver entered the manhole and installed a high-pressure mechanical pipe plug (maximum 150 psi) at the upstream end of 8-inch-diameter discharge conduit. The video inspection of plug installation can be found on the video titled “cerro install plug.”

o The west in-line gate valve being slowly opened to drain the outlet pipe. The west inline gate valve is typically in the closed position so the City fully opened the valve to drain the outlet pipe.

• The outlet pipe was inspected with a ROV camera with the pipe generally dewatered. The ROV consisted of a remote controlled, wheel-driven underwater camera that was used to video inspect the dewatered outlet pipe. The camera lens was articulated and could be panned to obtain a 360-degree view of the conduit interior surfaces. The ROV wheels were studded since the ROV was experiencing instability and slippage with non-studded rubber wheels. All collected video imaging was digitally recorded. Upon completion of the inspection and upon direction from the City, the plug was deflated and left in place as part of an emergency reservoir operation and monitoring plan. A high pressure air hose was installed from the mechanical plug to the concrete valve operator box located on the dam crest. If the need should arise, the mechanical plug can be easily re-inflated and the outlet conduit detwatered without the need for divers. The video inspection of outlet pipe interior can be found on the video titled “cerro crawler camera.”

4.2 8-Inch-Diameter Outlet Pipe According to the Project drawings, the modified outlet conduit consisted of the original 8-inch-diameter cast iron pipe with a length of 307.4 feet and a newer downstream section of added 8 inch-diameter pipe that includes 36 feet of cast iron pipe and 57.7 feet of Transite pipe (Johns-Manville brand name for Asbestos Cement Pipe). The Project drawings shown the east in-line gate valve at the downstream end of the original outlet pipe and the west in-line gate valve inside the outfall structure near the downstream end of the outlet works. Discrepancies were observed during the inspection with the outlet works components and the inspection video recorded distances, pipe material types, and interior surface conditions. Deviations against the original Project drawings and corrections are noted below and annotated Project drawings are provided in Attachment 1. Distances were measured from the discharge end of the conduit located in the valve house. Observed outlet pipe conditions and relative pipe stations are as follows:

• Pipe Section: 0 - 25 feet

o This pipe section consists of an 8-inch-diameter steel pipe from the discharge (i.e., daylight) end to the west in-line gate valve, which is currently used to regulate flow and was confirmed operational during the inspection by exercising through a full cycle.

o This pipe section was in relatively good condition with minor to moderate corrosion.

-7- January 23, 2018

o Pipe staining from water flow was observed along the bottom portion of the pipe.

o Pipe joint offsets were observed at approximately 4 feet.

• In-line Gate Valve at 25 feet

o The functional west in-line gate valve is at approximately 25 feet.

o The valve seats appeared to be in good condition with no visible defects.

o No leakage from the valve was noted prior to dewatering the outlet pipe.

• Pipe Section: 25 - 66 feet

o This pipe section is a 41-foot length of 8-inch-diameter Transite (Asbestos Cement) and was found to be on good condition with no holes or cracks.

o A sealed pipe tap was observed at the crown of the pipe at approximately 27 feet.

o A pipe joint at approximately 30.1 feet was observed with a joint separation and offset. A crack in the invert was also observed at this location. Drainage water appeared to be flowing into the pipe invert crack and exiting the outlet pipe.

o Pipe joint spacing varied from 5 feet to 15 feet.

o Negative camber (e.g., a “sag” or “belly”) was observed between approximately 45 to 55 feet with water up to about 2 inches deep. No visible major pipe defects were observed (e.g., cracking, ruptures, etc.); except for a pipe joint at approximately 51.7 feet with an approximately 1/4- to 1/2-inch joint separation.

• In-line Gate Valve at 66 feet

o The pipe joint was observed at approximately 66 feet to have water leakage at the pipe invert. The condition of the pipe significantly worsens upstream of this location (see notes below).

• Pipe Section: 66 - 101.4 feet

o This pipe section is a 35.4-foot length of 8-inch-diameter cast iron pipe, according to Project drawings, that was installed during the 1953 reservoir enlargement and terminates at the original east in-line gate valve.

o The pipe had moderate corrosion with moderate tuberculation nodules observed throughout the pipe section.

o A crack approximately 1/8- to 1/4-inch wide and generally around the perimeter of the pipe wall was observed with water leaking out of the pipe.

o A slight pipe joint separation and offset was observed at approximately 83.1 feet with severe corrosion at the joint and water leaking out of the pipe.

• In-line Gate Valve at 101.4 feet

o The east in-line gate valve is at approximately 101.4 feet.

o The gate was not functional and the valve seats appeared to be worn and partially filled with dislodged pipe corrosion and sediment.

o Water leakage appeared to be occurring at the invert of the gate valve.

o The bottom of the gate disc was visible and appeared to have significant corrosion on the seating surfaces.

-8- January 23, 2018

• Pipe Section: 101.4 – 102.9 feet

o 1.5-foot length of 8-inch-diameter cast iron pipe was apparently installed during the reservoir enlargement circa 1953. The pipe section upstream of this location is the original 8-inch cast iron outlet pipe. This pipe section was observed upstream of the valve and appeared to be in a similar condition as the downstream pipe demonstrating it was likely installed at that time.

o The pipe joint at this location had a noticeable joint offset observed in the bottom half of the pipe.

• Pipe Section: 102.9 - 406.84 feet

o This pipe section is a 303.5-foot length of 8-inch-diameter cast iron pipe installed during the original dam construction (date unknown).

o Severe corrosion and tuberculation was observed throughout the full length of this pipe section. The tuberculation made it difficult to observed the pipe joint conditions and if there were any cracks or separations at the joints. Pipe joint displacements with water leakage were observed at 114.8, 128.1, 139.3, 151.1, 162.8, 175.6, 223.6, 237.0, 260.4, 271.8, 284.9, 296.2, 308.7, 321.9, and 347.2 feet. Likely more pipe joints exist but could not be confirmed because of the severe tuberculation and high water level in the upstream end of the pipe.

o The severe corrosion appears to have reduced the interior diameter (area) of the pipe; however, the extent of reduction is unknown but could be an inch or more.

o A corroded metal object was observed laying on the pipe invert at approximately 165.5 feet. The camera was able to drive over the object.

o Negative camber in the pipe was observed from approximately 170 to 280 feet with water up to approximately half depth of the pipe.

o Negative camber in the pipe was observed at approximately 350 feet and gradually increased until the water completely covered the camera lens at 370 feet. The camera remained submerged to the upstream end of the pipe at 406.4 feet.

o The high-pressure plug was observed at the upstream end of the pipe.

• The total measured length of the outlet pipe was approximately 406.4 feet, which generally agrees with the Project drawings.

• A number of pipe joints had cracks at the joint that appeared to have water leakage exiting the pipe. The cracks were not large and the joints were not significantly separated.

• No infiltration into the outlet pipe was observed but there were two relatively long sections of pipe that had standing water from approximately a half full pipe to a near completely full pipe. Infiltration could be occurring in the submerged pipe sections and not be visible.

4.3 Brick Manhole with Hydraulic Gate Valves The-brick manhole was inspected with divers; however, full inspection of the manhole structure and hydraulic actuated gate valves was not possible because of poor visibility and the narrow size of the manhole and obstructions limiting diver movement inside the manhole. The manhole was consistent with the 1953 drawing details that showed a 3-foot-diameter section installed during the dam raise circa 1953 on top of the original 4-foot-diamater manhole.

-9- January 23, 2018

The divers encountered wood boards and hydraulic lines that hampered access into the 4-foot-diameter (i.e., lower) manhole. A wood board was cut and removed and the hydraulic lines were pulled to the side to clear space for the diver to access the lower manhole section. Inside the lower manhole, the diver’s movement was limited in the locations of the hydraulic actuated gate valves. Significant cracking of the manhole bricks was observed inside the manhole resulting in concern about the structural integrity of the manhole. Divers indicated there may be missing bricks but this could not be confirmed. The gate valves were located on both discharge ends of the intake conduits and on the upstream end of the outfall pipe; however, the intake valves could not be reviewed by the diver. The cover on the concrete box attached to the east side of the brick manhole was removed and the structure was in good condition. The control stem covers were in place, but were not removed for inspection because the gate valves are inoperable. 4.4 Low Level Intake – Structure, Conduit, and Control Valve The low-level intake structure was inspected with divers; however, significant sedimentation and poor water visibility made a full inspection not possible. The low-level structure is located at the upstream toe of the western embankment with a vertical headwall and no sidewalls. The lack of side walls causes sediment build-up from embankment sloughing and erosion. A pneumatic depth measurement was taken and the top of structure was approximately 38 feet below the existing water surface. The intake structure appears to consist of a conventional concrete headwall and masonry brick inlet. The headwall of the masonry brick inlet structure was measured to be about 3 feet wide and 2 feet high. Dimensions of the intake headwall could not be made because of limited visibility. Observed sediment consisted of silt and hard clay that has caused the intake to become partially blocked. Divers attempted to measure the depth of sedimentation and remove the sediment with air blasting to access the intake conduit; however, this was not possible because of the hard clay and sediment side slopes were steep (i.e., mounded) and quickly infilled when sediment was removed. Air blasting contributed to the poor visibility. Sedimentation was estimated to be several inches (maybe 4 inches) inside the structure based on diver observations and this made inspection difficult. The trashrack was vertically installed and appeared cast into the intake side walls, which differs from the 1953 drawing details. An inspection photograph in the 1981 Phase 1 Inspection Report confirms this configuration. The entire trashrack was generally covered with severe corrosion and rust nodules. The diver was unable to survey the full extents of the trashrack because of poor water visibility. The diver made the determination that the structural steel appeared sound; however, because of the limited visibility we were not able to perform a full inspection and determine if there were any compromised structural members. The diver was able to observe the top portion of the intake structure headwall (conventional concrete) and the masonry brick inlet. The full extents of the structure could not be inspected because of poor water visibility. The 1953 Project drawing details indicate the structure was comprised of conventional concrete; however, this could not be confirmed during the dive. Limited details generally matching are shown in the 1981 Phase 1 Inspection Report photographs. The headwall had several locations of significant concrete spalls and a large vertical crack near the center of the wall ranging from 6 inches wide at the top to 1 inch wide at the bottom of the wall. The left corner of the inlet structure was missing a significant amount of bricks. The structural integrity of the wall appears to be compromised and replacement of the structure should be considered.

-10- January 23, 2018

4.5 Mid-Level Upstream Intake Conduit, Structure , and Control Valve The mid-level intake structure was inspected with divers; however, sedimentation and poor water visibility made a full inspection not possible. The mid-level structure is located on the lower third of the western embankment upstream slope. A pneumatic depth measurement was taken and the top of structure was approximately 30 feet below the existing water surface. The intake structure appears to consist of a conventional concrete headwall with masonry brick inlet. The headwall of the masonry brick inlet structure was measured to be about 3 feet wide and 2 feet high. Dimensions of the intake headwall could not be made because of limited visibility. Observed sediment consisted of silt and hard clay that has caused the intake to become partially blocked. Divers attempted to measure the depth of sedimentation but this was difficult due to the hard consistency of the sediment and murky water visibility as a result of air blasting the sediment for removal. Sedimentation was estimated to be several inches (maybe 4 inches) deep at the inlet. Full inspection of the structure was not possible. The trashrack was vertically installed and appeared cast into the intake sidewalls, which differs from the 1953 drawing details. An inspection photograph in the 1981 Phase 1 Inspection Report confirms this configuration. The entire trashrack was generally covered with severe corrosion and rust nodules. The diver was unable to survey the full extent of the trashrack because of poor water visibility. The diver made the determination that the structural steel appeared sound; however, because of the limited visibility we were not able to perform a full inspection and determine if there were any comprised structural members. The diver was able to observe the top portion of the intake structure headwall (conventional concrete) and the masonry brick inlet. The full extent of the structure could not be inspected because of poor water visibility. The 1953 Project drawing details indicate the structure was comprised of conventional concrete; however, this could not be confirmed during the dive but limited details shown in the 1981 Phase 1 Inspection Report photographs appear to be similar. The headwall had several locations of significant concrete spalls and the inlet was missing a few bricks. The structural integrity of the wall could not be confirmed in this dive but should be further evaluated if a rehabilitation concept is selected. 4.6 Hydraulic Actuation System and Ancillary Components The hydraulic actuation system was in an inoperable condition and the components appear to be abandoned. The hydraulic actuation system consists of a concrete vault with hydraulic controls at the dam crest, and hydraulic lines that extend to the submerged water control slide gate valves inside the brick manhole. The slide gate valves control flow through the intake conduits and outlet pipe and as noted in those individual sections, do not appear operational. The concrete vault cover and other hydraulic equipment appears to be missing. 4.7 In-line Gate Valves and Turnout Boxes The outlet works is currently controlled with 8-inch-diameter, in-line gate valves on the downstream side of the outlet pipe near the outfall structure. The west gate valve is located approximately 25 feet from the pipe outfall and was found to be in operable condition. The east gate valve is located approximately 101 feet from the pipe outfall and was difficult to operate so the valve was deemed inoperable until properly maintained. The camera inspection of the interior valve bodies was documented in Section 4.2. The valve turnout boxes had minor to moderate corrosion but were in a functional state. The west gate valve is in satisfactory condition but has experienced moderate operational wear,

-11- January 23, 2018

while the condition of the east gate valve is unknown, but may be inoperable and requiring replacement. 4.8 Outfall Structure

The outfall structure consists of a masonry brick building with steel door and roof. The building was in good condition and no major maintenance items identified. The interior floor of the building consists of a shallow concrete wet well for the outlet pipe outfall and the water treatment plant delivery pipe inlet, which were found to be in satisfactory condition. The wet well is covered with steel grating that has exhibited minor corrosion. No major maintenance or replacement items were identified. Section 5 Inspection Findings and Conclusions Based on the work performed for the outlet works inspection, RJH offers the following findings and conclusions:

1. The 8-Inch-diameter outlet pipe is in a severely deteriorated state and several structural deficiencies were observed that could compromise the pipe under a normal hydraulic (pressurized) loading condition. The pipe interior diameter on the original pipe has been reduced due to severe tuberculation and could limit the ability of a slip-lining pipe rehabilitation.

2. The low-level and mid-level intake structures were in poor shape and demonstrated structural deficiencies including:

a. Moderate concrete deterioration at various locations.

b. Missing significant portion of the masonry brick inlet headwall on the mid-level structure.

c. A significant vertical crack was observed on the low-level structure headwall.

d. Trashracks were severely corroded and should be replaced.

e. Significant sedimentation is occurring in the structures and may no longer be functional.

3. The brick manhole was in a severe deteriorated state and significant structural defects (e.g., cracks and missing bricks) were observed on the original brick manhole. Also, the limited space inside the manhole will restrict rehabilitation concepts and poses a safety risk to dive teams.

4. The upstream (submerged) water control valves and hydraulic control system was inoperable and several components were in poor condition or distress. The only functional water control component was the west in-line gate valve, but was observed to be in a deteriorated condition. The water control equipment has likely served its intended service life and should be replaced.

5. The existing outfall structure was found to be in good condition and could be salvageable for any future outlet works rehabilitation or replacement project.

6. RJH has concern that the existing outlet works could exhibit several failure

possibilities (i.e., modes) and poses significant dam safety risk that should be further evaluated and addressed in a timely manner. The SEO has noted in the 2017 inspection that the pressurized outlet works poses a dam safety concern and the outlet works findings presented in the memorandum identifies structural issues with the outlet works and do not resolve the SEO concerns.

-12- January 23, 2018

7. RJH will present the findings and conclusions presented in this memorandum with the City and SEO at an Alternatives Evaluation workshop to assess risk reduction with the dam along with possible advantages and disadvantages for outlet works rehabilitation and complete replacement concepts.

Figures:

Figure 1 Site Location Figure 2 Outlet Works and Surveyed Features Plan

Attachments:

Annotated Project Drawings DVD of Inspection Photos

KJK/tjp

£¤50

PROJECT VICINITY MAP(NOT TO SCALE)

PROJECT LOCATION MAP(NOT TO SCALE)

SITE LOCATION MAP(NOT TO SCALE)

GrandJunction

Pueblo

Ft. Collins

Burlington

§̈¦25

§̈¦70§̈¦70§̈¦76

!(

!(

£¤50

£¤550

SITE LOCATION MAPSJanuary 2018

CERRO RESERVOIRDAM

PROJECT NUMBER 17130 Figure 1

P:\17

130 -

Cerr

o Res

ervoir

\Engin

eerin

g\GIS

\Fig_

1.1-S

ite_L

ocati

on.m

xd

CERRO RESERVOIRDAM

MESACOUNTY

ColoradoSprings

DELTACOUNTY

SAN MIGUELCOUNTY

Denver

MONTROSECOUNTY

OURAYCOUNTY

³

^MONTROSE

TO MONTROSE

ATTACHMENTS

ANNOTATED PROJECT DRAWINGS

DVD OF INSPECTION PHOTOGRAPHS