warren reservoir (lower) dam · 2017-11-24 · the warren reservoir (lower) dam is about 130 feet...

-- WARREN RESERVOIR (LOWER) DAM -- VISUAL

INSPECTION / EVALUATION REPORT

Dam Name:

State Dam ID#:

Owner:

Town:

Consultant:

Date of Inspection:

Warren Reservoir (Lower) Dam 479 Bristol County Water Authority Warren Pare Corporation July 20, 2012

Warren Reservoir (Lower) Dam

Inspection Date: July 20, 2012 Insp Report 479-Warren Reservoir (Lower) Dam i

INSPECTION SUMMARY

Dam Name (No): Warren Reservoir (Lower) Dam (479) Location: Warren Hazard Classification: Significant Inspector: David M. Matheson, P.E. Inspection Date: July 20, 2012

When describing the dam, “left” and “right” refer to the respective sides of the dam as viewed when facing downstream (with normal flow of water).

DAM LOCATION41.72974ºN 71.26305ºW WARREN, RI BRISTOL QUADRANGLE


Inspection Date: July 20, 2012 Insp Report 479-Warren Reservoir (Lower) Dam iii

TABLE OF CONTENTS Page No. INSPECTION SUMMARY i PREFACE ii 1.0 DESCRIPTION OF PROJECT 1

1.1 General............................................................................................................ 1 1.1.1 Authority 1 1.1.2 Purpose of Work 1 1.1.3 Definitions 1

1.2 Description of Project ..................................................................................... 1 1.2.1 Location 1 1.2.2 Owner/Caretaker 2 1.2.3 Purpose of the Dam 2 1.2.4 Description of the Dam and Appurtenances 2 1.2.5 Operations and Maintenance 3 1.2.6 Hazard Potential Classification 3

2.0 INSPECTION 4 2.1 Visual Inspection ............................................................................................ 4

2.1.1 General Findings 4 2.1.2 Dam Embankment 4 2.1.3 Appurtenant Structures 5 2.1.4 Downstream Area 6 2.1.5 Reservoir Area 6

2.2 Caretaker Interview ........................................................................................ 7 2.3 Operation and Maintenance Procedures ......................................................... 7

2.3.1 Operational Procedures 7 2.3.2 Maintenance of Dam and Operating Facilities 7

3.0 ASSESSMENTS AND RECOMMENDATIONS 8 3.1 Assessments .................................................................................................... 8 3.2 Recommendations .......................................................................................... 9 3.3 Alternatives .................................................................................................... 10

ATTACHMENTS: Definitions References and Resources Photographs

Figure 1: Site Sketch

Warren Reservoir (Lower) Dam Description of Project

Inspection Date: July 20, 2012 Insp Report 479-Warren Reservoir (Lower) Dam 1

1.0 DESCRIPTION OF PROJECT 1.1 General

1.1.1 Authority The RIDEM Office of Compliance and Inspection has retained Pare Corporation of Foxboro, Massachusetts and Lincoln, Rhode Island to perform a visual inspection and develop a report of conditions for the Warren Reservoir (Lower) Dam along the Kickamuit River in Warren, Rhode Island. This inspection and report were performed in accordance with current Rhode Island laws.

RIDEM will develop an overall condition rating based upon the data presented herein. It is understood that this rating will consider operational and structural deficiencies and will be presented under separate cover.

1.1.2 Purpose of Work The purpose of this investigation was to inspect and evaluate the present condition of the dam and appurtenant structures in accordance with current dam safety regulations to provide information that will assist in both prioritizing dam repair needs and planning/conducting maintenance and operation.

The investigation was divided into three parts: 1) obtain and review reports, investigations, and data pertaining to the dam and appurtenant structures available within the Rhode Island Department of Environmental Management files; 2) perform a visual inspection of the site; and; 3) prepare and submit a final report presenting the evaluation of the structure, including recommendations and remedial actions.

1.1.3 Definitions

To provide the reader with a better understanding of the report, definitions of commonly used terms associated with dams are provided in Appendix B. Many of these terms may be included in this report. The terms are presented under common categories associated with dams which include: 1) orientation; 2) dam components; 3) hazard classification; 4) general; and 5) condition rating.

1.2 Description of Project

1.2.1 Location The Warren Reservoir (Lower) Dam is located in the Town of Warren approximately 1.0 mile west of the Town’s center. The dam impounds water along the Kickamuit River to form the Warren Reservoir and is located at the southeastern end of the impoundment area near coordinates 41.72974ºN/71.26305ºW. Please refer to the inspection summary for a locus plan depicting the area of the dam and its immediate surroundings. To reach the dam, head east on I-195 away from Providence, RI, or head west on I-195 away from Fall River, MA. In Massachusetts, take exit 2 and head South on MA-136 South/James Reynolds Road and continue to follow MA-136 for roughly 1.5 miles before crossing into Rhode



Island. Once in Rhode Island the road will be RI-136; follow this for 2.0 miles before turning left onto RI-103 East/Child Street. After approximately 0.4 miles the dam and impoundment will be on the left.

1.2.2 Owner/Caretaker The dam is currently owned and operated by the Bristol County Water Authority (BCWA). Ms. Pamela Marchand the Owner’s Executive Director and Chief Engineer can be reached at 401-245-2022 Ext. 19.

1.2.3 Purpose of the Dam The dam currently impounds water for water supply purposes and was reportedly constructed in 1883. No other purposes past or present were identified during the preparation of this report.

1.2.4 Description of the Dam and Appurtenances

The following is based upon information contained within the RIDEM files and observations made during the inspection:

The Warren Reservoir (Lower) Dam is about 130 feet long and consists of a 55 foot wide

spillway structure starting at the left abutment and an approximate 75 foot long earthen embankment with the right abutment at the west bound (east) shoulder of Child Street, two (2) tidal gates, and a fish passageway structure. The function of the dam is to reduce salt water backflows from coming into the impoundment during tidal influxes.

The earthen embankment is triangular shaped and is supported and protected upstream by a

concrete capped stone masonry wall, is grass covered along the crest, and is grass and weed covered along the earthen downstream slope that winds downstream and to the left towards the downstream channel between the primary spillway and Child Street.

The primary spillway consists of a series of 20, 30" wide, 30" high flap gates hinged at the top

and installed below a continuous vertical plate that connects to concrete abutments and is supported by a concrete cap and individual concrete piers founded on a concrete slab bearing within the river bottom. The steel plate, about 29 inches high, is anchored at its base onto the concrete cap and is braced on its bottom third with steel rakers anchored in the downstream area (the former rakers used to brace the spillway are still in place though rotted along their base). The flap gates are each supported above by a bolt and nut. The connection at the bottom of the flap gates were not viewed as they were underwater at the time of the inspection. It doesn’t appear that the spillway structure regulates the level of the impoundment as the top of the crest above the flap gates is even with the top of the training walls and top of the embankment crest. It appears that this structure will serve to discharge water from the impoundment during times of extreme flooding or for maintenance purposes.

The low level outlet consists of a lift gate located within a concrete structure right of the

primary spillway but to the left of the upstream end of the fish ladder. The concrete structure consists of two training walls starting at the impoundment and fitting into the upstream concrete wall on the right and an upstream stone masonry wall to the left. A trash rack consisting of steel (or aluminum) grating is fitted between the training walls via slots formed within the inside face of these walls. About 2 feet downstream of the trash rack is the gate structure which is operated by a detachable hand wheel that turns a geared lifting mechanism. The lifting mechanism is mounted onto a concrete slab that bridges across the two training walls and a headwall slightly downstream. The outlet to the low



level outlet is reportedly located within 20 feet (+/-) of the primary spillway; however, this could not be verified as this area was underwater at the time of the inspection.

About 25 feet right of the primary spillway, a fish passageway, constructed of concrete

channel walls and timber baffles, cuts perpendicularly through the embankment for about 35 feet before turning 90 degrees to the left and extending into the downstream channel.

1.2.5 Operations and Maintenance

BCWA, the Owner, is primarily responsible for operations and maintenance at the dam, including undertaking routine maintenance of vegetation along the length of the dam, completing regular inspection, and completing other maintenance as required.

1.2.6 Hazard Potential Classification In accordance with current classification procedures under State of Rhode Island dam safety rules and regulations, Warren Reservoir (Lower) Dam has been classified as a Significant hazard potential dam by RIDEM.

Warren Reservoir (Lower) Dam Inspection


2.0 INSPECTION 2.1 Visual Inspection Warren Reservoir (Lower) Dam was inspected on July 20, 2012. At the time of the inspection, the weather was near 45F and mostly cloudy. Photographs to document the current condition of the dam were taken during the inspection and are included in Appendix A. The level of the impoundment appeared to be about 19 inches below normal operating levels, which is defined as the top of the flap gates within RIDEM’s Dam Inventory Coding Sheet for this dam. Underwater areas were not inspected as part of the field activity. For reference purposes, a baseline was established along the crest of the dam embankment. Station 0+00 was located at the left abutment with the baseline extending to Station 1+30 at the right abutment. Observations are reported in relation to their location along the baseline as noted herein.

2.1.1 General Findings In general, Warren Reservoir (Lower) Dam was found to have a deteriorated primary spillway with leaking flap gates, cracked training walls, and an overgrown left abutment contact; tree growth along the right abutment contact, deteriorated and undermined concrete at the low level outlet, an upstream wall with aged jointing and emerging growth within joints, and other dam safety deficiencies. The specific concerns are identified in more detail in the sections below:

2.1.2 Dam Embankment

The embankment at the dam consists of an earthen section in generally satisfactory condition. It appears that the Owner is maintaining the dam; however, some deficiencies beyond routine maintenance appear to exist. The following was noted during the inspection: Upstream Side

The stone masonry wall along the impoundment right of the dam is in satisfactory condition with aged but intact mortar, good alignment, and no ground surface depressions observed behind the wall. Underwater areas were not viewed.

A tree stump was observed at the base of this wall about 15 feet right of the fish ladder with no resulting movement of the wall. Between the area of the stump and the right abutment, vegetation is growing out of the masonry section above the water with no displacement observed.

The wall continues past the right abutment to support the west-bound shoulder of Child Street with no unusual movement at the right abutment contact area.

The left side of the upstream wall is cast into the concrete structure that supports the fish ladder inlet. This connection interface appears in good condition.

Crest

The surface of the crest appears to have a good alignment and is covered with well-maintained grass.



No animal burrows, depressions, rutting, or puddling was observed. A medium sized (18”+/- diameter) tree is growing near the right abutment. The surface near the right abutment contact appears good with no cracking or unusual

movement observed. The left side of the crest abuts the fish ladder with good contact observed.

Downstream Slope

The downstream slope is protected by stone rip rap along the base and is in good condition with no depressions and even coverage observed.

The top of the downstream slope is covered with well-maintained grass. No animal burrows were observed. No seepage was observed; however, the tail water was at high tide, which submerged part of

the downstream toe; therefore, underwater areas could not be inspected. The downstream slope was observed to have a good vertical and horizontal alignment. The right abutment contact area is identified as the fence line along the east –bound shoulder

of Child Street. A medium size tree was observed growing near the top of the slope in this area.

The surface area at the right abutment contact looks good with no cracking or unusual movement observed.

The left side of the downstream slope abuts the fish ladder with good contact observed.

2.1.3 Appurtenant Structures Primary Spillway

The surface of the flap gates and steel plate are corroded along the surface but appear structurally sound.

The alignment of the primary spillway looks good. There is leakage noted along the base of the spillway through the flap gates at less than 3

GPM just above the downstream water line. The flap gates appear structurally sound. Operation of these gates was not verified during this

inspection. The newer rakers installed on the downstream side appear in satisfactory condition. The older

rakers are still in place and are rotted out along the base and no longer provide support for the spillway.

The condition of both abutments looks good with minor cracking with efflorescence within the cracks on the left concrete abutment.

There is an aged concrete slab section right of the spillway adjacent to and behind the upstream wall that has cracking with differential movement observed and sounds hollow when struck with the heel of the inspector’s boot.

The impoundment level at the time of the inspection is about 4 feet below the top of the steel plate (highest part of the spillway).

The downstream water level is tidal and is about 3 to 5 inches lower than the impoundment level. It appears that this is at high tide.

The left abutment contact could not be viewed due to heavy brush growth. The contact area where the primary spillway transitions to the low level outlet looks good with no cracking or unusual movement observed.



The discharge area appears to be a concrete splash pad and is clear of debris. The splash pad was below water and could not be viewed at the time of the inspection.

The approach was clear of debris.

Low Level Outlet

The low level outlet appears to consist of a lift gate located right of the primary spillway. The Owner stated that this gate has not been operated in at least a decade. The approach was underwater at the time of the inspection and could not be viewed. The

above water sections of the trash rack appeared in satisfactory condition with surface corrosion observed at and slightly above the water line.

The discharge end was underwater and could not be located. The concrete slab downstream of, and to the left of the low level outlet behind the upstream

wall near the primary spillway is in poor condition with a hollow sound when tapping on this. The slab area has been patched and does not have significant cracking.

A short (2 foot tall) wall is located downstream of the low level outlet controls and is undermined on the downstream side on its right side and is cracked on top of the wall and on the left side with about a 1/2 inch opening and noted differential movement in the horizontal direction. Cracking with efflorescence within the cracks was observed on the downstream side of this wall. No leakage was observed through the undermined area.

There is a grassed area bordered by the fish ladder, low level outlet, and primary spillway. The grass is well maintained with no depressions, animal burrows, or unusual movement observed; however, a tree about 8 inches in diameter, is growing on the downstream side of this area.

Assessment for leakage could not be fully completed due to the low differential head of water at the time of the inspection.

Fish Ladder

The Fish Ladder was observed in good condition with no cracking along the concrete surface or unusual movement observed. The outlet consists of a hand wheel operated, aluminum lift gate that appears new and operational.

2.1.4 Downstream Area

Approximately 130 feet downstream of the dam is the Child Street Bridge. Roughly 1,200 feet further downstream (approximately 1,350 feet downstream), there is an embankment with an open center allowing for water to flow through freely. After this point the water opens into a larger body before flowing into Mount Hope Bay and beyond. There are residential developments along the downstream area on either side, including an apartment complex to the east immediately downstream of Child Street. The larger body of water has relatively dense residential developments on its western side with less dense residential developments to the east.

2.1.5 Reservoir Area The dam is located within the southern portion of the impoundment, which has a slight crescent shape and is approximately 3,600 feet long and approximately 300 feet wide. Serpentine Road follows the western edge of the impoundment for its entire length with agricultural land and commercial buildings beyond the route. The eastern edge of the impoundment is primarily wooded or



grassy with an apartment complex at the southeastern corner. Flows enter into the impoundment from the north via Kickamuit River, the Warren Reservoir Upper and the Warren Reservoir Upper Dam (#480).

2.2 Caretaker Interview Mr. Kenneth Burke, General Manager at Rhode Island Water Resources Board (RIWRB) and Mr. Romeo Mendes, Supervising Engineer the RIWRB, were present during the inspection as part of an informational visit. The inspector met with Ms. Pamela Marchand in her office prior to the inspection. Information provided by Mr. Burke, Mr. Mendes, and Ms. Marchand has been incorporated into this report.

2.3 Operation and Maintenance Procedures There was no formal operations and maintenance manual for the dam available at the time of the inspection.

2.3.1 Operational Procedures Operational components at the dam include the flap gates at the spillway and the low level outlet gate. The operations of these components were not confirmed during this inspection. No operational plan was indicated to exist at the time of the inspection.

2.3.2 Maintenance of Dam and Operating Facilities There was no maintenance manual for the dam available at the time of the inspection. However, it is evident that routine maintenance is completed at the dam to control vegetation along the length of the embankment with the exception of the two trees at the right abutment, and the brush growth at the dam’s left abutment. The caretaker also routinely completes informal inspections to check the condition of the dam. In general, the caretaker was knowledgeable of current conditions at the dam.

Warren Reservoir (Lower) Dam Assessments and Recommendations


3.0 ASSESSMENTS AND RECOMMENDATIONS 3.1 Assessments The Warren Reservoir (Lower) Dam was found to have the following deficiencies:

1. Aged Mortar along the upstream wall with vegetation growing out of the joints. 2. Two medium sized trees were observed growing out of the downstream slope and crest near the

right abutment. 3. The primary spillway was found with surface corrosion on the flap gates and upper steel plate,

leakage along the base of the gates, cracking along both spillway abutment walls with efflorescence within the cracks on the left wall, a deteriorated and hollow sounding concrete slab section right of the spillway adjacent to and behind the upstream wall, and an overgrown and un-viewable left abutment contact.

4. Surface corrosion was observed on the trash rack at the approach to the low level outlet. 5. The concrete slab downstream of and to the left of the low level outlet behind the upstream wall

near the primary spillway is in poor condition with a hollow sound. 6. The short wall, located downstream of the low level outlet controls, is cracked and undermined on

the downstream side with differential movement observed. 7. A tree was observed growing out of the grassed area bordered by the fish ladder, low level outlet,

and primary spillway. The RIDEM completed an inspection of the dam on April 25, 1995. Based upon a comparison to reported conditions, some repairs have been completed; however several deficiencies still remain and have continued to deteriorate.

Previously Identified Deficiency/Recommendation Resolution or Current Condition The upstream retaining wall at the right embankment is in good condition.

The mortar within joints is aged with vegetation growing out of the joints.

The training walls on each side of the primary spillway are in good condition.

Cracking with efflorescence was observed at the training walls.

The steel flap gates appear in good condition. Surface corrosion was noted on the downstream face with apparent leakage along the base.

The draw-down gate was not tested on this date. The operation of the gate was not demonstrated during the current inspection. Note: Based on a review of inspection reports dating back to 1984, the operability of this gate has not been confirmed.

The following recommendations and remedial measures generally describe the recommended approach to address current deficiencies at the dam. Prior to undertaking recommended maintenance, repairs, or remedial measures, the applicability of environmental permits needs to be determined for activities that may occur within resource areas under the jurisdiction of RIDEM or other regulatory agencies.



3.2 Recommendations The following present additional studies, routine and recurrent operations and maintenance activities, and repairs recommended to address deficiencies noted during the inspection and the completion of this report. The recommendations provided below should be implemented in accordance with general dam safety practice. Further, if left unaddressed, many of the conditions identified above will continue to deteriorate and could compromise the future safety of the dam and appurtenant structures.

1. Develop and implement a monitoring program and evaluation to further assess the observed leakage at the flap gates within the primary spillway. The program should include procedures for recording observed flow rates, relating flow rates with increasing head differential between the impoundment and tail water levels.

2. Complete a video inspection and underwater inspection of the low level outlet pipe to evaluate

the current condition of the pipe, condition of the intake and control mechanism, and location and condition of the discharge opening. During this time, it is recommended to confirm the operability of the low level outlet; however, because this outlet has not been operated for some time, it is suggested that the underwater inspections of the pipe and lifting mechanism be done first with an evaluation completed to determine that it is safe to attempt the opening of the gate. It is standard practice to include a low level outlet or other means by which to draw down the level of the impoundment for all dams. Based upon the findings, repair or replace the low level outlet gate and/or operator.

3. During times of low water, completed a video and underwater inspection of the upstream wall, spillway approach area, and upstream side of the flap gates. During this time, it is recommended to confirm the operability of the flap gates. Similar to the recommendations for the operation of the outlet gate, it is suggested that the underwater inspection and an evaluation be completed first. Based on the results, complete repairs as needed.

4. Based on the results of the monitoring program and evaluation, implement repairs to flap gates to mitigate leakage. At the same time as the repairs to leaks, it is recommended that the corroded surfaces of the flap gates and the steel plate above the gates.

5. Repair and seal the cracks along the spillway’s training walls.

6. Complete structural analyses to evaluate the aged concrete, differential movement, and hollow soundings along the concrete slab between the spillway and outlet structure, and the undermined and cracked short wall. Based upon the results of the evaluation, complete repairs as needed, which may include additional patching work or possibly removing and replacing some or all of the noted structures.

7. Clear the vegetation from the upstream walls, remove loose and aged mortar and perform repointing including areas that are currently underwater. Based on the results of the underwater inspection of the wall, perform additional repairs if needed.

8. Clear the brush growth from the abutment contact area left of the primary spillway, the tree between the spillway and the low level outlet and the two trees along the embankment at the right abutment. Tree growth is detrimental to the structural integrity of the dam. If trees are uprooted during a storm, the loss of part of the embankment section could result causing an



unstable condition, and the resulting tearing out of the roots from within the embankment could trigger uncontrolled seepage or a failure of the dam due to piping. When trees die, the rotting root systems within the embankment cold develop uncontrolled seepage as well. Biannual clearing (i.e. late spring and fall) is recommended to keep the vegetation from returning. The clearing should extend to the edge of the gravel access road at the toe of the dam. When brush is cut down, it should be removed from the dam to permit a clear view of the embankment. Significant root systems should also be pulled and the resulting holes properly filled.

9. Stumps need to be removed, the root systems grubbed from the embankment and the resulting

holes promptly filled with suitable compacted material. Depending upon the type of tree stumps to be removed, the procedure for removing the root system may vary. Some trees have taproots while others have a shallow network of roots that cover a large area. The impacts to the embankment should be evaluated by an engineer prior to grubbing roots from the dam and dike. Given the conditions prevalent at the time of the work, instability, seepage or piping conditions could develop if not undertaken in a controlled manner.

10. A formalized Operations and Maintenance Manual should be developed for this structure. This manual should include procedures for maintaining the level of the impoundment, including adjusting the level of the impoundment in anticipation of rain events to provide additional free board during the wetter months. Additionally, the manual should include periodic inspection schedules and operational and maintenance procedures required to ensure satisfactory operation and minimize deterioration of the facility. The manual should also provide record keeping procedures for ongoing inspection and monitoring, including the periodic inspection of the culvert at the low level outlet, monitoring of the leakage at the spillway, and other areas of potential movement and deterioration.

The manual should include schedule for regular maintenance activities to be continued to control and prevent growth of unwanted vegetation.

11. Complete detailed hydrologic and hydraulic (H&H) analyses to evaluate the capacity of the structure to accommodate various storm events that would be typical for the watershed. It is recommended that the analyses consider flows associated with the 100-year through the one half probable maximum flood (1/2 PMF) storm events. The analysis should account for the routed inflow that utilizes the full storage capacity within the impoundment and drainage area. A structure that cannot discharge the inflow associated with normal storm events will be overtopped in an uncontrolled manner that could damage the structure and threaten downstream areas.

12. Implement a program of regular inspection and monitoring of the dam. As the dam is

currently classified as a high hazard potential dam, the completion of a formal visual inspection by a RI registered professional engineer familiar with dam engineering is recommended every 2 years.

3.3 Alternatives The following alternatives are presented based upon a conceptual review of the concerns. Additional studies and or considerations may indicate that some or all of the options presented below are not suitable for the conditions specific to this dam and dam site. In addition to the general activities,



appropriate environmental permits will be required to complete many of the alternatives presented below. Dam Removal/Breaching: Alternative to implementing any of the repairs noted above, breaching of the dam is a viable alternative for addressing safety and stability concerns at the dam. While this alternative will address the safety concerns at the dam, it will result in the loss of the recreational and environmental resource and reduce potential flood control capacity provided by the dam and impoundment. Additionally, while removal will result in elimination of yearly operating and maintenance expenses, permitting activities and construction costs associated with dam removal may exceed those of rehabilitation and operations and maintenance. Because this is a part of the water supply system to the BCWA,, this alternative is likely not practical or feasible. Lower the Dam: Complete modifications to the dam to reduce the dam height, thereby reducing the maximum height and volume of water that may be impounded by the dam. Evaluate the impact of the lowered dam upon the hazard potential. While this alternative may result in reducing the hazard potential, recommendations listed above remain valid and should be implemented in accordance to general dam safety practice. Additionally, permitting activities and construction costs associated with reducing the dam height may exceed those of repair.


Inspection Date: July 20, 2012 Insp Report 479-Warren Reservoir (Lower) Dam

COMMON DAM SAFETY DEFINITIONS For a comprehensive list of dam engineering terminology and definitions refer to State of Rhode Island Rules and Regulations for Dam Safety, or other reference published by FERC, Dept. of the Interior Bureau of Reclamation, or FEMA.

Orientation Upstream – Shall mean the side of the dam that borders the impoundment. Downstream – Shall mean the high side of the dam, the side opposite the upstream side. Right – Shall mean the area to the right when looking in the downstream direction. Left – Shall mean the area to the left when looking in the downstream direction. Dam Components Dam – means any barrier made by humans, including appurtenant works, that impounds or diverts water. Embankment – means the fill material, including but not limited to rock or earth, placed to provide a permanent barrier that impounds water. Crest – Shall mean the top of the dam, usually provides a road or path across the dam. Abutment – Shall mean that part of a valley side against which a dam is constructed. An artificial abutment is sometimes constructed as a concrete gravity section, to take the thrust of an arch dam where there is no suitable natural abutment. Appurtenant Works – means any ancillary feature of a dam including such structures as dikes, training walls, spillways, either in the dam or separate there from, low level outlet works, and water conduits such as tunnels, channels, pipelines or penstocks, either through the dam or its abutments. Spillway – means a structure, a low area in natural grade or any part of the dam which has been designed or relied upon to allow normal flow or major flood flow to pass over or through while being discharged from a reservoir.

Hazard Classification High Hazard – means a dam where failure or misoperation will result in probable loss of human life. Significant Hazard – means a dam where failure or misoperation results in no probable loss of human life but can cause major economic loss, disruption of lifeline facilities or impact other concerns detrimental to the public’s health, safety or welfare. Examples of major economic loss include but are not limited to washout of a state or federal highway, washout of two or more municipal roads, loss of vehicular access to residences, (e.g. a dead end road whereby emergency personnel could no longer access residences beyond the washout area) or damage to a few structures. Low Hazard – means a dam where failure or misoperation results in no probable loss of human life and low economic losses. General EAP – Emergency Action Plan – Shall mean a predetermined (and properly documented) plan of action to be taken to reduce the potential for property damage and/or loss of life in an area affected by an impending dam failure. O&M Manual – Operations and Maintenance Manual; Document identifying routine maintenance and operational procedures under normal and storm conditions. Normal Pool – Shall mean the elevation of the impoundment during normal operating conditions. Acre-foot – Shall mean a unit of volumetric measure that would cover one acre to a depth of one foot. It is equal to 43,560 cubic feet. One million U.S. gallons = 3.068 acre feet.



Height of Dam– means the vertical distance from the elevation of the uppermost surface of a dam to the lowest point of natural ground, including any stream channel, along the downstream toe of the dam. Hydraulic Height – means the height to which water rises behind a dam and the difference between the lowest point in the original streambed at the axis of the dam and the maximum controllable water surface. Maximum Water Storage Elevation – means the maximum elevation of water surface which can be contained by the dam without overtopping the embankment section. Spillway Design Flood (SDF) – Shall mean the flood used in the design of a dam and its appurtenant works particularly for sizing the spillway and outlet works, and for determining maximum temporary storage and height of dam requirements. Maximum Storage Capacity – The volume of water contained in the impoundment at maximum water storage elevation. Normal Storage Capacity – The volume of water contained in the impoundment at normal water storage elevation. Condition Rating Unsafe – Means the condition of a regulated dam, as determined by the Director, is such that an unreasonable risk of failure exists that will result in a probable loss of human life or major economic loss. Among the conditions that would result in this determination are: excessive vegetation that does not allow the Director to perform a complete visual inspection of a dam, excessive seepage or piping, significant erosion problems, inadequate spillway capacity, inadequate capacity and/or condition of control structure(s) or serious structural deficiencies, including movement of the structure or major cracking.* Poor – A component that has deteriorated beyond a maintenance issue and requires repair.; the component no longer functions as it was originally intended. Fair – Means a component that requires maintenance Good – Meeting minimum guidelines where no irregularities are observed and the component appears to be maintained properly. * Structural deficiencies include but are not limited to the following:

Excessive uncontrolled seepage (e.g., upwelling of water, evidence of fines movement, flowing water, erosion, etc.)

Missing riprap with resulting erosion of slope Sinkholes, particularly behind retaining walls and above outlet pipes, possibly indicating loss

of soil due to piping, rather than animal burrows Excessive vegetation and tree growth, particularly if it obscures features of the dam and the

dam cannot be fully inspected Deterioration of concrete structures (e.g., exposed rebar, tilted walls, large cracks with or

without seepage, excessive spalling, etc.) Inoperable outlets (gates and valves that have not been operated for many years or are broken)



REFERENCES AND RESOURCES

The following reports were located during the file review completed at RIDEM Offices in Providence, Rhode Island:

1. “Dam Inspection Report, Warren Lower Reservoir Dam No. 479”, Rhode Island Department of Environmental Management, April 26, 1984.

2. “Dam Inspection Report, Warren Lower Reservoir Dam No. 479”, Rhode Island Department of Environmental Management, August 15 and September 17, 1986.

3. A letter from BCWA to the RIDEM Dam Safety Program Division regarding the restoration of the Kickemuit Reservoir Dam [Warren Reservoir (Lower) Dam)], dated September 27, 1989.

4. “Dam Inspection Report, Warren Lower Reservoir Dam No. 479”, Rhode Island Department of Environmental Management, September 4, 1990.

5. “Special Dam Inspection Report, Warren Reservoir Lower Dam No. 479”, Rhode Island Department of Environmental Management, April 25, 1995.

The following were referenced during the completion of the visual inspection and preparation of this report and the development of the recommendations presented herein: 1. “Design of Small Dams”, United States Department of the Interior Bureau of Reclamation,

1987 2. “ER 110-2-106 - Recommended Guidelines for Safety Inspection of Dams”, Department of

the Army, September 26, 1979. 3. “Guidelines for Reporting the Performance of Dams” National Performance of Dams

Program, August 1994. The following provides an abbreviated list of resources for dam owners to locate additional information pertaining to dam safety, regulations, maintenance, operations, and other information relevant to the ownership responsibilities associated with their dam. 1. RIDEM Office of Compliance and Inspection Website:

http://www.dem.ri.gov/programs/benviron/compinsp/ 2. “Dam Owner’s Guide To Plant Impact On Earthen Dams” FEMA L-263,September 2005 3. “Technical Manual for Dam Owners: Impacts of Plants on Earthen Dams” FEMA 534,

September 2005



4. “Dam Safety: An Owners Guidance Manual” FEMA 145,December 1986

5. Association of Dam Safety Officials – Website: www.asdso.org/ 6. “Dam Ownership – Responsibility and Liability”, ASDSO

Warren Reservoir (Lower) Dam, Warren, RI Inspection Photographs

Inspection Date: July 20, 2012

Photo No. 1: View of the upstream concrete wall from the right abutment of the fish ladder looking right towards the right abutment. Vegetation can be seen growing in the cracks of the upstream wall.

Photo No. 2: View of the dam crest from the right abutment of the fish ladder looking right towards the right abutment. The embankment consisting of a grassed crest varying from about 25 feet in width adjacent to and parallel to the Roadway (Child Street) to 10 feet in width closer to the fish ladder.



Photo No. 3: View of the crest and right abutment adjacent to Child Street. Note tree near the upstream side of the crest.

Photo No. 4: View of the primary spillway from the right spillway abutment. Also seen here is the left abutment, at the time of inspection the left abutment was too overgrown to access for observation.



Photo No. 5: The primary spillway consists of a series of 20, 30" wide, 30" high hinged flap gates installed below a continuous vertical plate that connects to concrete abutments and is supported by a concrete cap and individual concrete piers founded on a concrete slab bearing within the river bottom. The flap gates are each supported above by a bolt and nut. The connections at the bottom of the flap gates were submerged and were not viewed.

Photo No. 6: The upstream side of the primary spillway as viewed from the right side looking left. The surface of the flap gates and steel plate at the primary spillway are corroded but appear structurally sound.



Photo No. 7: The alignment of the primary spillway looks good. The impoundment level at the time of the inspection is about 4 feet below the top of the steel plate. The downstream water level is tidal and is about 3 to 5 inches lower than the impoundment level.

Photo No. 8: From background to foreground, view of the primary spillway, the low level outlet and the fish ladder. Between the fish ladder and the primary spillway is a section of the embankment. The fish ladder is built into the embankment.



Photo No. 9: View of the upstream concrete at the low level outlet. The concrete appears in poor condition.

Photo No. 10: View of a void on the embankment going under the concrete headwall of the low level outlet.



Photo No. 11: View of the fish ladder.

Photo No. 12: View of exposed PVC waterstop at a joint in the downstream fishladder wall.



Photo No. 13: View of the downstream channel.

Photo No. 14: View of the impoundment.

warren reservoir (lower) dam · 2017-11-24 · the warren reservoir (lower) dam is about 130 feet...

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