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4.3. ERMUSR 06-16-2015
Elk River Municipal Utilities UTILITIES COMMISSION MEETING TO: FROM: Elk River Municipal Utilities Commission Eric Volk—Water Superintendent John Dietz—Chair Al Nadeau—Vice Chair Daryl Thompson—Trustee MEETING DATE: AGENDA ITEM NUMBER: June 16, 2015 4.3 SUBJECT: Elk River Dam Emergency Action Plan BACKGROUND: In June 2014, the commission approved the updated Elk River Dam Emergency Action Plan (EAP),which was required by the Minnesota Department of Natural Resources (DNR). DISCUSSION: Since the dam EAP was approved last June, there have been a few changes based on the recommendation of the Minnesota DNR, among them the addition of an updated Dam Failure Analysis (DFA). We also updated the points of contact to reflect the current responsibilities pertaining to the dam, and the notification list for emergency. ACTION REQUESTED: Staff requests that the Commission receive the updated Elk River Dam Emergency Action Plan. ATTACHMENTS: • Elk River Dam Emergency Action Plan Ii4ATUP Page 1 of 1 Reliable Public Power Provider P O W E R E D T O S E R V E 156 EMERGENCY ACTION PLAN Elk River Dam (aka Orono Dam) Elk River, Minnesota -'.. iIIIII, I,, � � J ff l :+^ ,r e { r y Prepared for: The City of Elk River May 2015 Controlled Copy of 157 EMERGENCY ACTION PLAN ELK RIVER DAM, AKA ORONO DAM LOCATED ON THE ELK RIVER IN THE CITY OF ELK RIVER, MN NATIONAL INVENTORY OF DAMS ID: MN-00516 COUNTY: SHERBURNE COUNTY OWNER: CITY OF ELK RIVER OWNER REPRESENTATIVE: CITY ADMINISTATOR OFFICE: (763) 635-1001 ADDITIONAL CONTACT: STREET SUPERINTENDENT OFFICE: 763-635-1120 DAM OPERATOR: ELK RIVER MUNICIPAL UTILITIES OFFICE: (763)441-2020 ADDITIONAL CONTACT: WATER SUPERINTENDENT OFFICE: 763-441-2020 OWNER MAILING ADDRESS: CITY ADMINISTATOR CITY OF ELK RIVER 13065 ORONO PARKWAY ELK RIVER, MN 55330-0430 158 TABLE OF CONTENTS Page No. I. Notification Flowchart 1 Table 1. Notification List for Emergency Levels 1 and 2 2 II. Statement of Purpose 4 III. Project Description 4 Figure 1. Dam Location 5 Figure 2. Plans for the Elk River Dam 6 IV. Emergency Detection, Evaluation, and Classification 7 Table 2. Guidance for Determining the Emergency Level 8 V. General Responsibilities under the Plan 9 A. Dam Owner Responsibilities 9 B. Responsibility for Notification 10 C. Responsibility for Evacuation 10 D. Responsibility for Duration, Security, Termination, and Follow-Up 10 E. EAP Coordinator Responsibility 11 VI. Preparedness 11 A. Surveillance 11 B. Response During Periods of Darkness 12 C. Access to the Site 12 D. Response During Weekends and Holidays 12 E. Response During Periods of Adverse Weather 12 F. Alternative Systems of Communication 13 G. Emergency Supplies and Information 13 1. Stockpiling Materials and Equipment 13 2. Coordination of Information 14 3. Other Site-Specific Actions 14 VII. Inundation Maps 15 Figure 3. Inundation Map 16 VIII. Appendices 17 159 Notification Flowchart See Table 1 (page 2)for phone numbers and Appendix F for secondary numbers. Observer V Sherburne County Sheriff's Communications Division 911 V Dam Operator Elk River Elk River Elk River Police Department — Fire Department Municipal Utilities W National Weather Elk River Residents Service See Appendix F DNR Wright County State Dam Safety Sheriff's Office E Engineer 4 Water Otsego Residents Superintendent See Appendix F Dam Owner Wright County City of Elk River Emergency Management E City Administrator Coordinator City of Elk River Sherburne County Public Works Emergency Services E Department Director Ayres Associates Hennepin County Contracted Engineer Emergency Management E 160 After receiving notification from an observer, the Sherburne County Sheriff's Communications Division (911) shall determine the appropriate emergency level for the specific situation based on the classification as defined in Section IV Emergency Detection, Evaluation, and Classification of this Emergency Action Plan (EAP). Emergency Level 3 merely requires notification of Elk River Municipal Utilities. Emergency Levels 1 and 2 require notification of a broad range of departments, officials, and Emergency Level 1 also requires evacuation of downstream residents. Parties on the notification flowchart shall be contacted by phone or, if necessary, in person. Radio communication is available between the power plant, the Street Department, and the Sheriffs Office. When notifying the parties for whom they are responsible, each caller should inform them of the emergency level that has been activated, explain the exact conditions, and—if applicable—refer the party to the EAP for their responsibilities. Downstream residents who are notified should be informed that an emergency situation now exists, and that evacuation is necessary. Contact information for the parties in Table 1 can be found in Appendix F. Table 1. Notification List for Emergency Levels 1 and 2 Caller To Be Notified Phone Observer 1. Sherburne County Sheriffs Communications 911 Division (911 Dispatch) 1. Dam Operator- Elk River Municipal Utilities 763-441-2020 Sherburne County Sheriffs Communications 2. Elk River Police Department 763-635-1200 Division (911 Dispatch) 3. Elk River Fire Department 763-635-1100 1. National Weather Service 952-361-6671 2. DNR State Dam Safety Engineer 651-259-5715 Elk River Municipal 3. Water Superintendent 612-802-4582 Utilities 4. Dam Owner- City of Elk River City Administrator 763-635-1001 5. City of Elk River Public Works Department 763-635-1120 161 6. Ayres Associates 715-834-3161 1. Elk River Residents See Appendix F 2. Wright County Sheriffs Office 763-682-7600 Elk River Police 3. Wright County Emergency Management 763-684-2364 Department Coordinator 4. Hennepin County Emergency Management 612-296-7514 5. Sherburne County Emergency Services Director 763-765-3531 Wright County Sheriffs 1. Otsego Residents See Appendix F Office 162 II. Statement of Purpose The purpose of this Emergency Action Plan (EAP) is to provide the owner/operator of the Elk River Dam with a clear plan of action when any dam emergency arises, with the intent of safeguarding the lives and reducing damage to the property of the citizens of Sherburne County, Wright County, and Hennepin County living along the Elk River. An emergency is identified as any condition which: • develops unexpectedly; • endangers the structural integrity of the dam; and • could result in the dam's failure producing downstream flooding, requiring immediate action. This EAP provides information about the dam and contact information for all parties involved in responding to or affected by an emergency at the dam. The EAP outlines what actions are required in the event of an emergency. III. Project Description The Elk River Dam (aka Orono Dam) is located in Section 33 of Township 33 North, Range 26 West, within the City of Elk River, Sherburne County, Minnesota. The dam impounds the Elk River, forming Orono Lake, a recreational waterbody. The Main Street Bridge is located immediately downstream. The Mississippi River is located approximately one mile downstream. A location map is presented in Figure 1 on the following page. The Elk River Dam is a high hazard concrete gravity dam with a structural height of 15 feet, and a structural length of 207 feet. The dam consists of the following components, from left to right looking downstream: a concrete flood wall, an earthen embankment fuse plug, an abandoned powerhouse (foundation only), a fixed crest overflow spillway, a concrete tainter gate spillway with three steel gates, a fixed crest overflow spillway, and an earthen embankment fuse plug. A plan and section of the dam are presented in Figure 2 on page six. The contributing watershed area at the dam is 640 square miles. At a normal elevation of 871.3 mean sea level (msl) the pool is 281 acres, with a maximum depth of 18 feet. The normal storage is 1,600 acre-feet, and the maximum capacity is 2,800 acre-feet. The maximum discharge is 10,000 cubic feet per second. The nearest upstream dam is Eagle Lake Dam on a tributary to the Elk River, approximately 10 miles from the Elk River Dam. The nearest downstream dam is the Coon Rapids Dam on the Mississippi River, approximately 17 miles from the Elk River Dam. 163 , r— i�-� .;✓ �— ` I � ; f " f a r04 ^.,` -.. t a :•.A...., . .. 1 4 I^ i/ -t I • „.. . L.,. : Il C 1 ' ce �. ..' - '- .�' f r A'W, a • – r ',,,�j i\ 1 c . '4,-'','e.:''.',-.',':4:".:...:.,,,:11,i,i r,..,,... :T.--.,-.A.,:..." a., 2 \-:. .. . . -- - .1 / f'/ 7 - 1 0 M 1. liipi , . i •• \ ' .0. ,.. ,. r: ' - - - -- Wir49,'fi, . ' (i________. , , • , L .. .._ , , . .... , . i ,. _„,., •,, \1 i ,.... . , . : . 0 tiit. ,. _1. , ...... ...,-, ,. _ , , . / . . . „,. / i.‘,., • L \ 1. tt IQ . \ i. o � s O J Q o it 4 C;)1 Z © tik bithillik t tT__f.41441/4 ! inz I W u�i2 co „I o ,� J .J W 3 +u `� r.. LO CO V its J <mv0 '^ z W CitIll 101 i at~ Z . : 2 ,j ti 8 N z ;g gitt io/ _ Q r� 1 l 1 r IL 1 I 1 if o v Y L.-- rJ m ki I 0 0, ic t I i j w k 1 a r in ,..§ t i :1 1 41 ti N * �I C r a R ; J k N m f * qi C CD Z LL IV. Emergency Detection, Evaluation, and Classification Dam tenders perform a general inspection of the Elk River Dam on a daily basis, and a detailed inspection at least once a year using the inspection form in the Inspection, Operation, and Maintenance Plan. Every five years inspection of the dam is required of a professional engineer proficient in dam structure and safety. During these inspections situations that could lead to emergency conditions are closely evaluated. Comparison of data from one inspection to another can potentially reveal progression of issues. There are three emergency levels that correspond with the severity of a condition, as well as the degree of threat to life and/or property. These levels are detailed in steps below which outline the general procedures to be taken during an emergency situation. Step 1: Event Detection • Detect event • Assess situation Step 2: Emergency Level Determination • Table 2 on the following page provides guidance on determining the emergency level. The emergency levels are as follows: • Level 1 — Urgent; dam failure appears to be imminent or in progress • Level 2 — Potential dam failure situation; rapidly developing • Level 3 — Non-failure condition; slowly developing; high water • It may be necessary to consult with other parties prior to determining an emergency level. This may include the General Manager of Elk River Municipal Utilities, the DNR's State Dam Safety Engineer, or a private consulting engineer. Note: Timely determination of the appropriate emergency level is critical to maximize the available response time. Step 3: Notification and Communication • Level 1 — Activate Level 1 Emergency Notification Flowchart • Level 2 —Activate Level 2 Emergency Notification Flowchart • Level 3 —Activate Level 3 Emergency Notification Flowchart Step 4: Expected Actions • Level 1 — Save people; evacuate • Level 2 — Save dam; protective actions; potential evacuation warning • Level 3 — Monitor situation Step 5: Termination and Follow-up 166 Table 2. Guidance for Determining the Emergency Level Event Situation Emergency Level Spring run-off or major storm event 3 High Flow Spillway flow that threatens to flood people downstream 2 Spillway flow that is flooding people downstream 1 Fuse Plug Reservoir level is 1 foot below either of the fuse plugs 2 Overtopping Water from the reservoir is flowing over either of the fuse plugs 1 New seepage areas in or near the dam 3 Seepage New seepage areas with cloudy discharge 2 Seepage with cloudy discharge; increasing flow rate 1 Observation of new sinkhole in reservoir area or on 2 Sinkholes embankment 2 Rapidly enlarging sinkhole 1 Structural New cracks in the structure greater than 1/4-inch wide without seepage 3 Cracking Cracks in the structure with seepage 2 Structural component deformation 1 Structural Displacement of dam 1 Failure Gate failure or malfunction 1 Embankment Visual movement/slippage of the embankment slope component 2 Movement Sudden or rapidly proceeding slides of the embankment slopes 1 Verified bomb threat that, if carried out, could result in damage to the 2 dam Security Threat Detonated bomb that has resulted in damage to the dam or 1 appurtenances Unauthorized operation of the dam 3 Damage to dam or appurtenance with no impacts to the functioning of 3 the dam Sabotage or Modification to the dam or appurtenances that could adversely impact 2 Vandalism the functioning of the dam Damage to dam or appurtenances that has resulted in seepage flow 2 Damage to dam or appurtenances that has resulted in uncontrolled 1 water release 167 V. General Responsibilities under the Plan A. Dam Owner Responsibilities The City of Elk River owns the Elk River Dam and it is operated by Elk River Municipal Utilities. Familiarity with federal guidelines for the inspection and evaluation of dams will assist dam owners in maintaining safe dams. Understanding and recognition of potentially dangerous conditions may prevent dam failure. The Dam Operator shall advise the dam tenders of the importance of the EAP, and shall keep dam tenders trained in use of the EAP, and in detection of situations that trigger use of the EAP. Operators' duties under the EAP are to: detect situations that require the activation of one of the Emergency Levels; determine the appropriate Emergency Level (conferring with the owner's representative as necessary); activate the notification flowchart as necessary; and provide assistance and monitoring as required by the dam owner's representative. When activating the notification flowchart, the operators shall at a minimum inform the party which Emergency Level has been activated for the Elk River Dam, the reason for activation (refer to Table 2), and to refer to the EAP for details on their duties. For example: Dispatch, Emergency Level 1 has been activated for the Elk River Dam. This is due to failure of one of the tainter gates. Please refer to the EAP for details on the notifications you must immediately initiate. Only after the notification flowchart has been activated should dam operation actions be taken. Actions should preferably be done under guidance of Ayres Associates in order to ensure that measures are both necessary and safe. The City of Elk River is the official representative for EAP situations. The Dam Owner will consult with the Dam Operator to obtain advice concerning predetermined remedial action to delay, moderate, or alleviate the severity of the emergency condition. The duties (which may be delegated to the Elk River Police and Fire Departments) of the dam owner and operator are to: • contact parties for whom they are responsible in the notification flowchart; • provide information to Ayres Associates on existing severity and rate of change of the problem; • request assistance from Ayres Associates (personnel for expert supervision and monitoring, equipment, materials) as necessary; • ensure that operations and repairs directed by Ayres Associates are carried out; • and to act independently to implement emergency operations and repairs in the event communications with Ayres Associates are disrupted or immediate action is required, including deciding the urgency of correction, carrying out appropriate portions of the emergency operations and repairs, obtaining needed personnel, equipment, and materials, and providing for 24-hour monitoring of the situation. 168 C. Responsibility for Notification For any Level Emergency, the observer is responsible to activate the flowchart by contacting the Sherburne County Sheriffs Communications Division (911). The Sherburne County Sheriff's Communications Division will make the determination as to the level of the emergency. For a Level 1 or Level 2 Emergency situation, the Sherburne County Sheriff's Communications Division is responsible for contacting Elk River Municipal Utilities, the Elk River Police Department, and the Elk River Fire Department. The Elk River Police Department shall ensure that downstream residents receive notification in the case of a Level 1 Emergency situation. Communication will be achieved by phone, or by door-to- door notification. The Elk River Fire and Police Departments will activate the Elk River Emergency Operations Center. Elk River Municipal Utilities is authorized to contact all other state and local officials as necessary, including (but not limited to): the National Weather Service, the Minnesota Department of Natural Resources, the Elk River Public Works Department, and the Elk River City Administrator. If a situation arose in which Elk River Municipal Utilities could not be reached, authority to contact all other state and local officials would fall to Elk River Police and Fire Departments. The National Weather Service (Twin Cities, MN Weather Forecast Office) shall issue flood warnings in the case of a Level 1 or Level 2 Emergency. D. Responsibility for Evacuation In case of a Level 1 Emergency, the Elk River Police Department is responsible for evacuation of downstream Elk River residents, and the Wright County Sheriff's Office is responsible for evacuation of downstream Otsego residents. Although the list of residents that fall within the theoretical inundation area will be updated regularly by the EAP coordinator, it could possibly be incomplete at any future time. Evacuation should, therefore, include all residents within or near the inundated areas (shown on the map in Section VII) and not exclusively the residents on the notification flowchart. E. Responsibility for Duration, Security, Termination, and Follow-Up Elk River Municipal Utilities will be responsible for on-site monitoring of the situation at the dam and keeping local authorities informed of developing conditions at the dam from the time that the emergency starts until the emergency has been terminated. In the case of a Level 1 or Level 2 Emergency, assistance may be requested of the DNR for expert supervision and monitoring of a situation. During a Level 1 or Level 2 Emergency, access to the dam shall be restricted by means of temporary barriers and fencing. A Level 1 or Level 2 Emergency at the Elk River Dam will not be terminated until inspected by a qualified engineer, and the DNR State Dam Safety Engineer has been 169 consulted. Only once the emergency is terminated shall Elk River Municipal Utilities utilize the notification flowchart so that all notified parties are made aware of the end of the emergency condition. After termination of an emergency, a qualified engineer should inspect the dam for any damage. A post-disaster review of the inspection will be held with the DNR State Dam Safety Engineer to ensure that the dam is in compliance with state standards. This review may result in formal orders issued to the dam owner and may require the submittal of plans and specifications for repair. A follow-up evaluation should be held as soon as possible following an emergency event. This evaluation shall address events prior to, during, and following the emergency; significant actions taken by each participant; what improvements would be desirable for future emergencies; and all deficiencies found in procedures, materials, equipment, manpower, leadership, and funding. A post-emergency report should be prepared by the Dam Owner, issued to the DNR State Dam Safety Engineer, and distributed to all organizations that participated in or have a direct interest in the emergency. Any changes deemed necessary for the EAP will be made by the EAP coordinator, and an updated EAP—including an updated Approval sheet—will be distributed to all holders of the EAP. B. EAP Coordinator Responsibility The City of Elk River shall serve as the EAP coordinator. As the EAP coordinator, The City of Elk River is responsible for preparing revisions to the EAP, distributing the EAP to involved agencies and parties, establishing EAP training seminars for dam tenders and other involved parties, and coordinating EAP exercises. The City of Elk River is the EAP contact should any of the involved parties have questions about the plan. VI. Preparedness A. Surveillance The Elk River Dam is not operated remotely- everything is manual. Conditions indicating a possible emergency situation and the potential for dam failure are outlined in Table 2, and can be observed via daily inspection. The dam tenders must also be able to identify potentially dangerous flow conditions. Potential flood conditions are characterized by: extended periods of greater than average precipitation or combined melting periods greater than average precipitation; and rapidly increasing headwater levels (greater than 2 inches increase per hour). Factors which require consideration in light of potential emergency flood situations include: initial water elevation and gate operation; previous weather history; and predicted weather. 170 B. Response During Periods of Darkness The Elk River Dam is equipped with lights. Hand-held lights and/or generator-powered floodlights can be used to aid in illumination of the dam, and will be provided by Elk River Municipal Utilities in the event of a power failure. Should an emergency be identified during a power failure, it may be necessary for notification to occur via handheld radios, cell phone numbers, or in person. C. Access to the Site The primary means of accessing the Elk River Dam is by the embankments which abut either end of the Main Street Bridge over the Elk River, with access to the observation deck at the northeast end, and access to the gates from the southwest end. Access to the upstream face of the dam can also be made by boat on Lake Orono. The most direct route for personnel from Elk River Municipal Utilities, the Elk River Police Department, and the Elk River Fire Department to access the site is via Orono Parkway and Main Street. This route has a distance of approximately 3/4 of a mile, a travel time of two minutes, and approaches the dam from the southwest. Should access be required at the northeast end of the dam but the bridge is unavailable, the shortest route is via Orono Parkway, Joplin Street, Highway 10 East, Upland Avenue, and Main Street. This route has a distance of approximately 2.2 miles, and a travel time of five minutes. The most direct route for personnel from the Sherburne County Sheriffs Department is via Business Center Drive Northwest, Joplin Street, Orono Parkway, and Main Street. This route has a distance of 2.0 miles, a travel time of five minutes, and approaches the dam from the southwest. Should access be required at the northeast end of the dam but the bridge is unavailable, the shortest route is via Business Center Drive Northwest, Joplin Street, Highway 10 East, Upland Avenue, and Main Street. This route has a distance of approximately 2.2 miles, and a travel time of five minutes. D. Response During Weekends and Holidays In the event that a Level 1 or Level 2 Emergency is activated during a weekend or holiday, it will be necessary to contact parties on the notification flowchart at their home phone or cell phone numbers, if their primary number is not staffed 24/7. The secondary phone numbers are provided in Appendix F. E. Response During Periods of Adverse Weather During adverse weather, it may be necessary to alter access to the dam, and/or contact methods for parties in the notification flowchart. The dam is checked twice per day during these periods. 171 F. Alternative Systems of Communication In the event that the primary system of communication fails, and/or parties cannot be contacted via their primary contact number, it may be necessary to use alternative channels of communication. Alternative means of communication shall include handheld radios (800 MGHZ system), cell phone numbers, or in-person contact. G. Emergency Supplies and Information Emergency Operations Center 1. Stockpiling Materials and Equipment Dam repair materials and equipment are not stockpiled at the dam for potential emergency situations, but many resources are available within 1.5 miles of the site. Sources for these and other items have been identified, and are outlined below. Engineering: Ayres Associates 3433 Oakwood Hills Pkwy Eau Claire, WI 54701 715-834-3161 Labor: City of Elk River Streets Department 1900 Proctor Road Elk River, MN 55330 763-635-1120 Elk River Municipal Utilities 13069 Orono Parkway Elk River, MN 55330 763-441-2020 MN Warn — Mutual Aid 217 12th Ave SE Elbow Lake, MN 56531 800-367-6792 MMUA— Mutual Aid 3025 Harbor Ln N — Suite 400 Plymouth, MN 55447 763-551-1230 Materials: Cretex Companies 311 Lowell Ave NW Elk River, MN 55330 763-441-2121 172 - - 1 Equipment: City of Elk River Streets Department 1900 Proctor Road Elk River, MN 55330 763-635-1120 Elk River Municipal Utilities — Plant 1705 Main Street Elk River, MN 55330 763-441-2020 MN Warn — Mutual Aid 217 12th Ave SE Elbow Lake, MN 56531 800-367-6792 MMUA— Mutual Aid 3025 Harbor Ln N — Suite 400 Plymouth, MN 55447 763-551-1230 2. Coordination of Information Operation of the Elk River Dam is overseen by Elk River Municipal Utilities. In the event of a Level 1 or Level 2 Emergency, the National Weather Service (Twin Cities, MN Forecast Office) should be coordinated with in order to monitor storms, river stages, and flood waves resulting from a dam break. If it becomes necessary to lower the reservoir water surface elevation during an emergency, Elk River Municipal Utilities will contact the DNR State Dam Safety Engineer for advice about any drawdown processes in order to ensure that the drawdown is done in the most safe and effective manner possible. Actions that reduce inflow to the reservoir through coordination with upstream dams do not apply to this EAP. Actions that reduce downstream flows through coordination with downstream dams do not apply to this EAP. 3. Other Site-Specific Actions At a Level 1 emergency, the Emergency Operations Center would be opened. 173 VII. Inundation Maps The purpose of an Inundation Map is to provide a picture of the area that would be affected by a complete failure of the dam in order to determine who must be notified and/or evacuated in an emergency. The Inundation Map should clearly identify residences, businesses, storage facilities, bridges, downstream dams and other structures such as roads, power lines, sewer, gas and water lines and other infrastructure that could be affected by the failure of the dam. There is currently one (1) residence that could potentially be affected. The Main Street Bridge could also potentially be affected, although not expected to overtop during a dam failure. The Inundation Map for the Elk River Dam was produced in March 2015, based on the information from the dam failure analysis conducted by Ayres Associates. The Inundation Map—which also shows the potentially affected residence—can be found on the following page. For further information on the dam failure analysis, see Appendix A. 174 — s _ Wz e • .n z E=woo e'_ .9 e" ..�lS 1 O m II.e ma' I ,1 y J \1, Alf tt E t` . ' .0 .:3 iga-Iii 7.- wt./le- '*'.�" ' O U o w m .a � CO �L . -za o s ii J,/ Si I I ► +n..MM1 t fj e „arr. J ti ° f i4, i - 1 -t-. o tP Z O m2o •. of ' w Oa•a E°.Id� s .~. n X.zv, s p v x II w - ,rte o o 00 y I mN ' J •i, € JZ = Eom...3 ,N w�au -- U m w d d '>r- 1 lt„ mss.O m al 3 . , +y.ti 2 1 Y • a t i � if' N..li .•.1 vi ?Li __... - i -„iti - ,, 4, \ ..., _.... ,_ ,N,..... . , . , , •. , ... ,,. ,, 0 , „„.,.,3 Edo ImNr !. {// V, p¢ O II II NfV - 0O ii N wz !]JIj •-1- /' JO 1u. 900 j i m a m ir y ° rte! d,„ % 61- m - f .men p+ C, G y M W cEo o t ,,,, w E a 1 -'s• ��♦i��+.�j_� °n Z ill a E^°v,¢a �o II °1 �',7 o F�_a q a- -+r 1.�+ l� oOw a, oa a, �°' -+ y,ti. O `� `1„e- . %A.-,1 2 x . r. .. -.=,-.. ri V.l•- _Z m u. E a 2 o o o! 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Appendices Appendix A— Investigation and Analyses of Dambreak Floods Appendix B — Plans for Training, Exercising, Updating, and Posting the EAP Appendix C — Site-Specific Concerns Appendix D —Approval of the EAP Appendix E — Control Copy Holders of the EAP Appendix F — Notification List for Emergency 176 APPENDIX A Investigation and Analyses of Dam Break Floods 177 Dam Failure Analysis Orono Dam, Elk River, MN Prepared for: Elk River Municipal Utilities Elk River, MN March 2015 178 Dam Failure Analysis Orono Dam, Elk River, MN A RES ASSOCIATES 3433 Oakwood Hills Parkway Eau Claire, WI 54701-7698 715.834.3161 • Fax: 715.831.7500 www.AyresAssociates.com Ayres Associates Project No.26-0839.00 File:k:\water resource eng\elk river mn\2015 dfa&map\report\report 0320.docx 179 Contents Page No. Summary 1 Description of Dam 1 Flood Frequency 1 Hydraulics 2 Hydraulic Model Development 2 Hydraulic Model Assumptions 3 Consequences of Failure 4 Conclusions 7 List of Appendices Appendix A Orono Dam Plans Appendix B Hydrologic Analysis Appendix C Hydraulic Analysis Appendix D Inundation Maps File:k:\water resource eng\elk river mn\2015 dfa&map\report\report 0320.docx 180 Summary The discharges, flooding depths, inundation area, and flood wave travel times associated with a failure of the Orono Dam were estimated using the unsteady-flow routines of the Corps of Engineers HEC-RAS software. A normal-flow failure and a failure during a flood equivalent to the zero freeboard flood (16,600 cubic feet per second (cfs))with a 10-year flood on the Mississippi River were considered. The zero freeboard flood failure produces a worst-case inundation scenario for residential, commercial, and public use areas in the city of Elk River and is documented in the Emergency Action Plan inundation maps. The normal-flow failure would cause little overbank flooding, but poses hazards to recreationists in and on the banks of the Elk River and Mississippi River. Description of Dam The Orono Dam consists of earthen embankments and an approximately 225-foot long, 15-foot high concrete dam structure on the Elk River in Sherburne County, Minnesota. Originally constructed in 1916 for hydroelectric power, the dam no longer produces power but provides recreation benefits. The upstream pool level is maintained by overflow weirs with crest elevations of 871.3 feet. Floods are passed over the dam through the 117-foot-wide "main overflow weir" on the left side of the dam, the 24-foot-wide "south overflow weir" on the right, and three Tainter gates between the overflow spillways. Fuse plugs are located on the left and right sides of the dam and construction drawings indicate they were originally designed to deploy at floods exceeding the 500 year flood. On the right side, riprap has been added in the area of the fuse plug and may inhibit its operation. A plan view of the dam, taken from the 1980 CH2M Hill Elk River Dam Rehabilitation plan set, is included in Appendix A. The Elk River joins the Mississippi River approximately one mile downstream of the dam. Flood Frequency An updated flood frequency curve for the Orono Dam was developed using two methods: a Log Pearson Type 3 (LP3) analysis and drainage area transfer from USGS Gage 05275000 (Elk River near Big Lake); and the Minnesota regional equations applied through the USGS StreamStats online software. The LP3 analysis of 80 annual peak flows at USGS Gage 05275000 was completed using the HEC-SSP software. The HEC-SSP summary table is attached as Appendix B. The drainage area at the gage site is 559 square miles, 92 percent of the area at Orono Dam. Drainage area exponents for each recurrence interval were calculated from the regional equations given in USGS Scientific Investigations Report 2009-5250, Techniques for Estimating the Magnitude and Frequency of Peak Flows on Small Streams in Minnesota Based on Data through Water Year 2005. The SSP results and transfer to the dam site are summarized in Table 1 below. Also shown in Table 1 are the StreamStats results for the dam site. 181 Table 1 Flood Frequency Calculations for the Orono Dam Return Qgage from Drainage area exponent Qdam by drainage HEC-SSP (cfs) area transfer(cfs) Qdam from period (Minnesota equations - Drainage area Drainage area StreamStats (years) SIR 2009-5250) = 605 mil 2 1,684 0.785 1,790 1,820 5 2,835 0.759 3,010 2,910 10 3,661 0.753 3,890 3,910 25 4,700 0.740 4,980 5,100 50 5,585 0.726 5,920 5,870 100 6,432 0.718 6,810 6,850 500 8,454 0.700 8,940 9,060 The two sets of estimates are very close to one another. Using the higher figures from the StreamStats procedure, the 100-year flood of 6,850 cfs would be passed at a reservoir elevation of approximately 875 feet with all gates open. The 500-year flood of 9,060 cfs could be passed at a reservoir elevation of approximately 876 feet. The minimum dike crest elevation is 879 feet; all elevations are in NAVD88. The spillway rating curve was scaled from the CH2M Hill rehabilitation plans (Appendix A). The same drawings show flood frequency estimates which are higher than those shown in Table 1, presumably because they lack the 33 additional years of gage record now available. Hydraulics Hydraulic Model Development The Corps of Engineers HEC-RAS model, Version 4.1.0, was used to simulate the normal-flow and overtopping flood failures of the Orono Dam. Data sources used in the HEC-RAS model development included the following: • HEC-2 model SHERMUL1.DAT of the Mississippi River, provided by the Minnesota DNR. • FEMA National Flood Hazard Layer cross sections, used to adjust the cross section distances specified in the HEC-2 Model. • HEC-RAS model of the Elk River from a point in Orono Lake just downstream of US Highway 10 to the upstream extent of the model, provided by the Minnesota DNR. • Lidar topography downloaded from the Minnesota DNR's website. File:k:\water resource eng\elk river mn\2015 dfa&map\report\report 0320.docx 2 182 • 1971 Orono Lake map from the State of Minnesota Department of Conservation. • Sherburne County FIS dated November 16, 2011. • 1980 CH2M Hill Elk River Dam Rehabilitation plan set. Three bridges (USH 10 over Orono Lake, Parrish Avenue NE over the Mississippi River, and Highway 101 over the Mississippi River)were included in the Minnesota DNR's Elk River HEC- RAS model and the Mississippi River HEC-2 model, and are incorporated in the new HEC-RAS model. A fourth bridge, the Main Street NW bridge, crosses the Elk River immediately below the dam. Its low beam elevation is approximately the same as the overflow spillway crest elevation. Preliminary flood simulations showed that the highest flow modeled (the overtopping flood plus the breach flow)would pass below the low beam of the Main Street bridge. Therefore, this bridge was omitted from the model to improve model stability and performance. In terms of estimating the downstream impacts of failure, this is a conservative approach because the Main Street bridge, if it did impede flow at the downstream face of the dam, would tend to store and submerge the breach outflow. The three modeled bridges also proved to be unaffected by the dam overtopping flow on the Elk River and 10-year flood level of the Mississippi River. The model extends from a point on the Elk River 2.6 miles upstream of the dam to a point on the Mississippi River 6.3 miles downstream of the dam. The upstream boundary was chosen because it represents the upstream limit of impoundment by Orono Dam. The dam is 1.0 mile upstream of the confluence with the Mississippi River. The Mississippi River portion of the model extends 2.8 miles upstream and 5.3 miles downstream of the confluence with the Elk River. The 2.8-mile Mississippi River reach upstream of the confluence was included because a sudden flood wave entering the junction from the Elk River would affect stages and flows on the Mississippi both upstream and downstream of the confluence. The downstream boundary condition on the Mississippi River was a normal depth condition, with the friction slope being taken from water surface profiles shown in the Sherburne County Flood Insurance Study. Hydraulic Model Assumptions Pre-Failure River Flows. For the normal-flow failure, the assumed Elk River discharge was 300 cfs and was selected based on a review of flow data for USGS gage 05275000 upstream of the reservoir. The Mississippi River was assumed to have a base flow of 6,000 cfs, based on US Army Corps of Engineers data for USGS gage 05288500 downstream of the confluence of the two rivers. The zero freeboard flood flow of 16,600 cfs for the Orono Dam was taken from the 1980 CH2M Hill Elk River Dam Rehabilitation plan set. This zero freeboard flow assumes that the fuse plug on the left side of the dam is not utilized. The Mississippi River was assumed to have a 10-year flow at the time of the failure. The 10-year flow of the Mississippi River provided in the 2011 FIS for"Above the confluence of the Elk River" is 36,400 cfs. There is a reasonable likelihood that the Mississippi River would be experiencing a flood larger than the 10-year event during the zero-freeboard flood at the Orono Dam. However, the larger the pre-failure flood is on the Mississippi, the less consequential the additional flow from a dam File:k:\water resource eng\elk river mn\2015 dfa&map\report\report 0320.docx 3 183 failure on the Elk River is. As discussed below, the assumption of a zero-freeboard flood on the Elk River and a 10-year concurrent flood on the Mississippi River resulted in the dambreak flood wave height being almost negligible on the Mississippi, and only about one foot at the most on the Elk River. Therefore, this combination of flood discharges was determined to provide an appropriate upper limit for identifying potentially significant dambreak hazards. Breach Dimensions and Timing. A breach having a bottom width of 40 feet, a bottom elevation of 858 feet, 1:1 side slopes, and a formation time of 0.5 hour was modeled. The assumed failure parameters correspond to an average breach width three times the height of the dam. The assumed breach is located in the left embankment to the left of the main overflow spillway and powerhouse. The failure was assumed to extend down to the deepest portion of the Orono Lake bed just upstream of the dam. Following failure, the upstream water level would draw down very quickly, and continued enlargement of the breach would be unlikely and inconsequential if it did occur. The breach plot from the HEC-RAS model is attached as Appendix C. Consequences of Failure Tables 2 and 3 summarize the consequences of failure during the zero freeboard flood at the Orono Dam and 10-year flood on the Mississippi River (Table 2) and the normal flow case (Table 3). In the case of the flood failure the incremental consequences of failure, relative to the pre-existing flood, become negligible as the flood wave moves towards the Mississippi River. The only significantly impacted properties for the flood failure case are along the Elk River within the first quarter mile downstream of the dam. In the case of a failure at normal flow, the dambreak flood wave is higher relative to the pre- existing profile but is for the most part contained within the river banks. For this case the computed wave heights and travel times are listed to assist in warning recreationists or persons working on or near the river. Inundation maps of the flood failure and normal failure flow are attached as Appendix D. These maps also show the cross section locations referenced in Tables 2 and 3. File:k:\water resource eng\elk river mn\2015 dfa&map\report\report 0320.docx 4 184 Table 2 Downstream Consequences of Failure during a Zero Freeboard Flood on the Elk River and 10-year Flood on the Mississippi River Elk River Pre-Failure Flow= 16,600 cfs and Mississippi River Flow= 36,400 cfs Distance Peak Flood Flood Wave Flood HEC- Downstream Wave Height Wave Peak RAS Location Above No- Arrival Discharge from Dam Elevation Section (miles) (feet NGVD) Failure Time (cfs) Profile(feet) (minutes) Elk River—Just 5895 Downstream of 0.00 868.16 1.14 0 25,090 Dam Elk River— 5620 Upstream of 0.06 868.21 1.19 0 24,940 Affected Properties 3748 Elk River 0.25 867.45 1.20 0 22,860 Elk River— 1849 Upstream of 0.77 864.52 0.43 4 22,510 Confluence Mississippi River— 28 Upstream of 1.58 864.59 0.40 4 37,423 Confluence 29 Mississippi River— 1.97 864.93 0.37 6 37,320 Upstream Mississippi River— 27 Downstream of 1.34 863.03 0.34 4 55,590 Confluence Mississippi River— 22 Just Downstream 1.63 862.51 0.32 6 55,570 of HWY 10 Bridge File:k:\water resource eng\elk river mn\2015 dfa&map\report\report 0320.docx 5 185 Table 3 Downstream Consequences of Failure during Normal Flow Conditions Elk River Pre-Failure Flow = 300 cfs and Mississippi River Flow = 6,000 cfs Distance Peak Flood Flood Wave Flood HEC- Height Wave Peak Downstream Wave RA S Location Above No- Arrival Discharge Section from Dam Elevation Failure Time (cfs) (miles) (feet NGVD) Profile(feet) (minutes) Elk River-Just 5895 Downstream of 0.00 862.49 6.54 4 5,730 Dam Elk River- 5620 Upstream of 0.06 862.47 6.52 4 5,570 Affected Properties 3748 Elk River 0.25 860.97 6.06 8 5,000 Elk River- 1849 Upstream of 0.77 856.30 3.77 12 4,930 Confluence Mississippi River- 28 Upstream of 1.58 853.86 1.34 14 6,300 Confluence 29 Mississippi River- 1.97 854.06 1.14 18 6,180 Upstream Mississippi River- 27 Downstream of 1.34 853.47 1.37 12 9,980 Confluence Mississippi River- 22 Just Downstream 1.63 853.37 1.31 14 9,930 of HWY 10 Bridge Mississippi River- 19 Just Upstream of 2.51 851.80 1.08 20 9,670 HWY 101 Bridge 13 Mississippi River 3.00 851.54 1.01 21 9,550 File:k:\water resource eng\elk river mn12015 dfa&map\report\report 0320.docx 6 186 Conclusions Significant incremental flooding hazards from a failure of the Orono Dam are generally limited to the Elk River between the dam and the Mississippi River, with impacts on the Mississippi River being confined to the channel at low flows and insignificant during natural flood flows on the Mississippi. Previous inundation maps for the Orono Dam have suggested a hazard to homes on the south bank of the Mississippi about 0.25 mile downstream of the confluence. The analyses reported here suggest that a failure of Orono Dam having significant consequences along the Mississippi would not coincide with flooding large enough to reach the neighborhoods in question. Therefore, the Emergency Action Plan should primarily focus on properties along the Elk River for normal-flow and flood conditions, and incidental users of the Mississippi River for low-flow conditions. Finally, the finding described above that the dambreak wave would pass under the Main Street NW bridge should not be construed to mean the bridge should remain open when a flood threatens to overtop the dam. The effects of very turbulent flow, debris, and scour cannot be predicted and closing the bridge and approaches would be prudent. 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Z .3 Li • 0 : T x LC d !. 0 >la 0,... r„,. flii !0 5,,i" !I 11111 2 III no uj ' V 4 '4 LI-1 < fr .co ! > Af , w M kL.L. z t L CO: . 1-.., � c A' IL m O i 21 X,1 ^ a III, , mil LU l: pil EU IN Ili ° p a� urw r � [ 4 0 . ga..., la 2 0 h t v es'do i 1111 sr ail tii cl 0 • a — ado r g [ ‘1199 mmyy cal C7Z At ' z z Z cal z M R W Z � I— I— 1--a p 414C ) 1 . cm L 000[ 6 o oLL ‘t y acc1iz q Lq tW * I u9ILF(ICC 11:%03 w 1 =2 W W #t W II / t\lit - to • 1 I'•;4 -u.iift:: ,s .-f.fo, ` 1xc11•t3• 's. 3 eEf I :S P o If the reservoir water surface elevation rises to , i B77.O feet, maintain Gate No. 3 full open and open 1 Gates Nos. 1 and 2 to the full. open position. o If the reservoir water surface` lowers to elevation 871,, 3 (crest of the overflow weir) at any -time during ;# opening of the gates, then begin closing the gates. Close only one gate at a time. Close date No 3• first, followed by Gate No. 1, and finally I i Gate No, 2. Close. the second and third gates only 1 after the previous gate has been closed completely ��s and the reservoir water surface is at or below 8i.3 feet and continuing to drop. Never stop the gates when water is flowin3 over- the toy and under the bottom at the same time. Whin open, the top of the gate should be wWII. above the reservoir water surface - elevat .on. ' If water flows both over and under the gate at the same time for a prolonged period, vibration may damage the gate. IMPENDING DAM FAILURE `I f In the event that severe damage occurs to the dam for whatever reason, and sudden or impending failure is suspected, the damtender should immediately contact the Elk River Police I Department (phone 444 .2323} . 3 . The police department should in turn contact the following : agencies and immediately coordinate efforts with these agencies to warn residents and, if necessary, to evacuate areas in the downstream flood plain. s , o Minnesota Department of Natural Resources, Division $ ;s of Waters . f i o Sheriff's Office - o State Police { o , City Hall If possible, open all radial gates and drain the reservoir. i Clear the downstream area to the Mississippi of all people :1 before opening the gates, because the downstream river level # may rise several feet when the gates are openep., Contact a qualified engineer and advise of existing conditions. :•. :i 2-3 'i 204 . . . .. art.... flood preparation at Elk River Dam. The City should also coordinate efforts with the National Weather Service and local agencies (sheriff, city and state police, radio and television stations) in disseminating flood information to residents in the flood plain. GATE OPERATION This section describes the radial gate operation plan during • flood or other periods of high water elevation. The gates should always be operated in general accordance with the operation plan described here. During extreme floods, some deviation from the operation plan may be required. Such deviation should only be permitted when the reservoir water surface rises very rapidly and normal gate operation proce- dures are impractical. • Figure 2-1 shows the gate operation curve related to spillway • discharges and reservoir water surface elevations. Figure 2-2 shows the anticipated reservoir response to an approximately 10- and 25-year flood. A complete description of the gate operation plan is presented below: • o Always clear the downstream area of any personnel at or near river level before opening a gate. o When the reservoir level reaches elevation 875.0 feet and rising, open Gate No. 2. (middie gate) approximately 6 feet. - To open the gate 6 feet, the electrical • operator should be engaged for approximately 8 to : . 9 minutes. the gates can also be opened manually with the handwheel : 670 rotations of the' stem nut . will open the gate approximately 6 feet. The amount of gate opening can also be estimated by . visually observing the takeup on the wire cables on the drum hoist. When the gate is open 6 feet, . the top of the gate will be approximately 1 foot lower than the top of the operation deck. o if the water surface elevation rises to 875.5 feet, maintain Gate .NO. 2 at 6 feet and open Gate No. i (south gate, farthest from the main weir) 6 feet. • Close the Main Street Bridge to all traffic except . emergency vehicles if this has not already been done. .. o If the water surface elevation rises to 876. 2 feet, . maintain Gates Nos. 1 and 2 at 6 feet arad 'open Gate No. 3 (north gate, nearest to-the main weir) . • to the full open position. (All gates are equipped .. with switches that will automatically shut off . when the gate reaches its full open position. ) Close the Main Street Bridge to all traffic if this has not already been done. 2-2 S 205 .. Appendix B Hydrologic Analysis 206 1 co N CO LC) 0 e- CV CO CO N CO 0 -- O CO Ln W N e- t� d' (O I-.: (O N I O O N 0 0 I• CO O LO e- CO CO d) N CO CO •ch CO CO Lan) LO CO CO N CO LC) N 1 to O O E O II Z U U E U J U a) U •c ' W O ? I,- LL) Cr) CO O e- O) d: CO LO CO w a _O 4 M M CO 4 e- 4 O N 6 CO N 0 co II 4 a) CO co a0 O O) O - co O) L- C LL e- e- O 4 () N CO 0 CO CO CO O 0 !r- O CO CO LO cF• CO e- %- ' a z I U Ln ! O I O O C LL a) U Z ! W 1 O, N 1_ d I 1 ` co cn Lj .O i I > •— N U U a) o j jW P d _ L W 0 I� CO N- O 4 , O 4 N N U CA ` U y >, Iv CV 44 � Lri4a) (\i cc; a) 22JNCfl12 C) U Lr) O M CO CO CO M CO LC) 0 M e- _ C) i NC) z CO N- in!1 (Co N CO O N- La co . e- N- (CO O r CO CV o ! co O O O V O U 2 a) 0 a •— m ' I > ' U LL 1 I ' - I Cl)cn I o LL : E O N LO O O O 010 0 0 -4--_, 0 ._.. ._� O O e- N Ln 6 I0 O O O Ln O E ` i 1 e- N LO CO O O O u) o j a) ' I J C 1 1 m a) I O , .c j.. Y Y1 I 1 i i� Y �l"O U)I. c 1 i I i%co a�' CC a) �! i O,'O O O€�rnj 1 O O . - _.I• File: Elk River.rpt, Page: 1 Bulletin 17B Frequency Analysis 16 Feb 2015 02:12 PM --- Input Data--- Analysis Name: Elk River Description: Elk River near Big Lake Data Set Name: Peak Flows DSS File Name: K:\Water Resource Eng\Elk River MN\2015 DFA Map\hydrology\SSP\Elk_River_MN\Elk_River_MN.dss DSS Pathname: ////01jan1900/IR-CENTURY// Report File Name: K:\Water Resource Eng\Elk River MN\2015 DFA Map\hydrology\SSP\Elk_River_MNBulletin 17bResults\Elk_River\EI XML File Name: K:\Water Resource Eng\Elk River MN\2015 DFA Map\hydrology\SSP\Elk_River_MN\Bulletinl7bResults\Elk River\Elk_ Start Date: End Date: Skew Option: Use Station Skew Regional Skew: -Infinity Regional Skew MSE: -Infinity Plotting Position Type: Median Upper Confidence Level: 0.05 Lower Confidence Level: 0.95 Display ordinate values using 3 digits in fraction part of value --- End of Input Data--- --- Preliminary Results--- << Skew Weighting >> Based on 80 events, mean-square error of station skew= 0.118 Mean-square error of regional skew= -? << Frequency Curve >> Peak Flows Computed Expected I Percent I Confidence Limits 1 Curve Probability I Chance I 0.05 0.95 I FLOW, CFS I Exceedance I FLOW, CFS 1 I I I 6,595.811 --- 0.2 I 8,551.405 5,348.2371 6,073.479 --- 0.5 I 7,793.607 4,961.3481 5,624.399 --- 1.0 I 7,149.781 4,625.518 1 5,121.979 --- 2.0 I 6,438.585 4,245.901 1 4,362.524 --- 5.0 1 5,383.728 3,663.0981 3,701.748 --- 10.0 1 4,488.440 3,145.495 1 2,946.881 --- 20.0 1 3,496.231 2,538.894 1 1,730.076 --- 50.0 1 1,987.254 1,511.254 1 885.428 --- I 80.0 I 1,024.853 749.839 1 588.476 --- I 90.0 I 698.747 478.937 1 406.922 --- 1 95.0 I 498.073 317.167 1 188.133 --- 1 99.0 I 248.114 132.484 1 I I I << Systematic Statistics>> Peak Flows Log Transform: I I FLOW, CFS 1 Number of Events 1 I 1 Mean 3.196 1 Historic Events 0 1 Standard Dev 0.319 1 High Outliers 0 1 Station Skew -0.796 1 Low Outliers 0 1 Regional Skew --- 1 Zero Events 0 1 Weighted Skew --- 1 Missing Events 0 I Adopted Skew -0.796 1 Systematic Events 80 1 I 208 File: Elk_River.rpt, Page: 2 --- End of Preliminary Results--- << Low Outlier Test>> Based on 80 events, 10 percent outlier test deviate K(N)=2.94 Computed low outlier test value= 181.1086 2 low outlier(s) identified below test value of 181.1086 Statistics and frequency curve adjusted for 2 low outlier(s) << Systematic Statistics>> Peak Flows Log Transform: I I FLOW, CFS I Number of Events I I I Mean 3.222 I Historic Events 0 I Standard Dev 0.280 I High Outliers 0 I Station Skew -0.298 I Low Outliers 2 I Regional Skew --- I Zero Events 0 I Weighted Skew --- I Missing Events 0 I Adopted Skew -0.796 I Systematic Events 80 I I I << High Outlier Test>> Based on 78 events, 10 percent outlier test deviate K(N)=2.931 Computed high outlier test value= 10,999.1013 0 high outlier(s)identified above test value of 10,999.1013 Note: Statistics and frequency curve were modified using conditional probablity adjustment. --- Final Results--- << Plotting Positions>> Peak Flows Events Analyzed I Ordered Events FLOW I Water FLOW Median I Day Mon Year CFS I Rank Year CFS Plot Pos I I I 10 Apr 1932 436.000 I 1 1965 7,360.000 0.87 I 30 May 1933 178.000 I 2 1969 5,980.000 2.11 I 25 Sep 1934 144.000 I 3 1952 5,330.000 3.36 I 20 Mar 1935 690.000 I 4 1984 4,980.000 4.60 I 28 Mar 1936 2,000.000 I 5 2001 4,490.000 5.85 I 12 Apr 1937 1,160.000 I 6 1997 4,070.000 7.09 I 11 May 1938 2,740.000 1 7 1943 3,500.000 8.33 I 27 Mar 1939 2,920.000 I 8 1951 3,280.000 9.58 I 09 Apr 1940 1,240.000 I 9 -1945 3,150.000 10.82 1 08 Apr 1941 1,450.000 I 10 1954 3,120.000 12.06 1 18 May 1942 1,560.000 1 11 1956 3,100.000 13.31 I 03 Apr 1943 3,500.000 I 12 1986 2,990.000 14.55 I 07 May 1944 1,740.000 1 13 1939 2,920.000 15.80 I 19 Mar 1945 3,150.000 I 14 1975 2,910.000 17.04 I 21 Mar 1946 1,960.000 I 15 2009 2,810.000 18.28 I 15 Apr 1947 950.000 1 16 1948 2,800.000 19.53 I 29 Mar 1948 2,800.000 I 17 1983 2,750.000 20.77 I 31 Mar 1949 1,750.000 I 18 1979 2,740.000 22.01 I 08 May 1950 2,730.000 1 19 1938 2,740.000 23.26 I 10 Apr 1951 3,280.000 I 20 1950 2,730.000 24.50 I 09 Apr 1952 5,330.000 I 21 1967 2,630.000 25.75 I 26 Mar 1953 1,320.000 I 22 1985 2,520.000 26.99 I 30 Apr 1954 3,120.000 I 23 1957 2,500.000 28.23 I 05 Apr 1955 1,470.000 I 24 1973 2,440.000 29.48 I 209 File: Elk River.rpt, Page: 3 07 Apr 1956 3,100.000 I 25 1982 2,380.000 30.72 I 26 Jun 1957 2,500.000 I 26 2014 2,290.000 31.97 I 11 Apr 1958 538.000 I 27 2011 2,260.000 33.21 I 09 May 1959 330.000 I 28 2002 2,240.000 34.45 I 02 Apr 1960 1,580.000 I 29 1972 2,140.000 35.70 I 18 May 1961 486.000 I 30 1966 2,090.000 36.94 I 27 May 1962 2,040.000 I 31 1991 2,070.000 38.18 I 10 Jun 1963 982.000 I 32 1978 2,060.000 39.43 I 12 May 1964 1,620.000 I 33 1962 2,040.000 40.67 I 15 Apr 1965 7,360.000 I 34 1936 2,000.000 41.92 I 14 Mar 1966 2,090.000 I 35 1976 1,980.000 43.16 I 03 Apr 1967 2,630.000 I 36 1946 1,960.000 44.40 I 17 Mar 1968 633.000 I 37 1992 1,790.000 45.65 I 09 Apr 1969 5,980.000 I 38 1949 1,750.000 46.89 I 27 Apr 1970 1,200.000 I 39 1944 1,740.000 48.13 I 11 Apr 1971 1,630.000 I 40 1995 1,730.000 49.38 I 25 Mar 1972 2,140.000 I 41 2006 1,720.000 50.62 I 17 Mar 1973 2,440.000 I 42 1971 1,630.000 51.87 I 13 Jun 1974 599.000 I 43 2013 1,620.000 53.11 I 22 Apr 1975 2,910.000 I 44 2003 1,620.000 54.35 I 31 Mar 1976 1,980.000 I 45 1964 1,620.000 55.60 I 19 Mar 1977 779.000 I 46 1960 1,580.000 56.84 I 10 Jul 1978 2,060.000 I 47 2012 1,570.000 58.08 I 14 May 1979 2,740.000 I 48 1942 1,560.000 59.33 I 06 Apr 1980 912.000 I 49 1955 1,470.000 60.57 I 19 Jun 1981 686.000 I 50 1941 1,450.000 61.82 I 06 Apr 1982 2,380.000 I 51 2010 1,370.000 63.06 I 02 Jul 1983 2,750.000 I 52 1953 1,320.000 64.30 I 15 Jun 1984 4,980.000 I 53 1998 1,260.000 65.55 I 27 Apr 1985 2,520.000 I 54 2005 1,250.000 66.79 I 13 May 1986 2,990.000 I 55 1940 1,240.000 68.03 I 26 Mar 1987 590.000 I 56 2008 1,200.000 69.28 I 09 May 1991 2,070.000 I 57 1970 1,200.000 70.52 I 09 Mar 1992 1,790.000 I 58 1996 1,180.000 71.77 I 29 Jun 1993 716.000 I 59 1937 1,160.000 73.01 I 05 May 1994 1,130.000 I 60 2004 1,130.000 74.25 I 17 Mar 1995 1,730.000 I 61 1994 1,130.000 75.50 I 19 Apr 1996 1,180.000 62 2007 1,110.000 76.74 I 06 Apr 1997 4,070.000 63 1963 982.000 77.99 07 Apr 1998 1,260.000 64 1947 950.000 79.23 21 May 1999 921.000 65 1999 921.000 80.47 02 Mar 2000 426.000 I 66 1980 912.000 81.72 I 26 Apr 2001 4,490.000 67 1977 779.000 82.96 16 Jul 2002 2,240.000 I 68 1993 716.000 84.20 I 23 Apr 2003 1,620.000 69 1935 690.000 85.45 05 Jun 2004 1,130.000 70 1981 686.000 86.69 13 Jun 2005 1,250.000 71 1968 633.000 87.94 12 Oct 2005 1,720.000 72 1974 599.000 89.18 04 Apr 2007 1,110.000 73 1987 590.000 90.42 16 Jun 2008 1,200.000 74 1958 538.000 91.67 27 Mar 2009 2,810.000 I 75 1961 486.000 92.91 I 17 Mar 2010 1,370.000 I 76 1932 436.000 94.15 I 09 Apr 2011 2,260.000 I 77 2000 426.000 95.40 I 02 Jun 2012 1,570.000 I 78 1959 330.000 96.64 I 29 Jun 2013 1,620.000 I 79 1933 178.000* 97.89 I 06 Jun 2014 2,290.000 I 80 1934 144.000* 99.13 I I I *Outlier << Skew Weighting >> Based on 80 events, mean-square error of station skew= 0.081 210 Appendix C Hydraulic Analysis 211 l 7 L 7 u. 1 0 0 '� 0 LL Z LL Z I O 'O 0 ,O C I- . - F- F- c 0 .0 I 0 4 0 /o , J U) cn (n (1) 0 X X X x C) O o 0 co O o CN I - O N L C 0- 1 to ' CD CD N M W 0 Z as o U_ I- O o U- &... o LL I 3 Q m u) = r- N e- W _N 1' - O $ I C > 0 iii �I ` O ✓ W N I O c M CZ CZ EO (B L a) i 0 N 0 C Y_ L W i N W m 1— -.p O mm E coZ 0 in O m co C O c' cu .O 2 co o W in / CD i2 Y_ W I i ,\ o o 0 0 0 o o Q> co h c0 Ln 7 (}f)UOI;2AO13 — - • T, o .F3 o u_ Z I u_ z O _• 0 0 o -o c H H H H c o> O . 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N N N N_ o > o _ o Lu ,:, \ U o _ . _ _ 4 O . . . .co co ao W co ao (II)uoRenal3 3 &st' 3 a) a) a) m c = 3 C7 C7 C, '''..d a) . a) _o i O i O 4 O '.. �a Cr' 1L J (n g lL lL LL i6 m CO a) CO a) (sp)Mold E O O O O O O o 0 0 () 0 O 0 O 0 0 0 O ") N V M N O O C Q• ' O L O � to O O C a p m O 2 CO L C Co I O w 1 y O U a) 8 I v) N (/) —se i O W 1 0 O O 1 0 1 >_ O iE L = m 0 co— ' 0 N m T -) O a °3 >+ 0 ;-- O Q F- C 13 T M E - >, " C C c o CO• CO 0 CI) a O O 0 0 0 N 0 0 0 CV W T CO CO CO CO CO CO 10 U) �N (u)e6e3S c �, c ; 0) 0 JI LL (Sp)MOIj E as 0 • 0 0 0 0 0 0 o Cop C0f1 •V M N O� 0 00 L O C 4— • Ct co E I -S Cu Cn- c c 2 o o U N i a) I LO ct 0') CO LO j N p — , N _g a W _ I 1 0 O - o0d L o , U o<1- L CO c LL c 00 (n o CIS 0 o_ C c 0 0 (✓) O _ 0 0 N 0 0 CO CO N (O co CLC) U) t) CO U)N 0 0 0 0 0 0 0 (0 0 (4)a6elS J N U C N C (s;p)Mold 0 0 L a) NN> Ld_ N Q tx °o 00 O) 0 0 c0 O U)7 O • U th O 2 - I C C O U m0 m i L O > u-) i L 1— (OO 0 w N i 4_ C O E U o co as a) O N fn O O N C Q • o .„nu) I ;` o i O O N N >_ o Q F- O c' N li co 00 U o O >- c U C 1 (1) • 0 00 = v a O LL >, ----------- ----- CIS o o >' o C C C1) O O V N O CO CO V N O N CO CCO CO OOD CO COO CO CO (j)e6e1S o c 3 d Cr 0 (940)Mold O C (6 L co I- o +� O O O O 00 o 0 o 0 (� ° C) 60) . coo r 0 (0 0 00 co CD W U) C U N (0 — 0 Q C o _ U 0 ca a) o L L U) 0 U 0• `a CV O I 0 N N 'Q 000 N u) W u) 'u) co o° a) rnE 0 oQH C > co 7$ U- N > 0 U o 0 c a) = U) •- c 0 0 0 LL a o >, ` --______ C O C 0 = o in . 0 0 V N O co N O O O W c W ix) C) (4)a6e1S c m d m o J (A LI- (Sjo)MOld CD V O O (n O o O O o O o CLo ct m Q) O co O h N-O co co __.. _ _...... . ____ _.__•_ CO O a> U CD m V C c = 0 o O U ov m p E CD C o 3 O D 1.f) N C 0_ o o N O U O o It co 0 C C 0 III ! 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APPENDIX B Plans for Training, Exercising, Updating, and Posting the EAP 229 Training Training shall be conducted to ensure that parties involved in implementation of the EAP are familiar with all elements of the plan, the availability of equipment, and their responsibilities and duties under the plan. A careful record and roster for each training should be maintained. An annual training shall be held for Elk River Municipal Utilities personnel involved in dam activities and operation. This training should prepare personnel for problem detection and evaluation, how problems relate to determining the appropriate emergency level, and appropriate responses during emergency situations. This training should also be held within 30 days after assignment of new dam operation personnel. An annual review of the EAP will be conducted for all involved parties. The purpose of this training will be to train parties in the procedures to follow in the event of an emergency, to answer questions regarding the procedures, and to test understanding of the EAP. Feedback shall be obtained during this review and be taken into account during update of the plan. Exercising On an annual basis, a test of the emergency preparedness of dam operating personnel and other parties involved in implementation of the EAP shall be made to evaluate the effectiveness and understanding of the EAP. These exercises will include an annual drill, as well as periodic tabletop and functional exercises, all of which should include participation by all parties in the notification flowchart. During these exercises, the dam owner and operator will choose a hypothetical situation to which the appropriate procedures and responses will be determined by each involved party. Upon completion of each exercise, the Dam Owner and Dam Operator will verify that the plan is adequate and, if not, will revise the EAP based on the comments and outcome of the evaluation. Updating A review of the adequacy of the EAP shall be conducted at least annually. During this review, an evaluation of any changes in flood inundation areas, downstream developments, or in the reservoir should be made to determine whether any revisions to the current EAP (including inundation maps) are necessary. The EAP should be updated promptly after each change in involved personnel or their contact information, or after completion of the exercises or trainings. If no revisions are necessary within a given year, a statement that the review was made and no revision to the EAP was necessary should be provided to each recipient of the original EAP. Copies of any revisions that do result from updating the EAP should be furnished to all individuals to whom the original EAP was distributed. The list of EAP holders in Appendix E should be followed to ensure that all copies of the EAP are revised. Posting An up-to-date copy of the notification flowchart shall be posted on the observation deck at the dam and at the Elk River Emergency Operations Center. Copies of the complete EAP are also held by all of the parties in Appendix E. 230 APPENDIX C Site-Specific Concerns 231 Flood Data Flood warning and flood forecasting services in the Elk River area are provided by the National Weather Service Forecast Office at Minneapolis. Technological support is provided by a staff of professional hydrologists at the North Central River Forecast Center also located in Minneapolis. Lead time between distribution of flood forecasts and arrival of the flood crest may range from a few hours to several weeks, in the case of snowmelt. Lead time for crests resulting from rainfall is normally 3 to 7 days, depending on the area and magnitude of the storm. Floods of record in the Elk River Basin have historically occurred in March, April and May as a result of rapid snowmelt. The worst conditions will occur when rainfall accompanies the snowmelt. The most common indication of a potentially hazardous spring flood will be a snowpack greater than 18 inches in the drainage basin. If a rapid warming trend occurs under these conditions, a flood is highly probable. The peak flood flow under these conditions will generally occur about 7 days after the start of snowmelt, which allows adequate time for preparation. The worst conditions will occur if a rainstorm accompanies the warming trend. Under these conditions, advance notice may be reduced to a few days or less, depending on the area, magnitude, and distribution of the rainfall. When the reservoir elevation is high or during floods, the dam operator should maintain communications with the National Weather Service in Minneapolis. The National Weather Service will provide details regarding river stages and flows upstream from the dam and anticipated weather conditions. Whenever conditions that may cause a flood appear to be developing, the dam operator should keep in touch will all of the sources mentioned above in order to maximize lead time for flood preparation at Elk River Dam. The dam operator should also coordinate efforts with the National Weather Service and local agencies in disseminating flood information to residents in the flood plain. Structural Drawings Structural drawings can be obtained by request from dam owner. Gate Operation This section describes the radial gate operation plan during flood or other periods of high water elevation. The gates should always be operated in general accordance with the operation plan described here, or in a separate Inspection, Operation, and Maintenance Manual. During extreme floods, some deviation from the operation plan may be required. Such deviation should only be permitted when the reservoir water surface rises very rapidly and normal gate operation procedures are impractical. A complete description of the gate operation plan is presented below, with a graphic following: • Always clear the downstream area of any personnel at or near river level before opening a gate. • When the reservoir level reaches elevation 875.0 feet and rising, open Gate No. 2 (middle gate)approximately 6 feet. To open the gate 6 feet, the electrical operator should be engaged for approximately 8 to 9 minutes. The gates can also be opened 232 manually with the handwheel: 670 rotations of the stem nut will open the gate approximately 6 feet. The amount of gate opening can also be estimated by visually observing the take-up on the wire cables on the drum hoist. When the gate is open 6 feet, the top of the gate will be approximately 1 foot lower than the top of the operation deck. • If the water surface elevation rises to 875.5 feet, maintain Gate No. 2 at 6 feet and open Gate No. 1 (south gate, farthest from the main weir)6 feet. Close the Main Street Bridge to all traffic except emergency vehicles if this has not already been done. • If the water surface elevation rises to 876.2 feet, maintain Gates Nos. 1 and 2 at 6 feet and open Gate No. 3 (north gate, nearest to the main weir)to the full open position. (All gates are equipped with switches that will automatically shut off when the gate reaches its full open position.) Close the Main Street Bridge to all traffic if this has not already been done. • If the reservoir water surface elevation rises to 877.0 feet, maintain Gate No. 3 full open and open Gates Nos. 1 and2 to the full open position. • If the reservoir water surface lowers to elevation 871.3 (crest of the overflow weir) at any time during opening of the gates, then begin closing the gates. Close only one gate at a time. Close Gate No. 3 first, followed by Gate No. 1, and finally Gate No. 2. Close the second and third gates only after the previous gate has been closed completely and the reservoir water surface is at or below 871.3 feet and continuing to drop. Never stop the gates when water is flowing over the top and under the bottom at the same time. When open, the top of the gate should be well above the reservoir water surface elevation. If water flows both over and under the gate at the same time for a prolonged period, vibration may damage the gate. NOTE: The fuse plug dikes are designed to be overtopped and erode during extremely large floods. The increase in reservoir level caused by inflowing flood water will be delayed by this erosion, and the impact of the flood flow downstream will consequently be reduced. The fuse plug dikes are constructed of fine sand and silty sand and have been seeded to provide a lawn area and prevent surface erosion. Neither sand bags nor any other type of erosion protection should be placed on the embankments to prevent overtopping. 233 us H G 4 . Z gi Z o Z � CO � 5 W Ps co, N �'' O W Z Z Z .:./-0. •� o aW vj � �� _ •° 4jAPf H G O Li CC w W JV CCU " w im U) wpW o CI at Z eh • z F- °>W�a n, � aH i "� � I Oo Q ac 1-a as to a Q -is , S oz • W 3 Q c J w L1J °CiW ,-J oz j IX �j � voi°z W ~ I- Q got a W ci w Q QW .... Q Q a W QO 2Q _ w • W of W= Fc H W F-- > W• W a „t W > CL ; Z< 0o N 1b O� sM J ( fie 0o cN ON CC 0 W ° W• � t Nil W W N 0 ~ a° w2 ! ! UW Q • ;Z lig I- 0 ��g V >�W 0.o 2ZZ Z ix 0 U z () e� N 1 W arc Q w U' �2 � a au Q Z Z it:gi d2 W W W° W oog d d O.J d t OOOC? O o i � w� i O 111 Z O IA N O a ,I \It, >Wt,CA 1s. ti ti co W Q raj,� co 00 00 CO �3�Z W W W W y ¢ tlly . APPENDIX D Approval of the EAP 235 Approval of the EAP By my signature, I acknowledge that I, or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. City of Elk River-Control Copy Holder Number 1 Printe me and title: (-.AL-V I N PPo IJ E-+'t-/ Cf-Cr -A oati tuo-ciewro il. ..0 __,/e... 0 Y2 - 6-.27- ; Signature Date 236 • Approval of the EAP By my signature, I acknowledge that I, or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. Elk River Municipal Utilities—Control Copy Holder Number 2 Printed name and title: ���t`v kt 6- twc \ vvtan e�. 6 ) rr / Signature Date 237 Approval of the EAP By my signature, I acknowledge that I, or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. Elk River Police Department—Control Copy Holder Number 3 Printed name and title: Igo t4 N 'RS•S KA U,Sl Y.3 Signature Date 238 Approval of the EAP By my signature, I acknowledge that I, or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. Elk River Fire Department—Control Copy Holder Number 4 Printed name and title: I . ■)0 N a al Ili II:)A.)61—Wm, 11'i g.e- (-(wee' 7-„, ignature Date 239 Approval of the EAP By my signature, I acknowledge that I, or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. Sherburne County Sheriff's Communications Division—Control Copy Holder Number 5 Printed flair and title: --( 6 ri? frCtV'\ lc Signature Date 240 Approval of the EAP By my signature, I acknowledge that I, or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. Wright County Sheriff's Office—Control Copy Holder Number 6 Printed name and title: S i r P`-/EN L. Bc:p( _s/072/0zi5-- Signature Date 241 Approval of the EAP By my signature, I acknowledge that I,or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. Hennepin County Emergency Management—Control Copy Holder Number 7 Printed name and title: S C.l.& k71...per #6vA/Efr,../ 47ruv 'S Signature Date • c 242 Approval of the EAP By my signature, I acknowledge that I, or my representative, have reviewed this plan and concur with the tasks and responsibilities assigned herein for me and my organization. Minnesota Department of Natural Resources—Control Copy Holder Number 8 Printed nam nd title: ! J 4.foh 86//e, /57�afz 044, $ !%N9;Meer 4"y� 3117 /20/5—ure Date 243 APPENDIX E Control Copy Holders of this EAP 244 APPENDIX E - CONTROL COPY HOLDERS OF THIS EAP Copy Organization Person receiving copy Number 1 City of Elk River Calvin Portner, City Administrator 2 Elk River Municipal Utilities Troy Adams, General Manager 3 Elk River Police Department Ron Nierenhausen, Police Chief 4 Elk River Fire Department T. John Cunningham, Fire Chief Sherburne County Sheriff's Kyle Breffle, 5 Communications Division Emergency Services Director Wright County Sheriff's Office Steve Berg, 6 Emergency Management Coordinator 245 Copy Organization Person receiving copy Number 7 Hennepin County Emergency Management Watch Leader 8 Minnesota Department of Natural Resources Jason Boyle Note: The Elk River Dam EAP is a controlled document held by the eight control copy holders listed above. If an extra copy is required, the control copy holder is responsible for making and updating any additional copies made. Copies must state: Uncontrolled Copy — For Reference Only. 246 APPENDIX F Notification List for Emergency (Controlled Document) 247