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HomeMy WebLinkAboutC-1553 - Big Canyon Reservoir Inundation Study�- S5 i JAN 1 4 1974 January 14, 1974 By fhs CITY COUNCIL CITY M_Ma !p? RR09H CITY COUNCIL AGENDA ITEM NO. G -1 TO: CITY COUNCIL FROM: Public Works Department SUBJECT: INUNDATION STUDY FOR BIG CANYON RESERVOIR RECOMMENDATION: 1. Receive the study. 2. Refer the study to the Civil Defense and Disaster Council for formation of emergency procedures. DISCUSSION: The completion of this study constitutes the City's partial con- formance with the mandate of Senate Bill 896, adopted as Chapter 780, Statutes of 1972, which added Section 8589.5 (relating to possible inundation below dams) to the Government Code. The legislation became effective on March 7, 1973 with an initial study submittal deadline of September 7, 1973 to the State Office of Emergency Services (OES). The OES has reviewed and approved the calculations and the preliminary study map. Following submittal of the final study to OES, the legislation re- quires the City to refer the study to its appropriate public safety entity for adoption of emergency procedures for the evacuation and control of the populated area below the dam. Following adoption of the procedures, DES shall review them to determine their adequacy. In the case of Newport Beach the emergency procedures needed should be relatively simple inasmuch as the study discloses that developed areas will not be involved except for a possible minor effect on a portion of the Harbor View Apartment area. Copies of the study are attached for the Council's use. Because of the limited supply, it is requested that unneeded copies be returned to the Public Works Department. The study was prepared by James M. Montgomery, Consulting Engineers of Irvine, California. l oseph T. Devlin ublic Wrks Director :hh ''� • C _ 15-53 >a76 r JUL 231973 By the CITY COUNCIL r. sic.: V047 Y"H TO: CITY COUNCIL FROM: Public Works Department July 23, 1973 CITY COUNCIL AGENDA ITEM NO. H-2(b) SUBJECT: ENGINEERING SERVICES AGREEMENT FOR PREPARATION OF AN INUNDATION STUDY FOR BIG CANYON RESERVOIR RECOMMENDATION: Adopt a resolution authorizing the Mayor and City Clerk to execute the subject agreement with James M. Montgomery, Consulting Engineers, Inc. DISCUSSION: This project will provide for the preparation of a study to determine areas subject to possible inundation, should a failure of Big Canyon Reservoir occur. This study is mandated through recent legislation of the State of California, Senate Bill 896, adopted as Chapter 780, Statutes of 1972, which added Section 8589.5, relating to possible inunda- tion below dams, to the Government Code and became effective on March 7, 1973. The deadline for submittal of the final study to the State Office of Emergency Services is September 7, 1973. The scope and content of the inundation study will be governed by the criteria set out in a letter from the Office of Emergency Services to the City dated April 27, 1973, copy attached. A proposal has been obtained from the firm of James M. Montgomery, Consulting Engineers Inc. of Irvine, California for performing the study and coordinating the work with the Office of Emergency Services. This firm has performed engineering studies and design work for the City previously and is well qualified to prepare a study of this nature. Compensation will be based on standard hourly rates with a maxi- mum fee not to exceed $5,000.00. Funds for the study are appropriated in account No. 50- 9297 -014. eph T. Devlin lic W rks Director hh Att. -2- April 27, 1973 The list of dams for which inundation maps will be necessary is being prepared on a statewide basis in three categories, as follows: All dams in the ten counties which have a population density of 300 or more persons per square mile (Enclosure 3); 2. In the remaining 48 counties, all dams 75 feet or more in height or having a capacity of 10,000 acre feet or greater; and 3• In those 48 counties, dams of less than Category 2 height or capacity as determined by DES. Dams under your ownership in Categories 1 and 2 are listed in Enclosure 8. Category 3 dams currently are being subjected to individual study by this office, using maps and field reconnaissance. Upon completion of this work, we will notify owners of those Category 3 dams for which inundation maps will be required. If you consider that the failure of any dam shown in Enclosure 8, and the re- sulting release of water, would not endanger life, you may request the Office of Emergency Services to reconsider, stating the reason therefor. By the same token, you are responsible for notifying DES if the list does not include a Category 1 or 2 dam which you own. Consideration is being given to amending Senate Bill 896 to require that only one map, with reservoir at full capacity (spillway level), be prepared for each dam, and to make the submission of maps at median and normally low storage levels optional. Hence, only the map for reservoir at full capacity need be submitted at this time. The proposed amendment further specifies that the owner shall submit maps to DES only, and not to the public safety agency (local jurisdiction) affected. I am sure you will agree that determination of the area of inundation which would result from a breached dam is complicated and difficult. Elaborate calculations and theoretical analyses to locate precisely the inundation boundaries are impractical. The Office of Emergency Services carried out considerable research, contacting the U.S. Army Corps of Engineers, the Depart- ment of Water Resources, and the engineering staffs of large public and private dam owners, to determine a methodology that meets the requirements of the act and at the same time imposes a minimum burden on you, the dam owner. Enclo- sures 4 and 5 embody the general concept and describe two methods of analysis which we believe are adequate. However, your determination of the area of potential inundation is not restricted to these two methods. It should be noted that the cited or similar methods are intended to result in a conserva- tive yet simplified and relatively inexpensive analysis. The analysis must, of course, be accomplished by a California- registered civil engineer. To assist in developing your rationale for the determination of the area of inundation, the following considerations are offered: Assume full storage capacity. In the case of a multiple- spillway dam, this ordinarily would require selection of the upper- spillway level. I STATE OF CALIFORNIA RONALD REAG AN, G.",r o, OFFICE OF EMERGENCY SERVICES POST OFFICE BOX 9577 a SACRAMENTO, CALIFORNIA 95821 - ', April 27, 1973 City of Newport Beach 3300 Newport Blvd. Newport Beach, CA 92660 Dear Sir: 1 J 'l� i As you probably are aware, Senate Bill 896, adopted as Chapter 780, Statutes of 1972, added Section 8589.5, relating to possible inundation below dams, to the Government Code. It became effective March 7, 1973• Enclosure 1 hereto is a copy of the Act, for your reference. Other material enclosed is: Definition of Dam - Enclosure 2 High - population- density counties - Enclosure 3 Analysis Methods - Enclosures 4 and 5 Map Preparation Procedures - Enclosures 6 and 7 List of your dams in Categories 1 and 2 - Enclosure 8. The purpose of the Act is, of course, to protect the lives of persons in popu- lated areas below dams. For the purpose of this Act, such areas are defined as those which include any permanent dwelling, facility, or organized recrea- tion area permanently or intermittently occupied. Thus a heavy responsibility has been placed upon you, as the owner of a dam or dams, and upon the state and local agencies concerned. You will note that under the provisions of the above -cited Section, the Office of Emergency Services (DES), after consultation with the Department of Water Resources (DWR), identifies those dams the partial or total failure of which could cause death or personal injury due to flooding of the area below the dam. The owner of each dam so identified must then prepare and file inundation maps which show the areas of potential flooding in the event of sudden or total failure of the dam. Local jurisdictions are then required to adopt procedures for the emergency evacuation of such areas. It is incumbent on all parties to carry out the provisions of the Act in a manner which will ensure the fulfillment of its purpose. OES, after extensive study icd cons;A tatlon with DWR, established procedures for selecting the dams for which map, are required. (In this connection, dams are defined in para- gra,.h, (�) of Section 8589.r in Enclosure 1, and in Enclosure 2.) EXN /A /T '0A'� 1 T • -3- E April 27, 1973 The impact of downstream conditions at the time of dam failure depends upon the volume of stored water, the rate of discharge, and the down- stream terrain, and each case must be considered individually. For broad guidance, the ten -year average maximum flow may be assumed, unless in your judgment a different condition should be postulated. Similarly, in tidal areas, mean high tide may be assumed. In the case of multiple dam failures along single or confluent waterways, it is not considered feasible to prescribe detailed, uniform procedures for determining the area(s) of inundation. The engineers involved should keep in mind that the purpose of the inundation map is to provide the basis for evacuation planning. Logical judgments should be applied, to reach a coordinated set of computations and maps. Regarding the above considerations, a key point is to determine the limits of possible inundation on a conservative basis. Flood plain information and flood insurance studies covering some parts of California have been prepared by a number of agencies, including the Corps of Engineers, the U.S. Geologic Survey, and the Soil Conservation Service. They have partial application to the problem of flooding resulting from a breached dam, and their use would in some cases reduce costs. Information concerning the availability of these studies may be obtained from the appropriate C/E District Engineer office in San Francisco, Los Angeles, or Sacramento. A list of communities for which flood insurance studies have been prepared also may be obtained by request to DES. In addition, some county and city planning departments have developed topographic data in connection with their master planning. The procedures for preparing and submitting the inundation map are described in Enclosures 6 and 7. It is of vital importance that the map scale selected be large enough to permit clear identification, on the ground, of the limits of potential flooding. This will facilitate the development of an effective evacuation plan by the public safety agencies concerned. (See paragraph 4 of Enclosure 6.) In order to minimize costs due to possible corrections resulting from the State engineering review, three checkprint copies of the inundation area boundaries, d6 d prepared in accordance with paragraphs 3, 4, and 6 -8 of Enclosure 6 and with 11,4't Enclosure 7, will first be submitted to the Office of Emergency Services. Two copies of the method used in deriving the area of inundation, including basic Q<z data, assumptions, rationale, and calculations, must accompany the prints. Please note that the engineering work is to be accomplished by a California - registered civil engineer, and the appropriate block on the checkprint and on the Cronaflex authenticated by him. Following the State's engineering review, one of the checkprints, indicating °kk ?1 any for will be h6 Cronaflex reproducibles Enclosures and the reviewing official's comments, and submitted to OES only. h' Please note that the engineering work is to be accomplished by a California - registered civil engineer, and the appropriate block on the checkprint and on the Cronaflex authenticated by him. 0 -4- April 27, 1973 Final inundation maps must be prepared and submitted within six months after the effective date of the Act, or by September 7, 1973, unless DES extends that date for good reason. As the review burden will be substantial, it will be appreciated if checkprint maps are submitted as soon as they can be completed. Any questions concerning the provisions of this letter should be addressed to the Office of Emergency Services, where the point of contact is Mr. Eric Orme. The telephone number is (916)421 -4990. Sincerely, H. R. TEMPLE. Director enclosures cc: Dept. of Water Resources DES Regions County Emergency Services Coordinators Chairmen, County Boards of Supervisors Presidents, Emergency Services Directors Assns. Y • • Enclosure 1 Senate Bill No. 896 CHAPTER 780 An act to add Section 8589.5 to the Government Code, relating to dam safety. (Approved by Governor August 11, 1972. Filed with Secretary of State August 11, 1972.) LEGISLATIVE COUNSEL'S DIGEST SB 896, Alquist. Seismic safety. Requires filing of inundation maps by certain dam owners with Office of Emergency Services, Department of Water Resources, and specified local agencies. Provides that cities and counties hav- ing territory designated by Office of Emergency Services as being in area where death or personal injury would occur as a result of dam failure, shall adopt emergency procedures for evacuation and control of populated areas below dams, and requires Office of Emergency Services to review such procedures and make recommenda- tions relative to the adequacy thereof. Requires such emergency procedures to conform to local needs, and sets forth suggested possible elements of such procedures, but specifies that Office of Emergency Services may require other appropriate elements. Requires report to Legislature. The people of the State of California do enact as followst SECTION 1. The Legislature intends, by this act, to establish procedures for the emergency evacuation and control of populated areas below dams. The value of such a program has been demon- strated by that of the Los Angeles Department of Water and Power, administered by the Los Angeles Police Department, which has been very successful. SEC. 2. Section 8589.5 is added to the Government Code, to read: 8589.5. (a) Inundation maps showing the areas of potential flooding in the event of sudden or total failure of any dam, the partial or total failure of which the Office of Emergency Ser- vices determines, after consultation with the Department of Water Resources, would result in death or personal injury, shall be prepared and submitted as provided in this subdivision within six months after the effective date of this section, unless the time for submission of such maps is extended 'for reasonable cause by the Office of Emergency Services. The local governmental or- ganization, utility, or other owner of any dam so designated shall submit to the Office of Emergency "Services three such maps, which shall delineate potential flood zones that could result in the event of dam failure when the reservoir is at full capacity, at median storage level, and at normally low storage level. After submission of copies of such maps, the Office of Emergency OES 4/73 2. 0 0 Service.3 shall review the maps, and shall return those maps which do not meet the requirements of this subdivision, together with recommendations relative to conforming to such provisions. Maps rejected by the Office of Emergency Services shall be revised to conform to such recommendations and resubmitted. The Office of Emergency Services shall keep on file those maps which conform to the provisions of this subdivision. Maps approved pursuant to this subdivision shall also be kept on file with the Department of Water Resources. The owner of a dam submitting copies of such maps to the Office of Emergency Services shall concurrently submit iden- tical copies to the appropriate public safety agency of any city, county, or city and county likely to be affected. (b) Based upon a review of inundation maps submitted pursuant to subdivision (a), the Office of Emergency Services shall desig- nate areas within which death or personal injury would, in its determination, result from the partial or total failure of a dam. The appropriate public safety agencies of any city, county, or city and county, the territory of which includes such an area, shall adopt emergency procedures for the evacuation and control of popu- lated areas below such dams. The Office of Emergency Services shall review such procedures to determine whether adequate public safety measures exist for the evacuation and control of populated areas below the dams, and shall make recommendations with regard to the adequacy of such procedures to the concerned public safety agency. In conducting such review the Office of Emergency Ser- vices shall consult with appropriate state and local agencies. Emergency procedures specified in this subdivision shall con- form to local needs, and may be required to include any of the following elements or any other appropriate element, in the dis- cretion of the Office of Emergency Services: (1) delineation of area to be evacuated; (2) routes to be used; (3) traffic control measures; (4) shelters to be activated for the care of the evacu- ees; (5) methods for the movement of people without their own transportation; (6) identification of particular areas or facili- ties in the flood zones which will not require evacuation because of their location on high ground or similar circumstances; (7) identification and development of special procedures for the evac- uation and care of people from unique institutions; (8) procedures for the perimeter and interior security of the area, including such things as passes, identification requirements, and antiloot- ing patrols; (9) procedures for the lifting of the evacuation and reentry of the area; and (10) details of which organizations are responsible for these functions and the material and personnel resources required. It is the intent of the Legislature to en- courage each agency that prepares such emergency procedures to establish a procedure for their review every two years. (c) "Dam," as used in this section, has \the same meaning as specified in Sections 6002, 6003, and 6004 of the Water Code. SEC. 3. The Office of Emergency Services shall report to the Le�jislature on the plans specified by this act on or before the fifth day of the 1074 Rtcular So ssiun of the Legislature. (N.f io•c ti.':•c '.:ciich 7, 1973.) • 0 Enclosure 2 Excerpt from STATUTES AND REGULATIONS PERTAINING TO SUPERVISION OF DAMS AND RESERVOIRS (Water Code) DIVISION 3. .DAMS AND RESERVOIRS PART 1. SUPERVISION OF DAMS AND RESERVOIRS Chapter I. Definitions 6000. Unless the context otherwise requires, the definitions in this chapter govern the construction of this part. 6002. "Dam" means any artificial barrier, together with appurtenant works, which does or may impound or divert water, and which either (a) is or will be 25 feet or more in height from the natural bed of the stream or watercourse at the downstream toe of the barrier, as determined by the department, or from the lowest elevation of the outside limit of the barrier, as determined by the department, if it is not across a stream channel or watercourse, to the maximum possible water storage elevation, or (b) has or will have an impounding capacity of 50 acre -feet or more. 6003. Any such barrier which is or will be not in excess of 6 feet in height, regardless of storage capacity, or which has or will have a storage capacity not in excess of 15 acre -feet, regardless of height, shall not be considered a dam. 6004. No obstruction in a canal used to raise or lower water therein or divert water therefrom, no levee, including but not limited to a levee on the bed of a natural lake the primary purpose of which levee is to control floodwaters, no railroad fill or structure, and no road or highway fill or structure, no circular tank constructed of steel or concrete or of a combination thereof, no tank elevated above the ground, and no barrier which is not across a stream channel, watercourse, or natural drainage area and which has the principal purpose of impounding water for agricul- tural use shall be considered a dam. in addition, no obstruction in the channel of a stream or watercourse which is 15 feet or less in height from the lowest elevation of the obstruction and which has the single. purpose of spreading water within the bed of the stream or watercourse upstream from the obstruction for percolation underground shall be considered a dam. 6004.5• "Reservoir" means any reservoir which contains or will contain the water impounded by a dam. 4/73 0 CALIFORNIA COUNTIES WITH POPULATION DENSITY COUNTY San Francisco Orange Los Angeles Alameda San Mateo Santa Clara Contra Costa Sacramento Marin San Diego OES 4/73 OF 300 OR MORE PERSONS /SQUARE MILE POPULATION DENSITY 15,701.0 1,802.2 1,718.7 1,451.6 1,232.7 813.1 755.0 652.4 392.4 317.0 Enclosure 3 LAFCD -2 of 2 4. Assume Qmax occurs at the midpoint of the outflow hydrograph. Using an isoceles triangle with Qmax at the apex, adjust the rising and falling limbs of the hydrograph so that the volume in the hydrograph equals the storage in the reservoir. 11. Route the calculated hydrograph downstream A. Divide the area downstream into reaches of constant slope and cross section 1. Choose a trapezoidal section that best represents the existing section 2. Choose an appropriate "n" factor B. Route the hydrograph through the reaches by the "Modified Puls3/ method "and Manning's equation C. Determine the downstream limits of flooding 1. Route to a point where existing conveyance (channels, storm drains, streets, etc.) are capable of carrying the flow without flooding 2. Or route to a depressed area that has the storage capacity to retain the flow. III. During the routing process, calculate flow cross sections through the selected reaches A. Use Manning's equation (Q = 1.49 AR 213 5112) to determine the depth of flow through each reach n B. Using the depth just determined, define the limits of flooding through each reach. IV. Construct a flooded area map A. Using a 1" = 2000' scale quadrangle map, plot the limits of flooding for each reach on a transparent overlay* B. By a smooth line, connect the limits of flooding for all reaches. 'TOES Note: Re P. above, Enclosure 6 applies) REFERENCES 1/ "Military Hydrology Bulletin No. 9: Flow Through a Breached Dam ", Corps of Engineers, 1957, pg. 21. 2/ Miscellaneous Paper No. 2 -374, Report 2, "Floobs Resulting from Suddenly Breached Dams; Conditions of High Resistance ", Corps of Engineers, 1961, pg. 15. 31 Flood Routing Chapter 6/0 in Flood Hydrology Part 6 in Water Studies, Volume IV, U.S. Bureau o` Reclamation Manual, 1947. 01-:er r"J'crences) CES 4/73 I • Enclosure 4 reprinted and distributed witk per^rissio7a of LOS ANGELES COUNTY -FLOOD CONTROL DISTRICT HYDRAULIC DIVISION Procedures for the Determination of Inundation Maps Showing Areas of Potential Flooding in the Event of Sudden or Total Failure of Any Dam To Comply with Senate Bill No. 896 It is intended to try the following procedures to develop inundation maps for areas downstream of all District dams and reservoirs where required. These procedures contain many assumptions, so a great deal of engineering judgment is required for their application. 1. Calculate a hydrograph at the dam site A. Concrete dam 1. Assume sudden and complete failure 2. Calculate the maximum outflow (Qmax) by: Qmax 27 B(g)0.5Ho1.5 Qmax = maximum discharge through the breach 8 = effective reservoir width g = gravitational constant Ho = specific head (initial depth of reservoir at dam) 3• Assume Qmax to occur at approximately t = 1 minute 4. Adjust the recession leg of the hydrograph (a straight line) so that the volume in the hydrograph equals the storage in the reservoir B. Earthfill or rockfill dam 1. Assume failure by erosion 2. Assume a median size for a partial breach 3. Calculate the maximum outflow (Qmax) by: 2/ (W Y ) 0'.28 Qmax = 0.29 Wb Db3 /2(Wb \Db) Qmax = maximum discharge through the breach l g = gravitational constant Wb = width of breach at original water surface W = width of dam at original water surface D = vertical distance From original water surface to bottor:: of breach Yo = depth of water at the dam before breach OES 4/73 ;..'r ?.e..: au .0r of 1 t o CITY OF LOS ANGELES DEPARTMENT OF WATER AND POWER DETERMINATION OF DAM BREACH INUNDATION AREA EARTH DAMS PROCEDURE Average Outflow Determination Enclosure 5 Each reservoir was assumed to be at high water at the time of the dam break. The time of emptying, and thus the average rate of outflow, was related to the height of the dam by arbitrarily assuming a 200-foot-high dam to empty in one hour and the time of emptying (T) to vary inversely as the square root of the head (h). Having calculated the time of emptying by the above method, the average rate of outflow was obtained by dividing the reservoir capacity by the time of emptying. Note: Average Slope Determination T= 200 fcr earth dcvns. The slope of the flow path from the reservoir to a flood control channel large enough to convey the average outflow, or to a basin large enough to contain the entire reservoir storage, was determined by plotting a profile of the flow path. The profile was divided into reaches, if necessary, so that each reach had ap- proximately a constant slope. The average slope of each flow path or reach thereof was then obtained by dividing the elevation change by the length of the reach. Use of Manning's Basic Formula A. Assumptions as to 11n n V= 1.486r "3 s "z n and "r " . Basically, n =0.10 was assumed for well- defined canyon areas in which houses and other similar obstacles exist, arld n =0.033 was assumed for more or less unconfined floc, in wide, fairly level areas in which the flow was concentrated in streets. However, the "n" also depended on the "0" ; t.e., for a large "Q" in an unconfined area n =0.1 was assumed because the flow would be very deep and, therefore, would not be concentrated in the streets. The opposite case of a small flow in a canyon was also true. DES 4/73 LAWO - 2 • 2. r The hydraulic radius equals the cross - sectional area divided by the wetted perimeter. The wetted perimeter was assumed to be equal to 1.2 times the flow width. The area equals the flow width multiplied by the average depth, there being three assumed conditions for the average depth as a function of the maximum depth: a. Canyon or plain with approximate triangular cross - section. L W. Average depth d - 0 b. Plain area with two or more channel depressions in cross-section. T d : 310 D c. Flat plains with abrupt changes in topography. 0 EM OES 4/73 LAWGP - 3 • 0 B. Solution of Manning's Formula for the product of "L" and "d" V- 1.486r213s �2 n r = F = 1 d (L = flow width) _ d r 1.2 V= 1.486/12 // "3s n �z ` but V= A _ Q - 1.486rz13s2 A n1.2213 Q = 1.486dz13s' 12 LO 2/ zi (Ld)d2l3 = Qn(1.2) 3 1.468 s'1z Ld313 = Qn(1.2)21 3 =K 1.486 s'iz IV. Determination of „d" vs. "L" Curve "K" was calculated from the above formula, a different "K" being calculated for each change in "n11 or "s" Having determined "K the „d„ vs. "L" curve was plotted. In a situation where the flow splits, new curves were plotted for the fractional flows by holding d in the equation Ld /3= K constant. The new points were easily determined since "K" is directly proportional to Q" , and L" is directly proportional to "K V. Determination of Inundation Area Two methods were employed, depending on the topography. If the topography was confining or channel -like, Method I was used. If the topography was cone -like; i.e., sloping off, both parallel and perpendicular to the flow line, Method 2 was used. Following is a brief explanation of the two methods. DES 4/73 LA'90 - 4 0 A. Method I With the confining topography, the ,d" vs. 11 L.. curve was used, and a trial and error method was employed. On the drainage maps, cross - sections perpendicular to the flow line were set up at arbitrarily- spaced intervals and /or at logical changes in topography. At each cross - section, the maxi- mum depth, "D" was assumed and, depending on the type of confining topog- raphy, a relationship between "D" and "d" was selected. The flow width between contours corresponding to the assumed "D" was measured on the drain- age map and this point, coordinates (d,L) , was checked against the "d" vs. "L" curve to see if the assumed point falls on the curve. If it did, the flood limits for that cross - section had been determined. If the point fell above or below the "d" vs. "L" curve, a smaller or larger "D" re- spectively, was assumed until the assumed point was on the curve. This process was continued at each cross-section to obtain the flood limits. B. Method 2 With the cone -like topography, the flood limit was determined not on a "cross-sectional area required for flow" basis, but by a consideration of the behavior of the limits of the flow; i.e., by following the path of a particle of water under the influence of slopes in mutually perpendicular directions. Specifically, when the cone -type topography was first encountered, the nearest street intersection to the edge of the flow at the beginning of said topography was selected. At this intersection, the slope for the first block in each direction was determined. The angle between the flow line and the resultant velocity vector was then calculated by the following formula: Slope in direction lateral to FL. T 8 =tan Slope in direction porollel to FL. A line was then drawn at 9 to the flow line and extended until it came near or went through another intersection, at which point the process was repeated. Between the intersections where 9 was determined, the flood limit was assumed to follow streets, but for the final map the limit was obtained by drawing a smooth line through the corners of the preliminary limit. This method was used for both the progression and recession of the flood limit in the lateral direction. DES 4/73 LAW&P - 5 • Example c 0 STREETS PRELIMINARY �\ BOUNDARY 7 SP OP RY It was assumed that the only forces acting are those due to the slopes. The momentum of the flow parallel to the flow line, as well as the head (or depth) of the water at the intersection were neglected. It was also assumed that the "n" and hydraulic radius were the same along the two directions for which the slopes were calculated. In Method 1, the water surface was assumed horizontal; whereas, in this method, the water was assumed to have a mound configuration. In Method 1, the depth was assumed to be the independent variable, and the width of flow the dependent. In Method 2, the width was assumed to be the independent variable, and the depth was the dependent. Actually, no depth was calculated in Method 2, but it could have been, simply by establishing a relation between "D" and "d" as in Method 1. 0 OEs 4/73 S�L-/---�,I SL s�� P� I ^ V P �� �I �?i _ SL FINAL BOUNDA �� SL.— R ' P � R �P I I I� R I �� SP R, I SP SL SL �S R p� I I -- R1I� -- 0 �• R SP OP RY It was assumed that the only forces acting are those due to the slopes. The momentum of the flow parallel to the flow line, as well as the head (or depth) of the water at the intersection were neglected. It was also assumed that the "n" and hydraulic radius were the same along the two directions for which the slopes were calculated. In Method 1, the water surface was assumed horizontal; whereas, in this method, the water was assumed to have a mound configuration. In Method 1, the depth was assumed to be the independent variable, and the width of flow the dependent. In Method 2, the width was assumed to be the independent variable, and the depth was the dependent. Actually, no depth was calculated in Method 2, but it could have been, simply by establishing a relation between "D" and "d" as in Method 1. 0 OEs 4/73 LAW&P - 6 • CONCLUSIONS AND RECOMMENDATIONS 0 The method used in this study was applied to the Baldwin Hills Reservoir dam and the calculated flood area compared favorably with the actual flood area. It is, there- fore, concluded that this study presents a representative picture of the flood area which could develop if any of the ten major reservoir dams investigated should breach. The greatest difficulty, aside from trying to determine a realistic time of empty- ing for each reservoir, was that of determining the rate of lateral progression and recession of flood waters on cone -like topography. DES 4/73 LAW&P - 7 %ZI] 10 H B a ei 6 � 4 x a i � 2 0 9 BALDWIN HILLS RESERVOIR ;,- — - - -= as /3 of I I- 10 5f"p - I- Gmdo i I 0.5 Y 0.5 O. I 10000 GES 4/73 • Enclosure 6 PROCEDURES FOR PREPARING AND SUBMITTING INUNDATION MAPS The inundation maps required by Senate Bill 896, adopted as Chapter 780, Statutes of 1972, Section 8589.5 of the Government Code, shall be prepared as outlined herein. The purpose of these maps is to provide guidance for public safety personnel in the development of a plan for evacuation of an endangered area. If in some unanticipated circumstance, maps prepared in accordance with these instructions appear to not meet this objective, please contact the Office of Emergency Services for additional instructions. The maps shall conform to the dimensions and format of the sample shown in Enclosure 7. 2. The maps shall be prepared on Cronaflex sensitized film, such as DPM -4, CFM -4, PFM -4, or equivalent. 3. The base map(s) shall be prepared using the USGS Quadrangle map(s) (without green overlay). The quadrangle shall be printed on the reverse side of a posi- tive Cronaflex. If a negative step is required, the negative scale shall be the same as the original quadrangle map scale. Negative(s) should be retained for possible future use. 4. The map scale utilized shall ensure that the limits of the inundated area can be clearly identified on the ground. The minimum scale to be used is 1:24,000 (1 inch = 2,000 feet). A larger scale is desired where the area of inundation and its immediate environs at such scale can be accommodated on the sheet size specified in Enclosure 7. 5. The boundary of the area of inundation shall be added, using Peliken T black ink and a k3 Rapidograph pen, or equivalent, on the top side of the Cronaflex. Identifying data (paragraph 6 below) also shall be added. Water depths need not be shown. This Cronaflex is for owner retention. 6. Physical features in the vicinity of the inundation line not designated by name on the USGS Quadrangle shall be labeled if place names do exist. Where geographic /place names needed for clear identification of the inundation area boundary are lacking, dimensional offsets to that boundary from easily identi- fiable features shall be shown. Lettering equivalent to Leroy 100 /00,as a minimum, shall be used. 7. If more than one map sheet is required for the area of inundation below a dam, a map index showing the location of all map sheets shall be prepared and shown on each sheet. 8. Where large areas will be inundated, only the maps required to identify the limits of inundation shall be submitted. 9. The following final work shall be submitted to'OES: a. One Cronaflex or equivalent reproducible of the base map only; b. One reverse print Cronaflex or equivalent reproducible of the base map, inundation area boundary, and identifying data; C. Two blue ozalid prints of the Cronaflex, paragraph 9b above. DES 4/73 i 2 as 4/71 /111 11 yz A Enclosure INUNDATION MAP OF (Name of damisi) /" 11 • CITY OF NEWPORT BEACH Category 1 & 2 Dams BIG CANYON DAM 0 Enclosure 8 JAMES M. NIONTGOM FRY. CON51j�TING ENGINEERS, INC. 555 Sl,eul Pa;;a C:: ^! /( ^!7i 796- 114: 7?G?i 4.155 HOURLY RATE SCHEDULE, Effective January 1, 1973 Senior Company Officer $45.00 per man -hour Principal Engineer $40.00 per man -hour Supervising Engineer $30.00 per man -hour Senior Engineer $25.00 per man -hour Engineer $20.00 per man -hour Associate Engineer $17.00 per man -hour Engineering - Geologist $27.00 per man -hour Senior Chemist $22.00 per man -hour Senior Designer $18.00 per man -hour Designer $16.00 per man -hour Draftsman $13.00 per man -hour Laboratory Technician $12.00 per man -hour Senior Resident Engineer $18.00 per man -hour Resident Engineer- Inspector $12.00 per man -hour Survey Party (3 -man) $54.00 per crew -hour Survey Party (2 -man) $38.00 per crew -hour Mileage @ 12 cents per vehicle -mile (other than for survey party) Computer @ $50.00 per meter hour *The individual hourly rates include salary costs, overhead, administration, profit, typing and clerical costs. Survey party rates also include survey equipment rental, stakes, flagging, supplies, and vehicle mileage. ,Ex H/air "8" LAWSP - 2 • 2. r The hydraulic radius equals the cross - sectional area divided by the wetted perimeter. The wetted perimeter was assumed to be equal to 1.2 times the flow width. The area equals the flow width multiplied by the average depth, there being three assumed conditions for the average depth as a function of the maximum depth: a. Canyon or plain with approximate triangular cross- section. L- W. S. Average depth d = 2 b. Plain area with two or more channel depressions in cross-section. L S. d = 314 D c. Flat plains with abrupt changes in topography. L W. S. j = D OES 4/73 M LAW&P - 3 • B. Solution of Manning's Formula for the product of "L" and "d " 1.486rz13 s '12 n r= P = 1 d (L =flow width) _ d r 1.2 V = 1.486 (1 -d ) 2/3 s'1z n but V' A Q _ 1.486r2 13s z A n 1.2 z/3 Q = 1.486d/3s'/2 Ld n1.2 z13 21 (Ldldzi3 = Qn(1.2) 3 1.468 s'1z Ld313 = Qn(1.2)z13 = K 1.486 s'1z IV. Determination of "d" vs. "L" Curve "K" was calculated from the above formula, a different "K" being calculated for each change in "n" or "s" Having determined "K" the "d" vs. "L" curve was plotted. In a situation where the flow splits, new curves were plotted for the fractional flows by holding "d" in the equation Ld'13 =K constant. The new points were easily determined since "K" is directly proportional to "Q"' , and L" is directly proportional to "K V. Determination of Inundation Area Two methods were employed, depending on the topography. If the topography was confining or channel -like, Method I was used. If the topography was cone -like; i.e., sloping off, both parallel and perpendicular to the flow line, Method 2 was used. Following is a brief explanation of the two methods. OES 4/73 I.AwsP - 4 0 A. Method 1 • With the confining topography, the „d" vs. "C' curve was used, and a trial and error method was employed. On the drainage maps, cross-sections perpendicular to the flow line ::ere set up at arbitrarily- spaced intervals and /or at logical changes in topography. At each cross - section, the maxi- mum depth, "D" was assumed and, depending on the type of confining topog- raphy, a relationship between "D" and "d" was selected. The flow width between contours corresponding to the assumed "D" was measured on the drain- age map and this point, coordinates (d,L), was checked against the "d" vs. "L" curve to see if the assumed point falls on the curve. If it did, the flood limits for that cross - section had been determined. If the point fell above or below the "d" vs. "L" curve, a smaller or larger "0" re- spectively, was assumed until the assumed point was on the curve. This process was continued at each cross- section to obtain the flood limits. B. Method 2 With the cone -like topography, the flood limit was determined not on a "cross-sectional area required for flow" basis, but by a consideration of the behavior of the limits of the flow; i.e., by following the path of a particle of water under the influence of slopes in mutually perpendicular directions. Specifically, when the cone -type topography was first encountered, the nearest street intersection to the edge of the flow at the beginning of said topography was selected. At this intersection, the slope for the first block in each direction was determined. The angle between the flow line and the resultant velocity vector was then calculated by the following formula: Slope in direction lateral to FL. z Slope in direction parallel to FL. ) A line was then drawn at 9 to the flow line and extended until it came near or went through another intersection, at which point the process was repeated. Between the intersections where a was determined, the flood limit was assumed to follow streets, but for the final map the limit was obtained by drawing a smooth line through the corners of the preliminary limit. This method was used for both the progression and recession of the flood limit in the lateral direction. OES 4/73 LAWO - 5 Example STREETS PRELIMINARY BOUNDARY/ SP JP RY It was assumed that the only forces acting are those due to the slopes. The momentum of the flow parallel to the flow line, as well as the head (or depth) of the water at the intersection were neglected. It was also assumed that the °n° and hydraulic radius were the same along the two directions for which the slopes were calculated. In Method 1, the water surface was assumed horizontal; whereas, in this method, the water was assumed to have a mound configuration. In Method 1, the depth was assumed to be the independent variable, and the width of flow the dependent. In Method 2, the width was assumed to be the independent variable, and the depth was the dependent. Actually, no depth was calculated in Method 2, but it could have been, simply by establishing a relation between "D" and 11d " as in Method 1. DES 4/73 SLR ' SL S� L P �I R� - yS L /r---BOUNDA FINAL Ll _ I 1 SP SL L— R P I R SP AII _ — — R I� SP R iSP SL �_ SL �S R PT A Loll/ L� I SL 4 -1 - -- P O .•1 R SP JP RY It was assumed that the only forces acting are those due to the slopes. The momentum of the flow parallel to the flow line, as well as the head (or depth) of the water at the intersection were neglected. It was also assumed that the °n° and hydraulic radius were the same along the two directions for which the slopes were calculated. In Method 1, the water surface was assumed horizontal; whereas, in this method, the water was assumed to have a mound configuration. In Method 1, the depth was assumed to be the independent variable, and the width of flow the dependent. In Method 2, the width was assumed to be the independent variable, and the depth was the dependent. Actually, no depth was calculated in Method 2, but it could have been, simply by establishing a relation between "D" and 11d " as in Method 1. DES 4/73 LAW &P - 6 • • CONCLUSIONS AND RECOMMENDATIONS The method used in this study was applied to the Baldwin Hills Reservoir dam and the calculated flood area compared favorably with the actual flood area. It is, there- fore, concluded that this study presents a representative picture of the flood area which could develop if any of the ten major reservoir dams investigated should breach. The greatest difficulty, aside from trying to determine a realistic time of empty- ing for each reservoir, was that of determining the rate of lateral progression and recession of flood waters on cone -like topography. DES 4/73 LAW&P - 7 PICO7 10 8 a 6 i i 4 X Q i 2 0.5 G[5 4/73 BALDWIN HILLS RESERVOIR d.(3 )a• 7 L Sreep Grade • • Enclosure 6 PROCEDURES FOR PREPARING AND SUBMITTING INUNDATION MAPS The inundation maps required by Senate Bill 896, adopted as Chapter 780, Statutes of 1972, Section 8589.5 of the Government Code, shall be prepared as outlined herein. The purpose of these maps is to provide guidance for public safety personnel in the development of a plan for evacuation of an endangered area. If in some unanticipated circumstance, maps prepared in accordance with these instructions appear to not meet this objective, please contact the Office of Emergency Services for additional instructions. The maps shall conform to the dimensions and format of the sample shown in Enclosure 7. 2. The maps shall be prepared on Cronaflex sensitized film, such as DPM -4, CFM -4, PFM -4, or equivalent. 3. The base map(s) shall be prepared using the USGS Quadrangle map(s) (without green overlay). The quadrangle shall be printed on the reverse side of a posi- tive Cronaflex. If a negative step is required, the negative scale shall be the same as the original quadrangle map scale. Negative(s) should be retained.for possible future use. 4. The map scale utilized shall ensure that the limits of the inundated area can be clearly identified on the ground. The minimum scale to be used is 1:24,000 (1 inch = 2,000 feet). A larger scale is desired where the area of inundation and its immediate environs at such scale can be accommodated on the sheet size specified in Enclosure 7. 5. The boundary of the area of Inundation shall be added, using Peliken T black ink and a k3 Rapidograph pen, or equivalent, on the top side of the Cronaflex. Identifying data (paragraph 6 below) also shall be added. Water depths need not be shown. This Cronaflex is for owner retention. 6. Physical features in the vicinity name on the USGS Quadrangle shall geographic /place names needed for boundary are lacking, dimensional fiable features shall be shown. minimum, shall be used. of the inundation line not designated by be labeled if place names do exist. Where clear identification of the inundation area offsets to that boundary from easily identi- - ettering equivalent to Leroy 100 /00,as a 7. If more than one map sheet is required for the area of inundation below a dam, a map index showing the location of all map sheets shall be prepared and shown on each sheet. 8. Where large areas will be inundated, only the maps required to identify the limits of inundation shall be submitted. 9. The following final work shall be submitted to'OES: a. One Cronaflex or equivalent reproducible of the base map only; b. One reverse print Cronaflex or equivalent reproducible of the base map, inundation area boundary, and identifying data; c. Two blue ozalid prints of the Cronaflex, paragraph 9b above. OES 4/73 i /„ oEs 4/73 /1 11 71 24 " /„ tnciusu,re INUNDATION MAP OF (Name at damis)) /„ CITY OF NEWPORT BEACH Category 1 & 2 Dams BIG CANYON DAM • Enclosure 8 JAMES M. ENGINEERS, INC. 555 HOURLY RATE SCHEDULE4 Effective January 1, 1973 3) 796 .p1141!i213) 6N1 4!55 Senior Company Officer $45. 00 per man -hour Principal Engineer $40.00 per man -hour Supervising Engineer $30.00 per man -hour Senior Engineer $25.00 per man -hour Engineer $20.00 per man -hour Associate Engineer $17.00 per man -hour Engineering - Geologist $27.00 per man -hour Senior Chemist $22.00 per man -hour Senior Designer $18.00 per man -hour Designer $16.00 per man -hour Draftsman $13.00 per man -hour Laboratory Technician $12.00 per man -hour Senior Resident Engineer $18.00 per man -hour Resident Engineer- Inspector $12.00 per man -hour Survey Party (3 -man) $54.00 per crew -hour Survey Party (2 -man) $38.00 per crew -hour Mileage @ 12 cents per vehicle -mile (other than for survey party) Computer @ $50.00 per meter hour -The individual hourly rates include salary costs, overhead, administration, profit, typing and clerical costs. Survey party rates also include survey equipment rental, stakes, flagging, supplies, and vehicle mileage. ExN/AS/r "B„ • w AGREEMENT FOR ENGINEERING SERVICES Inundation Study for Big Canyon Reservoir This Agreement is made and entered into this day of 1973, by and between the City of Newport Beach, a municipal corporation, hereinafter referred to as "CITY" and the firm of James M. Montgomery, Consulting Engineers, Inc., Consulting Civil Engineers, hereinafter referred to as "ENGINEER "; W I T N E S S E T H WHEREAS, CITY in compliance with Section 8589.5 of the Government Code, State of California, must present to the State Office of Emergency Services no later than September 7, 1973 a.study on the limits of possible inundation from Big Canyon Reservoir, in the City of Newport Beach; and WHEREAS, engineering services are necessary to prepare the above mentioned study; and WHEREAS, ENGINEER has submitted a proposal to perform the "Inundation Study for Big Canyon Reservoir "; NOW THEREFORE, the parties agree as follows: 1. GENERAL CITY engages ENGINEER To furnish the services hereinafter specified for the compensation herein stipulated, and ENGINEER agrees to perform such services upon said terms. 2. DUTIES OF ENGINEER The ENGINEER shall: (a) Prepare an Inundation Study for Big Canyon Reservoir, complete with maps indicating areas subject to inunda- tion in the event of reservoir failure, in accordance with Section 8589.5 of the Government Code of the State of California. (b) Confer with and coordinate the preparation of the study with the State Office of Emergency Services, and other interested parties. Basic development of the study should be in conformance with the criteria as noted in a letter, dated April 27, 1973, including attachments, from the Office of Emergency Services to the City of Newport Beach, which letter is attached hereto as Exhibit "A" and is incorporated herein as if fully set forth. -1- (c) Review elements of the study with the City staff at appro- priate points during preparation. The ENGINEER shall determine when review and decisions by the CITY are needed. (d) Provide the CITY with two (2) reproducible copies of all study exhibits, and drawings, two (2) copies of all study calculations. (e) Prepare a draft report and furnish the CITY with two (2) copies for formal review by the CITY staff. (f) Prepare a final report. It is the CITY's intention that CITY agrees to pay Engineer for all services called for under the provisions of this agreement on the basis of the hourly rate schedule attached hereto as Exhibit "B ", which is incorporated herein as if fully set forth; but not to exceed the total sum of Five Thousand ($5000.00) dollars. The amount to be paid ENGINEER shall be payable as follows: (a) Monthly partial payment, each payment to be the amount this report be as concise in presentation as possible, con- sistent with conveying the information required by the Office of Emergency Services. Background information and calculations shall be presented in appendix form separately. Twenty (20) copies of the final report shall be furnished. As noted above two (2) copies of the appendix shall be furnished. 3. DUTIES OF CITY CITY agrees to provide ENGINEER the following: (a) Available topographic and relief maps, drawings, and other data pertaining to the study area. (b) Supplemental field survey information to clarify or extend the limits of available topographic information outlined in (a) above. (c) Consultation with the ENGINEER as needed to accomplish the study. 4. COMPLETION OF SERVICES Engineer agrees to complete all of the services specified herein within forty -five (45) calendar days following execution of this Agreement. 5. PAYMENT BY CITY CITY agrees to pay Engineer for all services called for under the provisions of this agreement on the basis of the hourly rate schedule attached hereto as Exhibit "B ", which is incorporated herein as if fully set forth; but not to exceed the total sum of Five Thousand ($5000.00) dollars. The amount to be paid ENGINEER shall be payable as follows: (a) Monthly partial payment, each payment to be the amount earned as determined by the fee schedule. The sum of the monthly partial payments shall not exceed ninety percent (90 %) of the above maximum fee. (b) Balance of the total amount to be paid upon receipt of Final Report. 6. TERMINATION This Agreement may be terminated at any time by CITY upon three (3) days' written notice to ENGINEER by placing said notice in the United States mail, postage prepaid, addressed to Engineer's business office. In the event of termination due to the fault of Engineer, City shall be relieved of any obligation to compensate Engineer. If this Agreement is terminated for any reason other than the fault of Engineer, City agrees to compensate Engineer for the actual services performed up to the effective date of the notice of termination on the basis of the fee schedule contained in this Agreement. 7. AMENDMENT The scope of the services to be furnished by Engineer may be changed and the maximum fee amended upon prior written approval of the Public Works Director, except that any increase in the maximum fee exceeding One Thousand ($1,000.00) dollars shall be approved by the City Council. 8. ASSIGNMENT This Agreement or any portion thereof shall not be assigned without the written consent of the City. 9. HOLD HARMLESS Engineer shall assume the defense of and indemnify and save harmless the City, and its officers and employees, from all claims, loss, damage, injury and liability, directly arising from any errors, omissions, or negligence in Engineer's performance of this Agreement or from the engineering work and services herein provided. -3- u u IN WITNESS WHEREOF, the parties hereto have executed this Agreement on the date first above written. APPROVED AS TO FORM: City Attorney CITY OF NEWPORT BEACH Mayor ATTEST: City Clerk CITY JAMES M. MONTGOMERY CONSULTING ENGINEERS, INC. By: Title By:, Title: -4- ENGINEER C -1553 (3s-) CITY OF NEWPORT BEACH INUNDATION STUDY FOR BIG CANYON RESERVOIR ORANGE COUNTY, CALIFORNIA NOVEMBER 1973 JAN 14 1974 By the CITY COUNCIL CITY fo 0000091 W10,CH WAN . JAMES M. MONTGOMERY, CONSULTING ENGINEERS, INC. PASASENA • iRVittE • LA JOLLA • WALNUT CREEK • PORT LAUSEROALE • LAS VEGAS �. J G1 JAMES M. MONTGOMEHX CONSULTING ENGINEERS, INC. 17802 Sky Park Circle, Suite 201, Irvine, California 92707/ (714) 979 -8733 Du Wayne R. Lidke Vice President and Manager November 30, 1973 City of Newport Beach 3300 Newport Boulevard Newport Beach, California 92660 Attention: Mr. Joe Devlin Director of Public Works Subject: Inundation Study For Big Canyon Reservoir Gentlemen: In accordance with authorization from the City of Newport Beach, we are transmitting the following final engineering report for the Big Canyon Reservoir Inundation Area Boundary Study, This report has been prepared in accordance with the requirements of Section 8589. 5 of the Government Code of the State of California. Basic development of the study is in accordance with criteria as noted in letter dated April 27, 1973, including attachments, from the office of Emergency Services to the City of Newport Beach, which letter is referred to as Exhibit "A" and incorporated with this report. We wish to thank you for your assistance and cooperation during the prepa- ration of this report, particularly to Messrs. Ben Nolan, City Engineer and Steve Bucknam, Project Engineer, who supplied us with basic data needed to make this study. We are available to discuss this report with you at your convenience. Respectfully submitted, Blu4. '' JC. "'I 'ke DuWayne R. Lidke /da CITY OF NEWPORT BEACH INUNDATION STUDY FOR BIG CANYON RESERVOIR ORANGE COUNTY, CALIFORNIA NOVEMBER 1973 JAMES M. MONTGOMERY, CONSULTING ENGINEERS, INC. 17802 Sky Park Circle, Suite 201 Irvine, California 92707 I TABLE OF CONTENTS Page SUMMARY S -1 INTRODUCTION 1 DESCRIPTION OF DAM 1 LOCATION OF RESERVOIR 1 FLOOD ROUTING PROCEDURES 2 DAM FAILURE OUTFLOW 2 FLOOD ROUTING 3 INUNDATION MAPS 4 SIGNIFICANT FEATURES OF FLOOD ROUTING 4 -6 REFERENCES 7 EXHIBIT "A" - O. E. S. GUIDELINES 8 LIST OF ILLUSTRATIONS Plate I - Big Canyon Area - Capacity Curves Plate II - Inundation Map of Big Canyon Reservoir APPENDIX - See Appendix Under Separate Cover i I SUMMARY Summary This report represents the findings of a study conducted to determine areas subject to inundation in the event of reservoir failure of the City of Newport Beach's Big Canyon Reservoir. A summary of the findings, with specific problem areas designated, is presented therein. This study has been prepared to provide guidance to the concerned public safety agencies for development of adequate public safety measures for the evacuation and control of populated areas below the reservoir in the event of flooding resulting from partial or total failure of the dam. General guidelines and format established by the office of Emergency Services, State of California, to determine the methodology of outflow from a breached dam and the routing of the flood eaters resulting from such a failure havebeen utilized for this study. In the event of failure of Big Canyon Reservoir with the reservoir at full capacity, the resulting release of water upon areas downstream of the dam breach would result in inundation within the potential limits of flooding determined by the downstream topography. The inundation area boundary as shown on Plate II delineates this area of potential flooding. The total distance of flood flow from Big Canyon Reservoir through the Big Canyon drainage course to its terminus into upper Newport Bay is approximately two and one half miles. S -1 INTRODUCTION Effective March 7, 1973, the State of California adopted by Statute, (Section 8589. 5 of the Government Code) the requirement that an inundation study be prepared for areas downstream of dams meeting established criteria as to location, height and capacity. Big Canyon Reservoir meets the statutory requirement for these three catagories. This study has been prepared to provide guidance to the concerned public safety agencies for development of adequate public safety measures for the evacuation and control of populated areas below the dam in the event of flooding resulting from partial or total failure of the dam. The office of Emergency Services, State of California, has established guidelines and format for the preparation of inundation studies. The study is in accordance with those guidelines and format. DESCRIPTION OF DAM Big Canyon Reservoir is formed by an earthfill dam. It is approximately 64 feet high with a total crest length of 3824 feet. The dam is 20 feet wide at the top with 3 to 1 slopes upstream and downstream. A valved 48 -inch steel cylinder concrete pipe enters the reservoir through a reinforced concrete tunnel under the dam. The maximum inflow to the reservoir is limited by the capacity of a 30 -inch connection to the Orange County Feeder Extension of the Metropolitan Water District of Southern California. The reservoir is used to store filtered water for the domestic supply of the City of Newport Beach. The spillway has a rectangular box inlet set flush on the upstream slope. It is connected to a 30 -inch reinforced concrete pipe buried in the downstream slope. A 54 -inch outlet pipe is installed through the dam in a reinforced concrete tunnel. The area - capacity curves for the dam are shown on attached Plate I. LOCATION OF RESERVOIR Big Canyon Reservoir is located in Orange County, California, within the corporate limits of the City of Newport Beach. It is situated in a rudimentary drainage course, Big Canyon, a tributary to Upper Newport Bay. However, due to its design, no surface runoff is impounded. The surface runoff is ' diverted around the reservoir. The existing canyons are characterized by steep hills in the upper reaches lending to gently sloping mesas which end in steep bluffs at the edge of the ocean and bays. Historic storm water -1 - } runoff has incised deep gullies in the land and has established the pattern of the drainage system. Development of some portions of the canyons have resulted from grading and filling operations which have modified the natural drainage pattern. The Big Canyon drainage area of approximately 1200 acres commences on a ridge southerly of Bonita Canyon Reservoir and drains northwesterly to Upper Newport Bay. FLOOD ROUTING PROCEDURES General guidelines and format established by the Office of Emergency Services to determine the methodology of outflow from a breached dam and routing of the flood waters resulting from such dam failure are described in its letter to the City, dated April 27, 1973 (See Exhibit "A" attached). The methodology used as a basis for this study is described in the following sections. DAM FAILURE OUTFLOW The specific method of determination of dam failure outflow is in accordance with the procedures as outlined in the City of Los Angeles, Department of Water and Power Enclosure 5, of reference letter of April 27, 1973, "Determin- ation of Dam Breach Inundation Area -Earth Dams. " In addition, the following assumptions were also utilized. Assumptions 1. The failure of Big Canyon Reservoir dam will be by erosion as opposed to instantaneous failure. The time of emptying, and thus the average rate of outflow, was related to the height of the dam by arbitrarily assuming a 200 -foot high dam to empty in one hour and the time of emptying (T) to vary inversely as the square root of the head (h). The average rate of outflow was obtained by dividing the reservoir capacity, assumed to be at high water (maximum surface elevation) at the time of dam breaching, by the time of emptying. I (200)1/2 Q Capacity (C) h T Where T = Time in hours Where 0 = Average outflow in cu. ft. /sec. h = head in feet C = Capacity of reservoir in cu. ft. T = Time in Seconds -2- 2. The dam breach will occur in the northwest area of the dam in the location of maximum height of dam embankment above the area of the natural stream bed of Big Canyon. The breaching of the dam at this location ,vould result in the maximum discharge of released water, resulting in the areas of greatest downstream flooding. 3. The Big Canyon Reservoir at failure will be at maximum level elevation 302. 4, U. S. G. S. datum, with a storage of 600 acre -feet. Based on the methodology and assumptions herein described, the calculations for the outflow from the dam breach are included in the Appedix to this study on Sheet 18. The outflow determination shows that the average outflow would be 3149 cfs and that approximately two hours and twenty minutes would be required for the reservoir to empty. FLOOD ROUTING For flood routing Manning's equation was used as follows: Q = 1.486AR2/3SI/2 n Where: Q = Flow rate (cfs) n = Friction factor R = Hydraulic radius (A /P) S = Slope of reach (ft /ft) A = Area of flow cross section (ft2) P = Wetted perimeter (ft) Cross sections were selected at logical changes in topography. Basically, n = 0.10 was assumed for well defined canyon areas in which houses and other similar obstacles exist. Modifications were made to Manning's formula for ease of calculations as follows: Ld 5/3 = On (1, 2) 2/3 = K 11.42 Where the wetted perimeter was assumed to be equal to 1. 2 times the flow width (L). A ten year average maximum stormwater runoff flow was assumed for down- stream conditions at the time of failure. Percolation losses throughout the contributing watershed were neglected as being insignificant in comparison to the flows. -3- The Rational Method as adopted by the Orange County Flood Control District was utilized in the hydrologic analysis of the assumed 10 -year average maximum downstream storm flows. INUNDATION MAPS An inundation map showing the areas inundated by the flood waters is made a part of this report. This map is based on U. S. G. S. maps and is scaled at 1 -inch equals 800 feet. This map is shown on Plate II, attached. The inundation area boundary has been derived using, where available, current topographic information. These modifications have been shown on the U. S. G. S. base map. SIGNIFICANT FEATURES OF FLOOD ROUTING Following is a summary of significant features determined from the flood routing: 1. The breaching of Big Canyon Reservoir Dam with water level at maximum elevation of 302.4 and 600 acre -feet in storage will result in an initial average outflow of 3149 cfs. 2. A maximum flood floe of 4226 cfs, downstream on the junction of the north and south legs of Big Canyon will create depths ranging from approximately 2 feet to 12 feet with a maximum of 35 feet depths immediately upstream from roadway obstacles within the flood path. 3. The travel times of the flood wave at specific locations considered significant in inundation planning are as follows: Elapsed Time After Location Dam Breaching New MacArthur Blvd. Old MacArthur Blvd. @ South Leg Big Canyon Old MacArthur Blvd. @ North Leg Big Canyon Big Canyon Drive on North Leg Big Canyon Jamboree Road Backbay Drive -4- 5 Minutes 30 Minutes 1 Hour. 2 Minutes 1 Hour, 32 Minutes 1 Hour, 57 Minutes 2 Hours, 10 Minutes Existing downstream roadway obstacles in the flow path of waters released from dam breaching will impound water until topping or breaching of these roadways occur. Measures to mitigate breaching of existing roadways might include, but not be limited to, effective slope erosion control. With topping of roadways it can be expected that failure of roadways under such conditions will commence on the downstream slopes. Erosion control cover planting might retard or prevent such failure from downstream slope erosion dependent on the magnitude and velocities of the released waters passing over these obstacles. It is generally considered impractical to provide for drainage conveyances to pass waters of the magnitude involved in a dam breaching. However, such consideration might be given to specific areas where the prevention of topping or breaching at these highway and roadway locations would be considered essential in a general emergency plan of evacuation and control in the event of upstream dam failure. The determination of whether the prevention of flooding at specific downstream locations would be considered essential, is beyond the scope of this work. An alternate flood routing analysis was made considering the assumption that roadways are breached at times of maximum storage capacity at these locations. This analysis established that the increased maximum down- stream discharge of waters was not significant in comparison to the mag- nitude of discharge initially assumed. The inundation area boundary map therefore does not reflect additional flows in the event of downstream road- way breaching's at maximum storage capacities created by these obstacles. A specific area of concern for public safety would be the existing development of Harbor View Apartments immediately downstream of Big Canyon Reservoir. Assuming failure in accordance with the assumptions noted, this complex would be subjected to inundation approximately 5 minutes after dam breaching. Based on the outflow quantities at this location, the depth of flooding within the develop- ment complex is mitigated by the widening of the inundation boundary due to the dam effect of New MacArthur Boulevard. Due to grade differences between New MacArthur Boulevard and this complex immediately adjacent, high initial velocities will be developed to a maximum magnitude of 22 fps as flood water overflows the roadway and enters the complex. These erosive velocities will be dissipated as the flow moves into the development, reducing to approximately 4 -feet per second at a depth of 2 feet above existing structure pad elevations.. As the flow moves through the area in its northerly course, the defined canyon adjacent to the area will provide the major conveyance of these released waters. The duration of maximum flooding within the apartment complex would be approx- imately two and one half (2-1/2) hours. -5- Initial inundation of Old MacArthur Boulevard would commence 30 minutes after dam breaching, reaching a maximum flooding depth of 3 feet within approximately 1 hour. Flood depths to approximately Z feet �;:ould inundate the area between Big Canyon Drive and Royal Saint George approximately 1 hour and 30 minutes after dam breaching. Maximum flooding elevation would be experienced at Jamboree Road approximately Z hours after initial breaching, reaching a maximum flooding depth of slightly less than 6 feet. Back Bay Drive adjacent to Upper Newport Bay would be inundated as the released water enters the Upper Bay. This roadway presently is subject to closures during seasonal rainy periods. Notification to this effect is posted to alert vehicular traffic entering this peripheral roadway along Upper Newport Bay. References 1, Letter from Office of Emergency Services, State of California to City of Newport Beach, April 27, 1973, with Enclosures 1 through 8. (See Exhibit "A" Following). 2. "Flood Routing" Chapter 6. 10 in Flood Hydrology, Part 6 in Water Studies Vol. IV, U.S. Bureau of Reclamation Manual, 1947. 3. City of Newport Beach Report on Master Drainage Plan -Dec. 1961, by J. M. M. 4. Big Canyon Reservoir - Application for State Approval. 5. Big Canyon Reservoir Plans - Drawings 1, 2, 4, 6, 12, 13, 14, 16, 17, 31 - Spec. No. W- 4996 -5. dE EXHIBIT "A" $LAU V CALIFORNIA RONALD REAGAN, Gomm., OFFICE OF EMERGENCY SERVICES POST o"Ka sox "" SACRAMENTO, CALIKW" 95523 �I- April 27, 1973 City of Newport Beach 3300 Newport Blvd. Newport Beach, CA 92660 Dear Sir: As you probably are aware, Senate Bill 896, adopted as Chapter 780, Statutes of 1972, added Section 8589.5, relating to possible inundation below dams, to the Government Code. It became effective March 7, 1973• Enclosure 1 hereto is a copy of the Act, for your reference. Other material enclosed is: Definition of Dam - Enclosure 2 High-population- density counties - Enclosure 3 Analysis Methods - Enclosures 4 and 5 Map Preparation Procedures - Enclosures 6 and 7 List of your dams in Categories 1 and 2 - Enclosure 8. The purpose of the Act is, of course, to protect the lives of persons in popu- lated areas below dares. For the purpose of this Act, such areas are defined as those which include any permanent dwelling, facility. or organized recrea- tion area permanently or intermittent ly occupied. Thus a heavy responsibility as been p ace upon you, as the owner of a dam or dams, and upon the state and local agencies concerned. You will note that under the provisions of the above -cited Section, the Office of Emergency Services (DES), after consultation with the Department of Water Resources (DWR), identifies those dams the partial or total failure of which. could cause death or personal injury due to flooding of the area below the dam. The owner of each dam so identified must then orepare and file inundation maos which show the areas of ntential flooding in the event of sudden or total failure of the dam. Local ju- isdictions are then required to adopt procedures for the emergency e•-acuati,: -` su.-h ::re,- . It is incumbent on all parties to car -y out the provisions of the Act in a manner ::'rich vii ensure the ful°i!!rrri of its purpose. DES, after extensive study acd consultation •:ith ^,.� e,taiIi0 ed procedures for select inq the dams for whic av< are roue r.d. Imo, this c.,,rnect:on, dams are defined in para- 9ra ti Ice o` Se :: k:; ii, a in E ^ "IC.;:'q 1, and in Enclosure 2.1 Xf//P,/ T ":1i'/ -2- April 27, 1973 The list of daces for which inundation maps will be necessary is being prepared on a statewide basis in three categories, as follows: 1. All dams in the ten counties which have a population density of 300 or more persons per square mile (Enclosure 3); 2. In the remaining 48 counties, all dams 75 feet or more in height or having a capacity of 10,000 acre feet or greater; and 3. In those 48 counties, dams of less than Category 2 height or capacity as determined by DES. Dams under your ownership in Categories 1 and 2 are listed in Enclosure 8. Category 3 dads currently are being subjected to individual study by this office, using maps and field reconnaissance. Upon completion of this work, we will notify owners of those Category 3 dams for which inundation maps will be required. If you consider that the failure of any dam shown in Enclosure 8, and the re- sulting release of water, would not endanger life, you may request the Office of Emergency Services to reconsider, stating the reason therefor. By the same token, you are responsible for notifying DES if the list does not include a Category i or 2 dam which you own. Consideration is being given to amending Senate Bill 8;0' to require that only 4Am o.,a" W1 tip rescr'vGi t fL� .. ;t' (' :111'. 1C %,2!) be nr CA fn •1 each dam, and to maize the submission of naps at median and normally low storage levels optio;al. Hence, only the map for reservoir at full capacity need be submitted at this tine. The proposed amendment further specifies that the owner shall submit maps to DES only, and not to the public safety agency - -- (local jurisdiction) affected. I am sure you will agree that determination of the area of inundation which would result from a breached dam is complicated and difficult. Elaborate calculations and theoretical analyses to locate precisely the inundation boundaries are ir.- practical. The Office of Emergency Services carried out considerable research, contacting the U.S. Army Corps of Engineers, the Depart- ment of hater Resources, and the engineering staffs of large public and private dam o,:ners, to determine a methodology that meets the requirements of the act and at the same time imposes a minimum, burden on you, the dam Owner. Enclo- surer 4 <nd 5 _ ^bcdy the ganeral concept and describe two methods of analysis which :.e believe are racqu;te. However, your determinaticn of the area' of potential inundation is riot restricted to these two methods. It should be noted that the cited or similar methods are intended to result in a conserva- tive yet simplified Lnd relatively inexpensive analysis. The analysis must, of course, be acco,. .iplished by a California- registered civil encineer. To assist in developing your rationale for the determination of the area of inundation, the following considerations are offered: Assua;e full storage cap ;city. In the case of a multiple- spillway dam, this ordinarily o-:ould require selection of the upper spillway level. L -3- April 27, 1913 The impact of downstream conditions at the time of dam failure depends upon the volume of stored rater, the rate of discharge, and the down - stream terrain, and each case must be considered individually. For. broad guidance, the ten -dear averaec maximum flow ma be assumed, unless in your judgment a dif Terent condition shou d e postulated. Similarly, in tidal areas, mean high tide may be assumed. In the case of multiple dam failures along single or confluent waterways; it is not considered feasible to prescribe detailed, uniform procedures for determining the area(s) of inundation. The engineers involved should keep in mind that the purpose of__the_inundation map_is to provide the 'basis-for evacuation planning. Logical judgments should be applied, to He—ac-E-5-7-33721nated set of computations and maps. Regarding the above considerations, a key point is to determine the limits of possible inundation on a conservative basis. Flood plain information and flood insurance studies covering some parts of California have been prepared by -a number of agencies, including the Corps of Engineers, the U.S. Geologic Survey, and the Soil Conservation Service. They have partial application to the problem of flooding resulting from a breached dam, and their use would in some cases reduce costs. Information concerning tte availability of these studies may be obtained from the appropriate C/E District Engineer office in San Francisco, Los Angeles, or Sacramento. A list of co- nunities for which fiood insurance studies nave i,eeu prcNaieu also [.'ay be obtained by request to OES. In addition, some county and city planning departnents have developed topographic data in connection with their master planning. The procedures for preparing and submitting the inundation map are described in Enclosures 6 and 7. It is of vital importance that the map scale selected be laroe enough to permit clear identification, on the ground, of the limits of potential flooding. This will facilitate the development of an effective evacuation plan by the public safety agencies concerned. (See paragraph 1i of Enclosure 6.) In order.to minimi--e coats due to possible corrections resulting from the State engipeering review, three che.ckF.rint topics of the inundation area boundaries, preprree in accord -.ncc with paragraphs 3, 4, and 6 -8 of Enclosure 6 and with Encies.re 7, o-:ill first be s :.:::fitted to the Office of E,:ergency Services. T:ro copies of the rethcd used in deriving the area of inundation, including basic data, assumptions, rationale, and calculations, must accompany the prints. Follor-ing the State's engineering review, cne of the eheckprints, indicating any need for correction, wall be returned to you. The Cronafic>: reproduciblcs will then be completed in accordance with Enclosures 6 and 7 and the reviewing official's eoar,:ents, and su'.,itted to DES only. Plcase note that the enninecring cork is to be accomplished by a California - registere_1 civil c.iaineer, ant the appropriate block on the eheckprint and on the Cronarlcx auth^nticated by hie. 3 -4- April 27; 1971 Final inundation maps must be prepared and submitted within six months after . the effective date of the Act, or by September %, 1 °73, unless OES extends that date for good reason. As the review burden will be substantial, it will be appreciated if eheckprint raps are submitted as soon as they can be completed. Any questions concerning the provisions of this letter should be addressed to the Office of Emergency Services, where the point of contact is Mr. Eric Orne. The telephone'nunber is (915)421 -4o6O. Sincerely, �G H. R. TEMPLE, Director enclosures cc: Dept. of '!alei kenuurceo OES Regions County lmargcncy Services Coordinators Chairmen, County Boards of Supervisors Presidents, Energency Services Directors Assns. OES 4173 Enclosure 1 Senol o 1'. i 1 1 \o. 896 Cll.'PTEP 780 An act to add Section 8589.5 to the Government Code, relating to dam safety. (Approved by Governor August 11, 1972. Filed with Secretary of State Aucust 11, 1972.) LEGISLATItiE COUNSEL'S DIGEST SE 896, Alquist. Seismic safety. Requires filino of inundation maps by certain dam owners with office of Emergency Services, Department of hater Resources, and specifiesl local agencies. Provides that cities and counties hav- ing territory designated by Office of Emergency Services as being in area u:here death or personal injury would occur as a result of dam failure, shall adopt emergency procedures for evacuation and control of populated areas beloe: dams, and requires Office of Emergency Services to review such procedures and make recommenda- tions relative to the adequacy thereof. Requires such emergency procedures to conform to local needs, and sets forth suggested possible elements of such procedures, but specifies that Office of Emergency Services may require other appropriate elements. Requires report to Legislature. The people of the State of Cali_- orni.a do enact as follo::s: S C -rio". 1. The Legislature intends, by this act, to establish procedures for the e.- ,,:ergency evacuation and control. of populated areas beloia dams. The value of such a program has been demon- strated Ly that of the Los Angeles Department of :'Dater and Power, administered by the Los Angeles Police Department, which has been very successful. SEC. 2. Section 8539.5 is added to the Government Code, to read: 8589.5. (a) Inundation naps showing the areas of potential flooding_ in the event of sudden or total failure of any dam, the partial. or total failure of which the Office of Emergency Ser- vices determines, after consultation ::itn the Department of Water Resource:., wou'_d . esn'.t in dc:xtti or personal injury, shall be prepared : +i.:± _ulciir as provid:d in ti-.is subdivision �.ithin six monlh_s aft e- the effcctivc c!: to of ti:i -s section, unless the time for sum- issic;n of such naps is exter;,3ed for reasonable cause by 1i1c Office of Er- :erpancy Services. The local governmental or- oanizatit.n, utility, or other oi:ncr of any darn so designated si�all suli.rt to the Office of Em,�rc,ancy Services three such maps, which Shall i'.el:.ncato pote:;_i,al flood zones that could result in the evenI of d =m fail:rc x :iicn the reservoir is at full capacity, at nediai sto :-A.gc level, and :.t normally low storage level. After =u! u,is..ica of co :,ies of such i.::ps, the Office of Emeruency 2. Services shall review the mars, a!td shall rc:urn those maps which do not meet the requirements of this sWl,.!ivis.ion, toc!ether with rotorciendz%tions rcla:ivc to conforninn to such provisions. Maps rejected by the Office of Emoznency Services shall be revised to confo_".a to such reco-_- endations and resubmitted. The Office of Ener(rcency Services shall !:cep on file those maps which conform to the provisions of this subdivision. )Iaps approved pursuant to thi: subdivision shall also be kept en file with the Department of b:ator Rosources. The owner of a dam sub^ittinn copies of such maps to the Office of Emergoncy Services shall concurrently submit iden- tical copies to the appropriate public safety agency of any city, county, or city and county likely to be affected. (b) Eased upon a review of inunda_zon . naps submitted pursuant to subdivision (a), the Office of Emergency Services shall desig- nate areas e:ithin tchich death or personal injury would, in its determination, result from the partial or total failure of a dam. The appropriate public safety agencies of any city, county, or city and county, the territory of which includes such an area, shall adopt emergency procedures for the evacuation and control of popu- lated areas below such dans. The Office of Emergency Services shall review such procedures to determine whether adequate public safety measures exist for the evacuation and control of populated areas below the dams, and shall make recommendations with regard to the adequacy of such procedures to.the concerned public safety agency. In conducting such revieic tine Office of Emergency Ser- vices shall consult with appropriate state and local agencies. Emergency procedures speclZleu 1.1 � :iio _hnll -nn.- form to local reeds, and :.it_y bs required to include any of the following elements or any other appropriate element, in the dis- cretion of the Office of Emergency Services: (1) del-ineation of area to be evacuated; (2) routes to be used; (3) traffic control measures; (t) shelters to be activated for the care of the evacu- ees; (S) methods for the movemont.of people without their own transportation; (6) identification of particular areas or facili- ties in the flood zones which 1•:ill not require evacuation because of their location on high ground or similar circumstances; (7) identification and developn.ent of special procedures for the evac- uation and care of people from :ic" -:c institutions; (8) procedures for thc,perir: t -r �.nd sn,orior sactt`ity of the area, including such things as t,ass s, i_l r.;.ific:.tio roquirements, and a:!*iloot- inC: patrols; (9'1 p;OCCdQ_3n fOr inC ...« 1ng of evacuation and reentry of the _zea; and (10) details o` :which ornanizations are L�S�'�::Sli•ln �O7 :;1C3r ] G!:.�'. i.J!: -i .,: a! tliv .._.LCi] -al a17Ct personnel resources racuirnd. It is c:ie inte:it of 1.ho Lecislature to on- coure.riQ each ac_ envy that prcnaies _ h er,�-reiency procedures to cstalia'., a procedure or their rm :cr. dvery tv:o years. (c) "Dwn," as used in this section, has the sane meaning as U)ispoc n Sectio:.e 14 Of the l.'ater Codc. SEC. 3. The Office of Cr:e,:cencv Sorvices sha.11 report to the Legi slatur._ on the J ans _n ec.i.i .e,t by this act on or before the fif th dal' of t :":C 19,4 PQC!LI t ] ua of th. Lccit.laturc. ikc- Ma cS 7, 1973.) Enclosure 2 Excerpt from STATUTES r.'.'D RE CULP,T!ONS TD SUPERVISION OF DAMS AND RESERVOIRS (Water Code) DIVISION 3. DAMS AND RESERVOIRS PART 1. SUPERVISION OF DAMS AND RESERVOIRS Chapter 1. Definitions 6000. Unless the context otherwise requires, the definitions in this chapter govern the construction of this part. .6002. "Dam" means any artificial barrier, together with appurtenant works, vrhich does or may impound or divert water, and which either (a) is or will be 25 feet or more in height from the natural bed of the stream or watercourse at the downstream toe of the barrier, as determined by the department, or from the lo::est elevation of the outside limit of the barrier, as determined by the department, if it is not across a stream channel or watercourse, to the maximum possible v:ater storage elevation, or (b) has or vtill have an impounding capacity of 50 acre -feet or more. 6003. Any such barrier which is or will be not in excess of 6 feet in height, regardless of storage capacity, or which has or will have a storage capacity not in excess of 15 acre-feet, regardless of height, shall not be considered a dam. vDDt:. .... �... :.: ....�. v., ... :. :.a.;.:.. ..::� tc ......z ..i !�..... or divert water cherefroa, no levee, including but not limited to a levee on the bed of a natural lake the primary-purpose of which levee is to control floodwaters, no railroad fill or structure, and no road or highway fill or structure, no circular tank constructed of steel or concrete or of a combination thereof, no tank elevated above the grourd, and no barrier which is not across a strewn channel, watercourse, or natural drainage area and %-.Hch has the principal purpose of impounding ;:ater for agricul- tural use shall be considered a dam. In addition, no obstruction in the channel of a stream or watercourse which is 15 feet or less in height from the lowest elevation of the obstruction and which has the single purpose of sprc<.dir,g water v:ithir, the bed of the stream or watercourse upstream from tb.e obstruction for percolation underground shall be considered a dam. 6004.5. "Reservoir" c._ans any reservoir which contains or will contain the t.-aier i..- pcunded b} a dab.. 4/73 7 CALIFORNIA COUNTIES WITH POPULATION DENSITY OF 300 OR MORE PERSONS /SQUARE MILE OES 4/73 Enclosure 3 POPULATION COUNTY DENSITY San Francisco 15,701.0 Orange 1,802.2 Los Angeles 1,718.7 Alameda I,451.6 San Mateo. 1,232.7 Santa Clara 813.1 Contra Costa 755.0 Sacramento 652.4 - Harin 392.4 San.Diego 317.0 OES 4/73 Enclosure 3 EnCiu�:J�e 'y r.?:tcd a,:.i c:., o<<e� ti ti: t :iscicr. of LOS ANGELES COUNTY FLOOD CONTROL DISTR.!CT HYDRAULIC DIVISION Procedures for the Determination of Inundation Maps Shot:•ing Areas of Potential Flooding in the Event of Sudden or Total Failure of Any Dam To Comply with Senate Bill No. 896 It is intended to try the following procedures to develop inundation maps for areas do�:.nstream of all District dams and reservoirs where required. These procedures contain zany assumptions, so a great deal of engineering judgment -is required for their application. 1.. Calculate a hydrograph at the dam site A. Concrete dam 1. Assume sudden and co^plete failure 2. Calculate the maximum outflow (Amax) by: 1/ Amax = 27 B(9)0.5Ho1.5 maximum discharge through the breach B. = effective reservoir width g = gravitational constant Ho = specific head (initial depth of reservoir at dam) 3. Assume Qf..ax to occur at approximately t = 1 minute 4. Adjust the recession leg of the hydrograph (a straight line) so that the volume in the hydrograph equals the storage in the reservoir B. EarthfIII or roc!-.fiII da ^. .1. Assume failure by erosion 2. Assume a median size for a partial breach 3. Calculate the maximum outflo.a (Onax) by: 2/ 3/2 (kr Yo) 0.23 Qmax 0.29 % 9 "b Db k Db) p nax = maximum discharge through the breach l g = gravitational constant Wb = width of breach at original water surface Wd = Width of dar•at original water surface D = vertical distance from original water surface to bottom of breach Yo = depth of water at the dam before breach OES 4/73 9 tc,FCD r.f 2 4. Assu, ^.c Qnax occurs of the midpoint of the outflow hydrograph. Using an isoceles triangle with enax at the apex, adjust the rising and falling limbs of the hydrograph so that the volume In the hydrograph equals the storage in the reservoir. II. Route the calculated hydrograph downstream A. Divide the area downstream into reaches of constant slope and cross section 1. Choose a trapezoidal section that best represents the existing section 2. Choose an appropriate "n" factor B. Route the hydrograph through the reaches by the "Modified Puls3/ method "and Manning.'s equation C. Determine the downstream limits of flooding 1. Route to a point where existing conveyance (channels, storm drains, streets, etc.) are capable of carrying the flow without flooding 2. Or route to a depressed area that has the storage capacity to retain the flow. III. During the routing process, calculate flow cross sections through the . selected reaches A. Use N =nning's equation (Q = 1•n9 AR2 13 C1 12) P depth to determine the d_p.h of flow through each reach B. Using the depth just determined, define the limits of flooding through each reach. IV. Construct a flooded area map A. Using a 1" _ 2000' scale quadrangle nap, plot the limits of flooding for each reach on a transparent overlay* B. By a smooth line, connect the limits of flooding for all reaches. tOFS Ilot< F= A cbc-,e, c .cZoeure 6 cppZieal P.EFEP:'t:C'S 1/ "Military Hydrology Bulletin No. 9: Flow Through a Breached Dam ", Corps of Engineers, 1957, ^g. 21. 2/ Miscellaneous Pacer No. 2 -374, Report 2, "Floods Resulting from Suddenly Breached Dams; Conditions of High Resistance ", Corps of Engineers, 1961, pg. 15. 3/ Flood Routirg Chcptcr 6/0 in Flood Hydrology Part 6 in Water Studies, Volume IV, U.S. Buraau of Recla.=.,aticn Vinual, 1 --47. (bo/,C. �;: r:,, .':,^.�, C: iC : ?: ctl:Cr re irvi.i;Ccs) DES 4/73 R ^� y71; c»_' EnC IOSUre �2.: t! C;:.[C., �� �!' .. ,,.,2G1: Cr S r _. CITY OF LOS ANGELES DEP;.4TN.E.„ ^_F I ;TEP, '..':O PO'::ER DETERMINATION OF DAM SREAOH INUNDATION AREA EARTH DENS PR0CED:;RE 1. Averace Outflo;: Determination 11 OES 4/73 Each reservoir was assumed to be at high water at the time of the dam break. The time of emptyinc, and thus the averace rate of outflow, was related to the height of the dam by arbitrarily assuming a 200 - foot -high dam to enpty in one hour and the time of emptyinq (T) to vary inversely as the square root of the head (h). Having calculated the time of enotyine by the above method, the average rate of outflow was obtained by dividing the reservoir capacity by the tine of emptying. Note: Average Slope Determination T = 200 frr earth cams. The slope of the flo:•: path from the reservoir to a flood control channel large enough to convey the average outflow, or to a basin large enough to contain the entire reservoir storaae, was determined by plotting a profile of the flow path. The profile a:as divided into reaches, if necessary, so that each reach had ap- nl. _ 1,.... e T�- l - ..t -k fl-,. �`_.. ...... ... ! _ �.....- �....� _. -te. _ ... ... agC s .. ..c. r .. ... �__ thereof was then obtained by dividing the elevation change by the length of the reach. Use of Mannino's Basic Formula A. Assumptions as to 1. n„ I. n r2 "3 --' /z n and r" Basically, n =0.10 leas assured for well- defined canyon areas in v.hich houses and otner similar obstacles exist, and n =0.033 was assu:,ed for more or less cncenfined floo. in l:idc, fairly level areas in which the flow % :as concentrated in streets. Roo-: ever, the "n., also depended on the "0" , %.e., for a farce ..C., in an unconfined area n =0.1 was assumed because the flow o-:ould be very deep and, therefore, would not be concentrated in the streets. The opposite case of a small flow in a canyon was also true_. LAW &P - 2 r The hydrdulic radius equals the cross - sectional area divided by the wetted perimeter. The wetted perimeter was assumed to be equal to 1.2 times the flow width. The area equals the flow width multiplied by the averace depth, there being three assumed conditions for the average depth as a function of the maximum depth: a. Canyon or plain with approximate triangular cross - section. L V.I. Average depth d= 2 b. Plain area with two or more channel depressions in cross - section. L W.S. d =' /,D c. Flat plains with abrupt chances in topography. VV S L Y T% z , 1 ' OE.S 4/73 M LAMEP - 3 B. Solution of Nanning's Formula for the product of "L" and "d" but V= q V. 1.486r213 s 11 n �- P 1 2L (L= flow width) _ d r 1.2 V= 1.486�2Jz/3 5 '12 n// Q _ 1.486 r zl3 s f/z A z - n1.2 �3 Q 1.486d213s1/2 Ld 21 zi3 (Ld)d213 = Qn(1.2) L 468 s z z Ld5 /3 Qn(t.2) 13 = K 1.486 5112 IV. Determination of "d" vs. "L" Curve ,. K" was calculated from the above formula, a different K being calculated for each charge in "n" or °s" Having determined K" , the "d" vs. "L' curve %:as plotted. In a situation where the flog: splits, near curves were plotted for the fractional flows b,. holdifg "d in the eauatien Ld53 =K constant. The nev., Foints were easily dctcrnined since "K" is directly proportional to :1Q and L" is directly proportional to `x ". V. Determination of Inundation Area Two methods were employed, dependi m on the topography. If the topography o-:as confining or channel- 1ik•_, f% thod 1 was used. If the topography was cone -like; i.e., sloping off, both parallel and pe.pendieular to the flow line, Method 2 was used. Followinn is a brief explanation of the two methods. DES 4!73 LANG° - 4 A. Method l With the confining topography, the 11d" vs. "L" curve was used, and a trial and error method was employed. On the drainage maps, cross - sections perpendicular to the flo:: line were set up at arbitrarily - spaced intervals and /or at logical changes in topography. At each cross - section, the maxi- mum depth, ..D,. i,as assumed and, depending on the type of confining topog- raphy, a relationship betv,,een "D" and "d" was selected. The floc: width between contours corresponding to the assumed "D" was measured on the drain- age nap and this point, coordinates (d,L) , was checked against the "d" vs. „L„ curve to see if the assumed point falls on the curve. If it did, the flood limits fer that cross-section had been determined. If the Point fell above or beloo-: the "d" vs. .1L" curve, a smaller or larger "D" re- spectively, was assumed until the assumed point was on the curve: This process was continued at each cross- section to obtain the flood limits. B. Method 2 With the cone -like topography, the flood limit was determined not on a "cross-sect lona I area required for float" basis, but by a consideration of the behavior of the limits of the flow; i.e., by following the path of a particle of water under the influence of slopes in mutually perpendicular directions. . Specifically, when the cone -type topography was first encountered, the np ?rvsf tr -et irter5=ction to the edee of the flow at the heoinning of said topogra "',i f i.as selected. At this intersecticn, the slcpe for the first block in each direction was determined. The angle between the flea: line and the resultant velocity vector was then calcLLlated by the following formula: y Slop^ in di,eefion loteral to FLM Z A= ton- siope in direction poroNef to FL. ) A line was then drawn at 0 to the floo-: line and extended until it came near or went through another ir,tersectien, at which point the process oras repeated. Eetween the inter=sections arhere © was determined, the flood limit was assured to foiloa; streets, but for the final nap the limit i :•as obtained by drawing a smooth line through the corners of the preliminary limit. This method ., s used for bot. the progression and recession of the flood limit in the lo'c'al direction. OES 4/73 a LAW - 5 DEs 4/73 — STREETS SL.f- P I R � ! SP R! ) 1 Sit L —., . .1 SP PRELII',1INAR BOUNDARY —> L R SP I S `f R�I/ SP W FINAL - BOUNDARY SL SP It was assumed that the only forces acting are those due to the slopes. The romentu^ of the flow parallel to the flow line, as well as the head (or depth) of the vdater at the intersection were neglected. It was also assum.ed that the ..n„ and hydraulic radius were the sane along the two directions for which the slopes v:ere calculated. In Method 1, the v:ater surface was assu—.ed horizontal; whereas, in this cethod, the water was assumed to have a round ccnficuration. In Method 1, the depth was assumed to be the independent variable, and the width of flow the dependent. In ,ethcd 2, O.Z width was asSMCed to be the independent variable, and the fepth ...as the d ^.c n,',cni. Actuall;,, no depth was calculated in Method 2, but it could 1-ave bcen, simply by establishing a relation between "D" and ,.d.. as in Method 1, MV - 6 CONCLUSIONS AND RECOM.'9ENDATIOHS The method used in this study was applied to the Baldwin Hills Reservoir dam and the calculated flood area compared favorably with the actual flood area. It is, there- fore, concluded that this study presents a representative picture of the flood area which could develop if any of the ten major reservoir dams investigated should breach. The greatest difficulty, aside from trying to determine a realistic time of empty- ing for each reservoir, was that of determining the rate of lateral progression and recession of flood waters on core -like topography. OLS 4/73 LAW&P - 7 Fm 10 � 6 c b 6 S c 4 JC a E 2 0.5 OES x+/73 B4LDNIN HILLS RESERVOIR d= 0a 31 1 o.a d_(78L / 2 1 Steep Grods Enclosure 6 PROCEDURES FOR PREPARING AND -SU:;MITTING INUNDATION MAPS The inundation maps required by Senate Bill E96, adopted as Chapter 780, Statutes of 1972, Section 6589.5 of the Government Code, shall be prepared as outlined herein. The purpose of these maps is to provide guidance for public safety personnel in the development of a plan for evacuation of an endangered area. If in some unanticipated eircumsta^ce, maps prepared in accordance with these instructions appear to not meet this objective, please contact the Office of Emergency Services for additional instructions. J. The maps shall conform to the dimensions and format of the sample shor:n in Enclosure 7. 2. The maps shall be ' prepared or. Cronaflex sensitized film, such as DPM-4, CFM -4, PFM -4, or equivalent. 3. The base rap(s) shall be prepared using the USGS Quadrangle maps) (without green overlay). The quadrangle shall be printed on the reverse side of a posi- tive Cronaflex. If a negative step is required, the negative scale shall be the same as the original quadrangle map scale. Negative(s) should be retained for possible future use. 4. The map scale utilized shall ensure that the limits of the inundated area can be clearly identified on the ground. The.minimum scale to be used is 1:24,000 (1 inch = 2,000 feet). A larger scale is desired a:here the area of inundation and its immediate environs at such scale can be accom.rodated on the.sheet size specified in Enclncvre 7. 5. The boundary of the area of inundation shall be added, using Peliken T black ink and a r'3 P,apidograph pen, or equivalent, on the top side of the Cronaflex. Identifying data (paragraph 6 belot.•) also shall he added. Water depths need not be sham. This Cronaflex is fqr owner retention. 6. Physical features in the vicinity name on the USES Quadrangle shall geographic /place names needed for boundary are lacking, dimensionai fiable features shall be shown. mini -tin, shall be used. of the inundation line not designated by be labeled if place names do exist. Where clear identification of the inundation area offsets to that boundary from easily identi- _ettering equivalent to Leroy 100/00,a5 a 7. If more than one map sheet is required for the area of inundation below a de.., a map index sho,.-Ang the location of all rap sheets shall be prepared and shorn on eacl. sheet. 8. Where laroe areas vA ll be inundated, only the maps required to identify the limits of inundation shall be submitted. 9. The following final work shall he submitted to OES: 4/13 ,-a. One Cronaflex or equivalent reproducible of the base map only; b. One reverse print Cronaflex or equivalent reproducible of the base nap, inundation area boundary, and ide.-.tifyinp data; e. Two blue czalid prints of the Cronaflex, paragraph 9b above. 9 I , S � I i N f of ; 11/7? INUNDATION f::AP OF (Nc:r „e of dcntsl) I 'r Category 1 & 2 Dams IMENNOW Q G (erg NYv N DAM Enclosure 8 302.4 300• j Q h no. c5 . 280• W W 270 266- AREA- ACRES 22 20 18 16 14 12 AREA VOLUME 0 100 200 300 400 VOLUME - ACRE -FT. BIG CANYON RESERVOIR AREA — CAPACITY CURVES 500 600 ELEV. 302. 4 = MAX. STORAGE ELEV. AT SPILLWAY AREA OF RES. AT MAX. STORAGE EL EV. = 21.6 ACRES PLATE I C -1553 See Contract File for Inundation Map of Big Canyon Reservoir CITY OF NEWPORT BEACH CALIFORNIA City Hall 3300 W. Newport Blvd. Area Code 714 673 -2110 DATE hagUet is 1972 TO: FINANCE DIRECTOR FROM: city Clerk SUBJECT: Contract No. Description of Contract R,� QIM= RaslaXvnir Immdation Study Authorized by Resolution No. 5868 adopted on 7 -28-78 Effective date of Contract July 11� 1C173 1 Contract with Tamar M. Montgmaj: /a C M il ing_EngirA m, Inc. Address 555 .act Walnut RtnAa PARaclnrA. CA. Amount of Contract erntma't city fter1k , August 1, 1973 PUBLIC WOW I£PAR1NM Attention: Steve Buckman CITY CLERK DMDATION Sr" FOR BIG CANYON RESERVOIR 0-1553 Enclosed are two fully executed eopies of an engineering services agreement with James H. Montgomery for subject study. Please forward one copy to Montgomery. Iaura Lagios City Clerk LL:swk enc. i 0 TO: CITY CLERK FROM: Public Works Department SUBJECT: INUNDATION STUDY FOR BIG CANYON RESERVOIR Laura: Attached is the original and two copies of the engineering services agreement for the preparation of the subject study. They have been executed by the engineer. Please return the two copies when they have been fully exe- cuted. One copy will be forwarded to the engineer. Steve Bucknam Project Engineer SB:jfd Att. .0 AGREEMENT FOR ENGINEERING SERVICES Inundation Study for Big Canyon Reservoir This Agreement is made and entered into this 3 /-a7 day of ET» / 1973, by and between the City of Newport Beach, a municipal corporation, hereinafter referred to as "CITY" and the firm of James M. Montgomery, Consulting Engineers, Inc., Consulting Civil Engineers, hereinafter referred to as "ENGINEER "; W I T N E S S E T H _WHEREAS, CITY in compliance with Section 8589.5 of the Government Code, State of California, must present to the State Office of Emergency Services no later than September 7, 1973 a;study on the limits of possible inundation from Big Canyon Reservoir, in the City of Newport Beach; and WHEREAS, engineering services are necessary to prepare the above mentioned study; and WHEREAS, ENGINEER has submitted a proposal to perform the "Inundation Study for Big Canyon Reservoir "; NOW THEREFORE, the parties agree as follows: 1. GENERAL CITY engages ENGINEER To furnish the services hereinafter specified for the compensation herein stipulated, and ENGINEER agrees to perform such services upon said terms. 2. DUTIES OF ENGINEER The ENGINEER shall: (a) Prepare an Inundation Study for Big Canyon Reservoir, complete with maps indicating areas subject to inunda- tion in the event of reservoir failure, in accordance with Section 8589.5 of the Government Code of the State of California. (b) Confer with and coordinate the preparation of the study with the State Office of Emergency Services, and other interested parties. Basic development of the study should be in conformance with the criteria as noted in a letter, dated April 27, 1973, including attachments, ` from the Office of Emergency Services to the City of Newport Beach, which letter is attached hereto as Exhibit "A" and is incorporated herein as if fully set forth. .1- 1: (c) Review elements of the study with the City staff at appro= priate points during preparation. The ENGINEER shall determine when review and decisions by the CITY are needed. (d) Provide the CITY with two (2) reproducible copies of all study exhibits, and drawings, two (2) copies of all study calculations. (e) Prepare a draft report and furnish the CITY with two (2) copies for formal review by the CITY staff. (f) Prepare a final report. It is the CITY's intention that this report be as concise in presentation as possible, con- sistent with conveying the information required by the Office of Emergency Services. Background information and calculations shall be presented in appendix form separately. Twenty (20) copies of the final report shall be furnished. As noted above two (2) copies of the appendix shall be furnished. 3. DUTIES OF CITY CITY agrees to provide ENGINEER the following: (a) Available topographic and relief maps, drawings, and other data pertaining to the study area. (b) Supplemental field survey information to clarify or extend the limits of available topographic information outlined in (a) above. (c) Consultation with the ENGINEER as needed to accomplish the study. 4. COMPLETION OF SERVICES Engineer agrees to complete all of the services specified herein within forty -five (45) calendar days following execution of this Agreement. N� '1.11 y 1 �L` � > • ]' L� 1 f �7 CITY agrees to pay Engineer for all services called for under the provisions of this agreement on the basis of the hourly rate schedule attached hereto as Exhibit "B ", which is incorporated herein as if fully set forth; but not to exceed the total sum of Five Thousand ($5000.00) dollars. The amount to be paid ENGINEER shall be payable as follows: (a) Monthly partial payment, each payment to be the amount earned as determined by the fee schedule. The sum of the monthly partial payments shall not exceed ninety percent (90 %) of the above maximum fee. (b) Balance of the total amount to be paid upon receipt of Final Report. 6. TERMINATION This Agreement may be terminated at any time by CITY upon three (3) days' written notice to ENGINEER by placing said notice in the United States mail, postage prepaid, addressed to Engineer's business office. In the event of termination due to the fault of Engineer, City shall be relieved of any obligation to compensate Engineer. If this Agreement is terminated for any reason other than the fault of Engineer, City agrees to compensate Engineer for the actual services performed up to the effective date of the notice of termination on the basis of the fee schedule contained in this Agreement. 7. AMENDMENT The scope of the services to be furnished by Engineer may be changed and the maximum fee amended upon prior written approval of the Public Works Director, except that any increase in the maximum fee exceeding One Thousand ($1,000.00) dollars shall be approved by the City Council. 8. ASSIGNMENT This Agreement or any portion thereof shall not be assigned without the written consent of the City. 9. HOLD HARMLESS Engineer shall assume the defense of and indemnify and save harmless the City, and its officers and employees, from all claims, loss, damage, injury and liability, directly arising from any errors, Omissions, or negligence in Engineer's performance of this Agreement or from the engineering work and services herein provided by the Engineer._ -3- IN WITNESS WHEREOF, the parties hereto have executed this Agreement on the date first above written. APPROVED AS TO FORM: F, i y ttorney CITY OF NEWPORT BEACH 1.1aI *IM aa4'Q. Certy Clerk CITY JAMES M. MONTGOMERY CONSULTING ENGINEERS, INC. By: Ti t EX9rC • -4- /�_ ' ENGINEER STATE Of CALIFORNIA' RONALD REAGAN, Governor OFFICE OF EMERGENCY SERVICES POST OFFICE BOX 9577 SACRAMENTO, CALIFORNIA 95843 April 27, 1973 City of Newport Beach 3300 Newport Blvd. Newport Beach, CA 92660 Dear Sir: i� Rfee/;'Cf, As you probably are aware, Senate Bill 896, adopted as Chapter 780, Statutes of 1972, added Section 8589.5, relating to possible inundation below dams, to the Government Code. It became effective March 7, 1973. Enclosure I hereto is a copy of the Act, for your reference. Other material enclosed is: Definition of Dam - Enclosure 2 High- population- density counties - Enclosure 3 Analysis Methods - Enclosures 4 and 5 Map Preparation Procedures - Enclosures 6 and 7 List of your dams in Categories 1 and 2 - Enclosure 8. The purpose of the Act is, of course, to protect the lives of persons in popu- lated areas below dams. For the purpose of this Act, such areas are defined as those which include any permanent dwelling, facility, or organized recrea- tion area permanently or intermittently occupied. Thus a heavy responsibility has been placed upon you, as the owner of a dam or dams, and upon the state and local agencies concerned. You will note that under the provisions of the above -cited Section, the Office of Emergency Services (OES), after consultation with the Department of Water Resources (DWR), identifies those dams the partial or total failure of which could cause death or personal injury due to flooding of the area below the dam. The owner of each dam so identified must then prepare and file inundation maps which show the areas of potential flooding in the event.of sudden or total failure of the dam. Local jurisdictions are then required to adopt procedures for the emergency evacuation of such areas. It is incumbent on all parties to carry out the provisions of the Act in a manner which will ensure the fulfillment of its purpose. DES, after extensive study and consultation with DWR, established procedures for selecting the dams for which maps are required. (In this connection, dams are defined in para- graph (c) of Section 8589.5 in Enclosure 1, and in Enclosure 2.) AEXi/ /�C3 /T '0 A'1 • f -2- April 27, 1973 The list of dams for which inundation maps will be necessary is being prepared on a statewide basis in three categories, as follows: 1. All dams in the ten counties which have a population density of 300 or more persons per square mile (Enclosure 3); 2. In the remaining 48 counties, all dams 75 feet or more in height or having a capacity of 10,000 acre feet or greater; and 3. In those 48 counties, dams of less than Category 2 height or capacity as determined by OES. Dams under your ownership in Categories 1 and 2 are listed in Enclosure 8. Category 3 dams currently are being subjected to individual study by this office, using maps and field reconnaissance. Upon completion of this work, we will notify owners of those Category 3 dams for which inundation maps will be required. If you consider that the failure of any dam shown in Enclosure 8, and the re- sulting release of water, would not endanger life, you may request the Office of Emergency Services to reconsider, stating the reason therefor. By the same token, you are responsible for notifying DES if the list does not include a Category 1 or 2 dam which you own. Consideration is being given to amending Senate Bill 896 to require that only one map, with reservoir at full capacity (spillway level), be prepared for each dam, and to make the submission of maps at median and normally low storage levels optional. Hence, only the map for reservoir at full capacity need be submitted at this time. The proposed amendment further specifies that the owner shall submit maps to OES only, and not to the public safety agency (local jurisdiction) affected. I am sure you will agree that determination of the area of inundation which would result from a breached dam is complicated and difficult. Elaborate calculations and theoretical analyses to locate precisely the inundation boundaries are impractical. The Office of Emergency Services carried out considerable research, contacting the U.S. Army Corps of Engineers, the Depart- ment of Water Resources, and the engineering staffs of large public and private dam owners, to determine a methodology that meets the requirements of the act and at the same time imposes a minimum burden on you, the dam owner. Enclo- sures 4 and 5 embody the general concept and describe two methods of analysis which we believe are adequate. However, your determination of the area of potential inundation is not restricted to these two methods. It should be noted that the cited or similar methods are intended to result in a conserva- tive yet simplified and relatively inexpensive analysis. The analysis must, of course, be accomplished by a California- registered civil engineer. To assist in developing your rationale for the determination of the area of inundation, the following considerations are offered: Assume full storage capacity. In the case of a multiple-spillway dam, this ordinarily would require selection of the upper spillway level. • -3- April 27, 1973 The impact of downstream conditions at the time of dam failure depends upon the volume of stored water, the rate of discharge, and the down- stream terrain, and each case must be considered individually. For broad guidance, the ten -year average maximum flow may be assumed, unless in your judgment a different condition should be postulated. Similarly, in tidal areas, mean high tide may be assumed. : In the case of multiple dam failures along single or confluent waterways, it is not considered feasible to prescribe detailed, uniform procedures for determining the area(s) of inundation. The engineers involved should keep in mind that the purpose of the inundation map is to provide the basis for evacuation planning. Logical judgments should be applied, to reach a coordinated set of computations and maps. Regarding the above considerations, a key point is to determine the limits of possible inundation on a conservative basis. Flood plain information and flood insurance studies covering some parts of California have been prepared by a number of agencies, including the Corps of Engineers, the U.S. Geologic Survey, and the Soil Conservation Service. They have partial application to the problem of flooding resulting from a breached dam, and their use would in some cases reduce costs. Information concerning the availability of these studies may be obtained from the appropriate C/E District Engineer office in San Francisco, Los Angeles, or Sacramento. A list of communities for which flood insurance studies have been prepared also may be obtained by request to OES. In addition, some county and city planning departments have developed topographic data in connection with their master planning. The procedures for preparing and submitting the inundation map are described in Enclosures 6 and 7. It is of vital importance that the map scale selected be large enough to permit clear identification, on the ground, of the limits of potential flooding. This will facilitate the development of an effective evacuation plan by the public safety agencies concerned. (See paragraph 4 of Enclosure 6.) In order to minimize costs due to possible corrections resulting from the State engineering review, three checkprint copies of the inundation area boundaries, prepared in accordance with paragraphs 3, 4, and 6 -8 of Enclosure 6 and with �c Enclosure 7, will first be submitted to the Office of Emergency Services. Two I opies of the method used in deriving the area.of inundation, including basic data, assumptions, rationale, and calculations, must accompany the prints. Following the State's engineering review, one of the checkprints, indicating t any need for correction, will be returned to yoy. The Cronaflex reproducibles ` }ka will then be completed in accordance with Enclosures 6 and 7 and the reviewing "1 official's comments, and submitted to OES only. 50''0 Please note that the engineering work is to be accomplished by a California - registered civil engineer, and the appropriate block on the checkprint and on the Cronaflex authenticated by him. -4- April 27, 1973 Final inundation maps must be prepared and submitted within six months after. the effective date of the Act, or _�y September 7, 1973, unless DES extends that date for good reason. As the review burden will be substantial, it will be appreciated if checkprint maps are submitted as soon as they can be completed. Any questions concerning the provisions of this letter should be addressed to the Office of Emergency Services, where the point of contact is Mr. Eric Orme. The telephone number is (916)421 -4990. Sincerely, H. R. TEMPLE, Director enclosures . cc: Dept. of Water Resources DES Regions County Emergency Services Coordinators Chairmen, County Boards of Supervisors Presidents, Emergency Services Directors Assns. • 0 Enclosure 1 Senate Bill No. 896 CHAPTER 780 An act to add Section 8589.5 to the Government Code, relating to dam safety. (Approved by Governor August 11, 1972. Filed with Secretary of State August 11, 1972.) LEGISLATIVE COUNSEL'S DIGEST SB 896, Alquist. Seismic safety. Requires filing of inundation maps by certain dam owners with Office of Emergency Services, Department of Water Resources, and specified local agencies. Provides that cities and counties hav- ing territory designated by Office of Emergency Services as being in area where death or personal injury would occur as a result of dam failure, shall adopt emergency procedures for evacuation and control of populated areas below dams, and requires Office of Emergency Services to review such procedures and make recommenda- tions relative to the adequacy thereof. Requires such emergency procedures to conform to local needs, and sets forth suggested possible elements of such procedures, but specifies that Office of Emergency Services may require other appropriate elements. Requires report to Legislature. The people of the State of California do enact as follows: SECTION 1. The procedures for the areas below dams. strated by that of administered by th, very successful. Legislature intends, by this act, to establish emergency evacuation and control of populated The value of such a program has been demon - the Los Angeles Department of Water and Power, Los Angeles Police Department, which has been SEC. 2. Section 8589.5 is added to the Government Code, to read: 8589.5. (a) Inundation maps showing the areas of potential flooding in the event of sudden or total failure of any dam, the partial or total failure of which the Office of Emergency Ser- vices determines, after consultation with the Department of Water Resources, would result in death or personal injury, shall be prepared and submitted as provided in this subdivision within six months after the effective date of this section, unless the time for submission of such maps is extended 'for reasonable cause by the Office of Emergency Services. The local governmental or- ganization, utility, or other owner of any dam so designated shall submit to the Office of Emergencylservices three such maps, which shall delineate potential flood zones that could result in the event of dam failure when the reservoir is at full capacity, at median storage level, and at normally low storage level. After submission of copies of such maps, the Office of Emergency OES 4/73 2. Services shall review the maps, and shall return those maps which do not meet the requirements of this subdivision, together with recommendations relative to conforming to such provisions. Maps rejected by the Office of Emergency Services shall be revised to conform to such recommendations and resubmitted. The Office of Emergency Services shall keep on file those maps which conform to the provisions of this subdivision. Maps approved pursuant to this subdivision shall also be kept on file with the Department of Water Resources. The owner of a dam submitting copies of such maps to the Office of Emergency Services shall concurrently submit iden- tical copies to the appropriate public safety agency of any city, county, or city and county likely to be affected. (b) Based upon a review of inundation maps submitted pursuant to subdivision (a), the Office of Emergency Services shall desig- nate areas within which death or personal injury would, in its determination, result from the partial or total failure of a dam. The appropriate public safety agencies of any city, county, or city and county, the territory of which includes such an area, shall adopt emergency procedures for the evacuation and control of popu- lated areas below such dams. The Office of Emergency Services shall review such procedures to determine whether adequate public safety measures exist for the evacuation and control of populated areas below the dams, and shall make recommendations with regard to the adequacy of such procedures to the concerned public safety agency. In conducting such review the Office of Emergency Ser- vices shall consult with appropriate state and local agencies. Emergency procedures specified in this subdivision shall con- form to local needs, and may be required to include any of the following elements or any other appropriate element, in the dis- cretion of the Office of Emergency Services: (1) delineation of area to be evacuated; (2) routes to be used; (3) traffic control measures; (4) shelters to be activated for the care of the evacu- ees; (5) methods for the movement of people without their own transportation; (6) identification of particular areas or facili- ties in the flood zones which will not require evacuation because of their location on high ground or similar circumstances; (7) identification and development of special procedures for the evac- uation and care of people from unique institutions; (8) procedures for the perimeter and interior security of the area, including such things as passes, identification requirements, and antiloot- ing patrols; (9) procedures for the lifting of the evacuation and reentry of the area; and (10) details of which organizations are responsible for these functions and the material and personnel resources required. It is the intent of the Legislature to en- courage each agency that prepares such emergency procedures to establish a procedure for their review every two years. (c) "Dam," as used in this section, has�the same meaning as specified in Sections 6002, 6003, and 6004 of the Water Code. SEC. I. The Office of Emergency Services shall report to the Legislature on the plans specified by this act on or before the fifth day of the 1974 Regular Session of the Legislature. (Effective March. 7, 1973.) • Enclosure 2 Excerpt from STATUTES AND REGULATIONS PERTAINING TO SUPERVISION OF DAMS AND RESERVOIRS (Water Code) DIVISION 3. ..DAMS AND RESERVOIRS PART 1. SUPERVISION OF DAMS AND RESERVOIRS Chapter I. Definitions 6000. Unless the context otherwise requires, the definitions in this chapter govern the construction of this part. 6002. "Dam" means any a.rtificial barrier, together with appurtenant works, which does or may impound or divert water, and which either (a) is or will be 25 feet or more in height from the natural bed of the stream or watercourse at the downstream toe of the barrier, as determined by the department, or from the lowest elevation of the outside limit of the barrier, as determined by the department, if it is not across a stream channel or watercourse, to the maximum possible water storage elevation, or (b) has or will have an impounding capacity of 50 acre -feet or more. 6003• Any such barrier which is or will be not in excess of 6 feet in height, regardless of storage capacity, or which has or will have a storage capacity not in excess of 15 acre -feet, regardless of height, shall not be considered a dam. 6004. No obstruction in a canal used to raise or lower water therein or divert water therefrom, no levee, including but not limited to a levee on the bed of a natural lake the primary purpose of which levee is to control floodwaters, no railroad fill or structure, and no road or highway fill or structure, no circular tank constructed of steel or concrete or of a combination thereof, no tank elevated above the ground, and no barrier which is not across a stream channel, watercourse, or natural drainage area and which has the principal purpose of impounding water for agricul- tural use shall be considered a dam. In addition, no obstruction in the channel of a stream or watercourse which is 15 feet or less in height from the lowest elevation of the obstruction and which has the single_ purpose of spreading water within the bed of the stream or watercourse upstream from the obstruction for percolation underground shall be considered a dam. 6004.5. "Reservoir" means any reservoir which contains or will contain the water impounded by a dam. 4/73 0 CALIFORNIA COUNTIES WITH POPULATION DENSITY COUNTY San Francisco Orange Los Angeles Alameda San Mateo Santa Clara Contra Costa Sacramento Marin San Diego OES 4/73 OF 300 OR MORE PERSONS /SQUARE MILE POPULATION DENSITY 15,701.0 1,802.2 1,718.7 1,451.6 1,232.7 813.1 755.0 652.4 392.4 317.0 Enclosure 3 Rented arid', distributed mitk per^r• ion. of LOS ANGELES COUNTY.FLOOD CONTROL DISTRICT HYDRAULIC DIVISION Procedures for the Determination of Inundation Maps Showing Areas of Potential Flooding in the Event of Sudden or Total Failure of Any Dam To Comply with Senate Bill No: 896 Enclosure 4 It is intended to try the following procedures to develop inundation maps for areas downstream of all District dams and reservoirs where required. These procedures contain many assumptions, so a great deal of engineering judgment is required for their application. I. Calculate a hydrograph at the dam site A. Concrete dam _ 1. Assume sudden and complete failure 2. Calculate the maximum outflow (Amax) by: 1/ Qmax - 27 B(g)0.5H0 1.5 Qmax = maximum discharge through the breach B = effective reservoir width g = gravitational constant Ho = specific head (initial depth of reservoir at dam) 3. Assume Qmax to occur at approximately t = 1 minute 4. Adjust the recession leg of the hydrograph (a straight line) so that the volume in the hydrograph equals the storage in the reservoir B. Earthfill or rockfill dam 1. Assume failure by erosion 2. Assume a median size for a partial breach 3. Calculate the maximum outflow (Amax) by: 2/ 3 /2 (W Y ) 0'.28 Qmax = 0.29 � Wb Db(Wb - 4 Qmax = maximum discharge through the breach l g = gravitational constant Wb = width of breach at original water surface W = width of dam at original water surface D = vertical distance from original water surface to bottom of breach Yo = depth of water at the dam before breach DES 4/73 LAFCD -2 of 2 • 0 4. Assume Qmax occurs at the midpoint of the outflow hydrograph. Using an isoceles triangle with Qmax at the apex, adjust the rising and falling limbs of the hydrograph so that the volume in the hydrograph equals the storage in the reservoir. Ii. Route the calculated hydrograph downstream A. Divide the area downstream into reaches of constant slope and cross section 1. Choose a trapezoidal section that best represents the existing section 2. Choose an appropriate "n" factor B. Route the hydrograph through the reaches by the "Modified Puls =/ method "and Manning's equation C. Determine the downstream limits of flooding 1. Route to a point where existing conveyance (channels, storm drains, - streets, etc.) are capable of carrying the flow without flooding 2. Or route to a depressed area that has the storage capacity to retain the flow. III. During the routing process, calculate flow cross sections through the selected reaches A. Use Manning's equation (Q = 1.49 AR2 13 S1 12) to determine the depth of flow through each reach n B. Using the depth just determined, define the limits of flooding through each reach. IV. Construct a flooded area map A. Using a 1" = 2000' scale quadrangle map, plot the limits of flooding for each reach on a transparent overlay's B. By a smooth line, connect the limits of flooding for all reaches. tOEE Note. Re A above, Enclosure 6 applies) REFERENCES 1/ "Military Hydrology Bulletin No. 9: Flow Through a Breached Dam ", Corps of Engineers, 1957, pg. 21. 2/ Miscellaneous Paper No. 2 -374, Report 2, "Floobs Resulting from Suddenly Breached Dams; Conditions of High Resistance ", Corps of Engineers, 1961, pg. 15. 3/ Flood Routing Chapter 6/0 in Flood Hydrology Part 6 in Water Studies, Volume IV, U.S. Bureau of Reclamation Manual, 1947. iio�e: F'u�s rre'l:oc, avai?a�i,e �� o;�:er ra; ererces) OES 4/73 Allirtec, and diatributed z ; t � peis for of CITY OF LOS ANGELES DEPARTMENT OF WATER AND POWER DETERMINATION OF DAM BREACH INUNDATION AREA EARTH DAMS PROCEDURE Average Outflow Determination Enclosure 5 Each reservoir was assumed to be at high water at the time of the dam break. The time of emptying, and thus the average rate of outflow, was related to the height of the dam by arbitrarily assuming a 200 - foot -high dam to empty in one hour and the time of emptying (T) to vary inversely as the square root of the head (h). Having calculated the time of emptying by the above method, the average rate of outflow was obtained by dividing the reservoir capacity by the time of emptying. Note: T =� 200 for earth dams. II. Average Slope Determination OES 4/73 The slope of the flow path from the reservoir to a flood control channel large enough to convey the average outflow, or to a basin large enough to contain the entire reservoir storage, was determined by plotting a profile of the flow path. The profile was divided into reaches, if necessary, so that each reach had ap- proximately a constant slope. The average slope of each flow path or reach thereof was then obtained by dividing the elevation change by the length of the reach. Use of Manning's Basic Formula A. Assumptions as to n V. 1.486r "3s " -- n „n" and ..r„ Basically, n =0.10 was assumed for well - defined canyon areas in which houses and other similar obstacles exist, and n =0.033 was assumed for more or less unconfined floc, in wide, fairly level areas in which the flow was concentrated in streets. However, the ..n.. also depended on the "Q" ; l.e., for a large "Q" in an unconfined area n =0.1 was assumed because the floc: would be very deep and, therefore, would not be concentrated in the streets. The opposite case of a small flow in a canyon was also true. LAWO - 2 • • 2. r The hydraulic radius equals the cross - sectional area divided by the wetted perimeter. The wetted perimeter was assumed to be equal to 1.2 times the flow width. The area equals the flow width multiplied by the average depth, there being three assumed conditions for the average depth as a function of the maximum depth: a. Canyon or plain with approximate triangular cross - section. L Average depth d = 2 b. Plain area with two or more channel depressions in cross-section. d = 314 D c. Flat plains with abrupt changes in topography. W.S. y D OES 4/73 m LAWEP -'3 . • B. Solution of Manning's Formula for the product of "L" and "d'1 V = 1.486rz�3s '�2 n r = P d = 1 (L = flow width) d r = 1.2 V= 1.486(Td—, )"3s'/z n but V= A Q _ 1.486rzl3s' /z 2 A n1.2 3 3 Q = 1.486d2X3s'/z Ld n1.2 z /3 (Ld)dzV3 = Qn(1.2)2�' 1.468 s112 Ld3j3 : QnN.2)213 K 1.486 02 IV. Determination of "d" vs. "L" Curve 11K" was calculated from the above formula, a different 11K" being calculated for each change in '1n" or "s Having determined "K the 11d vs. "L" curve was plotted. In a situation where the flow splits, new curves were plotted for the fractional flows by holding "d" in the equation Ld313 =K constant. The new Qoints were easily determined since "K" is directly.proportional to Q1, , and L11 is directly proportional to "K ". V. Determination of Inundation Area Two methods were employed, depending on the topography. If the topography was confining or channel -like, Method 1 was used. If the topography was cone -like; i.e., sloping off, both parallel and perpendicular to the flow line, Method 2 was used. Following is a brief explanation of the two methods. i OES 4/73 LA`d &P - 4 . • A. Method 1 With the confining topography, the "d" vs. "L" curve was used, and a trial and error method was employed. On the drainage maps, cross - sections perpendicular to the flow line were set up at arbitrarily- spaced intervals and /or at logical changes in topography. At each cross- section, the maxi- mum depth, "D" was assumed and, depending on the type of confining topog- raphy, a relationship between "D" and "d" was selected. The flow width between contours corresponding to the assumed' "D" was measured on the drain- age map and this point, coordinates (d,L), was checked against the "d" vs. "L" curve to see if the assumed point falls on the curve. If it did, the flood limits for that cross - section had been determined. If the point fell above or below the "d" vs. I" curve, a smaller or larger "D" re- spectively, was assumed until the assumed point was on the curve. This process was continued at each cross - section to obtain the flood limits. S. Method 2 With the cone -like topography, the flood limit was determined not on a "cross- sectional area required for flow" basis, but by a consideration of the behavior of the limits of the flow; i.e., by following the path of a particle of water under the influence of slopes in mutually perpendicular directions. Specifically, when the cone -type topography was first encountered, the nearest street intersection to the edge of the flow at the beginning of said topography was selected. At this intersection, the slope for the first block in each direction was determined. The angle between the flow line and the resultant velocity vector was then calculated by the following formula: y /Slope in direction lateral to F. L. z 9 = ton-'( Slope in direction parallel to FL. A line was then drawn at 9 to the flow line and extended until it came near or went through another intersection, at which point the process was repeated. Between the intersections where 6 was determined, the flood limit was assumed to follow streets, but for the final map the limit was obtained by drawing a smooth line through the corners of the preliminary limit. This method was used for both the progression and recession of the flood limit in the lateral direction. OES 4/73 •LAW &P - $ 0 • Example STREETS PRELIMINARY �\ \\ BOUNDARY % .. Sp 'P CRY It was assumed that the only forces acting are those due to the slopes. The momentum of the flow parallel to the flow line, as well as the head (or depth) of the water at the intersection were neglected. It was also assumed that the "n° and hydraulic radius were the same along the two directions for which the slopes were calculated. In Method I, the water surface was assumed horizontal; whereas, in this method, the water was assumed to have a mound configuration. In Method I, the depth was assumed to be the independent variable, and the width of flow the dependent. In Method 2, the width was assumed to be the independent variable, and the depth was the dependent. Actually, no depth was calculated in Method 2, but it could have been, simply by establishing a relation between "D" and 11 d" as in Method 1. OEs 4/73 SL4— SL SL R 9 ISP ' I ? P = sL a R SP I I FINAL BOUND S 1 SP Ste- R A� — — _ R 1 I� SP R I SP SL SL S I I Rig IR__p1 IY r�1 SL S .. Sp 'P CRY It was assumed that the only forces acting are those due to the slopes. The momentum of the flow parallel to the flow line, as well as the head (or depth) of the water at the intersection were neglected. It was also assumed that the "n° and hydraulic radius were the same along the two directions for which the slopes were calculated. In Method I, the water surface was assumed horizontal; whereas, in this method, the water was assumed to have a mound configuration. In Method I, the depth was assumed to be the independent variable, and the width of flow the dependent. In Method 2, the width was assumed to be the independent variable, and the depth was the dependent. Actually, no depth was calculated in Method 2, but it could have been, simply by establishing a relation between "D" and 11 d" as in Method 1. OEs 4/73 LAW &P - 6 • • CONCLUSIONS AND RECOMMENDATIONS The method used in this study was applied to the Baldwin Hills Reservoir dam and the calculated flood area compared favorably with the actual flood area. It is, there- fore, concluded that this study presents a representative picture of the flood area which could develop if any of the ten major reservoir dams investigated should breach. The greatest difficulty, aside from trying to determine a realistic time of empty- ing for each reservoir, was that of determining the rate of lateral progression and recession of flood waters on cone -Me topography. OES 4/73 LAW&P - 7 • • 20 f 10 B a 6 i S a X a S 2 0.5 OEs 4/73 x a W W Q K W a 0 BALDW I N HILLS RESERVOIR da(3 )aq / o.e L Sleep Grade • • Enclosure 6 PROCEDURES FOR PREPARING AND SUBMITTING INUNDATION MAPS The inundation maps required by Senate Bill 896, adopted as Chapter 780, Statutes of 1972, Section 8589.5 of the Government Code, shall be prepared as outlined herein. The purpose of these maps is to provide guidance for public safety personnel in the development of a plan for evacuation of an endangered area. If in some unanticipated circumstance, maps prepared in accordance with these instructions appear to not meet this objective, please contact the Office of Emergency Services for additional instructions. The maps shall conform to the dimensions and format of the sample shown in Enclosure 7. 2. The maps shall be prepared on Cronaflex sensitized film, such as DPM -4, CFM -4, PFM -4, or equivalent. 3. The base map(s) shall be prepared using the USGS Quadrangle map(s) (without green overlay). The quadrangle shall be printed on the reverse side of a posi- tive Cronaflex. If a negative step is required, the negative scale shall be the same as the original quadrangle map scale. Negative(s) should be retained for possible future use. 4. The map scale utilized shall ensure that the limits of the inundated area can be clearly identified on the ground. The minimum scale to be used is 1:24,000 (1 inch = 2,000 feet). A larger scale is desired where the area of inundation and its immediate environs at such scale can be accommodated on the sheet size specified in Enclosure 7. 5. The boundary of the area of inundation shall be added, using Peliken T black ink and a #3 Rapidograph pen, or equivalent, on the top side of the Cronaflex. Identifying data (paragraph 6 below) also shall be added. Water depths need not be shown. This Cronaflex is for owner retention. 6. Physical features in the vicinity of the inundation line not designated by name on the USGS Quadrangle shall be labeled if place names do exist. Where geographic /place names needed for clear identification of the inundation area boundary are lacking, dimensional offsets to that boundary from easily identi- fiable features shall be shown. Lettering equivalent to Leroy 100 /00,as a minimum, shall be used. 7. If more than one map sheet is required for the area of inundation below a dam, a map index showing the location of all map sheets shall be prepared and shown on each sheet. 8. Where large areas will be inundated, only the maps required to identify the limits of inundation shall be submitted. 9. The following final work shall be submitted to'OES: a. One Cronaflex or equivalent reproducible of the base map only; b. One reverse print Cronaflex or equivalent reproducible of the base map, inundation area boundary, and identifying data; c. Two blue czalid prints of the Cronaflex, paragraph 9b above. OES 4/73 _ Enclosure J /" z I 24" -- I i i — I i /u O rn M I i i i i i i I i 1 i I 1 i i INUNDATION MAP -- I _. DA N I 2 � OF 1 ,. (Name of dam(s)) r me 4i'7z 0 • Enclosure 8 CITY OF NEWPORT BEACH Category 1 & 2 Dams I UTiUQTui JAMES M.1TOVTGOMFIM CONSULTING ENGINEERS INC 555 East Walnut Street, Paasa.na. Cnl:ru ? '11/(213) 796-9141 /,213) 681 -4255 HOURLY RATE SCHEDULE== Effective January 1, 1973 Senior Company Officer $45. 00 per man -hour Principal Engineer $40.00 per man -hour Supervising Engineer $30,00 per man -hour Senior Engineer $25.00 per man -hour Engineer $20.00 per man -hour Associate Engineer $17.00 per man -hour Engineering - Geologist $27.00 per man -hour Senior Chemist $22.00 per man -hour Senior Designer $18.00 per man -hour Designer $16.00 per man -hour Draftsman $13.00 per man -hour Laboratory Technician $12.00 per man -hour Senior Resident Engineer $18.00 per man -hour Resident Engineer- Inspector $12,00 per man -hour Survey Party (3 -man) $54.00 per crew -hour Survey Party (2 -man) $38.00 per crew -hour Mileage @ 12 cents per vehicle -mile (other than for survey party) Computer @ $50.00 per meter hour "The individual hourly rates include salary costs, overhead, administration, profit, typing and clerical costs. Survey party rates also include survey equipment rental, stakes, flagging, supplies, and vehicle mileage. EX/� /4 /r �•B„ JUL 231973 By +h= CITY COUNCIL RESOLUTION NO. H O5 9 A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF NEWPORT BEACH AUTHORIZING THE EXECUTION OF AN ENGINEERING SERVICES AGREE- MENT BETWEEN THE CITY OF NEWPORT BEACH AND JAMES M. MONTGOMERY, CONSULTING ENGINEERS, INC. FOR PREPARATION OF AN INUNDATION STUDY FOR BIG CANYON RESERVOIR WHEREAS, there has been presented to the City Council of the City of Newport Beach an engineering services agreement between the City of Newport Beach and James M. Montgomery, Consulting Engineers, Inc., for preparation of an inundation study for Big Canyon Reservoir; and WHEREAS, the City Council has considered the terms and conditions of said agreement and found them to be fair and equitable; NOW, THEREFORE, BE IT RESOLVED that said engineering 12-G services agreement for the services above described is approved, and the Mayor and City Clerk are hereby authorized and directed to execute the same on behalf of the City of Newport Beach. ADOPTED this 23rd day of Mayor ATTEST: City Clerk 1973. DON dm 7/19/73