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HomeMy WebLinkAbout09 - Morning Canyon Stabilization Project• CITY OF NEWPORT BEACH CITY COUNCIL STAFF REPORT Agenda Item No. 9 September 13, 2005 TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL FROM: Public Works Department Bob Stein, P.E. 949 - 644 -3311 rstein@city.newport-beach.ca.us SUBJECT: MORNING CANYON STABILIZATON PROJECT - AWARD OF CONTRACT NO. 3517 RECOMMENDATIONS: 1. Approve the drawings and specifications. 2. Adopt the attached Resolution finding that the conditions in Morning Canyon constitute an emergency situation and that staff is directed to move forward with the Morning Canyon Stabilization Project so work can be completed in advance • of the rain season and continue working with California Coast Commission staff to secure a Coastal Development Permit and make their best efforts to incorporate the conditions of the permit into the ongoing project. 3. Award Contract No. 3517 to Sunquest General Engineering for the Total Bid Price of $796,518.50, and authorize the Mayor and the City Clerk to execute the contract. 4. Authorize the City Manager to enter into a contractual reimbursement agreement with the owners of 601 Rockford Road and 515 Rockford Place for their share of the proposed improvements and obtain a deposit of $300,000 from the owners. The agreement will also contain a waiver release. 5. Establish an amount of $60,000 to cover the cost of unforeseen work. 6. Approve Geotechnical work in the amount of $10,000. DISCUSSION: On March 9, 2004, City Council authorized a professional services agreement with RBF Consulting to prepare a stream stabilization and canyon restoration study. This year long process involved research, the preparation of conceptual plans, working with permitting agencies, and coordination with the adjacent property owners. On March 22, 2005 a Study Session was held to review the complex issues in Morning Canyon. (See • the attached Study Session Memo.) Later that evening at the Council Meeting, Council authorized RBF Consulting to proceed with preparation of final construction documents, Subject: Morning Canyon Stabilization Project - Award of Contract No. 3517 September 13, 2005 Page: 2 permit applications and easement agreements for the Morning Canyon Stabilization • project. Since that approval, Staff and RBF worked diligently to prepare plans and specifications with the goal of providing a completed project before the next rainy season. Upon plan completion, applications were made to the appropriate agencies and efforts to secure the necessary easements began. Contractors with appropriate gabion construction experience were pre - qualified to expedite the bidding process and disqualify lesser experienced contractors that may have difficulty completing the project before the next rainy season. Project Work The work necessary for the completion of this contract consists of two Project Tasks. Project Task 1 includes clearing and grubbing, dewatering and surface water control, constructing seven rock - filled gabion grade control structures, a rock - filled gabion bank protection structure, placing unclassified fill, grouted rock riprap, storm drain extensions, fencing, sediment and erosion control, dust control and all other work as required to bring the canyon into readiness to accept storm water flows. Project Task 2 work includes slope backfill, installing fencing, planting of various California native shrubs and trees, hydroseeding, and other landscaping tasks. Following completion of Project Tasks 1 and 2, there is a plant establishment and maintenance item of work. Also included in this project is the construction of a slope buttress which is necessary • for the repair of a previous private property slope failure at 601 Rockford Road and 515 Rockford Place. The estimated cost for the installation of the gabion slope buttress and associated work is $271,265. If authorized by Council, staff will enter into a contractual reimbursement agreement with these owners and obtain a deposit of $300,000 to cover the anticipated costs. The reimbursement agreement will include a waiver of liability for the work performed by the City for these property owners. Easements Staff has worked closely with the adjacent property owners and has secured all of the required easements and agreements that provide for the City's authority to construct and maintain the canyon stabilization project. Five temporary construction easements from property owners have also been obtained. The owner at 601 Rockford Road is working with staff to obtain a sixth construction easement from the owner at 607 Rockford Road that is needed for building the slope buttress at 601 Rockford Road. Since this easement is needed for the private slope repair, it will not delay the City's canyon stabilization project. If the sixth easement is not secured, staff will reduce the amount of private slope repair work and the owners at 601 Rockford Road and 515 Rockford Place will assume the responsibility of completing the work in conjunction with their slope repair project. City staff has met with The Irvine Company and is working to complete an entry agreement for access into the canyon via the Pelican Hill Golf Course. • Subject: Morning Canyon Stabilization Project - Award of Contract No. 3517 September 13, 2005 Page: 3 • Permits Four permits from jurisdictional agencies are required: • California Department of Fish and Game has issued a draft permit approving the project and only conditioning the project to have an approved hydroseed mix. The 1602 Streambed Alteration Agreement will be issued September 21, 2005. • The Regional Water Quality Control Board (RWQCB) has approved the project and is in the process of issuing the 401 Water Certification Permit. • The Army Corps of Engineers has approved the project and will issue the 404 Nationwide Permit once the RWQCB 401 Water Certification Permit and the Coastal Development Permit have been issued. • The California Coastal Commission (CCC) staff has deemed our application complete and has agendized our project for Commission review on October 12 or 13, 2005. CCC Staff will be issuing its recommendations no later than September 27, 2005. Project Schedule While we believe that our design team has expedited this project to the best of our • ability, the current Coastal Commission process will not allow us to secure a permit in sufficient time to complete the gabion construction (phase 1) of the work before the expected peak of the rainy season. City staff met with CCC staff on August 16 and discussed the distinct possibility that the City Council will direct City staff to proceed with this project on an emergency basis prior to receiving the Coastal Development Permit (CDP) from the CCC. CCC staff indicated that if the City must move ahead with the project without the CDP, the CCC may require alternative or additional mitigation measures and may assess penalties if the constructed project is not considered to be the best environmentally - sensitive solution. In essence, the CCC will conduct its analysis of the appropriate mitigation measures as if the Project had not been constructed. The ultimate determination by the CCC of what is the best environmentally - sensitive solution will be an item that is unresolved before the anticipated start of Project construction. RBF Consulting and City Staff think the proposed gabion system is indeed the best solution balancing engineering and environmental requirements. RBF has prepared and submitted a Feasibility Analysis to CCC staff that substantiates that conclusion. (See the attached June 10, 2005 analysis.) To substantiate the design team's concerns, staff retained Leighton Consulting, Inc. to prepare a risk assessment of the potential embankment failure for Morning Canyon (see attached). Their conclusion is as follows; "In general, it is our conclusion that within the stretch where manufactured fill comprises the major portion of canyon side, the landsliding risk is very high. Almost certainly, there will be massive landsliding even if the next rainy season produces moderate rain and stream flow. ". • Staff believes that it is imperative that the construction commence in a timely manner and complete prior to the peak rain season. Staff is working with the Contractor so that Subject: Morning Canyon Stabilization Project - Award of Contract No. 3517 September 13, 2005 Page: 4 construction may commence on October 3, 2005. Several measures will be • implemented to expedite the project. The Contractor is required to work a six -day week. The Contract calls for a bonus of $2,250 per day for completing the Project Task 1 work ahead of the 50 consecutive working day period. Alternatively, the Contractor will be assessed $2,000 per day in liquidated damages for not completing the Task 1 work within 50 days and $250 per day for not completing the Task 2 work within 60 working days. If Council prefers to wait for the CCC to issue the Coastal Development Permit expected in mid - October, then Council should provide direction on whether to commence with the project this season (with the higher risk of rains due to a later construction start) or be delayed until Spring 2006 (with the risk of substantial erosion /landslides occurring during the rain season). Project Bid Prior to the bid period, using the pre - qualification process, the City advertised for contractors interested in bidding the project to submit a Statement of Qualifications to the City. Three contractors submitted a Statement of Qualifications: GCI Construction Inc., S.P. Pazargad Engineering Construction, Inc. and Sunquest General Contracting. All three contractors possessed the required California State Contractors License, had adequate gabion installation experience and were deemed qualified. At 2:00 pm on August 30, 2005 the City Clerk opened and read the following bids • (column 3) for this project: Bidder Opening Bid Corrected Bid Low S.P. Pazargad Engineering * $880,057.00 $789,069.00 2 Sunquest General Engineering $796,478.50 $796,518.50 * Bid Withdrawn by S.P. Pazargad At the bid opening, the apparent low bidder was Sunquest General Engineering. However, a detailed review of the bids found that S.P. Pazargad Engineering Construction, Inc. had misread the quantity for one of the bid items. Using the correct quantity and recomputing the bid amount significantly lowered Pazargad's bid such that they were the low bidder. Pazargad was contacted and asked if it would honor its unit bid price for the lower bid item quantity. Upon review, Pazargad said it could not and asked to have its bid withdrawn. Staff concurred that the error was an honest and understandable mistake and agreed to allow Pazargad to withdraw its bid. Therefore, Sunquest General Engineering is the low bidder. Sunquest's corrected bid amount of $796,518.50 is two percent below the Engineer's Estimate of $810,000. Environmental Review: This project is categorically exempt from the provisions of CEQA per Section 15333 pertaining to small habitat restoration projects. A Notice of Exemption was filed with the County Clerk on June 6, 2005. • Subject: Morning Canyon Stabilization Project - Award of Contract No. 3517 September 13, 2005 Page: 5 • Public Notice: Staff has periodically sent letters to property owners along Morning Canyon summarizing the status of the project. Several meetings have also been held with property owners at City Hall to discuss the project. Staff has also met with various property owners on site on numerous occasions and walked the project. Property owners have also been notified through the Coastal Development Permit application process regarding the project. G eotech n ica I/S urveyServices: Geotechnical services will be provided by outside consultants per the On -Call Professional Services Agreement approved by Council on December 9, 2003. Funding Availability: There are sufficient funds available in the following accounts for the project: Account Descri lion General Fund Private Contributions (WynkooplWalton Reimbursement) Prepared by: Bob Stein, P. . Project Manager Attachments: Account Number Amount 7014- C5100805 $595,253.50 5100 -5864 $300,000.00 Total: $895,253.50 a. March 22, 2005 Study Session Report b. Project Location Map c. Bid Summary d. Feasibility Analysis prepared by RBF Consulting e. Declaration of Emergency Resolution f. Reimbursement Agreement with property owners at 601 Rockford Road and 515 Rockford Place g. Risk Assessment prepared by Leighton Consulting, Inc. • CITY OF NEWPORT BEACH CITY COUNCIL STAFF REPORT Study Session Item No. March 22, 2005 TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL FROM: Public Works Department Robert Stein, P.E. 949 - 644 -3311 rstein @city. newport- beach. ca. us SUBJECT: MORNING CANYON RESTORATION PROJECT, C -3517 Introduction • The Morning Canyon Stream Stabilization and Channel Restoration Study prepared by RBF Consulting (RBF) that you are receiving this evening, states that the erosion and slope failures in Morning Canyon have progressed to the point where damage to private improvements is a threat. This study recommends installation of engineered rock stabilization blankets (gabion) at strategic locations along the canyon bottom to forestall • further erosion of the canyon bed which undermines the canyon slopes. If these measures are implemented before the next rain season, further erosion of the canyon bed will be prevented. Property owners on the canyon have turned to the City for help. As a practical matter, the City stands as the most reliable entity to act in the best interest of the community and it is appropriate for the City to guide the corrective process and to prepare a master plan for drainage, restoration, and water quality for this channel. Project History The stability of Morning Canyon has been affected by actions in the canyon that have occurred over the past fifty years. The following timeline highlights major events in the canyon's history as based on information obtained from staff, property owners, consultants, and canyon reports. A more detailed recount of events follows. 1950-1980 Cattle grazing activities occur in hills of Newport Coast resulting in increase in canyon bed elevation 1959 Substantial grading activities for Cameo Highlands Development occur 1960 City incorporates Cameo Highlands 1980's Arundo donax invades canyon streambed disrupting flow pattern 1990 Construction begins on Pelican Hills Golf Course and housing • developments EXHIBIT A SUBJECT: MORNING CANYON RESTORATION PROJECT, C -3517 March 22, 2005 Page 2 • 1992 Significant increase in dry- weather flows entering canyon 1997 Massive failure of canyon slope at 607 Rockford Road (Wynkoop Slope) 2000 City staff identifies severe scour hole at 615 Rockford Road 2002 Rivertech completes concept -level stability analysis of canyon 2004 RBF hired to prepare Stream Stabilization and Canyon Restoration Study Prior to construction of the Cameo Highland tract, this area was drained by two canyons, Surrey Canyon flowing into Morning Canyon from the east, and Morning Canyon flowing to the ocean. At the confluence of two canyons, 2/3 of the flow was carried by Surrey Canyon and the remainder by Morning Canyon. Over a thirty -year period beginning in the 1950's, grazing activities and removal of natural vegetation in the upper watershed disrupted the soil and a surplus of material was washed into the canyon by storm water runoff. This surplus of material allowed several feet of sediment to accumulate in the canyon bottom and created a broadly rounded channel in the 1980's. The fill slopes (Cameo Highlands) have experienced failures on various occasions on several properties, including a report of a slope failure as early as 1977 (Lockwood -Singh & Associates, 1999). In the late 1950's, with the grading of the Cameo Highlands tract, the canyon that crossed the tract, Surrey Canyon, was filled and a 51 -inch storm drain was installed across the tract with the outlet about 250 feet north of the mouth of the now filled • Surrey Canyon. Two 18 -inch storm drain lines, one from Rockford Road and one from the Rockford Place cul -de -sac, were constructed and drain to Morning Canyon. A high slope on the east bank of Morning Canyon was created which partially intruded into the natural floWine of Morning Canyon. Slope grading and compaction would have been inspected by the County and would have been performed in accordance with the standards in force at that time. After completion of construction of the tract, the City accepted the tract in 1960. The tract map includes a 22 -foot easement along the western boundary of the tract for storm drain purposes. This easement is largely located on the fill slope. It is anticipated that this easement was required and granted to allow for the construction of a future storm drain facility in the event that the upstream properties were developed. The giant reed, Arundo donax, invaded the canyon bottom in the 1980's. Arundo and other dense vegetation in the channel bottom are contributing factors to the degradation of the channel. The heavy vegetation in the center of the canyon forces flood flows to run along the banks of the canyon. Erosive scour areas form along the toe of slope that will eventually undermine the slope and cause it to fail. Dramatic changes occurred when grading for the Pelican Hill Golf Course and housing developments commenced. Pictures of flood flows coming off the denuded slopes in 1990 show large amounts of muddy water flowing down the channel, a dramatic change from previous years. Two detention basins at the northern boundary of Cameo • Highlands (one on Morning Canyon and one at 'Surrey Canyon') became operational in 1991. The detention basins, designed per approved regulatory standards, reduced the SUBJECT: MORNING CANYON RESTORATION PROJECT, C -3517 March 22, 2005 Page 3 peak flows from large storms while increasing the duration of storm flows through the • canyon. More importantly from the standpoint of canyon stability, the beneficial transport of upstream sediment into the canyon was reduced by approximately 50 percent as estimated by Moffatt & Nichol Engineers. As a result, the clearer water entering the canyon within Cameo Highlands picks up sediment from the canyon bottom accelerating the natural canyon erosion process. The reduction of sediment supply to Morning Canyon is especially significant as this canyon is steep enough to force storm water runoff to move at a sufficiently high velocity to erode the channel bottom. Over time, this erosion creates deep incisions in the channel bottom. Prior to the construction of the golf course and detention basins, this naturally occurring erosive condition was counteracted in Morning Canyon by sediment washing into the canyon from the upstream grazing areas. With the construction of the golf course, the replenishing supply of sediment was reduced and erosive forces created an incision in the canyon bottom. With the formation of the incision, the erosive process accelerated because flood flows were now concentrated within the incised channel. The deepening incision is what motivated many property owners to act by reinforcing slopes with rock and concrete structures. These activities were ineffective. The rapid destabilization of the canyon became evident in the winter of 1997 -1998 when this area experienced above average rainfall and significant individual storm events. These storms and the resultant storm water runoff accelerated erosion and • entrenchment, and general degradation of the canyon particularly in the portion of the channel adjacent to the Wynkoop and Walton properties (601 Rockford Road and 507 Rockford Place respectively). Canyon downcutting and undercutting processes, along with surface failures associated with heavy rainfall directly on the slope, caused the Wynkoop/Walton slope to fail. In 2000, Staff discovered a deep scour hole approximately 120 -feet upstream of the Wynkoop property. Prior to the 2004/05 winter storms, continued downcutting has caused additional erosion pushing the drop in the canyon bed approximately 30 feet upstream to the outlet structure of the 51 -inch storm drain. The unusually high rainfall this season has Caused the downcutting to progress another 50 feet and has now reached the stormdrain outlet structure. While it appears the 51 -inch storm drain outlet structure will not be undermined this season, this severe erosion has resulted in surface erosion (sloughing) of the Patterson slope (621 Rockford Road) including the loss of a mature tree. Additionally, the McCabe slope (615 Rockford Road) appears on the verge of sloughing. Finally, many people have noted that there is now a continuous flow of water coming down Morning Canyon due to upstream irrigation and wash -down activities. With the upstream development of the golf Course and houses, there has been an increase of dry- weather flows into Morning Canyon. While the velocities are too low to cause any significant erosion, these flows do maintain a saturated condition in the canyon bottom • that potentially facilitates erosion during storm flows due to the reduction of interparticle SUBJECT: MORNING CANYON RESTORATION PROJECT, C -3517 March 22, 2005 Page A • cohesion. Additionally, this nuisance runoff transports pollutants, fertilizer and pesticide residues into the channel. The fertilizer and pesticide residues have most likely accelerated the vegetative growth in the canyon. The City on at least two occasions has cleared the bottom of the canyon of foliage and debris to prevent materials from being washed down to Coast Highway and potentially blocking the culvert under the highway. Of the actions that occurred over the past 50 years which finally resulted in altering stream stability in a negative manner for residents along the canyon, the most important factors were: 1. Loss of sediment re- supply due to upstream housing and golf course development including detention facilities. 2. Grading steep slopes that encroached into the canyon during the development of Cameo Shores 3. Diversion of Surrey Canyon flow upstream to a 51 -inch storm drain constructed as part of the Cameo Highlands development Less important, but contributing factors include: • Invasion of the Arundo • Certain property owner encroachments including fencing, weir, and rip -rap • Year -round low flow which saturates the canyon bottom • • Clearing activities in the canyon bottom • The design of certain storm drain and detention basin outlet structures were based upon older design standards that have since been updated due to advances in drainage science. • Climatic changes in rainfall intensity and durations (record rainfalls and storm events in 1982183, 1992193, 1997198 and this year) Issue at Hand On March 9, 2004, Council approved a Professional Services Agreement for RBF to prepare 1) a stream stabilization and canyon restoration study and 2) final construction documents, environmental documents, permits and easements for the stabilization project. Council approved proceeding with Phase 1 and reporting back to Council at the completion of this task with recommendations. The City has reviewed RBF's report and recommendations composed of the following key components: • Clearing non - native vegetation from the canyon bottom; • Importing soil to fill scour areas of the canyon; • SUBJECT: MORNING CANYON RESTORATION PROJECT, C -3517 March 22, 2005 Page 5 • Installing seven gabions at strategic locations along the streambed designed to protect the canyon from dangerous erosion from storms up to the 100 -year storm event; and • Planting drought tolerant, Fire Department approved landscaping in the canyon bottom. The preliminary cost estimate prepared by RBF is $825,000 which includes a 25% contingency. Maintenance of the stabilization and erosion control structures and the native landscaping is estimated at $5000 per annum. Staff is recommending approval of a professional services amendment with RBF at tonight's meeting for Phase 2 so the final construction document, environmental documents, permits and easements can be prepared. The schedule calls for these documents to be completed by July 2005 such that construction can proceed in the Fall of 2005. Prepared by: Robert Stein, P.E. Principal Civil Engineer Submitted by: Stephen G. 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F Y D N H O -Y O c N N fq D U '-l° .y U m in o N .o m c m m N O M L L IZ O. ❑ U O O O O d d C ❑ aTi c n E o aci m .Dd• o f CL U= O W N w C o d N m d N LL °= a c c 2 o 0 CL o y D N 5 o m d U c m e c °c (7o�� y me 0Co co L) m y y W mU V N N p N C N Q N> D V N C N e `�° 2� U U(7:) 0 0 io O W (7m�m�OStnrn WNth V N�n�mrno�NCOVN�nnmrno F N N N w m 0 Z `n G d 0 M 0 J d 3 N V y r c� E N o =� - c m N d � O !� V � C d D' m d y V L a� O 0 ,° E Y d D D N � D N ` O d C � f0 n N d D L D D d Y O D rn 3 M O 0 °m y M d 0 o N O O O N d E E ° N � m m N N U w d F � N � d d d Z Z Z EXHIBIT C m a i 7 0 M 0 d z N a 0 N Feasibility and Alternatives Analysis Morning Canyon Stabilization and Restoration Project PROJECT DESCRIPTION 1.1 Project Location The Morning Canyon Channel project site is located within the City of Newport Beach, Orange County. The channel runs through the study reach in a southwest direction from the northern boundary (outlet from Pelican Hills Golf Course Detention Basin), to an existing reinforced concrete box (RCB) culvert on Pacific Coast Highway (PCH). The creek itself is a natural drainage system that has an urbanized tributary drainage area of approximately 365 acres at the PCH Culvert. The creek is in an unimproved condition through the entire reach of the project site, and has been recently experiencing significant erosion and degradation. The project site is bounded by existing residential developments on both sides of the creek. The Corona Highlands development is to the northwest, and the Cameo Highlands development is located to the southeast. The downstream limit of the canyon is at Pacific Coast Highway. The upstream limit is an existing storm water detention basin constructed as part of the Newport Coast development. The creek discharges to the ocean approximately one - quarter mile south of the project site. 1.2 Project Applicant • This Analysis will support an application for a CDP issued by the CCC. The formal application will be filed by the following party, herein reference to as the Applicant: City of Newport Beach 3300 Newport Boulevard Newport Beach, California 92658 Contact: Mr. Robert Stein 949/644 -3322 1.3 Project Description (Original Project) Proposed Project Improvements: The proposed project includes the reconstruction and restoration of Morning Canyon channel through the use of grade control structures. Seven (7) grade control structures are proposed along the canyon to restore the stream invert to its original grade, and to establish an equilibrium slope to prevent future erosion and bank failures. The grade control structures are proposed to be rock - filled gabion baskets. Each structure would include a 3 -foot vertical drop height, and a length of approximately 35 feet. The banks of the gabion structures vary from 5- to 6 -feet in height, and are designed to contain the flow from a 100 -year frequency storm event. The voids in the rock - filled gabion baskets are proposed to be backfilled with soil and re- vegetated to restore the canyon to a more • natural channel system. Feasibility Analysis - 1 - June 10, 2005 EXHIBIT 0 • The project includes the use of approximately 800 cubic yards of earth fill to restore the canyon invert to its previous elevations, and approximately 910 cubic yards of rock - filled gabion baskets to form the 7 grade control structures. Future Maintenance Activities: Future maintenance activities for the proposed project are anticipated to be very minor, and would generally include the following: 1. Annual inspections of the grade control structures 2. Inspections after Major storm events 3. Routine general maintenance would include: a. Debris and exotic vegetation removal b. Minor repairs to the wire mesh of the gabion baskets 4. Non - routing maintenance and repair would include: a. Repair items identified during periodic inspections 5. Emergency repair work Constructing Phasing and Maintenance Access: Construction of the Morning Canyon Channel restoration is anticipated to occur from September 2005 — November 2005. Construction staging and equipment storage shall occur along Surrey Drive and the adjacent open space/park areas. • Temporary Construction Access: Construction of the proposed project would occur from the north end of the project site. Access to the site will occur from Surrey Drive along an existing ingress /egress easement previously dedicated to the City of Newport Beach. Implementation of the project will require permanent and temporary easements for the adjacent property owners. A 22 -foot drainage easement is currently dedicated from the properties along the southern side of the canyon. Additional easements will be obtained from properties on both sides of the canyon. A temporary construction access road is proposed to be graded to the channel invert within the existing ingress /egress easement. The access road is proposed to be a bladed earthen road that would be allowed to revegetate after construction. E Long -Term Maintenance Access: Long -term access for maintenance operations is proposed to occur within the existing ingress /egress easement. Annual inspections and minor maintenance would include pedestrian access only. Major maintenance activities, if required, would require reconstruction of the bladed earthen roadway installed during the initial construction activities. Feasibility Analysis - 2 - June 10, 2005 2.0 PURPOSE OF THE PROPOSED PROJECT • 2.1 Project Background /Need Morning Canyon was a natural stream located in the Newport Coast watershed area. The canyon extends from the Pacific Ocean upstream to the Pelican Hills Golf Course. The upper canyon includes the reach from Pacific Coast Highway to the Pelican Hills Golf Course, and is referred to as the "project reach." The upper canyon is bounded by the Corona Highlands development to the north, and the Cameo Highlands development to the south. The property lines for each of the developments generally extend to the centerline of the canyon stream. The Cameo Highlands and Corona Highlands developments were constructed in the 1950's. The construction of the Cameo Highlands development included the placement of fill adjacent to the creek for the creation of residential lots. The fill was placed at a slope of 1.5 horizontal to 1 vertical. The Pelican Hills Golf Course and upstream Newport Coast development were constructed in the 1990's. In recent years the canyon through the project reach has been experiencing significant erosion and degradation. The result of this stream erosion has been the development of an incised channel, and failure of adjacent fill slopes resulting in property damage. As a result of the erosion, some residents have installed ad -hoc scour protection measures to provide some site - specific protection. These measures tend to propagate the problem to a new location, and have resulted in lawsuit between property owners. Numerous • hydrology, hydraulic, geomorphic, and geotechnical analyses have been developed for Morning Canyon and its watershed in the past 15 years. These reports are generally a result of erosion, slope failures, and property damage that have occurred along the canyon, and attest to the need to develop a whole scale stream restoration project for the upper Morning Canyon. A sediment transport analysis was prepared for the project site to develop the recommended improvements for the proposed project. The analysis was based on the current condition of the watershed that has been fully developed. The purpose of the analysis was to develop an equilibrium slope for the canyon. This is the slope that the channel invert would tend to adjust to based on the current watershed conditions. Natural channels tend to adjust themselves toward a state of dynamic equilibrium such that the ability of a channel to transport water and sediment is in balance with the amount of water and sediment supplied from upstream and lateral sources. The equilibrium slope was determined to be approximately 0.0025 feet per foot. Over the length of the project reach, this equilibrium slope could result in the lowering of the invert by up to 21 feet. This theoretical analysis was checked with actual field conditions to determine the reasonableness of the predicted results. The construction of the Cameo Highlands development included the installation of a 51 -inch diameter pipe which outlets to the canyon via a box culvert energy dissipator at approximately the midpoint of the project reach. The outlet of the pipe was constructed at the invert of the canyon, as documented in a photograph in the Lockwood -Singh & Associates study of 1999. After the 2004 /2005 -storm season, visual and topographic surveys of the canyon were • performed by RBF. These surveys indicated that the invert of the canyon has dropped Feasibility Analysis - 3 - June 10, 2005 • by approximately 10 -feet at the outlet of the 51 -inch storm drain. This corresponds very closely with the predicted scour of 10.5 -feet at this location. Currently, a vertical drop of approximately 7 -8 feet exists just downstream of the pipe energy dissipator. This is an unsafe condition, and any further erosion will result in the failure of the energy dissipator structure, and could result in the potential for significant property damage. Stability analyses have been previously performed for the Cameo Highlands fill slope by Douglas E. Morgan, Inc (1999), Lockwood -Singh & Associates (1999), Lotus Consulting Engineers (2000), and Geofirm (2003). The results of these studies generally indicate that the factor of safety of these fill slopes is less than 1.25, and are therefore prone to failure. The Lockwood -Singh study indicated that during the 1997/1998 El Nino years, the down cutting and undercutting process contributed to the failure of the Wynkoop and Walton slopes within the Cameo Highlands development. The erosion and degradation of the channel invert removes some subjacent lateral support for the fill slopes and further exacerbates the already unstable slopes. To minimize this problem, the Morning Canyon stabilization project includes the filling of the incised canyon to reconstruct the original channel grades. Downstream Impacts The sediment distribution along Morning Canyon is characterized by a substantial concentration of clays and silts, roughly 30 to 40 percent by volume, and an estimated median grain size of 0.16 millimeters. In conjunction with its relative steepness, the Canyon is sensitive to changes in erosion processes. • The Morning Canyon project reach between Pacific Coast Highway and the Pelican Hill Golf Course is currently undergoing accelerated degradation in order to establish dynamic equilibrium. This is largely due to the concentration of runoff from two detention basins located upstream on the Pelican Hill Golf Course as well as the reduction of the sediment supply resulting from their function. In particular, the project reach has undergone 10 feet of head - cutting alone at the mid - reach outfall over the course of this current wet season, placing the adjacent slopes in I eopardy of significant destabilization and possible failure. In addition, the degradation of the project reach has resulted in further reduction of the sediment supply to the reach downstream of Pacific Coast Highway. The proposed improvements are not expected to cause further impacts to the reach downstream of Pacific Coast Highway since the intent is to emulate the conditions of dynamic equilibrium, which the Project reach has nearly established on its own. However, in addition to establishing dynamic equilibrium, the proposed improvements will provide the added benefit of protecting the adjacent slopes from potential failure. 2.2 Basic Purpose and Need Statement The basic purpose of the proposed project can be expressed as follows: Through the reconstruction and stabilization of Morning Canyon by the . use of seven (7) grade control structures, the project shall restore the stream to an equilibrium condition to prevent additional erosion and Feasibility Analysis - 4 - June 10, 2005 degradation; restore the canyon bottom to its previous bed elevations and • reduce the potential for adjacent slope failures; restore the canyon to a more natural condition through the removal of exotic species and replacement with native species. 2.3 Water Dependency Due to the type of project site (drainage channel), and the improvements proposed herein, this project has been identified as "water dependent ". No change of use is proposed. 2.4 Uniqueness The Morning Canyon Channel is unique due to regional /topographic conditions (i.e., watersheds), engineering challenges (water conveyance and erosion), and public health /safety with respect to slope stability. 3.0 EVALUATION OF FEASABILITY Existing off -site drainage patterns, the location of the Morning Canyon Channel, the surrounding urbanized land uses, and the confirmation of water dependency has established the criteria for alternatives relative to identifying a feasible environmentally • superior alternative, while achieving the Project's objectives and goals. 3.1 Analysis of the Alternatives RBF has examined several possible scenarios and configurations in determining the environmentally superior alternative for the canyon stabilization project. The proposed project consists of wholesale improvements with respect to stabilization of the canyon and protection of adjacent properties. The proposed Project concept has been designed to restore an equilibrium condition to the canyon, reconstruct the previous channel grades, and restore a more native canyon condition. Alternatives to the proposed Project were developed, evaluated, and selected based on their satisfaction of goals of the Project: • Restore the canyon gradient to an equilibrium condition to prevent further erosion and degradation; • Reconstruct the canyon bed to the original grade to alleviate stability impacts to the adjacent development slopes; • Minimize adverse environmental effects; and • Increase water quality associated with post - project conditions. 11 Feasibility Analysis - 5 - June 10, 2005 • More than seven (7) alternative project improvements have been considered during the development of the Original Project (Alternative 1), the No Project Alternative, Alternatives 2 through 5, and the "additional alternatives" not analyzed in detail within this analysis. Due to the type of the improvements proposed, and the need to build the improvements in the canyon, off -site "additional alternatives" beyond the immediate project reach were not evaluated in this study. 3.2 Discussion of Alternatives 3.2.1 No Project Alternative The No Project Alternative would not accomplish any of the project objectives or goals. The no- action plan would result in no improvements within the canyon, and would not address the existing erosion problems that currently threaten adjacent land uses. 3.2.2 Alternative 1: Original Project- Gabion Grade Control Alternative 1, also known as the original project, was considered by the Applicant in order to fulfill the basic need and purpose of the project. Alternative 1 consists of the installation of seven (7) rock - filled gabion grade control structures within the project reach. This Alternative was presented to CCC Staff during an on -site Pre - Application Field Meeting on April 28, 2005. Refer to the enclosed large -scale photographs and site plans for more detail. • Discussion of Alternative: Project Function. The grade control structures would stabilize the canyon by creating an equilibrium slope along the channel invert. The grade control structures use a 3 -foot drop height typically recommended for the stabilization of degrading channels. The structures would be placed along the creek to restore the canyon to the original grades. The structures are proposed to be rock - filled gabion baskets, and will be backfilled with soil and re- vegetated after construction. The location of the grade control structures and incised channel fill would be consistent with the project's purpose and goal. Public Health and Safety. Alternative 1 would achieve the Project's basic goal and purpose. The canyon gradient would be stabilized to a state of dynamic equilibrium. The incised channel would be filled to reconstruct the original grades and stabilize the adjacent fill slopes. Project Impacts. The proposed project includes the construction of 7 grade control structures and the placement of earthen fill within the existing canyon. The project includes approximately 910 cubic -yards of gabion baskets, and 800 cubic -yards of earth fill. The total area of impact is 0.32 acres. There is the potential that all alternatives (excluding the No Project) will create temporary impacts due to construction activities. Exposed surfaces, construction debris, equipment and truck traffic will temporarily impact the project site. These impacts are considered short-term, would cease upon project completion. Alternative No. 1 would minimize the • temporary construction impacts through the use of smaller equipment for the construction of the project improvements. The gabion baskets use smaller rock than a Feasibility Analysis - 6 - June 10, 2005 rock riprap structure, and do not require the large dump trucks or loaders to place the rock to fill the baskets. Table 1 Impact Summary: Alternative 1 Improvement Type Impact Type Impacts Grade Control Structures Permanent' 910 cy fill Elevation Fill Permanent 800 cy fill 5' Work Area Buffer Temporary 1.0 acres Potential Restoration of Habitat NA 0.32 acres 1. This improvement consists of all impacts associated with the grade control structures. 2. Temporary impacts include access roads, excavation and work areas around permanent impact areas. Water Quality. Alternative 1 includes the reconstruction of a stable slope through the project reach. This will eliminate erosion and scour issues currently associated with the project site. Vegetation Enhancement. The installation of gabion baskets will allow the grade control structures to be backfilled with soil and re- vegetated to restore the canyon to a more natural condition. The area of the gabion structures is 0.19 acres. The reconstruction of the incised channel will also allow the canyon bottom to be re- vegetated with the project construction. The area of the channel fill is 0.13 acres. 3.2.3 Alternative 2: No Elevation Fill Alternative 2 was created in an effort to develop an alternative that did not include placing fill within the existing canyon incised channel. This alternative would still include the necessary drop structures within the existing channel; however, the locations and heights are revised to work with the current condition. A large 12 -foot high drop structure would be constructed at the outlet of the 51 -inch storm drain pipe. Due to the height of the structure, this facility would need to be a reinforced concrete drop structure. Two additional structures would be located upstream of the 51 -inch outlet pipe similar to the locations in Alternative No. 1. These structures would be rock - filled gabion baskets. Discussion of Alternative: Project Function. The location of the grade control structures would be consistent with the project's purpose and goal for establishment of an equilibrium slope only. The stabilization of adjacent fill slopes would not be provided. Public Health and Safety. Alternative 2 would achieve only one of the Project's basic goal and purpose. A stable slope along the canyon bottom would be created. However, since fill in the existing incised channel would be eliminated, adverse affects such as Feasibility Analysis - 7 - June 10, 2005 9 • • • continued instability of the adjacent fill slopes would continue. This issue is considered important and is major public health and safety issue associated with the project. • Project Impacts. The proposed project includes the construction of 3 grade control structures only. No placement of earthen fill within the existing incised canyon is proposed. The project includes approximately 260 cubic -yards of gabion baskets, and a reinforced concrete straight drop structure. The straight drop would be required to be rectangular channel section with a length of approximately 40 feet, and with 20 feet of loose riprap downstream. The total area of impact is 0.07 acres. It should also be noted that there is a potential that Alternative 2 (as with Alternative 1) will create temporary impacts due to construction activities. Exposed surfaces, construction debris, equipment and truck traffic may temporarily impact views adjacent to the site. These impacts are considered short-term, would cease upon project completion. Alternative No. 2 would require the construction of a reinforced concrete structure within the existing channel. Construction of this type of facility would require access for large equipment such as concrete trucks, excavators, and dump trucks. This equipment would require the temporary establishment of a large construction access roadway. Table 2 Impact Summary: Alternative 2 Improvement Type Impact Type Impacts Grade Control Structures Permanent 0.07 acres Elevation Fill Permanent 0.00 cy 10' Work Area Buffer Temporary 1.2 acres Potential Restoration of Habitat NA 0.05 acres Water Quality. Alternative 2 includes the reconstruction of a stable slope through the project reach. This will eliminate erosion and scour issues currently associated with the project site. Vegetation Restoration. The installation of the 2 gabion baskets will allow the grade control structures to be backfilled with soil and re- vegetated to restore the canyon to a more natural condition. The area of the gabion structures is 0.05 acres. The existing incised canyon or reinforced concrete structure would not allow for vegetation restoration. 3.2.4 Alternative 3: Grouted Riprap Grade Control Alternative 3 is similar to Alternative 1, except that the rock - filled gabion grade control • structures would be replaced with grouted rock riprap structures. Grouted rock would be Feasibility Analysis - 8 - June 10, 2005 required, rather than loose rock, due to the slope and flow velocities within the structures. Discussion of Alternative: Project Function. The grade control structures would stabilize the canyon by creating an equilibrium slope along the channel invert. The grade control structures use a 3 -foot drop height typically recommended for the stabilization of degrading channels. The structures would be placed along the creek to restore the canyon to the original grades. The structures are proposed to be grouted riprap and would not allow for re- vegetated after construction. The location of the grade control structures and incised channel fill would be consistent with the project's purpose and goal. Public Health and Safety. Alternative 3 would achieve the Project's basic goal and purpose. The canyon gradient would be stabilized to a state of dynamic equilibrium. The incised channel would be filled to reconstruct the original grades and stabilize the adjacent fill slopes. Project Impacts. The proposed project includes the construction of 7 grade control structures and the placement of earthen fill within the existing canyon. The project includes approximately 1,050 cubic -yards of grouted rock riprap, and 800 cubic -yards of earth fill. The total area of impact is 0.35 acres. There is the potential that all alternatives (excluding the No Project) will create temporary impacts due to construction activities. Exposed surfaces, construction debris, equipment and truck traffic will temporarily impact the project site. These impacts are considered short-term, would cease upon project completion. Alternative No. 3 would require the construction of grouted rock riprap structures within the existing channel. Construction of this type of facility would require access for large equipment such as concrete trucks, excavators, and dump trucks. This equipment would require the temporary establishment of a large construction access roadway. Table 3 Impact Summary: Alternative 3 Improvement Type Impact Type Impacts Grade Control Structures Permanent' 1050 cy fill Elevation Fill Permanent 800 cy fill 10' Work Area Buffer Temporary 1.2 acres Potential Restoration of Habitat NA 0.13 acres Water Quality. Alternative 3 includes the reconstruction of a stable slope through the project reach. This will eliminate erosion and scour issues currently associated with the project site. Feasibility Analysis - 9 - June 10, 2005 • • • Vegetation Enhancement. The installation of grouted rock riprap structures would not allow the grade control structures to be re- vegetated after construction. The reconstruction of the incised channel will allow the canyon bottom to be re- vegetated with the project construction. The area of the channel fill is 0.13 acres. 3.2.5 Alternative 4: Vinyl Sheet Pile Grade Control Alternative 4 is similar to Alternative 1, except that the rock - filled gabion grade control structures would be replaced with vinyl (or steel) sheet piles for the drop structures, and 30 -feet of loose riprap for scour and erosion protection downstream of the drops. Final determination of vinyl or steel sheet piles would be dependant on the results of additional geotechnical analyses to determine the corrosive properties of the soil and bedrock elevations. Discussion of Alternative Project Function. The grade control structures would stabilize the canyon by creating an equilibrium slope along the channel invert. The grade control structures use a 3 -foot drop height typically recommended for the stabilization of degrading channels. The structures would be placed along the creek to restore the canyon to the original grades. The structures are proposed to be vinyl sheet pipes and loose riprap and would not allow for re- vegetated after construction. The location of the grade control structures and incised channel fill would be consistent with the project's purpose and goal. • Public Health and Safety. Alternative 4 would achieve the Project's basic goal and purpose. The canyon gradient would be stabilized to a state of dynamic equilibrium. The incised channel would be filled to reconstruct the original grades and stabilize the adjacent fill slopes. Project Impacts. The proposed project includes the construction of 7 grade control structures and the placement of earthen fill within the existing canyon. The project includes approximately 900 cubic-yards of loose rock riprap, and 800 cubic -yards of earth fill. The total area of impact is 0.32 acres. There is the potential that all alternatives (excluding the No Project) will create temporary impacts due to construction activities. Exposed surfaces, construction debris, equipment and truck traffic will temporarily impact the project site. These impacts are considered short-term, would cease upon project completion. Alternative No. 4 would require the installation of sheet piles and placement of large rock riprap within the existing channel. Construction of this type of facility would require access for large equipment such as excavators, and dump trucks. This equipment would require the temporary establishment of a large construction access roadway. Feasibility Analysis -to- June 10, 2005 Table 4 Impact Summary: Alternative 4 Improvement Type Impact Type Impacts Grade Control Structures Permanent' 900 cy fill Elevation Fill Permanent 800 cy fill 10' Work Area Buffer Temporary 1.2 acres Potential Restoration of Habitat NA 0.13 acres Water Quality. Alternative 4 includes the reconstruction of a stable slope through the project reach. This will eliminate erosion and scour issues currently associated with the project site. Vegetation Enhancement. The installation of sheet pile and rock riprap scour protection would not allow the grade control structures to be re- vegetated after construction. The reconstruction of the incised channel will allow the canyon bottom to be re- vegetated with the project construction. The area of the channel fill is 0.13 acres. 3.2.6 Alternative 5: Soil Cement Grade Control Alternative 5 is similar to Alternative 4, except that the sheet pile drop structures would be replaced with soil cement drop structures. The soil cement drop structures would have a crest width of 8 -feet and a 1:1 slope for the 3 -foot drop. Loose riprap would be required downstream of the drops, similar to Alternative 4. Discussion of Alternative: Project Function. The grade control structures would stabilize the canyon by creating an equilibrium slope along the channel invert. The grade control structures use a 3 -foot drop height typically recommended for the stabilization of degrading channels. The structures would be placed along the creek to restore the canyon to the original grades. The structures are proposed to be soil cement and loose riprap and would not allow for re- vegetated after construction. The location of the grade control structures and incised channel fill would be consistent with the project's purpose and goal. Public Health and Safety. Alternative 5 would achieve the Project's basic goal and purpose. The canyon gradient would be stabilized to a state of dynamic equilibrium. The incised channel would be filled to reconstruct the original grades and stabilize the adjacent fill slopes. Project Impacts. The proposed project includes the construction of 7 grade control structures and the placement of earthen fill within the existing canyon. The project includes approximately 460 cubic -yards of soil cement, 900 cubic -yards of loose rock riprap, and 800 cubic -yards of earth fill. The total area of impact is 0.34 acres. Feasibility Analysis - 11 - June 10, 2005 • • • There is the potential that all alternatives (excluding the No Project) will create temporary impacts due to construction activities. Exposed surfaces, construction debris, equipment and truck traffic will temporarily impact the project site. These impacts are considered short-term, would cease upon project completion. Alternative No. 5 would require the installation of soil cement and placement of large rock riprap within the existing channel. Construction of this type of facility would require access for large equipment such as concrete trucks, excavators, and dump trucks. This equipment would require the temporary establishment of a large construction access roadway. Table 4 Impact Summary: Alternative 4 Improvement Type Impact Type Impacts Grade Control Structures Permanent' 1,360 cy fill Elevation Fill Permanent 800 cy fill 10' Work Area Buffer Temporary 1.2 acres Potential Restoration of Habitat NA 0.13 acres • Water Quality. Alternative 5 includes the reconstruction of a stable slope through the project reach. This will eliminate erosion and scour issues currently associated with the project site. • Vegetation Enhancement. The installation of soil cement and rock riprap scour protection would not allow the grade control structures to be re- vegetated after construction. The reconstruction of the incised channel will allow the canyon bottom to be re- vegetated with the project construction. The area of the channel fill is 0.13 acres. 3.2.7 Alternatives Considered But Not Evaluated Several alternatives were considered during the planning process, but were not evaluated in detail due to the following: Offsite Proiect Location: The Morning Canyon Channel is unique due to regional /topographic conditions (i.e., watersheds), engineering challenges (water conveyance and erosion), and public health /safety with respect to slope stability. The 2 major components of the project's objective are to establish an equilibrium slope for the existing canyon bed, and stabilization of the adjacent fill slopes. Therefore, offsite project improvements would not meet the project goals. Feasibility Analysis -12- June 10, 2005 0 Full Channel Alternative: Installation of a channel system through the entire canyon was briefly reviewed as a potential project alternative to eliminate erosion and degradation in the canyon. This alternative would result in much greater impacts to the canyon which could not be mitigated by habitat restoration. A channel system would also result in significant impacts to properties in the lower one -third of the project reach. This segment would need to include channel improvements to convey the water to the existing culvert at Pacific Coast Highway, or would require construction of a large energy dissipator structure to reduce the higher flow velocities in an improved channel. Therefore, full channel alternatives were not considered. 4.0 CONCLUSION This Analysis focused on five (5) specific alternatives (including the No Project Alternative) in order to identify a feasible environmentally superior alternative that is consistent with the project objectives, purpose, and need. Those alternatives, and the results of the analysis, are as follows: The No Project Alternative, in which no discharge of fill material would occur on -site would have the least environmental impacts. However, this Alternative does not meet the project's objective and protect the public welfare and is inconsistent with the purpose • and need. No modifications to the canyon would occur and existing erosion and slope stability issues would remain. The No Project Alternative is not considered to be a feasible option. Alternative 1, the Original Project (Gabion Grade Control), meets all project objectives and goals. The Alternative was created to achieve all objectives; consequently, the Alternative is the recommended plan. Alternative 2, No Elevation Fill, meets only half of the project objectives and goals. Since the incised channel fill was eliminated, goals of improving public safety for the adjacent residential fill slope are not meet. Therefore, Alternative 2 is not considered to be a feasible option. Alternative 3, Grouted Riprap Grade Control, meets all of the project objectives and goals. As with Alternative 1, channel fill and rock will be placed in the existing canyon. However, due to the type of material used for the grade control structures, less restoration of habitat is possible with this alternative. This alternative also results in larger temporary construction impacts. Due to the increase of environmental impacts, this is not an environmentally superior alternative. Therefore, Alternative 3 is not considered to be a feasible option. Alternative 4, Vinyl Sheet Pile Grade Control, meets all of the project objectives and goals. As with Alternative 1, channel fill and rock will be placed in the existing canyon. However, due to the type of material used for the grade control structures, less restoration of habitat is possible with this alternative. This alternative also results in - Feasibility Analysis -13- June 10, 2005 • larger temporary construction impacts. Due to the increase of environmental impacts, this is not an environmentally superior alternative. Therefore, Alternative 4 is not considered to be a feasible option. • • Alternative 5, Soil Cement Grade Control, meets all of the project objectives and goals. As with Alternative 1, channel fill, soil cement, and rock will be placed in the existing canyon. However, due to the type of material used for the grade control structures, less restoration of habitat is possible with this alternative. This alternative also results in larger temporary construction impacts. Due to the increase of environmental impacts, this is not an environmentally superior alternative. Therefore, Alternative 5 is not considered to be a feasible option. Based on the discussion contained herein, Alternative 1 has been identified as the most feasible environmentally superior alternative. Feasibility Analysis -14- June 10, 2005 REFERENCES Douglas E. Morgan, Inc. 'Results of Investigation, Slope Damage, Wynkoop and Walton Properties, 601 Rockford Road and 515 Rockford Place, Corona Del Mar, California." January 29, 1999. Geofirm. " Geotechnical Evaution and Recommendation for Repair of Slope Failure, 515 Rockford Place and 601 Rockford Road, Corona Del Mar, California." May 28, 2003 Geotechnical Exploration, Inc. "Document Review and Site Observations, Wynkoop Property and Walton Property 601 Rockford Road and 515 Rockford Place, Corona Del Mar, California." January 12, 1999. John M. Tettemer & Associates, Ltd. "Report on Storm Runoff Conditions in Buck Gully and Morning Canyon." February 1996. Lawrence R. Wlezien, Inc. "Job No. 3154 — WYNKOOP, ET AL V. ROUSE, ET AL." January 27, 1999. Lockwood -Singh & Associates. "Hydrologic, Geomorphic, Hydraulic and Geotechnical Findings Regarding Morning Canyon Watershed, and Related Channel and Slope Processes, Newport Beach, California." February 1, 1999. Lotus Consulting Engineers, Inc. "Preliminary Geotechnical Report Existing 1997 -1998 Sloe Failure at the Rear of 601 Rockford Road & 515 Rockford Place, Corona Del Mar, California." September 25, 2000. Moffatt & Nichol, Engineers. "Morning Canyon Sedimentation (MNE 2450 -08)." April 14, 1992. RBF Consulting. "Morning Canyon Stream Stability and Channel Restoration Study." Draft March 2005. Rivertech, Inc. "Morning Canyon Stabilization, Hydrologic and Hydraulic Analyses." August 2002. Feasibility Analysis -15- June 10, 2005 E • • • RESOLUTION NO. 2005 - A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF NEWPORT BEACH DECLARING THE IMMEDIATE STABILIZIATION OF MORNING CANYON TO BE A MATTER REQUIRING EMERGENCY ACTION, CONFIRMING AUTHORIZATION OF THE PUBLIC WORKS DIRECTOR TO AWARD A CONTRACT FOR THE STABILIZATION OF THE CANYON , AND CONFIRMING THE AWARD OF THE CONTRACT TO SUNQUEST GENERAL ENGINEERING The City Council finds and declares as follows: WHEREAS, urban development in the Morning Canyon watershed over the past 60 years has reached a critical point such that the canyon bottom is rapidly eroding; and WHEREAS, the fill material on the Cameo Highlands canyon slopes sits on a clay layer which in turn sits on an adversely inclined bed surface, and that this barely stable slope condition can be disrupted with minor amounts of infiltrated rainwater, and that the 2005 catastrophic Bluebird Canyon slope failure in Laguna Beach was due to a similar failure mode and resulted in substantial loss of property and endangered residents; and • WHEREAS, the risk assessment by Leighton Consulting, Inc. dated August 8, 2005, states that in Morning Canyon, especially "... where the manufactured fill comprises the major portion of canyon side, the landsliding risk is very high. Almost certainly there will be a massive landsliding even if the next rainy season produces moderate rain and stream flood'; and WHEREAS, the storm season officially commences on October 15 and significant rainfall usually is expected no later than January; and WHEREAS, a rigorous assessment of the canyon hydrodynamics and sediment transport has been performed and has been used as the basis for the preparation of engineered drawings and specifications to repair the canyon flood plain and install engineered gabion control structures to forestall future streambed erosion in an environmentally sensitive manner in accordance with best practices and in concert with the regulatory agencies; and WHEREAS, the project will take approximately 60 days to complete; and WHEREAS, permit applications have been submitted and approved by State Fish and Game, Army Corps of Engineers and Regional Water Quality Control Board; and • WHEREAS, the permit application with the California Coastal Commission (CCC) has been deemed complete and City staff has met with CCC staff to discuss the project, CCC staff cannot agendize the permit application to be heard before the EXH161T E Commission until October 13 and such a delay will put the City in jeopardy of not being • able to complete the project in advance of the expected storms within the winter rain season. NOW THEREFORE, based upon the above findings, the City Council declares the conditions in Morning Canyon constitute an emergency situation and that staff is directed to: 1. Move forward with the Moming Canyon Stabilization Project so work can be completed in advance of the expected storms and 2. Continue working with California Coastal Commission staff to secure a Coastal Development Permit and make their best efforts to incorporate the conditions of the permit into the ongoing project. Adopted this day of 2005 John Heffernan Mayor ATTEST: City Clerk f:\users\pbvAshared \resolutions \moming canyon stabilization.doc • C� • REIMBURSEMENT AGREEMENT BETWEEN THE CITY OF NEWPORT BEACH AND CHRISTOPHER WYNKOOP AND JOY WYNKOOP AS INDIVIDUALS AND TRUSTEES OF THE WYNKOOP FAMILY TRUST AND CHARLOTTE WALTON AS AN INDIVIDUAL AND AS TRUSTEE FOR THE MENZIES FAMILY TRUST FOR CONSTRUCTION OF THE MORNING CANYON STABILIZATION PROJECT THIS REIMBURSEMENT AGREEMENT ( "Agreement "), is made and entered into on this day of 2005, by and between: THE CITY OF NEWPORT BEACH, California, a Municipal Corporation, hereinafter referred to as "City ", and Christopher Wynkoop and Joy Wynkoop, as individuals and as trustees of the Wynkoop Family Trust, hereinafter collectively referred to as the " Wynkoops" and Charlotte Walton as an individual and as trustee of the Menzies Family Trust, hereinafter collectively referred to as the "Waltons ". The Wynkoops and the Waltons shall hereinafter be referred to collectively as the "Owners." The Owners and City are sometimes hereinafter individually referred to as "party" and hereinafter collectively referred to as "parties." RECITALS WHEREAS, City is a municipal corporation duly organized and validly existing under • the laws of the State of California with the power to carry on its business as it is now being conducted under the statutes of the State of California and the Charter of the City; and WHEREAS, the Wynkoops are the owners of the real property located at 601 Rockford Road, Corona del Mar, California, APN 475 031 15, hereinafter referred to as the " Wynkoops Property "; and u WHEREAS, the Waltons are the owners of the real property located at 515 Rockford Place, Corona del mar, California, APN 475 031 13, hereinafter referred to as the "Waltons Property ", (hereinafter the Wynkoops Property and the Waltons Property shall be collectively referred to as the "Owners Property"); and WHEREAS, the City is proposing to construct the project commonly known as the "Morning Canyon Stabilization Project" shown in Exhibit "A" which includes the clearing of vegetation, importing of fill, localized regrading of the canyon bottom, installing seven gabion structures, installing grouted rock at the end structure of the 42 -inch storm drain main, installing gabion slope protection at selected locations, broadcasting hydroseed in the canyon bottom, revegetating areas of the canyon and other appurtenant and incidental items of work (the "Project "); and WHEREAS, the parties previously agreed that to construct the Project, certain improvements to the Owners Property would need to be made for which the City would be reimbursed; and Page 1 of 8 EXHIBIT F WHEREAS, based on the Owners representation that the Owners would reimburse the • City, the City did incorporate improvements to the Owners Property into the Project which improvements include an 18 inch RCP Strom Drain (fifty -one (5 1) linear feet of which is the responsibility of the Owners), excavating and dewatering for the gabion bank protection, installing gabion bank protection and backfilling behind the gabion bank protection as delineated and described in more detail as items 8, 11, 12, 13 and 14 respectively on Exhibit B which is attached hereto and incorporated by this reference, hereinafter collectively referred to as the "Owner Improvements "; and WHEREAS, the estimated cost of constructing Owner Improvements is Two Hundred Seventy -One Thousand Two Hundred Sixty -Five Dollars and No Cents ($271,265.00), hereinafter referred to as the "Cost Estimate "; and WHEREAS, the Owners have agreed to fully reimburse the City for all costs associated with constructing Owner Improvements even if said costs exceed the Cost Estimate; and WHEREAS, the City and Owners acknowledge that there is a risk in constructing the Project and Owner Improvements in that the construction of the Project and the Owner Improvements may cause slope failures on the Owners Property and other damages to the Owners Property and other properties adjoining the Project area; and WHEREAS, the Owners have agreed to expressly assume all risk of damages to the Owners Property that may result from the construction of the Project and Owner Improvements and to waive and release the City from all damages from the construction of the Project and • Owner Improvements including, but not limited to, slope failures or other acts of passive or active negligence; and WHEREAS, the Owners acknowledge and agree that the City is not guaranteeing that construction of the Project and Owner Improvements will prevent any damages to the Owner's Property including, but not limited to, slope failures or other damages and that the City is not assuming liability for any damages associated in any way with its construction of the Project; and WHEREAS, City has agreed to administer and manage the design and construction contracts for the Project subject to the conditions set forth below. AGREEMENT NOW THEREFORE, in consideration of the mutual promises set forth herein, the Parties hereto agree as follows: Section 1: Recitals. The Recitals above are deemed true and correct, are hereby incorporated in this Section as though fully set forth herein, and each Party to this Agreement acknowledges and agrees that such Party is bound by the same. Section 2: Elements of Agreement. City and Owners shall work cooperatively • together so the Project can be constructed in a manner that minimizes the costs and impacts to Page 2 of 8 • the public. The specific terms and conditions governing the elements of this Agreement are set forth hereinafter. Section 3: City's Specific Obligations. City shall administer and manage the design and construction contracts for the Project. The City shall have the sole and absolute discretion as to all aspects of design and construction of the Project, as well as construction change orders related thereto. The City shall be obligated to ensure that all necessary building permits to construct the Project are obtained. Section 4: Owner's Specific Obligation s. Owners shall: A. Reimburse the City for all costs associated with the construction of the Owner Improvements even if the costs exceed the Cost Estimate. The Waltons and Wynkoops shall split any cost of reimbursement on an equal basis. B. Concurrent with Owners execution of this Agreement, the Wynkoops and Waltons shall each tender a cashiers check made payable to the "City of Newport Beach" in the amount of One Hundred Fifty Thousand Dollars and No /Cents ($150,000.00) for a total of Three Hundred Thousand Dollars and No Cents ($300,000.00), hereinafter referred to as the "Deposit ". The City shall maintain the Deposit in a separate account. The City shall have the right to withdraw funds to pay for the construction of the Owner Improvements as the Owner Improvements are constructed. The City in its sole discretion may at any time • provide the Owners with written notice that additional funds must be placed on deposit with the City to cover actual or projected costs of constructing the Owner Improvements and the Owners shall have three (3) calendar days after receipt of this notice to deposit the additional funds with the City. Any additional deposit requested by the City shall be split between the Wynkoops and Waltons on an equal basis. Upon final completion of the Project, the City shall refund Owners funds on deposit with the City, if any, that were not necessary to pay for costs associated in any with the construction of the Owner Improvements. Any refund shall be paid to the Wynkoops and Waltons on an equal basis. C. The Owners agree that the Cost Estimate is only an estimate and that extra work, changed conditions, differing site conditions or other factors may result in change orders increasing the cost of constructing the Owner Improvements. The Owners agree that the City shall have sole discretion to approve any change orders that the City determines are necessary and that the Owners shall be liable for all change orders that relate in any way to the Owners' Improvements. The Waltons and Wynkoops shall split the cost of any change orders on an equal basis. D. Owners agree to accept the Owner Improvements upon final completion of the Project, as determined by the City in its sole and absolute discretion. After final completion of the Project, the City shall have no duty to repair, maintain, remove or take any other action associated in any way with the Owner Improvements. . Section 5: Hold Harmless. To the fullest extent permitted by law, Owners shall indemnify, defend and hold harmless City, its City Council, boards and commissions, officers, Page 3of8 consultants, contractors, subcontractors, vendors, volunteers, agents, attorneys and employees • (collectively, the "Indemnified Parties ") from and against any and all claims (including, without limitation, claims for bodily injury, death or damage to property), demands, obligations, damages, actions, causes of action, suits, losses, judgments, fines, penalties, liabilities, costs and expenses (including, without limitation, attorney's fees, disbursements and court costs) of every kind and nature whatsoever (individually, a Claim; collectively, "Claims "), which may arise from or in any manner relate (directly or indirectly) to the Owner Improvements including, but not limited to, the construction of the Owner Improvements, the effects of the Owner Improvements, and/or the impacts caused by the Owner Improvements on any other person or property including, but not limited to adjoining properties and/or adjoining property owners; any representation or warranty set forth herein that is determined to be false; and/or Owners' presence or activities conducted on or about the Project (including the negligent and/or willful acts, errors and/or omissions of Owners, their principals, officers, agents, employees, vendors, suppliers, consultants, contractors, subcontractors, anyone employed directly or indirectly by any of them or for whose acts they may be liable or any or all of them). Notwithstanding the foregoing, nothing herein shall be construed to require Owners to indemnify the Indemnified Parties from any Claim arising from the sole negligence or willful misconduct of the Indemnified Parties. The parties expressly agree that the design of the Owner Improvements was a collaborative effort among the parties and the City shall not be deemed to be solely negligent for the design of the Owner Improvements. Nothing in this indemnity shall be construed as authorizing any award of attorney's fees in any action on or to enforce the terms of this Agreement. This indemnity shall apply to all claims and liability regardless of whether • any insurance policies are applicable. Section 6: Waiver and Release of Liability: The Owners hereby acknowledge and agree as follows: A. THE OWNERS RECOGNIZE AND AGREE THAT: (1) CONSTRUCTION OF THE PROJECT AND OWNER IMPROVEMENTS IS DANGEROUS AND CONTAINS RISK OF PERSONAL INJURY, DEATH, DISABILITY, OR PROPERTY DAMAGE OR LOSS INCLUDING BUT NOT LIMITED TO SLOPE FAILURES ON THE OWNERS PROPERTY AND /OR OTHER DAMAGES (HEREINAFTER "DAMAGES "); (Z) THE CITY IS NOT GUARANTEEING THAT CONSTRUCTION OF THE PROJECT AND OWNER IMPROVEMENTS WILL PREVENT FUTURE DAMAGES TO THE OWNERS PROPERTY; AND (3) THE CONSTRUCTION OF THE OWNER IMPROVEMENTS MAY RESULT IN FUTURE DAMAGES TO OWNERS PROPERTY OR OTHER ADJOINING PROPERTIES. B. THE OWNERS RECOGNIZE AND AGREE THAT THEY HAVE BEEN FULLY INFORMED OF ALL ASPECTS OF THE PROJECT INCLUDING, BUT NOT LIMITED TO, THE CONSTRUCTION OF THE OWNER IMPROVEMENTS AND OWNERS EXPRESSLY APPROVE OF THE DESIGN FOR CONSTRUCTION OF THE OWNER IMPROVEMENTS. DESPITE THE POTENTIAL RISK OF DAMAGES TO OWNERS AS A RESULT OF THE CONSTRUCTION OF THE PROJECT AND OWNER IMPROVEMENTS, EACH OWNER HAS DECIDED TO • EXPRESSLY ASSUME THE RISK OF DAMAGES TO OWNERS CAUSED BY THE Page 4 of 8 • CONSTRUCTION OF THE PROJECT AND OWNER IMPROVEMENTS. THE OWNERS UNDERSTAND AND AGREE THAT THEY ARE VOLUNTARILY AGREEING TO THE CONSTRUCTION OF THE PROJECT AND OWNER IMPROVEMENTS. C. THE OWNERS HEREBY AGREE TO EXPRESSLY ASSUME ANY AND ALL RISK, RESPONSIBILITY AND LIABILITY FOR ALL RISKS ASSOCIATED IN ANY WAY WITH THE PROJECT AND CONSTRUCTION OF THE OWNER IMPROVEMENTS, WHETHER IDENTIFIED BY THE CITY OR NOT INCLUDING, BUT NOT LIMITED TO, THE FOLLOWING: (1) RISK OF SLOPE FAILURES ON OWNERS PROPERTY CAUSED BY THE CONSTRUCTION OF THE PROJECT AND OWNER IMPROVEMENTS; (2) RISK THAT THE PROJECT AND OWNER IMPROVEMENTS MAY NOT PROTECT OWNERS PROPERTY FROM FUTURE DAMAGES; (3) RISK THAT THE OWNER IMPROVEMENTS MAY CAUSE DAMAGES TO OWNERS PROPERTY OR OTHER PROPERTIES OR PERSONS INCLUDING, BUT NOT LIMITED TO, ADJOINING PROPERTIES AND ADJOINING PROPERTY OWNERS; AND (4) RISK OF PASSIVE OR ACTIVE NEGLIGENCE AND /OR OTHER ACT OR OMISSION THAT MAY RESULT IN DAMAGES. D. BY EXECUTING THIS AGREEMENT AND INITIALING BELOW THE OWNERS FOR THEMSELVES, THEIR HEIRS, OR ANYONE WHO MIGHT CLAIM ON THEIR BEHALF, AGREE NOT TO BRING ANY CLAIM, AND WAIVE, RELEASE AND DISCHARGE THE CITY OF NEWPORT BEACH, ITS CITY • COUNCIL, BOARDS AND COMMISSIONS, OFFICIALS, OFFICERS, AGENTS, VOLUNTEERS, CONSULTANTS, CONTRACTORS, ANY SUBCONTRACTORS, VENDORS, ATTORNEYS AND EMPLOYEES FOR ANY DAMAGES, LOSSES, COSTS AND EXPENSE ARISING OUT OF OR RELATED IN ANY WAY TO THE PROJECT AND OWNER IMPROVEMENTS INCLUDING, BUT NOT LIMITED TO, ALL LIABILITY FOR: (1) THE CONSTRUCTION OF THE PROJECT AND OWNER IMPROVEMENTS; (2) ANY FUTURE DAMAGES CAUSED BY THE PROJECT AND OWNER IMPROVEMENTS TO THE OWNERS PROPERTY OR OTHER PROPERTIES OR PERSONS INCLUDING, BUT NOT LIMITED TO, ADJOINING PROPERTIES AND /OR ADJOINING PROPERTY OWNERS; (3) THE FAILURE OF THE PROJECT AND OWNER IMPROVEMENTS TO PREVENT DAMAGES OF ANY NATURE; AND (4) ANY ACTIVE OR PASSIVE NEGLIGENCE OR ACT OR OMISSION BY THE CITY, ITS CITY COUNCIL, BOARDS AND COMMISSIONS, OFFICIALS, OFFICERS, AGENTS, VOLUNTEERS, CONSULTANTS, CONTRACTORS, ANY SUBCONTRACTORS, VENDORS, ATTORNEYS AND EMPLOYEES. THIS RELEASE AND WAIVER EXTENDS TO ALL CLAIMS OF EVERY KIND OR NATURE WHATSOEVER FORESEEN OR UNFORESEEN, KNOWN OR UNKNOWN. EACH OWNER EXPRESSLY INTENDS THIS RELEASE TO BE EFFECTIVE, REGARDLESS OF WHETHER THE CLAIM OF LIABILITY IS ASSERTED IN NEGLIGENCE, STRICT LIABILITY OR OTHER THEORY OF RECOVERY. • E. EACH OWNER HAS READ, UNDERSTANDS AND AGREES TO THE WAIVER AND RELEASE OF LIABILITY. EACH OWNER UNDERSTANDS Page 5 of 8 THAT BY THEIR SIGNATURE ON THIS AGREEMENT AND BY INITIALING • BELOW, THAT EACH OWNER IS WAIVING FOR THEMSELVES RIGHTS, INCLUDING ANY RIGHTS THEY MAY HAVE AGAINST THE CITY OF NEWPORT BEACH OR ITS CITY COUNCIL, BOARDS AND COMMISSIONS, OFFICERS, OFFICIALS, AGENTS, VOLUNTEERS, CONSULTANTS, CONTRACTORS, ANY SUBCONTRACTORS, VENDORS, ATTORNEYS AND EMPLOYEES. Christopher Wynkoop Joy Wynkoop Charlotte Walton Section 7 Improvements Constructed By Owners. Owners shall not construct or place any wall or structure that creates a water barrier across the Project area. Further, owners shall not construct or place any wall or structure that concentrates water flow entering the Project area without the express written permission of the City which may deny said request in accordance with Section 7(A) below. A. Before constructing or placing any wall or structure that concentrates water flow entering the Project area, the Owners shall be required to obtain the approval of the City which, in its sole discretion, may deny the request if the City determines that concentrating water flow would adversely impact flood control operations in the Project area, or the properties adjacent to the Project area. The Grantor shall provide any and all information; • drawing sand other materials requested by the Director of the Public Works Department of the City of Newport Beach or his/her designee necessary to make said determination. B. Any improvements permitted by the City which may be allowed shall be operated and maintained at no cost to the City. Section 8: Term. This Agreement shall be in full force and effect until the specified obligations of both Parties have been fulfilled or the Agreement is terminated as set forth herein. Section 9: Notices. All notices or other communications required or permitted hereunder shall be in writing and shall be personally delivered or sent by registered or certified mail, postage prepaid, return receipt requested, delivered or sent by electronic transmission, and shall be deemed received upon the earlier of: (i) the date of delivery to the address of the person to receive such notice if delivered personally or by messenger or overnight courier; (ii) three (3) business days after the date of posting by the United States Post Office if by mail; or (iii) when sent if given by electronic transmission. Any notice, request, demand, direction, or other communication sent by electronic transmission must be confirmed within forty -eight (48) hours by letter mailed or delivered. Notices or other communications shall be addressed as follows: To City: City of Newport Beach 3300 Newport Boulevard Newport Beach, CA 92663 Attention: Public Works Director • Facsimile: (949) 644 -3020 Page 6 of 8 • To Owners: Christopher Wynkoop Joy Wynkoop 601 Rockford Road Corona del Mar, California 92625 Facsimile (949) 851 -1740 Charlotte Walton 2133 E. Nicolet Phoenix, Arizona 85020 Facsimile (602) 264 -6140 Section 10: Controlling Law and Venue. The laws of the State of California shall govern this Agreement and all matters relating to it and any action brought relating to this Agreement shall be adjudicated in a court of competent jurisdiction in the County of Orange. Section 11: No Third Party Beneficiaries. This Agreement is entered into by and for the Owners and the City, and nothing herein is intended to establish rights or interests in individuals or entities not a party hereto. Section 12: Entire Agreement. This Agreement constitutes the entire understanding and agreement between the Parties and supersedes all previous negotiations between them pertaining to the subject matter thereof. • Section 13: Waiver. A waiver of a breach of the covenants, conditions, or obligations under this Agreement by either Party shall not be construed as a waiver of any succeeding breach of the same or other covenants, conditions, or obligations of this Agreement. Section 14: Modification. Alteration, change, or modification of this Agreement shall be in the form of a written amendment, which shall be signed by each Party. Section 15. Severability. Whenever possible, each provision of this Agreement shall be interpreted in such a manner as to be effective and valid under applicable law, but if any provision of this Agreement shall be invalid under the applicable law, such provision shall be ineffective only to the extent of such prohibition or invalidity, without invalidating the reminder of that provision, or the remaining provisions of this Agreement. Section 16. Warranties and Representations. The Wynkoops represent and guarantee that the Wynkoop Family Trust is the sole owner of the Wynkoop Property and that the Wynkoops are the trustees of the Wynkoop Family Trust and have the authority to enter into this Agreement. The Waltons represent and guarantee that the Menzies Family Trust is the sole owner of the Walton Property and that Charlotte Walton is the trustee of the Menzies Family trust and has the authority to enter into this Agreement. Section 17. Termination. In the event that either party fails or refuses to perform any of the provisions of this Agreement at the time and in the manner required, that party shall be • deemed in default in the performance of this Agreement. If such default is not cured within a period of two (2) calendar days, or if more than two (2) calendar days are reasonably required to Page 7 of 8 cure the default and the defaulting party fails to give adequate assurance of due performance • within two (2) calendar days after receipt of written notice of default, specifying the nature of such default and the steps necessary to cure such default, the non - defaulting party may terminate the Agreement forthwith by giving to the defaulting party written notice thereof. Notwithstanding the above provisions, City shall have the right, at its sole discretion and without cause, of terminating this Agreement at any time by giving seven (7) calendar days prior written notice to Owners. IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be executed as of the day and year first above written. APPROVED AS TO FORM 0 City Attorney CITY OF NEWPORT BEACH M Mayor ATTEST: By City Clerk • OWNERS 10 Christopher Wynkoop as an individual and as trustee of the Wynkoop Family Trust By Joy Wynkoop as an individual and as trustee of the Wynkoop Family Trust By Charlotte Walton as an individual and as trustee of the Menzies Family Trust • f.+rt \Pbv vdkmrxls \fy 01 -0S mso Ym Ch mlc- )slTxinbmecimu a pm wlms.d Page 8 of 8 0 • • RISK ASSESSMENT, EMBANKMENT FAILURE ALONG MORNING CANYON, WESTERLY OF ROCKFORD ROAD, NEWPORT BEACH, CALIFORNIA Prepared for: City of Newport Beach Public Works Department P.O. Box 1768 Newport Beach, California 92658 Project No. 600997 -001 August 8, 2005 4 Leighton Consulting, Inc. A LEIGHTON GROUP COMPANY EXHIBIT G 4 9 Leighton Consulting, Inc. A LEIGHTON GROUP COMPANY August 8, 2005 Project No. 600997 -001 To: City of Newport Beach Public Works Department P.O. Box 1768 Newport Beach, California 92658 Attention: Mr. Robert Stein Subject: Risk Assessment, Embankment Failure Along Morning Canyon, Westerly of Rockford Road, Newport Beach, California In accordance with your request, Leighton Consulting, Inc. has performed a limited review of the • geotechnical conditions along the banks of Morning Canyon where stream downcutting of the thread of the canyon has oversteepened the toe of canyon side slopes that support residences along Rockford Road, Rockford Place and Seaward Road. The purpose of our review was to provide risk assessment guidelines. In general, the thread of the canyon exposes bedrock of the Monterey Formation, a sedimentary rock with likely inclusion of weak sedimentary layers. Residential development of the area in the 1950's was achieved by placement of manufactured fill slope along the easterly sides of the canyon. Along most of the length of this stretch of the canyon, the manufactured slope appears to have been founded into bedrock some distance above the canyon bottom. Along a portion of the southeasterly side of the canyon, however the base of the fill is almost coincident with the canyon bottom. In general, it is our conclusion that within the stretch where the manufactured fill comprises the major portion of canyon side, the landsliding risk is very high. Almost certainly there will be massive landsliding even if the next rainy season produces moderate rain and stream flow. • 17781 Cowan • Irvine, CA 92614 -6009 949- 253 -9836 • Fax 949 - 250 -1114 • www.L- ightonconsutting.com J 600997 -001 Where stream flow is contained within bedrock and the fill starts higher up on the canyon side, the potential for landsliding is moderate. Continued canyon downcutting increases the potential for landslides. Massive landsliding could occur during an extreme rainy season. The following contains the details our review and the basis of our conclusions. Background The subject canyon slope has a history of surficial failures and the potential for future surficial failures remains high. The potential increases as the thread of the canyon deepens with erosion and meandering of the canyon, and locally exaggerates the steepness of the toe of the slope. To date, the failures appear to have impacted the backyards and backyard improvements in a piecemeal fashion. Leighton Consulting's study was performed to assess the risk of deep- seated instability of the canyon sides and the potential for more drastic damage to the adjacent properties. • Scope of Work The scope of our services included: 1. Background Review — The materials referenced in Appendix A were reviewed. 2. Geologic Reconnaissance — Reconnaissance level geologic mapping of the bedrock exposures along the thread of the canyon was performed on July 17'h. The limited observations are shown on Plate 1. 3. Soil Sampling — Four soil samples were obtained, one of fill materials, one of old canyon bottom materials below the fill, and two bedrock samples (Sample #3 was claystone and 44 was silty sandstone). Sample locations are shown on Plate 1 and photographs of the samples sites are at the rear of the text. 4. Laboratory Testing — Index properties of the obtained sample were determined (see Appendix B). 5. Slope Stability Analyses — Slope stability analyses were performed to quantify the stability level of the embankment sides (see Appendix C). z Leighton 600997 -001 • Site Geology The area around Morning Canyon is dominated by outcrops of the middle to late Miocene Monterey Formation, composed chiefly of siliceous and tuffaceous shale, siltstone and calcareous sandstone, extend from Upper Newport Bay southward along the coast of Laguna Beach (Tan and Edgington, 1976). Gradual, interrupted emergence of the region from the sea occurring in Pleistocene times created numerous wave -cut terrace platforms, most of which were covered by marine deposits. The subsequent erosion of adjacent highlands provided a non - marine colluvial cover that is mapped elsewhere as slope wash deposits. Minor stream deposits of Pleistocene age flank major drainages in some areas. Younger sur5cial deposits of Holocene age are alluvial and slope wash deposits and beach sediments along the coast (Tan and Edgington, 1976). Within Morning Canyon, mapped sur5cial deposits consist of artificial fill, alluvium, and non - marine terrace material. Artificial fill associated with the development of the Cameo Highlands is found in various locations along the canyon. The alluvial material is generally limited to the floor of the canyon, frequently incised by the active stream. The majority of the Monterey Formation, where exposed within the canyon, is massive to poorly • bedded clayey sandstone. While other well- bedded exposures of bedrock may exist within the canyon, only one location was observed during our recent site mapping. This one exception was a small outcrop on the west side of the canyon, near the rear property line of 522 and 524 Seaward Road. The bedrock exposed at this location is comprised of well bedded, silty sand that strikes (horizontal orientation) to the northwest (N44W and N33W) and dips (tilts downward) to the north (25 and 48 degrees, respectively). Poorly defined bedding was also measured on the north side of the canyon, at the rear of 528 Seaward Road, on a poorly bedded sandstone unit (N25E, 131). Review of mapping by others (Tan and Edgington, 1976) in the immediate area, reveals a wide range of bedding attitudes, possibly controlled by a fault mapped through the canyon within the project site. Stability Discussion Two distinct conditions are recognized along the canyon side walls. Where the side wall is essentially comprised of manufactured fill, the fill strength and down- cutting of the fill -slope toe controls stability. This condition occurs below residences at 601 Rockford Road and 515 • - 3 - Leighton • 600997 -001 Rockford Place. Elsewhere, the toe of the fill is above the active stream bed and stability is controlled by the strength of the bedrock and the orientation and dip of the sedimentary layers. 1. Active rotational (arcuate in shape) landsliding is on going within the artificial fill, which supports the backyards of these two residences. Typically rotational landslides self - stabilize and the slide movement ceases as the slide mass is shifted downslope. However, when the slide toe is within a canyon and subject to removal by stream flow, the fragile balance is upset, slide mass reactivates and headward retreat of the scarp area occurs. The present conditions at the area of the two properties are such that massive landslide reactivation is almost a certainty even in a moderately severe rainy season. 2. Upstream and downstream of the two residences mentioned above, the canyon bottom is incised to bedrock of the Monterey Formation. This sedimentary rock within the study area was generally found to be massive, but isolated inclusions of low strength (silt and clay) layers within the bedrock were observed. We have performed parametric stability analyses that indicate that if a weak layer (such as the one observed and sampled as our Sample #3 at 615 Rockford Road) with a steep inclination (downward tilt) towards the canyon bottom is daylighted (exposed) by the canyon thread downcutting, instability • could occur. The mapped geology of the site by us and by other investigators indicate that there is enough variability in dip angle (amount of dip) and orientation of the bedding that massive failure has a theoretical chance of occurrence. Without in -depth detailed investigation, it is not appropriate to quantify this chance except that it will significantly increase with continued canyon downcutting. 9 Leighton 600997 -001 • Should you have any questions concerning this report, please do not hesitate to contact this office. We appreciate this opportunity to be of service. QaOFESSION41 C Respectfully submitted, �O WOODY JOE �o pouewD LEIGHTON CONSULTING, INC. N& Z197 COMED OF Woody Joe Pollard, CEG 2297 Senior Project Geologist QPOFESS /py IHA.I �Fy � h DOORMAND No. 893 EV.9M /DS MX Iraj Poonnand, PE, GE 693 * * Senior Geotechnical Consultant o�1�HN��P WJP/IP /Ir Attachments: Site Photographs • Plate I — Site Map Appendix A — References Appendix B — Boring Logs Appendix C — Laboratory Test Results Distribution: (2) Addressee 5 Leighton