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HomeMy WebLinkAboutSS4 - Morning Canyon Drainage Issues & Status Report• CITY OF NEWPORT BEACH CITY COUNCIL STAFF REPORT Study Session Agenda Item No. ss4 June 24, 2003 TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL FROM: Public Works Department Stephen G. Badum, Director 949 -644 -3311 sbadum @city.newport- beach.ca.us SUBJECT: MORNING CANYON DRAINAGE ISSUES /STATUS REPORT DISCUSSION: Morning Canyon runs within private property from the Pelican Hills Golf Course to the Pacific Ocean. While the City does not have a maintenance easement in the channel, General Services periodically cleared the drainage course of growth and maintained a clear natural channel for flood flows during the 1980's. In the early 1990's, this service • was stopped due to opposition by some of the property owners. Since that time, there has been no comprehensive maintenance of the existing drainage course. In 1995, a massive slope failure occurred at two properties on Rockford Road. A lawsuit was filed by the property owners claiming that the failure was caused by un- permitted grading and the installation of improvements by one of the private property owners that diverted storm flows. At the conclusion of a civil suit between the property owners, the court awarded damages to the owners of these properties that experienced the slope failures. Some of the affected property owners have approached the City for guidance in obtaining design approval for work within the channel to repair the slope. Upon closer inspection of the existing drainage situation in Morning Canyon between the golf course and Coast Highway, City staff discovered the original drainage course has been modified at several locations by various property owners and the lack of maintenance and increases in dry weather flows (urban runoff) has allowed dense vegetation to grow which significantly affects the drainage flows in this portion of the canyon. While Morning Canyon Channel falls within private property' and the City is not responsible for maintaining the channel, 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. Recognizing this need, City Council authorized City staff to The City currently holds a twenty -two foot wide easement along the property lines of the Cameo • Highlands properties from the golf course to Coast Highway. It is assumed that the original intent of this easement was to enable the City to construct a subsurface drainage facility in the event that the golf course property was developed as a residential tract in lieu of the current use. Subject: Morning Canyon Drainage Issues /Status Report June 24, 2003 Page: 2 retain Rivertech, Inc. to develop the concept for stabilizing the channel and formulating • a plan to implement corrective measures at the April 9, 2002 meeting. A draft of the conceptual report from Rivertech, Inc. was delivered to the City in August 2002 (attached Exhibit A). In general, the concept plan called for the construction of several rock gabion drop structures to stabilize the canyon. The proposed conceptual plan was designed to stabilize Morning Canyon Channel in a manner that would not adversely impact the channel's hydraulics, biological resources, geotechnical stability, or water quality upstream or downstream of the affected reach of the channel. The proposed plan would require extensive permitting by various regulatory agencies and would probably cost as much as $1 million to build. In addition, this project would require the cooperation of all affected homeowners as the conceptual solution proposed the construction of several rock gabion structures on private property. A meeting was scheduled September 9, 2002 with the homeowners that border Morning Canyon to discuss the draft of the conceptual plan (See meeting announcement, Exhibit B). Topics of discussion included a brief history, drainage /erosion issues, water quality, and environmental habitat concerns as well as a presentation of the conceptual plan, costs and potential financial responsibilities. The responses from those that attended were mixed and no consensus was reached. Those that were experiencing erosion problems generally supported the plan while those that had not yet experienced problems were generally opposed. On December 24, 2002, a status report was sent to all affected homeowners • encouraging them to address their individual grading /erosion issues independently while the City continued to work with the regulatory agencies and further explored grant funding opportunities (See Exhibit C). As of this date, staff has not been successful in attracting any grant funding to finance this project. Although no funding sources have been currently identified, staff believes it is appropriate to continue to pursue a comprehensive solution that addresses drainage, erosion, water quality, and environmental habitat (ESHA) issues. If desired by City Council, staff would propose that a full service professional engineering firm be retained to develop plans and specifications and assist the City in securing appropriate permits for a proposed CIP that would address these ongoing issues in Morning Canyon. Submitted by: Stel5hen. . �adum P blic'Works Director Attachments: Draft Conceptual Report Meeting Announcement • Status Report, 12/24/02 0 MORNING CANYON STABILIZATION, HYDROLOGIC AND HYDRAULIC ANALYSES Prepared for: City of Newport Beach 3300 Newport Boulevard Newport Beach, CA 92658 Prepared by: Rivertech Inc. 23332 Mill Creek Drive Suite 210 Laguna Hills, California 92653 wwwAvertec. com R/VERTECH :-i August 2002 TABLE OF CONTENTS SUBJECT DESCRIPTION PAGE NO. INTRODUCTION 4 DESCRIPTION OF THE STUDY REACH 5 DEVELOPMENT OF CONCEPT PLANS, HYDROLOGIC AND HYDRAULIC ANALYSIS 6 APPROXIMATE COST OF STABILIZERS 7 REFERENCES 8 LIST OF PHOTOGRAPHS PHOTOGRAPH DESCRIPTION OF AFTER NUMBER PHOTOGRAPH PAGE 1 VIEW OF 42" STORM DRAIN AND OUTLET STRUCTURE 5 2 N71EW OF MORNING CANYON FROM PELICAN HILL 5 GOLF COURSE 3 AT MANY LOCATIONS MORNING CANYON IS INFESTED 5 WITH GIANT REED 4 VIEW OF HEADCUTTING DOWNSTREAM OF OUTLET 5 STRUCTURE • 5 VIEW OF HEADCUTTING DOWNSTREAM OF BASIN P3 5 0 • u LIST OF FIGURES FIGURE NO. 1 2 3 2 5 6 7 8 9 10 11 12 13 DESCRIPTION AFTER PAGE REGIONAL LOCATION MAP VICINITY MAP AND LAND USE DEFINITION SKETCH OF HEADCUTTING AND IT'S UPSTREAM PROGRESS TYPICAL ISOMETRIC VIEW OF STABILIZERS ALONG MORNING CANYON SCHEMATIC PROFILE OF MORNING CREEK USING GABION CHOKE AND STABILIZERS PLAN VIEW OF A TYPICAL STABILIZER SECTION A -A OF A TYPICAL STABILIZER SECTION B -B OF A TYPICAL STABILIZER SECTION C -C OF A TYPICAL STABILIZER HYDRAULIC PROFILES OF THE STUDY FOR EXISTING CONDITION HYDRAULIC PROFILES OF THE STUDY FOR ULTIMATE CONDITION PLAN OF THE STUDY REACH AND LOCATIONS OF STABILIZERS ARIAL VIEW OF MORNING CANYON 2 4 5 5 C 3 6 6 6 6 6 3 3 C LIST OF APPENDICES APPENDIX DESCRIPTION OF APPENDIX NUMBER I HYDROLOGIC ANALYSIS II HYDRAULIC ANALYSIS L� • . :1 - : ' .. - °' 3 i i INTRODUCTION . f i The primary purpose of this report is to present a conceptual plan to stabilize Morning Canyon upstream of the Pacific Coast Highway (PCH). In order to develop approximate dimensions and planning level estimates of construction costs hydrologic and hydraulic analyses were performed. Figure 1 shows the Regional Location of the Study Reach. Historically, prior to any interference by man the watersheds draining to streams in the Newport Coast area were covered with the coastal sage scrub. Morning Canyon being one of those streams had adjusted itself to the hydrologic conditions corresponding to that land cover. Prior to the development of Newport Coast during the 1900s the watersheds have been used for grazing and agriculture. The use of these watersheds for grazing had removed much of the natural vegetation. As a result, sediment yield from those watersheds had been significantly increased. This in turn had resulted into aggradation and sediment deposits above natural levels along the bed of streams in the area. • After the development of Newport Coast, which stabilized the watersheds, sediment yield into Morning Canyon was reduced. Based on the study by Moffatt & Nichol, Engineers (Ref 1) the average annual sand yield from the watershed of Morning Canyon was reduced by a factor of 50% for post - developed condition as compared to pre - developed condition. Consistent with this reduction in sediment yield during the planning of Newport Coast Rivertech Inc. designed special detention basins that allowed the bypass of coarse sediment while reducing the peak discharges significantly (Ref 1 and Ref 2). In 1996, in a study performed by John M. Tettemer & Associates, Ltd. (Ref 4) it was shown that the streams in Morning Canyon and Buck Gully performed similar to other natural streams within the Newport Coast area. As a result of the modifications within the watershed of Morning Canyon the stream initiated its process to attain its natural thalweg (low flow path) that had existed prior to 1900s. In addition, structural modifications by the residents along Morning Canyon destabilized the stream. One must understand that with or without development in the watershed of Morning Canyon, with or withoul structural modifications along Morning Canyon by the adjacent residents; erosion and deposition processes along an alluvial stream are rules, not exceptions. Therefore, if man desires to maintain riparian and natural characteristics of Morning Canyon he must expect such processes to occur and be prepared to periodically take preventive and corrective measures. The intent of this report is to identify those corrective and preventive measures. • ORANGE COUNTY Riverside Fwy 91 NORTH Orange Fwy. 57 Garden Newport - Grove f— Costa Mesa Fwy 22 Fwy 55 Toll Road 241 Santa Ana Fwy 5 r San Diego Fwy 405 Toll Road 133 Ortega Hwy Pacific Coast Hwy s �.r F-+ z Morning Canyo Toll Road 0 73 CJ` Laguna Canyon Rd 133 r� A z CALIFORNIA ORANGE COUNTY — RIVERTECH Regional Location Map Figure INC 1 z 31moli • ASIl QNF" I MV dVhT AIINIJIA N a 0 O y � U O 2 m 00 O d F U U S O o W z 0 0 4 K O F6 O N O ❑ p aC z 6� ° r°a° w 3 z a x �w x 0 F o C Cc z ww 2 w� a i I Z z aY O 26 a n� nm � F � Q w z K z m_ AE- N va �NiQ ►0; N33ii0 SO-w8i SOl • • DN/ HORIUR IR/ 0 ^J W .. C \ 0 ^J W \ C N � 3 N o z H �oz o U, pund APn7S • DESCRIPTION OF THE STUDY REACH Figure 2a shows the vicinity map of Morning Canyon and the land use in its watershed. Watershed 6 drains to Basin PI while Watershed 7 drains to Basin P3. Drainage areas to Basins P 1 and P3 are 100 acres and 208 acres respectively. Land use in Watershed 7 is medium/low residential and golf course while Watershed 6 has a combination of high, medium/low, natural, tourist/commercial and golf course land uses. As can be noted in Figure 2B Detention Basin P3 drains directly to Morning Canyon at concentration point "A ". At concentration point `B" Detention Basin P 1 drains to an alluvial channel having a length of 620 feet which drains into an 860 feet long 51 -inch reinforced concrete pipe (RCP). The 51 -inch RCP then drains into an 80 feet long 42 -inch RCP which in turn discharges to Morning Canyon at concentration point "C ". Between concentration points `B" and "C" an additional residential area of 26.4 acres drains to Morning Canyon. • As shown in Figure 2B, the Study Reach extends from the outlet of Detention Basin P3 to the PCH. Photograph 1 shows the outlet of the 42 -inch storm drain and its energy dissipator. The 42 -inch storm drain located along a very steep slope discharges with high kinetic energy into the "box type" energy dissipator. After making a 90- degree bend, flow then discharges into Morning Canyon alluvial channel. Photograph 2 shows the view of Morning Canyon from the Pelican Hill Golf Course while Photograph 3 depicts the infestation of Morning Canyon by the Giant Reed. The majority of the Study Reach is covered with heavy growth of vegetation and Giant Reed. Along the Study Reach several "headcuttings" are visible. Headcutting is a sudden drop in streambed generally associated with degrading streams. This feature has a scour hole at the bottom of the drop, which deepens during succeeding storms. As the depth of scour hole increases support for the face of the drop or headcutting is eliminated. As a result, the headcutting progresses upstream with concomitant increase in height. Figure 3 shows the mechanics and upstream progress of a typical headcutting along an alluvial stream. Along Morning Canyon channel the two most significant headcuttings are visible at about 50 feet downstream of the outlet structure shown in Photograph 1 and at about 100 feet downstream of the Basin P3 outlet. These two headcuttings are shown in Photographs 4 and 5 respectively. The scour hole having stagnant body of water is shown in the lower portion of Photograph 4. • 0 1u1 U M r" U W L L U R 3 b k LA R � � d x r p d r U O OR C$ p Y Y Y 2 w x LL x x 7 o „ „ U CIO O O pp i i i m W Q Q 1D O x L O U CIO .............. ....... L4 ` 0 ` a U C U R i r •- x V . V 1 A P ' �_'•' .,rte,. •� . C• ?:.` �` :;,4 .+fir �, yt,� sn w I !k;-,, 7 • Iv t ' - -7r. RIVER TECH View of 42" Storm Drain and Photograph %��� � iivc Outlet Structure 1 t y_• A P ' �_'•' .,rte,. •� . C• ?:.` �` :;,4 .+fir �, yt,� sn w I !k;-,, 7 • Iv t ' - -7r. RIVER TECH View of 42" Storm Drain and Photograph %��� � iivc Outlet Structure 1 .I� i iq j- a a 0 0 r C 0 U :r U Q/ U O U L w � o U w � o U C7 on C 0 w 0 .,i .. Jc ... V : P� 4Nkl- . 153P ,..-a J .r A: 4 I :4 ZP ^.•_ X Ilk It O O aw Fn I • 1 .r.. . RIVERTECH I View of Headcutting Do- wnstream I Photograph :, 7 INC of Outlet Structure 4 6 may' 4L IL <14 Sir 41 0 i I DEVELOPMENT OF CONCEPT PLANS, HYDROLOGIC AND j HYDRAULIC ANALYSES i i = After completing the reconnaissance level surveys and field observations it was determined that the best alternative to stabilize the stream along Morning Canyon is to create drops as nature is trying to establish and to chokcc&,flow in a controlled manner. Figures 4 through 9 show this concept. As can be depicted in Figure the chokes and stabilizers are constructed along the stream with milder streambed slope as�co`rfipared to existing. In this level of concept planning the ultimate stable slope is estimated to be 1 percent. Detailed cross - section survey, refined hydraulic analysis and sediment transportation analysis are required to determine the final ultimate stable slope. It should be mentioned that as the stream adjusts its existing steep slope to the ultimate mild slope, periodic maintenance between stabilizers along the banks would be required. These may vary from placing tetrahedrons to constructing "barbs" or "bendway weirs" along the banks of the stream. • Based on the County of Orange Hydrology Manual and AES computer program hydrologic analysis was performed to calculate peak discharges along the Study Reach. Appendix I include the details of the analysis while Table 1 summarizes the results of the analysis. TABLE 1 PEAK DISCHARGES IN CF'S ALONG THE STUDY REACH RETUILN PERIOD REACH "AC " (See Figure 2) REACH " CD <` (See Figure 2) 2 Years 46 157 10 Years 65 216 25 Years 89 262 100 Years 142 365 Based on the above discharges hydraulic analysis was performed for existing and ultimate conditions using the U.S. Army Corps of Engineers' HEC -RAS Model. Results of the analysis are appended in Appendix 11. Figures 10 and 1 1 show the hydraulic profiles of the Existing and Ultimate Conditions. As can be seen in Figure 11 four stabilizers at Stations 11 +16, 8 +46, 7 +76 and 6 +11 are recommended for the Ultimate Condition, Figure 12 shows the locations of the four stabilizers, topography, 100 -year floodplain, lot lines and 25 -feet easements along Morning Canyon. Figure 13 also shows the lot lines and the 25 -feet easement along Morning Canyon. / & { . A � 4 J \ 4 a3 > \ IM 3 Ln Ln [ RLL / \ # / \ °�) /9 \ o f w© \ 2= \\ \\ �� 8 ®7En cA � ® ®t q/ \f t �:. 7 \ } z Q , / \ L� j 1> ` \ . / k \) 2 \ 0 0 0 I r F k 1 FOOT GABION MATTRESS RIVERTECH Section C -C of a Typical Figure s IMC Stabilizer 9 • • • El— w. lh7 c� 8 4•' -1� I \�• i •�� II �l 1 N y v` ���.m I r 776 i .h 846 P [ 1.. V i �Il ll 11 J1 1 111 �l 4p n 0 94, i2 0 �1 \ 1 7 t \ O ; \ \\ x111 Y. \ 1 i I ^` R)VERTECH Hydraulic Profiles of the Study Reach for Existing Condition Figure ��rp (Sheet 1 of 2) 10 • • • ��l.MMFy� 'J,ait 4 . '� - F_. ' z • • • I • • Zl (Z do I7aagS) ONI or amS13 slazillqujSjo suo/ uao l puu yauag Spu7S a97 }o uutd HORUNRAIN 5AA 5p,0 L G C O G � edac i za�i� �owio aa�ao i 4 s 4 9 1. ` 1_wI� /II�EII a.5' ri U �% r \ �. 0" I 8+46 SIllRCP 6ti% }Y. i 4. �. • • \J a�ZI I (Z to ZiaagS) ONI a vaz!I!gu7S to sno!IUao7 puu gauaU Spu1S ag7 )o uuld HAAIN �1��. ;bar 'w � sr, • itX r;,�i `�, / - ; � � t g i � y 14(v a /� is- + �pV, Vii: , r r:.• - -�_ ,.�� J'Z' � \� j r \ dll s E APPROXIMATE COSTS OF STABILIZERS i This section provides planning level cost estimates for constructing the four stabilizers. In addition to constructing the stabilizers, construction access ramps or road will be required. Two alternatives are envisioned at this time. The first one is to construct an access road along Morning Canyon starting from the intersection of Rockford Road and Surrey Road (See Figure 13) and terminating at PCH. This alternative not only will be costly, it may not be viable from the perspectives of biological constraints and permit processing. The second alternative is to construct four ramps through the properties adjacent to Morning Canyon at locations where the stabilizers will be constructed. Assuming that this alternative is acceptable to the City of Newport Beach and homeowners associations for Corona Highlands and Cameo Shores, Rivertech Inc. estimates the cost of each ramp at $5,000. Estimated Construction Cost Per Stabilizer • Estimated volume of Gabion baskets = 1600 Cu. Ft. Estimated cost of Gabion structure = 1600 Cu. Ft X $35 / Cu. Ft. _ Excavation, backfill, and landscape = Access ramp = Eradication of Giant Reed = Total estimated cost= Contingencies at 30 %= Total cost per stabilizer = Total cost of four stabilizers = • $56,000 $15,000 $5,000 $1,000 $77,000 $23,000 $100,000 $400,000 • I . Moffatt & Nichol, Engineers. Letter report submitted to the City of Newport Beach, Dated April 14, 1992. Subject: Morning Canyon Sedimentation (NINE 2450 -08) 2. Master Drainage and Runoff Management Plan (MDRM) prepared for the Coastal Community Builders (A Division of The Irvine Company). Prepared by Rivertech Inc. September 1989. 3. Hydraulic Design of Detention Basins, Major Storm Drains, Riparian Corridors and Water Quality Monitoring Program at the Golf Course. Prepared for the Coastal Community Builders (A Division of The Irvine Company). Prepared by Rivertech Inc. May 1990. 4. Report on Storm Runoff Conditions in Buck Gully and Morning Canyon. Prepared by John M. Tettemer & Associates, Ltd. Prepared for the City of Newport Beach. February 1996. • • CI1 _)� OF NEWPORT BEACH PUBLIC WORKS DEPARTMENT 3300 NEWPORT BLVD. P.O. BOX 1768, NEWPORT BEACH, CA 92658 -8915 (949)644 -3311 STABILIZATION OF UPPER MORNING CANYON CHANNEL To Upper Morning Canyon Channel Property Owners: On September 9, 2002 at 6 pm, there will be a meeting in City Council Chambers to discuss options for the stabilization of Upper Morning Canyon Channel. The City has hired a consultant to prepare a preliminary study of Morning Canyon Channel and provide recommendations to stabilize the channel. Additionally, City staff have met with some property owners to review the drainage problems in the channel. A summary of this preliminary research along with some of the study results is summarized below. What is happening to Morning Canyon Channel? Here is a shorthand history of what's been going on in the channel over the past fifty • years based on information obtained from property owners and consultant reports. The core of the problem began in the late 50's with the grading of the Cameo Highlands tract that included the filling of `Surrey' Canyon and the creation of a high slope on the east bank of Morning Canyon Channel. Any slope grading and compaction would have been performed in accordance with the standards in force at that time. Over the next 30 years, grazing operations and removal of natural vegetation upstream stirred up the soil sufficiently such that storm runoff washed sediment into Morning Canyon Channel. This surplus of material allowed several feet of sediment to accumulate in the bottom and created the pleasant, broadly rounded channel that everyone is familiar with in the 1980's. However, during that time, five or six slope failures occurred on the east side of the channel. This quasi - stable state within the channel was changed with the construction of the golf course. This upstream area was graded and then lay fallow for several years. Pictures of flood flows coming off the denuded slopes in 1992 show large amounts of muddy water flowing down the channel, a dramatic change from the previous years. When the golf course construction recommenced and was finished, detention basins were operating. The detention basins were designed per approved regulatory standards. While these detention basins reduced the peak flows from large storms, the duration of storm flows through the channel increased, and perhaps more importantly, the sediment • transported into the channel from the hillside was reduced. Why is the loss of sediment supply important? • Morning Canyon Channel is a hydraulically steep channel causing storm water runoff to move at sufficiently high speed to erode the channel bottom. Over time, this erosion creates deep incisions in the channel bottom. Prior to the 1990s, this naturally occurring erosive condition was counteracted in Morning Canyon Channel by sediment washing into the channel from the upstream grazing area. With the construction of the golf course, the replenishing supply of sediment was reduced and erosive forces created an incision in the channel 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 channel used to be dry except after rainstorms. Now there is a continuous flow of water in the channel all through the dry season. What's going on? This nuisance water is coming from over - irrigation and washing (e.g. car and pavement washing) activities from homes in Newport Coast. There is also irrigation runoff from the golf course. Some of the water is originating in Cameo Highlands. Is this low flow, nuisance water causing erosion? No, the velocities are too low to cause any significant erosion. Only storms provide • enough water to create high velocity flows. Is this nuisance runoff doing any harm at all? This runoff does bring pollutants, fertilizer and pesticide residues into the channel. The fertilizer and pesticide residues may have accelerated the vegetative growth in the channel. Can we get rid of it? Yes. The Irvine Ranch Water District has volunteered to identify water usage from Newport Coast homes and can assist these homeowners to reduce runoff. The City's goal would be to significantly reduce these nuisance flows by next year. What about the City's clearing activities in the 1980's? The City on at least two occasions cleared the bottom of the canyon of foliage and debns to prevent materials from being washed down to Coast Highway and potentially blocking the culvert under the highway. It has been suggested by one property owner that clearing the natural vegetation allowed the anmdo to more readily take root in the channel. It should be noted that arundo also invaded Buck Gully in the late 80's where clearing • activities were not occurring. • The anmdo 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 channel pushes flood flows to the edge of the channel along the toe of slope. Scour areas form along the toe of slope that will eventually undermine the slope and cause it to fail. Are some properties more susceptible to damage? Yes. The east side of the channel, which was constructed on fill, is more susceptible to erosion. However the degraded and choked condition of the channel puts all properties at risk for future erosion. Okay, what's the solution? In Morning Canyon Channel, the consultant has recommended constructing four strategically located stabilizers. The stabilizers allow low flows to pass uninhibited through the notch in the structure. During flood flows, the runoff will be partially backed up which will reduce stream velocities and the resulting erosion. These stabilizers are created from large rock and would accommodate an approximate five -foot elevation difference. (Please see the attached concept drawing.) Rock aprons along the channel bottom would extend about 50 feet upstream and downstream of the stabilizers. The aprons would line the channel bottom and come up 5 or 6 feet on each slope. • Prior to the installation of the rock structures, the channel bottom would have to be cleared of the arundo, dense vegetation and other encroachments. Some grading would occur to smooth our channel irregularities. However, the channel incision would remain and the low flow notch in the rock structure would conform to the incision elevation. Why go to all the trouble of building these channel - stabilizing structures? Why not clear the channel of the arundo and just regrade the channel? That's an option, but only as a short-term solution. This channel is hydraulically steep and the erosive velocity of storm flows will strip sediment from the streambed and recreate the incisions in the channel bottom. Because there is no supplemental source of sediment, these incisions will eventually undermine the channel slopes. Shouldn't the upstream development be responsible for fixing this problem? Drainage law in California is evolving. Under the current `common sense' philosophy, upstream developers have to employ reasonable measure to mitigate downstream effects. Downstream properties must accept reasonable amount of storm water runoff, including increases in flow. All of the upstream developments were designed and approved per drainage and grading standards by the County of Orange. • There are many parameters that have contributed to the degradation of Morning Canyon Channel of which the upstream development is just one factor. We think only a cooperative approach with all the property owners within the watershed can have any • practical success. The City has a drainage easement in the channel and they need to maintain it. This easement was created during development of Cameo Highlands to allow the City to construct a future storm drain system if future development warranted an underground piping system. Upstream development has been constructed in a manner as not to need such a system. The City is considering a future relinquishment of the easement since it is not needed. There is no agreement with the City to maintain the channel as the drainage course is on private property. What specific activities can the City participate in for the remediafion of the channel? There are many obstacles to solving the problem. The City believes that the one approach that can reasonably be expected to succeed is a partnership between the City and the property owners. A partnership between the City and property owners can help get better assistance from the Corps of Engineers, Coastal Commission, Regional Water Quality Control Board, Irvine Company, and County of Orange. As a partner is stabilizing the canyon, the City could participate in the following tasks. • • The City has hired a consultant to study the channel and provide preliminary engineering and biological recommendations. • The City may enlarge the scope of work for the consultant to provide geological and survey data to allow more detailed preliminary engineering drawings to be prepared. • The City can take the lead in preparing applications for permits from the Coastal Commission, Corps of Engineers, Fish and Game, and the Regional Water Quality Control Board. • The City might engage an engineer to prepare final construction documents for the channel remediation. • The City can look for opportunities to get water - quality grant funding to support this proj ect. • The City can take the lead in working with the upstream development to see if there is common ground to support the project. How much will it cost? Preliminary cost estimates place the cost between $500,000 to $1,000,000 for the construction of the proposed concept. At this time, there is no estimate for annual channel maintenance. • • R'ho would be responsible for paying for such a project? Since the project largely benefits private property, it would be appropriate for the majority of the costs to be bome among the property owners. The level of City participation would be determined by the City Council. An appropriate funding mechanism may be an assessment district. How is an assessment district formed for construction of channel improvements and for •channel maintenance? A petition is circulated requesting formation of an assessment district and signatures are obtained from 60 percent of the homeowners. If the Council approves, the City advances money to hire an assessment district consultant and fund an engineering report. After City review of the proposed assessment district and Council approval, ballots go out and 51% of the returned ballots must be in favor of the district. Bonds are sold and levies assessed to each property. Property owners would have the option of paying cash up front or spreading the cost over 15 to 30 years in an annual payment on the property tax bill. What will be discussed at the September 9th meeting? • In the past month, the City has been briefed by 13 property owners on the complex drainage history of Morning Canyon Channel. The problems are complicated and unique to the city. A detailed conceptual solution has been proposed by the consultant to demonstrate one reasonable option. It is envisioned that the September 9th meeting is an opportunity for City staff to hear additional information and other possible solutions as well as answer questions about the proposed solution. The meeting agenda is as follows: I. Short introduction of some key City staff (5 minutes) H. Quick Overview of the City proposed solution (10 minutes) III. Open the floor for discussions and questions (60 minutes) IV. Summary of action items (10 minutes) At the end of the meeting, the City hopes to have action items for both City staff and property owners so that at the next meeting (in October) planning decisions can be made. Prepared by Bob Stein September 4, 2002 • :+• . �' .. . +. �; \mac •`ltC� r � �P• +7�t� � ir�;ic3 -' - -": 1. .". :�i'91. .,. ... _ sue..`• ^. �+•' ir lz gal iw ', yam:, CIT-i OF NEWPORT BEACH PUBLIC WORKS DEPARTMENT 3300 NEWPORT BLVD. P.O. BOX 1768, NEWPORT BEACH, CA 92658 -8915 (949)644 -3311 December 24, 2002 Upper Morning Canyon Channel Studies To Upper Morning Canyon Channel Property Owners: I wanted to update you on the status of the City study of the causes of the erosion in Morning Canyon Channel. We appreciate the fact that many Morning Canyon property owners have expressed a willingness to cooperate with the City in the process of evaluating the reasons for channel erosion and identifying measures designed to help minimize erosion while potentially enhancing the riparian area. The City recently conducted two site visits with representatives from four Federal and State Agencies: the Army Corps of Engineers, the Regional Water Quality • Control Board (RWQCB), the California Coastal Commission and State of California Department of Fish and Game. All four agencies have jurisdictional authority in Morning Canyon Channel and their approval would be required for any project to move forward. Agency representatives provided us with comments on issues that would need to be addressed during the permitting process for any project. A site visit was also conducted with two representatives from the Irvine Ranch Water District (IRWD). IRWD staff observed nuisance flows emanating from the golf course at the head of Morning Canyon channel, as well as from the 42 -inch reinforced concrete pipe outlet structure in Morning Canyon Channel located between 621 and 627 Rockford Road. IRWD will provide the City with water usage records and has expressed a willingness to provide any assistance they can relative to channel erosion. , Rivertech, the City's engineering consultant, has completed its draft report on the reasons for channel erosion and the options available to reduce erosion. The report concludes that channel erosion is attributable to a reduction in sediment transported into the channel and the relatively steep slope of the channel. The report suggests that the most feasible way to reduce erosion is the installation of drop structures to flatten the slope of the channel and reduce velocities. Rivertech has determined that additional studies must be conducted, and plans • prepared, before a project could be submitted to Federal and State agencies for approval. Rivertech's preliminary cost estimate to install the drop structures and enhance the riparian habitat is approximately $1,000,000, inclusive of a 30% • contingency. The City is pursuing possible solutions to channel erosion as a representative of the property owners along Morning Canyon and not as a party responsible for any channel erosion or related matter. We intend to discuss the Rivertech report with Coastal Commission staff and possibly other agencies to determine if they would be supportive of the concept. However, the City has not committed any funds for further studies and construction of any project will require the support and participation of Morning Canyon property owners. Each Morning Canyon property owner is responsible for protecting their own property and should periodically inspect their property for signs of erosion or slope damage. If signs of erosion or slope damage are present on your property, you are encouraged to contact a soils engineer and /or other professionals to evaluate the condition and submit proposed corrective measures to the City Building Department. The City Building Department will expedite their review and approval of plans designed to correct or prevent erosion or slope damage. Please feel free to call Bob Stein (949- 644 -3322) with your comments and questions. Sincerely, Stephe G. Badum Publ' Works Director • • Morning Canyon Status Report June 24, 2003 History • Watershed area was first used in the 1900's for grazing and agriculture. • Various developments have been added over time. Corona Highlands,1949; Cameo Highlands,1960; and Newport Coast, 1990 - present. • Cameo Highlands Tract constructed 15 ", 18 "and 42" diameter storm drains. • Golf Course constructed detention basin at the head of the canyon. Issues • Drainage • Slope Stability and Erosion • Water Quality • Environmental Sensitive Habitat Areas (ESHA) z Drainage Issue ■ Morning Canyon is the natural drainage course to the ocean for a 335 acre watershed. ■ The watershed has been developed in accordance with rules & regulations in place at the time of development. ■ 22' drainage easement dedicated to the City for future subsurface storm drain as a part of the Cameo Highlands development. Since upland areas were developed as a golf course with detention facilities, the storm drain was not built. Slope Stability and Erosion • Some property owners have actively and passively modified the natural drainage course. • Active modifications thru grading, hardscape, and landscape planting. • Passive modification thru lack of maintenance and uncontrolled growth of non - native plants (Arundo /Giant Reed). • Cameo Highlands was developed with steeper slopes (1.5:1) than currently allowed by Building Code. ■ Development has reduced the amount of sediment in stormwater flows which causes erosion. Water Quality ■ Dry weather flows (urban runoff) have steadily increased as upstream development occurs. ■ Overwatering and lack of water conservation efforts transport pollutants thru Canyon to the Ocean ESHAs • Morning Canyon is identified as an ESHA within the City's Draft Local Coast Plan • Increases in urban runoff have promoted uncontrolled growth of non - native plants such as Arundo /Giant Reed which choke out native plant species. • Some property owners have modified the natural habitat by planting ornamental landscaping, terracing, and channelizing low flows. E What's been done so far? • April 2002 — City Council authorizes a conceptual investigation, by Rivertech, Inc.. • September 2002 — Homeowners meeting to discuss the draft of the conceptual report. • December 2002 — City staff updates homeowners and recommends that affected homeowners address their individual erosion issues independently while the City pursues exploration of a comprehensive long term solution. e. t • � c E What's Next • The Rivertech conceptual report has provided the City with the basis for a long term comprehensive solution. • If desired by City Council, staff would propose that a full service professional engineering firm be retained to develop plans and specifications and assist the City in securing appropriate permits for a proposed CIP that would address these ongoing drainage, erosion, water quality, & environmental habitat (ESHA) issues in Morning Canyon.