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HomeMy WebLinkAboutAGENDA REPORT 1997 0618 CC REG ITEM 09EITEM�� �• • l�lvl CITY OF MOORPAM CALIFORM , AGENDA RE PORT City of Co ncil Meeting C I T Y O Y' &, 199 7 ACTION: terJ 7X TO: The Honorable City Council FROM: Kenneth C. Gilbert, Director of Publ DATE: June 6, 1997 (Council Meeting 6- 18 -97) SUBJECT: Consider Approval of the Preferred Alternative Design Concept for the Construction of Certain Drainage Improvements Required for the Gabbert Canyon and Walnut Canyon Watersheds, and Authorization for the City Manager to Proceed, if Necessary, with Efforts to Develop a Financing Program for Said Project This report 1) presents for discussion a study pertaining to needed regional drainage facility improvements; 2) requests approval of the preferred Alternative Design Concept for those needed facilities; and, 3) requests authorization for the City Manager to proceed, if necessary, with efforts which may be required to facilitate the development of a financing program for the construction of those improvements. A. Study In response to concerns raised by City staff and the owners of certain vacant properties being considered for development, the Ventura County Flood Control District (VCFCD) retained the firm of Robert Bein, William Frost & Associates (RBF), to prepare a report assessing the existing conditions of, and the future needs for, storm drain facilities serving the Gabbert Canyon and the Walnut Canyon watersheds. That report was recently completed and made available to the public. A copy of the Study has been distributed to the City Council under separate cover. Certain excerpts from the Study are attached hereto and listed as follows: Exhibit A: Executive Summary; Exhibit B: a map showing the combined watersheds for both Gabbert Canyon and Walnut Canyon; Exhibit C: a copy of Section 12 defining the recommended Design Alternative [Alternate B]; and, Exhibit D: a copy of Section 11 pertaining to Financing. Exhibit E: (Partial) List of Stakeholders gabbert 0000 Gabbert Canyon / Walnut Canyon Study June 18, 1997 Page 2 B. Existing Conditions It was known before the study was commissioned, that the existing drainage facilities for the subject watersheds were inadequate. These drainage facility deficiencies pose a number of rather significant problems, including the following: 1. Many properties in and adjacent to the lower reaches of these watersheds are subject to inundation during significant storm events. These properties are shown on the Federal Flood Insurance Rate Maps (FIRM) as being in flood prone areas. 2. The lack of a definite plan for the resolution of these problems has made it difficult to proceed with the development of many of these properties. The impact of any proposed property development, upon the design, nature and cost of future needed storm drain facilities, has been unknown. The purpose and objectives of the RBF Study was to clearly document the extent of the deficiencies and to recommend alternative design concepts to resolve those deficiencies. C. Improvement Techniques The design alternatives which have been developed basically utilize three approaches to construct improvements to the flood control handling capacity of the facilities serving these watersheds. Those techniques are generally described as follows: 1. Channel Improvement: The modification and /or replacement of existing facilities to increase capacity. 2. Detention: The construction of detention basins to hold rather than convey peak storm flows. 3. Diversion: The construction on new facilities along new alignments to divert storm flows away from existing facilities in order to render those facilities adequate. Note: In addition, the nature of proposed in many of the Alternatives allows or provides segments of the existing flood gabbert the modifications Conceptual Design for the removal of control facilities. Gabbert Canyon / Walnut Canyon Study June 18, 1997 Page 3 D. Design Alternatives Over seventy (70) separate alternative design concepts were considered by RBF. All of those alternatives utilized various combinations of the three design approaches described above. Obviously, most of the tentative design concepts were discarded for a variety of reasons (feasibility, costs, etc.). The Study selected eight separate design alternatives which were developed fully for consideration. Those options, which are briefly described in Exhibit 'A' attached, are identified as Alternates A through H. In should be noted that all of the Alternatives discussed are only conceptual in nature. The precise designs for the proposed improvements have not yet been established. The exact shape, size, and location of many of the improvements proposed will be determined as a function of the design process. Once the designs are determined, rights -of -way required for the selected final design will be acquired. E. Preferred Alternative The recommended option is design Alternate B. This option is described in more detail in Exhibit 'C' attached. As you can see from Table E -2 in Exhibit 'A', the range of estimated costs for all of the Alternatives is within ten percent (10 %). As a result, cost was not a determining factor in arriving at the recommended Alternate. Alternate B was selected because it is believed to be the most reasonable approach offering a lesser degree of adverse impacts upon affected properties. F. Shasta Diversion One element of the improvements proposed by Alternate B is the construction of twelve feet wide by five feet deep (12' x 51) covered box culvert to extend from the existing Walnut Canyon box culvert north of the railroad tracks at a point just west of Sierra Avenue, southerly along the west side of the rear of the residential properties located on the west side of Shasta Avenue [actual construction would occur along the easterly edge of the industrial property) and then southerly across the vacant property south of Los Angeles Avenue to the Arroyo Simi. The purpose of this facility is to divert a maximum flow of 300 cfs (cubic feet per second) to the south, rendering the existing down stream Walnut Canyon box culvert better able to handle storm flows from sources to the west. That portion of the new facility south of Los Angeles Avenue would replace existing VCFCD storm drains now located on the vacant property southwest of the intersection of Los Angeles Avenue and Liberty Bell Road. gabbert Qwos? Gabbert Canyon / Walnut Canyon Study June 18, 1997 Page 4 G. Pacific Communities Builder, Inc. [Tract 5053 Pacific Communioties Builder, inc. is now in the process of developing plans for the construction of a residential development on the above mentioned vacant property located southwest of Los Angeles Avenue and Liberty Bell Road [Tract 5053]. City staff, the developer and VCFCD have had meetings to discuss the feasibility of including in those proposed development plans, the construction of the southerly reach of the above described Shasta diversion box culvert. It should be noted that this property is not in the subject watersheds and is, therefore, not obligated to fund any part of the cost for these improvements. Regardless of that fact, the developer and VCFCD are in the process of developing a financing mechanism which will allow this construction to be undertaken by the developer on behalf of the VCFCD. It is the goal of all concerned that these facilities be constructed as a part of the infrastructure improvements to be constructed for that residential project. :T9• . on the morning of June 5, 1997, a meeting was held at the Moorpark Community Center to discuss the subject report. Although City staff hosted the meeting, the meeting was actually conducted by representatives of the VCFCD and its consultant (RBF). A number of owners of properties affected by the subject study and its recommendations were invited to this meeting. Lists of those invited and those in attendance are attached as Exhibit 'E.' The purpose of the meeting was to allow the VCFCD and its consultant (RBF) to explain the purpose, objectives, methodology, findings, conclusions and, recommendations set forth in the Study. Those noted on the above mentioned notified in writting that this discussed by the City Council on I. Financing Plan lists (plus others) have been matter is scheduled to be June 18th. Attached as Exhibit ' D' is a copy of Section 11 of the Study pertaining to financing. This discussion generally describes the options available to finance the construction of these facilities. In the opinion of staff, it will be necessary to retain the services of a consultant to "flesh -out" these and other possible financing options. It is also the view of staff that the key to success will be to enlist and involve the owners of a number of potentially affected properties. Those affected gabbert QQ ()® .3 3 Gabbert Canyon / Walnut Canyon Study June 18, 1997 Page 5 properties may include some or all of the following: a) properties contributing the storm flows; b) properties which will be assessed for the proposed improvements; and c) properties which will benefitted by the proposed improvements. J. VCFCD Project The existing and proposed facilities are and will be owned and maintained by the VCFCD. As shown on Exhibit 'B' the watershed areas extend well beyond the City limits. For these reasons this project must be undertaken and administered by the VCFCD. K. City Participation As you know, a number of properties affected by this project are within the City Limits. Many of those properties are proposed to be developed in the near future. The timely implementation of the subject project is seen to be a high priority of the City. It may, therefore, be desirable for the City to participate with the VCFCD in facilitating and expediting the process required to seek and obtain financing for this project. With the approval of the City Council, it would be the intent of staff to work with the VCFCD to maximize those options. It is proposed that all "out -of- pocket" City costs be funded by the VCFCD. Such costs would be funded from either existing Walnut Canyon / Gabbert Canyon drainage fees now retained by the VCFCD, and /or by future revenues for the proposed project. • ; I r 1:4 , _wob • Staff recommends that the City Council take the following actions: 1. Approval of the selection of design Alternate B for the construction of certain drainage facility improvements for the Gabbert Canyon and Walnut Canyon Watersheds. 2. Authorization for the City Manager to approve certain City efforts to work with the VCFCD on the development of the financing mechanism for the proposed project, provided that all "out -of- pocket" City costs are funded by the VCFCD. gabbert Ww)4 fno3a R ,L -T ' A I Executive Summary l The existing 1.57 miles of Uabbert Canyon Channel and 2.5 miles of Walnut Canyon Channel, located in the City of Moorpark (see Regional Vicinity Map), consist primarily of improved concrete channels which were originally constructed by the Soil Conservation Service (SCS) between 1959 and 1962. These facilities collect and convey storm runoff to the Arroyo Simi from a total tributary watershed drainage of 6.91 square miles. Comparison of the existing hydraulic capacities for the flood control channel sections to the estimated runoff quantities indicates that the channels cannot provide the desired level of flood protection. The limited hydraulic conveyance capacity of the existing channel system results in a flood protection deficiency and is documented on the current Flood Insurance Rate Map (FIRM) for the City of Moorpark. The existing hydraulic capacities can only provide conveyance which correspond to equivalent return periods as low as 5- years, depending upon the location in the channel. This report presents a comprehensive engineering investigation of the hydraulic deficiencies associated with this regional flood control channel system. The primary objective of the study is to develop and evaluate alternative drainage improvements and stormwater management measures that provide: (1) the necessary level of flood protection, (2) compatibility with existing and future landuse, (3) provide the maximum public benefit for least costs, (4) minimize impact to existing facilities, (5) eliminate hydraulic deficiencies, and (6) identify minimum drainage requirements for future development. within the watershed. The intent of this document is to develop a conceptual design for a recommended system of comprehensive stormwater management measures which will provide the watershed planning framework to allow implementation of the regional flood control improvements and continued development within the watershed. Various combinations of individual storage and conveyance oriented flood control elements were integrated into comprehensive system which would provide the required level of flood protection. The conveyance system improvements included: (1) increasing the hydraulic capacity of the existing channel section through either reconstruction to enlarge the section or extending wall heights, (2) construction of a channel diversion systems to split a portion of the flow, (3) removal of hydraulic restrictions, and (4) channel outlet relocation and reconstruction. The conveyance oriented improvements primarily involved modifications to the existing channel sections in order to maximize the overall drainage system capacity with minimum acquisition of additional right -of -way. • The flood control storage alternatives included both on -line and off -line gravity operated stormwater detention basins. The detention basins also incorporated requirements for debris storage. Detention basin configurations and locations were developed to maximize available storage volume while minimizing impact to property. Another primary consideration which limited the size of the flood control storage facilities was to ensure that the detention were not within the jurisdiction of the California Division of Safety of'Dams (DSOD) The proposed correction of the flood control deficiency must be evaluated on a watershed basis through the application of a systematic approach since the various drainage elements have a Gabbert and Walnut Canyon Channels Executive Summary - Flood Control Deficiency Stud) t?S 1 Q0 003 1 Y N-7 combined impact on the channel. The feasibility evaluation resulted in screening the available channel "system" alternatives to a maximum of eight for detailed consideration, from a total of ninety -eight which were developed in the plan formulation. The objective was to optimize the effectiveness of the system through incorporating the existing facilities into the recommended program to the maximum extent possible. The primary components associated with each of the eight channel "system" alternatives are indicated in the Table E.1 - Summary Description of Alternative Channel Systems, All alternatives have some similar required construction elements which include: (1) modification of Gabbert Canyon Debris Basin to provide detention storage, (2) additional detention basins located upstream at the headworks of Walnut Canyon, adjacent to Gabbert Road, and upstream of Casey Road, (3) channel reconstruction for the -1,900 -foot portion of Walnut Canyon Channel downstream of High Street, and (4) all systems require improvement of 2,655- feet Gabbert Canyon Channel between the Walnut Canyon Channel confluence and the existing Gabbert Debris Basin (See Exhibit 1_ Alt. B, for relative locations). In addition to these elements, the alternatives evaluated various combinations of additional detention basins, diversion systems, or relocated channel outlets to the Arroyo Simi Table EA - Summary Description of Alternative Channel Systems Alt. Gabbert Basin Additional Gabbert Walnut Diversion Channel No. Modification Detention Channel Channel Channel Outlet Basins Reaches Reaches System Relocation A Improved to 145 AF 0, 1,2,3 2. 2 300 cfs Gabbert & Detention Storage i V,,,a, == 140 AF I Walnut B Improved to 145 AF 03,2,3 2 300 cfs Walnut Detention Storage (v,,,,;,, — 140 Al 1 C Improved to 145 AF 0,1,23 2,3,4 2 300 cfs None Detention Storage V,),a, — 140 AF I D Improved to 145 Al 0,1,2,5 2, 1 2 None Gabbert & Detention Storage (V,,,,,, = 380 AF) Walnut E Improved to 145 AT 0,1,2,5 2 None Walnut Detention Storage (V a _ 380 AF: F Improved to 145 AF 0, 1,2,5 2.3A 2 None None Detention Storage (V,,,a -_ 380 AF) G Improved to 145 AF 0 1,2,4 2 100 cfs Gabbert & Detention Storage (V,,),a - 295 Al) Walnut H Improved to 145 AT 2 100 cfs Walnut Detention Storage (V,�,a, = 295 AF) Gabbert and Walnut Canyon Channels Flood Control Deficiency .Stud, f- S Executive Summary �t�096 A -3 ■ The total construction costs for each of the alternative drainage "systems" was estimated including land acquisition requirements. These costs provide the primary basis for selection of the r recommended drainage "system', however there are issues related to land acquisition which should be resolved before finalizing selection of the project design alternative. The summary of the various cost elements with and without right -of -way are indicated in the following Table E.2 Summary of ■ Alternative System Construction Costs. It appears, that of all the eight alternatives that Alternative "B" is the least -cost alternative; subject to more detailed estimates. Although the total costs of all alternatives are relatively close to each other for this level of estimates, so costs is not the primary ■ selection criterion. The feasibility of implementation is another important criteria which Alternative "B" ranks very high. If land acquisition costs are not included in the total costs then Alternative "E" becomes the recommended solution since the diversion system is replaced by a diversion detention basin that satisfies the same condition. It is tentatively recommended that Alternative `B" become the selected solution. This alternative includes (1) relocating the Walnut Canyon Channel outlet while continuing to utilize the existing Gabbert Canyon Channel outlet, (2) only improving one channel reach on both Gabbert and Walnut Canyon channels, (3) an underground diversion system adjacent to Shasta Avenue, and (4) an "offline" detention basin parallel to Poindexter Avenue. This alternative has one of the lesser land acquisition requirements and it appears to have a high degree of feasibility while compatible with the adjacent property owners. The configuration of the various recommended channel and watershed facilities :is on Exhibit - Alternative No. B - Schematic Map located on the following page r Table No. E.2 - Summary of Alternative Systems Construction Costs (Cost in thousand of dollars) Alt Detention Basins Divert Chann Walnut Chann Gabbert Chann Outlet Chann Capital Cost Subtotal R/W Total Costs 0,1,2 1 3,4,5 1 Gabbert (Alt. B) A $1,395 $587 $2,508 $2,266 $132 $984 $1,592 $8,827 $1,294 $10,121 *B $1,395 $587 $2,508 $2,266 $132 $298 $1,138 $8,663 $927 $9,590 C $1,395 $587 $2,508 $2,266 $132 $2,787 ---- - - - - -- $10,013 $767 $10,780 D $1,395 $2,252 $2,508 - - - - - - -- $132 $984 $1,592 $8,362 $1,917 $10,280 G $1,395 $2,252 $2,508 -- - - - - -- $132 $298 $1,138 $7,687 $2,405 $10,095 F $1,395 $2,252 $2,508 -- - - - - -- $132 $2,787 --- - - - - -- $8,774 $1,874 $10,648 G $1,395 $1,626 $2,508 $679 $1:32 $984 $1,592 $8,417 $1,564 $9,981 H $1,395 $1,626 $2,508 $679 $13 "Z $298 $1,138 $7,742 $2,056 $9,797 * Recommended alternative Gabbert and Walnut Canyon Chanrxct, Flood Control Defciencv Study l:S -; Executive Summary ®0009'7 T� -M F g C x'r �S A i o � f 'Ci,. t _ � 3 4+ 4 §Zff4 �.y$ €air FQ•�...�+.o.«u.d„ °� ■Q �>1 y� �':`r � - :ne.:fi % Null t l%- � �- !-T Section 12— Recommended Drainage System 12.1 Recommended System C onil?wzenl.� Based upon the costs and feasibilit\ of* implementation, drainage system Alternative "B" is the least -cost alternative and is the recommended alternative. The Rough Order Magnitude (R.O.M.) costs for this system include $8,663,00 in capital construction costs and $927,000 for land acquisition, which totals an estimated R.O.M. cost of $9,590,000. The total right -of -way required for this alternative is approximately 36.7 acres. The different project alternatives were developed ' with the goal of achieving a balance achieving the flood protection goal and providing the most economic solution. The primary system components associated Alternative "B" include: (1) _ reconstruction of Gabbert Debris Basin to provide detention storage through modification of the existing basin and construction of another storage reservoir upstream as well as a separate debris basin at the headworks which will provide 145 acre -feet of flood control storage and 53 acre -feet of debris storage, (2) a 14 acre -foot detention basin at the headworks to the Walnut Canyon Channel, (3) a 20 acre -foot detention basin at the location of an existing reservoir site in a tributary canyon _ at Casey Road, (4) a 36 acre -foot detention basin located in the tributary canyon adjacent to Gabbert Road, (5) constructing a 300 -cfs diversion system from Walnut Canyon Channel along Shasta Avenue to the Arroyo Simi, (6) relocation of the channel outlet for Walnut Canyon Channel along 3,000 feet of earthen trapezoidal channel from Los Angeles Avenue to the Arroyo Simi, (7) reconstruction of the Gabbert Canyon Channel from the debris basin to Los Angeles Avenue, and _ (8) construction of an 70 acre -foot off -line detention basin at the channel diversion location on Walnut Canyon Channel. There is the potential for additional alternatives to be evaluated through refinement of the proposed system. The storage capacity within the Gabbert Canyon detention basin can be further optimized if' a portion of the storage is utilized in the proposed upstream debris basin. Further study of the grading design and relative elevations of the interconnected ponds will assist in refining the hydraulic:, operation for the basin. However, the current analysis provides a conservative evaluation of the system while maximizing the flood control benefits. Recommended Detention Requirements for Future Development Projects .� General recommendations and guidelines are provided for future private development projects to ensure that hydrologic impacts are mitigated. The objective of this program attempts to maintain the existing hydrology can a watershed basis similar to current conditions studied as part of this investigation. The proposed Hitch Ranch development hydrologic impacts have been _ accommodated in the proposed detention basins located on their property. A drainage ordinance should be implemented on a watershed basis which outlines the specific requirements that can be used in planning the development projects. General guidelines include the following: 1. The peak outflow from one or more detention basins within a development project area under fully developed conditions should not exceed 90 percent of the peak flow under the -� existing pre - development conditions for all storm frequencies up to and including the 100 -year frequency and a single storm duration of up to 24- hours. Gabbert and Walnut Canyon Channels Section 12 Flood Control Deficiency Stud 12 -1 Recommended Drainage System fl(lfl►fi��.l C: - Z 2. Follow the requirements outlined by VCFCD for detention basin design. 3. Provide an ungated outlet large enough to permit the complete draining of each basin within 24 hours following a storm 4. Multi -use detention basins are acceptable and encouraged, including meeting the stormwater quality requirements for the project. 5. The regional effect of the local development project detention basin on the watershed must be evaluated to ensure that it does not have a negative effect on downstream flowrates in the main channel. The potential for increasing the peak flowrate at other downstream locations within the watershed must be avoided in the design of the basin. i In addition, it may be appropriate to consider utilizing a 10 -year storm frequency for the design on the on -site storm drain systems within the developments rather than a 50 -year frequency adopted by the City. The 10 -year design frequency is consistent with the current VCFCD guidelines and provides conveyance of the I 0 -year storms but residence are still protected from the 100 -year in order to satisfy FEMA requirements. The effect of changing the design frequency allows the ability JJto take advantage of local storage within the streets during large peak storm events and minimizing the impact on the flood control system with reduced efficiency of the local storm drain. 12.1.1 Operation and Maintenance Implementation of the recommended watershed drainage system improvements will generally result in higher annual maintenance costs primarily associated with the addition of the detention basins. The basins will require the periodic removal of sediment trapped to maintain the require minimum flood control storage volume. Long term development within the upper portions of the watershed will result in reducing the sediment production and in turn lowering some of the maintenance costs. The relocated outlet for Walnut Canyon will require maintenance since the proposed section is an earthen trapezoidal section with rock rip -rap side slopes. The total overall amount of channel does not increase from the length that VCFCD currently maintains, however, detention/debris basins are a significant feature requiring additional maintenance. Additional typical maintenance requirements associated with detention basins include: (1) periodic inspection, (2) weed removal,- (3) debris /sediment removal, (4) rodent control, (5) vector (mosquito abatement) control, (6) outlet structure and spillway inspection or repair for cracking, movement, seepage, and piping, and (7) inspection or repair of embankment and slopes for seepage, piping, and instability. There are a variety of elements which will be incorporated into the flood control improvements to facilitate maintaining and provide access to the drainage facilities. Many of these items are standard features for flood control facilities Top -of -Bank Maintenance Roads: Maintenance roads would follow the standards outlined by VCFCD for their facilities The roads would be either six inches of CMB or 3 inches of asphalt over 6 inches of CMB. d - -. _.. ....... . -- — Gabbert and Walnut Canyon Channels Section 12 Flood Control Deficiency Stu& 12 -2 Recommended Drainage. System VU��o� f t t - 4 A 0100 IN -547 CFS 0100 =476 CFS 0100 OUT -9 CFS CHNL- SECT. STOR, VOL. -70 AC -FT 8 =6' D =5' ml�pw- r `0100 -156 CFS iz EXIST. CHNL. c_cr? p R =10- D =5- 0100 -300 CFS- -.6 CHNL. SECT. 8 =12' D =5 0 .OS ANGELES AVE 0100 =493 CFS —' CHNL SECT. D -5' 9 -14' —OIDO -559 CFS '--{Di00-559 CFS CHNL SECT (EXIST. CHNL. SEC' 9 =8' 0=6' 8 -8 O =5' MODIFIED EXIST. GABBERT ) DETENTION BASIN SITE / 0100 IN -984 CFS i 0100 OUT =514 CFS • %YPASS =902 CFS \ -� -• STOR, VOL =145 AC -FT \ ® SED. VOL =53 AC -FT. f • OI00 IN =301 CF51 0100 =65 GF Jl pp °lay ;;S, OUT STOR. VOL.-FT SED B A AC AC -FT RCP SEC' jVOt� 0100 =354 CFS / EXIST. CHNL. SECT PROPOSED i �� B =7' 0=4' -6' DETENTION BASIN OI OD =902 CFS -- I NO / HNL SECT 6100 IN =536 CFS j 6100 CUT-143 C!� k --0100 -229 CF STOR. VOL= AC -F' SED VOL�3 AC -F' CASEY RD. CHNL. SECT. / PROPOSED DETENTION 8 =10' 0100 =1035 CF CHNL SECT 8 -14' D -4,5' U ss 0100 -1111 (,F<. -- CANYON CHNL, SECT B =16.5' `01 p0 -56t CFS D -6' EXIST, CHNL SE" PIER=S* 0100 -1035 CF ' B -12' 0=5' CHNL. SECT. I� m B 16 D-6 = a � 0100 -564 CFS - 46 QI00-1113 CFS— NATURAL TRAP. CHNL. SECT. CHNL SECT. 8 -14' 8 -14' D- 8' -15' Iq D =6.5' Z -2' S I I Ohl a� Robert Bein,Wiiliam Frost & Associates PROFESSIONAL ENGINEERS, PLANNERS 6 SURVEYORS PO BOX 57037. 14725 ALTON PARXVAY. IRVINE, CALIFORNIA 92619-7057 472 -3505 MVu) 0100 IN -547 CFS 0100 =476 CFS 0100 OUT -9 CFS CHNL- SECT. STOR, VOL. -70 AC -FT 8 =6' D =5' ml�pw- r `0100 -156 CFS iz EXIST. CHNL. c_cr? p R =10- D =5- 0100 -300 CFS- -.6 CHNL. SECT. 8 =12' D =5 0 .OS ANGELES AVE 0100 =493 CFS —' CHNL SECT. D -5' 9 -14' —OIDO -559 CFS '--{Di00-559 CFS CHNL SECT (EXIST. CHNL. SEC' 9 =8' 0=6' 8 -8 O =5' 0100 IN -390 CFS 0100 (DT -273 CFS �• STOR. VOL-14 AC -FT N SED. VOL. -11 AC -FT. • MODIFIED \ -� -• DETENTION BASIN ® SITE N0. 1 • OI00 IN =301 CF51 0100 =65 GF -N OUT STOR. VOL.-FT SED B A AC AC -FT jVOt� 0100 =354 CFS / EXIST. CHNL. SECT PROPOSED i �� B =7' 0=4' -6' DETENTION BASIN / I NO / 6100 IN =536 CFS j 6100 CUT-143 C!� k JUNCTION STRUCTURE STOR. VOL= AC -F' SED VOL�3 AC -F' CASEY RD. M I ICA ON / PROPOSED DETENTION 0100 IN -547 CFS 0100 =476 CFS 0100 OUT -9 CFS CHNL- SECT. STOR, VOL. -70 AC -FT 8 =6' D =5' ml�pw- r `0100 -156 CFS iz EXIST. CHNL. c_cr? p R =10- D =5- 0100 -300 CFS- -.6 CHNL. SECT. 8 =12' D =5 0 .OS ANGELES AVE 0100 =493 CFS —' CHNL SECT. D -5' 9 -14' —OIDO -559 CFS '--{Di00-559 CFS CHNL SECT (EXIST. CHNL. SEC' 9 =8' 0=6' 8 -8 O =5' DATE WALNUT /GABBERT CANYON 5/97 ALTERNATIVE N❑. B XHIBI SCHEMATIC MAP _EGENU EXISTING CHANNEL NO MODIFICATIONS MODIFIED CHANNEL SECTION • EXISTING CHANNEL REMOVAL \ -� -• PROPOSED CHANNEL ® DETENTION BASIN SITE • CHANNEL STRUCTURE MODIFICATION DATE WALNUT /GABBERT CANYON 5/97 ALTERNATIVE N❑. B XHIBI SCHEMATIC MAP C.� 4 Maintenance Road Turnout: The VCFCD maintenance staff has design requirements regarding turnouts at specified interval of long sections of channel maintenance roads. These turnout are generally double wide maintenance road locations which allow passing for vehicles or temporary parking. Vehicle Turnarounds: Areas to allow maintenance vehicles to turn- around at locations where the maintenance or road dead -ends without access to a major thoroughfare. The turn- around areas would generally consist of an unencumbered 50 foot square area. Basin Access Ramps and Perimeter Roads: Direct access for maintenance vehicles to the detention _ or debris basin locations and the ability for heavy equipment to clean out the basin floor, also accessing the basin outlet works. 12.2 Summari- 'I f� � ]I L� ij LT The hydraulic analysis of the existing Walnut and Gabbert Canyon Channel systems has confirmed that in its present condition that it does not meet the desired level of flood protection and there are hydraulic deficiencies which would cause flooding. Further development of this watershed without restrictions to limit the hydrologic impacts will worsen the condition. In order to alleviate the existing flood hazard potential it is recommended that the drainage system be improved to the extent necessary to provide the desired flood protection. The recommended improvement program outlined in this regional drainage system master plan have been formulated and evaluated on a watershed basis, but it must be implemented on a local basis Gabbert and Walnut Canyon Channels Flood Control Deficiency Study 12-1 Section 12 Recommended Drainage System WVVILQZ a J J 1 J ,J I J J I J RR EY 1A i V-1 k Z , D ' Section 11— Financing 11.1 Financing Methods Available The financing of public facilities by local agencies have a variety of financing mechanisms available to fund the infrastructure costs. Many methods cannot be used by private organizations or individuals, but offer great flexibility to public agencies. The two major categories of public work funding include pay -as -you go financing and debt financing (pay -as- you -use). Pay- as -you- go financing requires governments to pay for infrastructure costs directly from current revenues. These programs for pay -as- you -go include: creation of special assessment district, levying special property taxes, creating a special district, impact fees from new developments, grants or aid from the State and Federal government. Debt financing requires local governments to tap credit markets and raise funds through the issuance of dept obligations. The use of debt financing involves various type of financing tools which include. short term notes, unlimited tax general obligation bonds, limited tax general obligation bonds, and revenue bonds. Another type of financing is pay-as-you-need which is defined as a form of pay -as- you -go, which involves impact fees or assessments to support loan or bond payments. In this form of financing, payments collected vary depending upon the benefit received. The benefit in this case is not necessarily one of need, but rather one of forecasted or predicted need based upon potential flood damage. Assessment must be apportioned upon any basis which will reasonably measure these benefits. The advantage of this method is that only users benefitting from the improvements need to pay for. them. The following table outlines some of the most common California laws used as authority for levying special assessments which are available and their applicability according to the elements in the implementation of the recommended project. However, recent passage of Proposition 218 may influence the ability for the public agency to levee rates /charges, or establish fees to support the financing for construction, operation, and maintenance of public facilities. The costs for long term maintenance and monitoring may be a consideration in the selection of the financing mechanism, since many of the procedures do not include maintenance, but only consider capital construction. Table No. 11.1 - Project Related Allowable Uses of Assessment Laws Description of Act Drainage Flood Control Improvement Act of 1911 Capital Capital Municipal Improvement Act of 1913 Capital Capital Benefit Assessment Act of' 1982) Capital & Maintenance Capital & Maintenance Mello -Roos Community Facilities Act of 1982 Capital & Maintenance Capital Improvement Bond Act of 1915 Capital Capital Map Act Areas of Benefit Capital - - - - -- ** The table reflects the associated allowable uses based upon the specifics of each Act. The table indicates uses for either Capital Improvements or Capital Improvements and the Operation and Maintenance of the facility. Gabbert and Walnut Canyon Channel. Flood Control Deficiency Study 1 Section I Financing o (JIU1.®3 !I' ,y i D - Z, Stormwater Utility Fees is a utility approach to financing public drainage facilities. Stormwater utilities are public utilities that are financed by dedicated user charges. User charges for an individual property are based on the contribution of the property to the total volume of stormwater that must be managed. A general approach to developing a utility rate structure involves estimation of a charge per "equivalent runoff unit" (ERU) and then estimating the charge per parcel. In some areas the charge to the parcel is increased if located in a floodplain and the charge can be reduced if on -site detention is provided as part of the development. Exactions is the practice of requiring developers to provide certain physical facilities is one of the most important and well established means of financing infrastructure. In California subdivision exactions are worth over five times as much as all development - related fees and assessments, and now account for nearly half of the annual public capital formation in the state. Provisions with the State of California Subdivision Map Act include certain sections which provide for the dedication of land related to drainage systems. Section 66478.1 ensures that local agencies must require public easement along banks of rivers and streams and Section 66479 allows local ordinances to require that property be reserved for certain public facilities. There are certain requirements which must be satisfied by the public agencies in order to impose land reservations by local ordinance and the primary issues include: (1) the requirement of land reservation be based upon adopted specific plan or general plan, (2) the amount of land reserved will not make the development of the remaining land economically unfeasible. Drainage Fee Assessment Programs are possible through state legislation which enables the implementation of a drainage fee program by a public agency. Section 66483, Division 2 of Title 7 of the State of California Government Code (Subdivision Map Act), as amended January, 1, 1994, allows the creation of ordinances which require payment of fees for the purposes of defraying costs of constructing planned drainage facilities. Some of the specific requirements associated with the creation of a drainage fee program include the following: e An ordinance must be adopted to require the payment of a drainage fee as a condition of approval of final subdivision maps. • The ordinance must particularly refer to a drainage plan adopted for specific areas. • Prepare a drainage plan which includes (1) a map of the drainage area or areas showing J the boundaries and locations, type and size of planned drainage facilities, 'and (2)an estimate of construction costs of the drainage facilities for each area. • The government entity must adopt the drainage plan with a finding by resolution that the development of property within the planned drainage areas will require construction of the described drainage facilities, and a finding that the fees proposed are fairly apportioned —� on the basis of wither the benefits of, or the need for, drainage facilities created by .J proposed development o A "Planned Drainage Facilities Fund" is created for the various drainage area and funds are maintained separately The basic source of funds are drainage fees collected on a per- acre basis. JVCFCD Land Development Fee This fee was initially established in 1967 at $400 per acres and is updated annually based on the Engineering New Record Construction Cost Index for the Los Gabbert and Walnut Canyon Channels Flood Control Deficiency Study Section 11 Financing 000104 a D-7) Angeles Area. The VCFCD policy indicates that these monies can be utilized three ways, preferably to finance construction of VCFCD red line facilities, which include: (1) financing of improvements within a city, (2) finance construction outside the city that will be of benefit to the city, and (3) use all or part of the "local share" money required to finance federally funded construction. Two popular financing mechanisms which have been primarily utilized to development special assessment districts based upon the benefit from public improvements are the Mello -Roos Community Facilities Act of 1982 and the Municipal Lmnrovement Act of 191311915. The Mello- Roos Community Facilities Act of 1982 was enacted as an alternative method for local governments to provide facilities to serve their communities. It provides an alternative to making dedication and paying in -lieu fees as the method of satisfying requirements to provide certain `j public capital facilities and services. While not a true assessment, the "special tax" upon land -„i offered by this Act provides a financing tool that is treated in part like an assessment. �. The Mello -Roos Act allows the formation of "community facilities districts" in specified areas within their jurisdictions. A community facilities district is a special financing entity through which a local government is empowered to levy special taxes and issue bonds authorized by a two - thirds vote of the qualified elector of such district. In areas with less than twelve registered voters, the qualified electors are the landowners. Prior to initiation of proceeding to form a community facilities district, the developer may be required to enter into an agreement with the Issuer which will set out term under which the legislative body of the Issuer will form the community facilities district. Usually the developer will be required to advance all costs incurred by the public agency to form the community facilities district. The costs may include estimated engineering, planning, inspection, and administrative costs and expenses. These costs will be repaid to the developer from bond proceeds. Generally, with the cooperation of all parties involved, the proceedings to form a community facilities district may be completed and bond proceeds received in five to six months after the proceeding are initiated. 7 7 J J 1 i J The Municipal Improvement Act of 1913/1915, currently the most frequently used Assessment Act in California, allowed local agencies to impose assessment on benefitted property to finance the construction of various public improvements, the acquisition of real property rights, and the maintenance and repair of improvements constructed with this Act. Another funding mechanism which specifically focuses on flood control projects is the Benefit Assessment Act of 1982. This Act authorizes local agencies to impose assessments on benefitted property to finance the operation and maintenance of drainage, flood control services, and the installation and improvement of drainage and flood control facilities. In the case of an assessment for flood control services, the Act provides that the benefit may be determined on the basis of the proportionate storm water runoff from each parcel a bert and Walnut Canyon Channels Flood Control Deficiency Stud; 1.3 Section 11 Financing rull"I OS J b -A- Special assessment districts are a common funding program using a convenient designation for properties that receive a special benefit and are subject to the special assessment. The special assessment is designed to recover the costs of an improvement that directly benefits an individual property and these -assessment are based on formulas that relate the charge against a parcel to the i benefits. The capital is generated for the construction of the improvements through the sale of °j general obligation bonds Tax Increment Financing (TIF) uses increases in property values attributed to a capital project to recover the project's costs. Under this approach, a special tax increment district is created by the adoption of a plan for development of the infrastructure of a particular geographic area. Although the use of tax increment financing in rural area is not uncommon, this method is usually used to finance redevelopment in deteriorated areas characterized by declining property values. J A more detailed description of the process associated with the 1913/1915 Act have been provided, however, most of the other special assessment acts previously indicated follow similar procedures. Logic diagrams have been developed for the Special Assessment District and the Mello -Roos Community Facilities District proceedings which graphically illustrate the process for the major elements associated with each funding mechanism (See Exhibit 58 - Special Assessment District Flow Chart, and Exhibit 59 - Mello -Roos CFD Flow Chart). The general process for the 1915 Act when used in conjunction with the 1913 Act are generally as follows: *The public agency adopts the Resolution to order the improvement, briefly describing the proposed improvement, specify the exterior boundaries of the assessment district, providing for issuance of improvement bonds, declaring its intention to levy assessments to maintain, repair or improve the facility -� • The agency directs preparation of an Engineers Report which contains: plans and specifications of the proposed improvements, description of lands. and easements to be acquired, an estimate of the cost of the improvement and costs of lands and easements. The report is filed with the public agency. A preliminary approval is adopted and a public hearing is set for not less than thirty days after passage of the resolution. Bids for the construction of the improvements and sale of the bonds can be called for before the hearing. The notice inviting construction bids must be first published at least fourteen day days before the date set for receipt of the bids. • Prior to public hearing on the assessment district the public agency shall adopt a resolution describing the boundaries of the district. Notice of adoption of the resolution - and of the public hearing are published and posted at least twenty days prior to date set for the public hearing • After the public agency passes on the report and any interested person may object to the proposed improvement by filing a written protest before the hearing. if a majority of the owners protest the formation of the district or the levy of the assessment at or before the hearing, then no further proceedings may proceed for a period of one year from the date of the hearing Gabbers and Walnut Canyon (hannel.� Section 11 �. Flood Control Deficiency, Stud,. 11 -4 Financing -�1 • The assessments cannot be increased unless consent from the owner is obtained or an 1 additional noticed hearing is conducted r� •After confirmation by the public agency, the clerk files the final diagram and notice of assessment the county recorder, and the assessment and diagram with the appropriate local agency official J r 80 011 �I d go .. 4 A 1915 Act assessment district format was assumed for the purpose of developing an evaluation of the estimated assessment district bonded costs for the recommended drainage system construction costs, excluding land acquisition costs. This differs from an alternative of using a 1911 Act district which would have less administrative costs, but also less flexibility. Generally, the 1915 Act district is the more common format utilized to finance public improvements. Table No. 11.2 - Estimated Mood Control Assessment -District goaded Costs Cost Item Estimated Cost Description Estimated Construction Costs* $8,663,000 Construction costs for flood control improve- ments Contingency & Engineering $2,599,000 30% of construction costs Cost of Issuance $173,000 2% costs for underwriter & administration Formation Costs $86,000 1 % cost for bond counsel Assessment District Engineering $43,000 5 % costs for assessment district engineer Capitalized Interest (18 months at 6 %) $1,029,000 Finance costs or carry during construction period Bond Reserve $570,00() Ranges from 5 -10% determined by issuing agency and depends on risk. Total Amount Assessed [$13,164,000 ** Assumes the recommended project drainage system alternative and includes only capital construction costs, excludes R/W or land acquisition. The estimated construction costs reflect Drainage System Alt. "B" An estimate of the bond issuance costs is presented in Table No. 11.2 and these costs generally include bond counsel, underwriter discount, special tax consultant, debt service reserve fund, capitalized interest (1 -2 years), official statement and bond printing, trustee /paying agent, letter of credit or insurance premium, and other miscellaneous costs. Gabbert and Walnut Canyon Channels Flood Control Deficiency Study 11 5 Section 11 Financing 00010 - b A0 The determination of the funding for the maintenance of these facilities is important during the initial development of the special assessment district since many procedures do not allow maintenance costs to be included. An example is general obligation bonds are generally issued by public entities only for the purpose of acquisition and construction and may not be used to finance ongoing maintenance and operation costs. Additional limitations may be provided by the statutes of the local agencies and these should be investigated during the initial planning process. I L 1.1 Financing Issues and Policy Consideration s Several issues must be considered when evaluating public financing and these include (1) allocation of costs by benefit, (2) economic feasibility, (3) County policies, and (4) specific types of charges f and implementation measures. Assessment fees can either be distributed based upon actual benefits J received from implementation of the drainage improvement or based upon considering the negative impacts which result from development of property. The most obvious benefit received from construction of drainage improvements is the reduction or elimination of potential flood damage which could occur to property. The problem with assessing specific benefits is that of determining the value of an individual property is difficult and subjective. The "negative impact basis" is based on the concept that the charges to a parcel should be based on the contribution to the problem of flooding and proportional cost of a system designed to alleviate that problem. The This is a superior approach both on the basis of reasonableness as well as simplicity in determining assessment. An important aspect to consider in setting fees is legal constraints and statutory restriction on impact fees and assessments. Statutes (Section 66483 of the California State Government Code) governing the assessment of fees and charges to cover both operation and improvement or construction of new facilities state that "...fees should be reasonable, fair and equitable..." or "...fees should be fairly e apportioned... on the basis of benefits conferred on the property..." Other restrictions limit charges on individual properties to a prorata basis according to the acreage, and limit charges to cover only the cost of facilities which are not in existence at the adoption of any master plan for the area. 6q _J Another key element is the economic feasibility of development - related financing based upon the IA relationships of the financial burden to the underlying land values. If the burden is large, relative to land value for a particular use, the that use may be rendered uneconomic. sp i Gabbert and Walnut Canyon Channels Section 11 Flood Control Deficiency Studi 11.6 Financing 0 ()QILQS 11.1.2 Allocation of Financial Burden to Land Uses w Establishes a fee stricture within the watershed requires that the infrastructure costs outlined for the proposed drainage system be apportioned by some fair and reasonable method. In addition there must be a nexus to establish an assessment which provides a relationship between the land and the proposed infrastructure improvements. A Dwelling Unit Equivalent (DUE) can be utilized to To determine the relative responsibility of an acre of land in each landuse category compared to an acre of land in the single family residential category. Generally the DUE procedure are based on a "causes or uses" test : the cost of the drainage facilities are sized to accommodate the peak runoff were allocated in proportion to the extent. to which each land use category contributes to the peak runoff amount. Application of a DUE cost schedule provides the basis for a valid development impact fee. 11.2 Selection of the Financing Technique The decision regarding the financing method depends on several considerations which include: (1) cash flow, (2) landowner preferences, O adopted county policy. The time at which a particular drainage improvement must be implemented is compared to the amount of development impact fees ° that would have been collected up to that time. If the total collections are adequate or if an imbalance can be corrected over relatively few years, then impact fees are useable. It has been increasingly common in California for a comprehensive financing plan to include a mix of development impact fees and bonded debt. Bonded debt, is authorized to pay for those major improvements that are required immediately to implement the master plan of drainage. d Development impact fees, are used to pay for improvements that can be staged over the planning period. 7 WX Impact fees would appear to be most effective and simplest form of financing. Impact fees may be charged at the time the property is subdivided. at the time building permits are issued or a combination of both. If these drainage facilities are to be implemented prior to the development occurring in the upper watershed then some form of debt financing must be considered and drainage fees can be used to repay the debt. Exactions in the form of land reservations for stormwater storage detention basins or additional channel right- of -way will fulfill the land requirements in order to implement the drainage sYstem�, Gabbert and Walnut Canyon Chawleb 'u' Flood Control Deficiency Studi Section 11 Financing rl(Afll R_ 7A 11.1.2 Allocation of Financial Burden to Land Uses w Establishes a fee stricture within the watershed requires that the infrastructure costs outlined for the proposed drainage system be apportioned by some fair and reasonable method. In addition there must be a nexus to establish an assessment which provides a relationship between the land and the proposed infrastructure improvements. A Dwelling Unit Equivalent (DUE) can be utilized to To determine the relative responsibility of an acre of land in each landuse category compared to an acre of land in the single family residential category. Generally the DUE procedure are based on a "causes or uses" test : the cost of the drainage facilities are sized to accommodate the peak runoff were allocated in proportion to the extent. to which each land use category contributes to the peak runoff amount. Application of a DUE cost schedule provides the basis for a valid development impact fee. 11.2 Selection of the Financing Technique The decision regarding the financing method depends on several considerations which include: (1) cash flow, (2) landowner preferences, O adopted county policy. The time at which a particular drainage improvement must be implemented is compared to the amount of development impact fees ° that would have been collected up to that time. If the total collections are adequate or if an imbalance can be corrected over relatively few years, then impact fees are useable. It has been increasingly common in California for a comprehensive financing plan to include a mix of development impact fees and bonded debt. Bonded debt, is authorized to pay for those major improvements that are required immediately to implement the master plan of drainage. d Development impact fees, are used to pay for improvements that can be staged over the planning period. 7 WX Impact fees would appear to be most effective and simplest form of financing. Impact fees may be charged at the time the property is subdivided. at the time building permits are issued or a combination of both. If these drainage facilities are to be implemented prior to the development occurring in the upper watershed then some form of debt financing must be considered and drainage fees can be used to repay the debt. Exactions in the form of land reservations for stormwater storage detention basins or additional channel right- of -way will fulfill the land requirements in order to implement the drainage sYstem�, Gabbert and Walnut Canyon Chawleb 'u' Flood Control Deficiency Studi Section 11 Financing rl(Afll R_ invited to June 5th meeting Mailing List Walnut Canyon Channels Flood Control Deficiency Study .tune 5. 1997 Meeting 500.0.340.37 Bundy - Olympic Development 8750 Wilshire Blvd #300 Beverly Hills CA 90211 504.0.021.24 Margaret Waayers - TR et a] 912 S Windsor Blvd. Los Angeles CA 90019 Church Jesus Christ LDS Fax Division 22nd Fl SO E N Temple 500.0.340.14 Richard B & Shirley N Testa 180 Longhorn Lane Ojai CA 93023 500.0.250.15 Dennis - Christine Swinburne 6685 Aspen Hills Drive Moorpark CA 93021 500.0.050.10 Nancy P Barberis 1241 Drake Drive Simi Valley CA 91361 Development Planning Services Dennis Hardgrave 651 Via Alondra Suite 714 Camarillo CA 93012 Urban Strategies Elaine Freeman 2509 E Thousand Oaks Blvd Thousand Oaks CA 91362 500.0.340.22 A.C.Construction Paul D. & Lisa A. Burns 4875 Spring Road Moorpark CA 93021 141tch Ranch Tenants in Common Richard S. Hampleton Jr. 1000 S Seaward Avenue Ventura CA 93001 500.0.340.02 D. Me Grath Farms P.O. Box 1106 Oxnard CA 93030 500.0.340.28,- 29, -30, 500.0.340.23 Southern California Edison Company P O Box 800 Rosemead CA 91770 500.0.260.02,- 07,- 08,- 09, -04, 500.0.270.16,- 15,- 14, -09 James S Rasmussen 2360 Shasta Way Suite A Simi Valley CA 93065 500.0.250.13 Mark G -Trudy A Taillon 6617 Aspen Hills Drive Moorpark CA 93021 511.0.110.03, 511.0.020.02, -03, 511.0.040.19, 500.0.270.06 Abe Gunyy 7250 Walnut Canyon Road Moorpark CA 93021 Bollinger Development Inc Paul Bollinger 351 Rolling Oaks Drive Suite 100A Thousand Oaks CA 91361 Triliad Development Valerie Dragei 500.0.340.08 Bugle Boy Industries Diane L. Becker Esq. 2900 Madera Road Simi Valley CA 93065 500.0.340.15, -17 Jemeo Properties 9061 Santa Monica Blvd Los Angeles CA 90069 Westoaks Investments 951 S Westlake Blvd. Westlake Village CA 91361 504.0.021.02 Milligan AA TR et al Levy Tenancy in Common 1000 S Seaward Avenue Ventura CA 93001 500.250.14, - 27, -28 William Jr -C Houseman 150 E Los Angeles #205 Moorpark CA 93021 500.0.250.12, 500.0.330.31 Robert L Falke 13822 Kyte Avenue Me Farland CA 93250 Moorpark Partnership 8222 Melrose Avenue Los Angeles CA 90046 Pacific Communities Nelson Chung 1000 Dove Street Suite 100 Newport Beach CA Morrison - Fountainwood- Agoura 270 Conejo Ridge Avenue Suite 200 Michael Greynald Thousand Oaks C.A 91361 2584 W Thousand Oaks Blvd CERTIFICATION OF MAIUNG Calabasas CA 91302 'I hereby cedy that the attached notice was nom to the attached list of persona an 4L8/4r7 Dated —Z 9 FILE COPY SOW by.0— 0001.lo IALLeilUeU JLL W W W W W W W0h coo w00 ^- N lr rrr 0 `.f JLLL Lllee L;L1f6 �;> �. 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