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Drainage Master Plan - 2005LAWAAY Master Drainage Plan Rev. Oct. 2005 CITY OF PISMO BEACH DRAINAGE MASTER PLAN CITY COUNCIL Mayor Mary Ann Reiss Mayor Pro Tem Arlene Gonzales -Gee Council Member Bill Rabenaldt Council Member Rudy Natoli Council Member Shelly Higginbotham Kevin Rice City Manager Dennis Delzeit Public Works Director/City Engineer CITY OF PISMO BEACH DRAINAGE MASTER PLAN The Pismo Beach Drainage Master Plan was prepared under the direction of the following registered Civil Engineer: No 55158 EXPA-40 Roberto s�q CML o���Q Senior Engineer OFCAUF TABLE OF CONTENTS CHAPTER PAGE NUMBER ' 1 EXECUTIVE SUMMARY Cost Estimates Site Evaluation and Capital Improvements 1-1 Drainage Water Quality 1-1 Figure 1-1: Drainage System Project Locations 1-2 Project Cost Summary 1-3 2 INTRODUCTION 2-1 3 EVALUATION OF SPECIFIC SITES Introduction 3-1 Site No. 1: Wadsworth Culvert System at Cypress Street (Phase 1) .� 3-2 Site No. 2: Wadsworth Culvert System at Dolliver Street (Phase 2) 3-4 Site No. 3: Wadsworth Culvert System at Price Street (Phase 3) 3-6 Site No. 4: Wadsworth Culvert System at Bello Street (Phase 4) 3-8 Site No. 5: Wadsworth Culvert System at San Luis Ave. (Phase 5) 3-10 Site No. 6: Wadsworth Culvert System at Longview Street (Phase 6) 3-12 - Site No. 7: Longview Inlet Upgrade at Merced Street 3-14 Site No. 8: Bakersfield Street Storm Drain Extension 3-16 Site No. 9: Intersection at Selma & Lemoore 3-18 Site No. 10: Price Canyon Road Culvert Outlet 3-20 Site No. 11: Intersection of Park Avenue & Cypress Street 3-22 Site No. 12: Hanford Street - Potential Flooding of Residence 3-24 Site No. 13: Detention Ponds Within the Tributary Watershed of 3-26 Pismo Creek 4 CAPITAL IMPROVEMENTS Prioritization 4-1 Cost Estimates 4-1 Project Cost Summary 4-2 Detailed Cost Estimates 4-3 5 DRAINAGE WATER QUALITY Best Management Practices 5-1 Storm Water Quality Mitigation Measures 5-3 TECHNICAL APPENDICES Appendix A: Drainage Definitions Appendix B: Preliminary Runoff Calculations ' CHAPTER 1 EXECUTIVE SUMMARY ' The City of Pismo Beach (City) is located in the southern portion of San Luis Obispo County along the Pacific shoreline. The City is approximately 7 miles long by'/z mile wide, operates, and maintains public streets and storm drain systems within the City limits. Two ' areas have been identified by City staff for the consideration and study of flood related problems and potential solutions. These areas are Pismo Heights and the Downtown ' Commercial Core as depicted in Figure 1-1. Wallace Group was retained, by the City, to implement a plan to overcome deficiencies in existing flood control and storm water conveyance. Site Evaluation and Capital Improvements City staff identified several known problem locations within the study area (as shown in figure 1-1). Each location was subsequently analyzed and reviewed during wet weather, and a program of ranked capital improvements was assembled as described in Chapter 3. Table 1-1 summarizes the problems, recommended solutions, and estimated project cost for each of the identified locations. The cost estimates listed represent total budget costs and include engineering, testing, administration, and construction. The projects were also ranked based on the severity of the existing conditions and the anticipated effectiveness of the proposed solution. Drainage Water Quality Drainage water quality is of particular concern to municipalities and regulatory agencies. Human activities, both during and after construction, can alter natural drainage patterns, adding pollutants to rivers, streams, and the other water bodies. Municipalities typically address these concerns through the establishment of Best Management Practices (BMP's) that relate to the issues of storm water runoff and water quality. BMP's are those practices that have been refined and tested over time and have been shown to be effective in mitigating storm water quality problems. Chapter 5 describes five categories of BMP's and provides specific construction details for a number of effective mitigation measures. City of Pismo Beach Chapter 1 Drainage Master Plan 1-1 Executive Summary ',J 71 8 W. "Z2-- 10 Legend ------------- 1 F4 1������� 0 High Priority Project Medium Priority Project Low Priority Project 12 Site Number 600 300 0 600 SCALE 1 1'= 600' a CHAPTER 2 " INTRODUCTION The purpose of this Drainage Master Plan is to provide a thorough review of identified drainage deficiencies within the Pismo Heights and Downtown Commercial areas of the - City of Pismo Beach. Problem sites were identified by City Public Works staff based on previous experience with flood events in these areas. During the preparation of the report, each site was visited in wet weather to confirm existing drainage patterns and identify potential solutions. The site locations were previously identified in Figure 1-1. After the completion of field investigations, the following scope of work was performed for each problem area: • The tributary drainage area was identified and storm flows were calculated. • A preliminary hydraulic analysis was performed and potential drainage solutions were identified. • Preliminary pipe sizes, drainage inlet configurations, and other hydraulic parameters were determined. • A preliminary design and budget -level cost estimate was prepared for each project. • The projects were ranked in order of recommended implementation. J Chapter 3 summarizes the existing problems and proposed solutions for each site. Chapter 4 describes the recommended capital improvement program including project ranking, and Chapter 5 discusses storm water quality issues. J City of Pismo Beach Chapter 2 Drainage Master Plan 2-1 Introduction CHAPTER 3 EVALUATION OF SPECIFIC SITES This chapter summarizes existing drainage problems at 12 sites within the City of Pismo Beach and describes potential solutions. The drainage problems were identified through field visits with City staff and by performing preliminary hydrology and hydraulic analyses. Foreach of the problem sites identified, hydraulic and hydrologic analyses were performed to determine the preliminary sizes and scope of the needed facilities. These preliminary designs were used as the basis for the cost estimates and will have to be refined during the detailed design process. The analyses performed, as discussed in Appendix -B, were based on a 25 -year storm event. This design storm provides a reasonable balance between economic feasibility and adequate flood protection. The Wadsworth Culvert System has been broken into six phases, designated as Sites 1 through 6. Site numbering begins with Site No. 1, a new ocean outfall and proceeds upstream to Site No. 6. Each of the remaining sites then builds on the preceding phase. This phased approach was designed to maximize financial flexibility through smaller projects providing incremental drainage benefits to the City. The cost estimates presented with each project are based on an Engineering News Record (ENR) Index of 6604 (August 2002). The costs represent the total recommended project budget including construction, engineering, and administration. City of Pismo Beach Chapter 3 Drainage Master Plan 3-1 Capital Improvements Site No. 1: Wadsworth Culvert System at Cypress Street—Phase 1 Problem: Excessive runoff exceeds street capacity, flooding adjacent property. Solution: Construct drainage inlets and storm drain pipes. An excessive amount of runoff at this intersection exceeds street capacity. The runoff watershed begins at the top of Longview Avenue and continues down to the bottom of Wadsworth Avenue, and does not include the storm flow that is dispersed at Price and Dolliver Streets. The storm water discharges 200 feet south of the Cypress Street intersection onto the beach from the cliff. This site poses a significant concern during a 25 - year storm, since water will discharge to the beach at over 135 cubic feet per second (CFS). The drainage system proposed for Site No. 1 represents the initial component of a larger proposed drainage network identified as the Wadsworth Culvert System. Phase 1 includes curb openings and grated inlets along Cypress Street to intercept the storm runoff generated by a 25 -year storm event. The runoff would be conveyed to the beach and dispersed through an energy dissipating structure at the bottom of the cliff. Resulting benefits are as follows: 1) Portions of the excessive amounts of runoff at this intersection would be intercepted. 2) Excessive runoff cascading and eroding down the beach cliff would be reduced. Water cascades down the cliff atthe existing outfall over a combination of a concrete swale and vegetation, and then flows into an energy dissipation structure near the base of the cliff. The existing facilities are undersized for a 25 -year storm event. However, the proposed culvert and energy dissipater will have sufficient flow capacity and will provide protection against erosion. Construction constraints at the proposed outfall locations appear minimal, especially if the new outfall is constructed upstream from the existing outfall, as shown in the photographs below. Figure 3-1. Existing Outfall at Site 1 Figure 3-2. Cypress Street at Wadsworth Avenue looking towards the outfall. City of Pismo Beach Chapter 3 Drainage Master Plan 3-2 Capital Improvements r No CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 1: Wadsworth City of Pismo Beach Drainage Master Plan 3-3 Culvert System at Cypress Street—Phase 1 Problem: Excessive runoff exceeds street capacity, flooding adjacent property. Solutions: 1. Construct 4 drainage inlets 7 feet wide each. 2. New storm drain pipe, (approx. 40 feet of 24" & 340 feet of 48" diameter pipe. 3. New energy dissipation structure. Estimated Cost: $ 221,700 Chapter 3 Capital Improvements Site No. 2: Wadsworth Culvert System at Dolliver Street—Phase 2 Problem: Excessive runoff exceeds street capacity, flooding adjacent property. Solution: Construct drainage inlets and storm drain pipes. There is an excessive amount of runoff at this intersection. A large amount of storm runoff is dispersed and flows towards downtown Pismo Beach as well as continuing down Wadsworth. In order to mitigate the storm runoff, Phase 2 of the Wadsworth Culvert System is proposed, which consists of curb openings and grated inlets to intercept the storm runoff generated by a 25 -year storm event. The proposed storm drain at Dolliver & Wadsworth would intercept runoff and deliver it to Phase 1 of the Wadsworth Culvert System through 48" culverts. J City of Pismo Beach Chapter 3 Drainage Master Plan 3-4 Capital Improvements CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 2: Wadsworth Culvert System at Dolliver Street—Phase 2 i _11 Problem: Uty of F'ismo Leach Drainage Master Plan 3-5 Excessive runoff exceeds street capacity, flooding adjacent property. Solutions: 1. Construct 4 drop inlets 7 feet wide each. 2. Add pipes to convey runoff downstream (Approx. 150 feet of 24" & 415 feet of 48" diameter pipe) Estimated Cost: $176,800 Chapter 3 Capital Improvements JSite No. 3: Wadsworth Culvert System at Price Street—Phase 3 i Problem: Excessive runoff exceeds street capacity, flooding adjacent property. Solution: Construct drainage inlets and storm drain pipes. There is an excessive amount of runoff at this intersection. A large amount of storm runoff is dispersed and travels towards downtown Pismo Beach as well as continuing down Wadsworth. Site 3 is located at the convergence of runoff that travels from the top of Longview Avenue and spills over to Price Street from upstream watersheds (Tributary Watersheds 1, 2, 3, & 5 of Figure B-1). In order to convey this flow before it continues on Price Street, Phase 3 of the proposed Wadsworth Culvert System is proposed. Curb openings and grated inlets would intercept the storm runoff generated by a 25 -year storm event and convey the storm water to Phase 2 of the system via 42 -inch diameter pipes. This approach will reduce flooding in the downtown area of Pismo Beach. J City of Pismo Beach Drainage Master Plan Chapter 3 Capital Improvements CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 3: Wadsworth Culvert System at Price Street—Phase 3 IN 3 N PRice sr City of Pismo Beach Drainage Master Plan 3-7 Problem: Excessive runoff exceeds street capacity, flooding adjacent property. Solution: 1. Construct 4 drop inlets 7 feet wide each. 2. Add pipes to convey runoff downstream (approx. 50 feet of 24" & 380 feet of 42" diameter pipe). Estimated Cost: $ 147,950 Chapter 3 Capital Improvements JSite No. 4: Wadsworth Culvert System at Bello Street—Phase 4 Problem: Excessive runoff exceeds street capacity, flooding adjacent property. Solution: Construct drainage inlets and storm drain pipes. J Above the intersection of Bello Street and Wadsworth Avenue, the cross slope of Wadsworth Avenue forces runoff to the south side of the street where 95% of the flow is conveyed. The runoff flows pastthe intersection, via a concrete cross gutter, and continues down Wadsworth Avenue. Additional runoff originates from a bubbler system at the intersection of Longview and Wadsworth Avenues. This bubbler system collects and J conveys storm water to Wadsworth Avenue, adding runoff from tributary watersheds 1, 2, & 3 (see Fig. B-1). As a result, there is excessive runoff at this intersection. The proposed solution involves the construction of Phase 4 of the Wadsworth Culvert System. Constructing Phase 4 concurrently with Phase 6 would afford the best results at this intersection. Curb openings and grated inlets would intercept the storm runoff generated by a 25 -year storm event and convey it to Phase 3 of the system via 36 -inch culvert pipes. At Bello Street, the proposed Wadsworth Culvert System could have a lateral extension to where it intersects Harloe or San Luis Avenue (Site 5). The intersection of Bello & San Luis Avenue is lower than the intersection of Bello & Wadsworth Avenue. Therefore, the Wadsworth Culvert System at Bello Street would need to be constructed deep enough to accommodate the elevation differences. J JCity of Pismo Beach Chapter 3 Drainage Master Plan 3-8 Capital Improvements J CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 4: Wadsworth Culvert System at Bello Street—Phase 4 "Ity of risrno oeacn Drainage Master Plan 3-9 Problems: Excessive runoff exceeds street capacity, flooding adjacent property. Solutions: 1. Construct 2 drop inlets 7 feet wide each, and 1 inlet 14 feet wide. 2. Add pipes to convey runoff downstream (approx. 50 feet of 24" & 540 feet of 36" diameter pipe) Estimated Cost: $167,750 Chapter 3 Capital Improvements Site No. 5: Wadsworth Culvert System at Bello and San Luis Avenue—Phase 5 Problem: —Undersized drainage system, near Bello Street —Partially buried curbs at intersections Solution: —Construct drainage inlets & drain pipes —Re -grade intersections to increase curb heights The intersection of Bello & San Luis Avenue is the low point of Area 5 in Figure B-1. San Luis Avenue ends at the Highway 101 right of way approximately 50 feet south of the Bello a intersection. At this point the runoff enters a Cal Trans culvert system consisting of three 24 -inch culverts. The runoff is conveyed under the highway and outlets onto San Luis Avenue on the west side of the highway. During large storm events this culvert system will back up at the inlet. The anticipated water surface elevation atthe inlet of the three culverts has a potential to flood nearby homes. Secondly, at the intersection of Bello & San Luis Avenue sections of the 6 -inch concrete curb have been partially buried by past street overlay projects, thereby reducing storm water capacity. The proposed solution involves the construction of Phase 5 of the Wadsworth Culvert System. Curb openings would intercept the storm runoff generated by a 25 -year storm event and convey it to Phase 4 of the system via 24 -inch culvert pipes. Additionally, the street should be re -graded, restoring the 6" concrete curb design in the general area. City of Pismo Beach Chapter 3 Drainage Master Plan 3-10 Capital Improvements r F i CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 5: Wadsworth Culvert System at Bello and San Luis Avenue—Phase 5 City of Pismo Beach Drainage Master Plan 3-11 Problems: 1. Undersized drainage system, near Bello Street. 2. Partially buried curbs at intersections. Solution: 1. Construct 6 drop inlets 7 feet wide each. 2. Add pipes to convey runoff downstream (approx. 730 feet of 24" diameter pipe). Estimated Cost: $ 207,600 Chapter 3 Capital Improvements Site No. 6: Wadsworth Culvert System at Longview Street—Phase 6 Problem: Undersized bubbler system Solution: Construct new drainage inlets and pipes to convey runoff to site improvements There is an undersized bubbler system at the intersection of Longview and Wadsworth Avenues that encounters excessive flows. The bubbler system was designed to convey runoff onto Wadsworth Avenue. Currently, a portion of the runoff goes down Wadsworth Avenue and a portion continues down Longview Avenue. The runoff that continues down Longview Avenue spills uncontrolled over the hill on the South side of Hanford Street. Damage to new and existing homes could result from this condition. The proposed solution involves the construction of Phase 6 of the Wadsworth Culvert System. Curb openings and grated inlets would intercept the storm runoff generated by a 25 -year storm flow event and convey it to Phase 4 of the system via 24 -inch culvert pipes. City of Pismo Beach Chapter 3 Drainage Master Plan 3-12 Capital Improvements J F L CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 6: Wadsworth Culvert System at Longview Street—Phase 6 Uly or rismo tseacn Drainage Master Plan 3-13 Problem: Undersized bubbler system Solution: 1. Construct 2 drop inlets 14 feet wide, and 5 drop inlets 7 feet wide each. 2. Add pipes to convey runoff downstream (approx.1,810 feet of 24" diameter pipe) Estimated Cost: $ 446,550 Chapter 3 Capital Improvements Site No. 7: Longview Inlet Upgrade at Merced Street Problem: Undersized drainage inlets Solution: Upgrade drainage inlets and pipes Much of the runoff from tributary watershed area one (see Fig. B-1) bypasses the drainage inlets at the intersection of Merced Street and Longview Avenue due to undersized drain inlets. This runoff adds to the problems at Site 7, Site 8, and ultimately Site 6 at Longview and Wadsworth Avenues. As a result, the westerly drain inlet at the intersection of Merced Street and Longview Avenue should be increased in size from 3.5 feet to 7 feet wide. City of Pismo Beach Chapter 3 Drainage Master Plan 3-14 Capital Improvements CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 7: Longview Inlet Upgrade at Merced Street City of Pismo Beach Drainage Master Plan 3-15 Problem: Undersized drainage inlets Solutions: Construct 1 drop inlet 7 feet wide. Estimated Cost: $ 14,900 Chapter 3 Capital Improvements r r' Site No. 8: Bakersfield Street Storm Drain Extension Problem: Undersized drainage system Solution: Extend new drainage pipes from the existing drainage inlet to new drainage I inlets at Longview Avenue. F Much of the runoff from tributary watershed area No.2 (see Fig. B-1) bypasses the undersized gutter that crosses Longview Avenue at Bakersfield Street. Watershed area No.2 would be best drained by installing new drop inlets at the intersection of Bakersfield Street and Longview Avenue. The inlets would convey runoff through a new 24 -inch diameter culvert pipe to the existing drain inlet on the east end of Bakersfield Street. City of Pismo Beach Drainage Master Plan 3-16 Chapter 3 Capital Improvements 0 CITY OF PISMO BEACH - Storm Drain Master Plan 'I Site No. 8: Bakersfield Street Storm Drain Extension City of Pismo Beach Drainage Master Plan 3-17 Problems: Undersized drainage system Solutions: 1. Construct 1 drop inlet 7 feet wide and 1 drop inlet 14 feet wide. 2. Add pipes to convey runoff downstream (approx. 270 feet of 24" diameter pipe) Estimated Cost: $ 75,150 Chapter 3 Capital Improvements r Site No. 9: Intersection at Selma & Lemoore ■ Problem: Storm run-off overflows drainage structures and floods residence. r Solution: —Construct a drop inlet upstream of Selma Street. —Improve the drainage discharge at the south end of Strafford Street. r —Improve the berm at the intersection of Longview Avenue and Stratford Street. Between Porterville Street and Selma Street, Lemoore Street has a constant cross slope which concentrates storm run-off flows to the northerly side of the street. Atthe intersection of Selma and Lemoore Street, the runoff travels directly toward the driveway apron of 320 Selma. Two sump inlets have been constructed at this location, one in the gutter and the other in the sidewalk portion of the driveway apron. The runoff that enters the sump inlet is conveyed back to Lemoore Street (below Selma) via a bubbler system. The steep streets and the high storm flowvelocity is causing runoff to jump the sump inlets and the sidewalk, potentially flooding the residence. Furthermore, additional flow is added to the system at the south end of Strafford Street where there is evidence that runoff currently enters the Lemoore Street drainage system via a vacant lot between 690 & 710 Lemoore. Likewise, the A.C. berm at the intersection of Longview and Stratford, constructed to prevent Longview runoff from entering Strafford Street, may be over -topped during large storm events. In order to counteract these conditions, the following measures are proposed: 1) Improve the drainage at the southeast end of Strafford Street by conveying a 100 year storm event to the hillside at the end of Strafford. This would prevent runoff from entering Lemoore Street via the vacant lot between 690 & 710 Lemoore. 2) Construct a drop inlet west (upstream) of Selma Street that would intercept a 25 -year storm flow event in conjunction with the existing sump inlet at 320 Selma. The storm flow would be conveyed East (downstream) of Selma via an existing bubbler system. 3) Improve the berm at the intersection of Longview Avenue and Stratford Street. This would block storm flow from entering Strafford Street from Longview Avenue. .J City of Pismo Beach Chapter 3 Drainage Master Plan 3-18 Specific Site Evaluation r CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 9: Intersection at Selma & Lemoore '3�0 SELMA r SITE 7 (EXISTINt SUMP IP PROP05ED D LOCATION OF NEEDED DRAINAGE IMPROVEMENTS I/ City of Pismo Beach Drainage Master Plan 3-19 Problems: Storm runoff overflows drainage structures and spills into residence. Solutions: 1. Construct 1 drainage inlet 10.5 feet wide & 180 feet of 24" diameter storm drain pipe. 2. Improve the berm at Longview & Stratford. Estimated Cost: $ 52,100 Chapter 3 Specific Site Evaluation r Site No. 10: Price Canyon Road Culvert Outlet Problem: Culvert discharges storm flow into street Solution: Construct energy dissipation outlet structure The culvert at this location drains a portion of the school directly onto Price Canyon Road. The discharge deteriorates the asphalt pavement in the road and creates a slick driving hazard during significant storm events. The problem can be mitigated by constructing an energy dissipation structure at the end of the culvert pipe. 1 City of Pismo Beach Drainage Master Plan 3-20 Chapter 3 Specific Site Evaluation CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 10: Price Canyon Road Culvert Outlet Problems: City of Pismo Beach Drainage Master Plan 3-21 Culvert projects runoff into the street. Solutions: Construct an energy dissipation outlet structure. Estimated Cost: $ 20,000 Chapter 3 Specific Site Evaluation Site No. 11: Intersection of Park Avenue & Cypress Street Problem: Excessive runoff exceeds street capacity, flooding adjacent property. Solution: Construct drainage inlets and storm drain pipes, and re -grade the general area around the curbs. r At the intersection of Park & Cypress Streets, sections of the 6 -inch concrete curb have been partially buried by road overlay projects, thereby reducing the storm water carrying capacity. In addition, Dolliver Street conveys storm flow generated by a 14 acre watershed r to Pismo Creek (Drainage Area 10 of Figure B-3). However, during large storm events, runoff will overtop Dolliver Street and flow to the intersection of Park & Cypress Streets. In order to mitigate this problem, the existing drainage system at the intersection of Addie & Cypress, consisting of one drop inlet and a 24 -inch culvert draining into Pismo Creek, could be extended to the intersection of Park & Cypress and also to Park & Ocean View. i Additionally, Cypress Street should be reconstructed to restore the 6 -inch concrete curb design in the general area. J City of Pismo Beach Chapter 3 Drainage Master Plan 3-22 Specific Site Evaluation CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 11: Intersection of Park Avenue & Cypress Street __ __11 Problem: If :XIS IN D. 1, EX. City of Pismo Beach Drainage Master Plan 3-23 Excessive storm flow at intersection combined with curbs partially buried by road overlays. Solution: 1. Construct 6 drainage inlets 7 feet wide each, and storm drain pipes (610 feet of 24" diameter pipe) 2. Re -grade the general area around the curbs. Estimated Cost: $ 184,650 Chapter 3 Specific Site Evaluation r Site No. 12: 951 Hanford Street—Potential Flooding of Residence { Problem: Runoff flows down an existing driveway and can potentially flood the residence. ■ Solution: Construct a new asphalt concrete berm along the property perimeter. Check _ maintenance schedule of existing inlets. r Street runoff is currently conveyed to the downward sloping driveway of 951 Hanford. The runoff volume is modest but is currently directed to the garage door. There is a slotted drain running along the length of the garage door that intercepts the runoff and conveys r it to a drain pipe running to the back of the house. The slotted drain is undersized or the drainage system is not being maintained. There is potential flooding of the garage floor. The solution proposed is to build a new asphalt concrete berm along the perimeter of the property. Additionally, the property owner should pro -actively maintain the existing on-site drainage system. City of Pismo Beach Chapter 3 Drainage Master Plan 3-24 Specific Site Evaluation C v CITY OF PISMO BEACH - Storm Drain Master Plan Site No. 12: 951 Hanford Street STRA TF -ORD STREET ----------- WADSWORT14 AVE. A. EX. SLEDR401 =L=WANFU0 279EFT JAII, ----1951 HA,�NLII �RD --J &A Y 57R&7 --------- - City of Pismo Beach Drainage Master Plan 3-25 Problem: Runoff flows down an existing driveway and can potentially flood the residence. Solution: 1. Construct asphalt berm around property adjacent to the street 2. Check drainage maintenance schedule. Estimated Cost: $4,470 Chapter 3 Specific Site Evaluation CITY OF PISMO BEACH - Storm Drain Master Plan r r Site No. 13: Detention Ponds Within the Tributary Watershed of Pismo Creek r Pismo Creek conveys stormwater for a portion of the City, including much of the Pismo Heights subdivision. Pismo Creek does not have extra capacity to accommodate increased peak flows. Therefore, the drainage strategy should be to limit or reduce peak flow in the r creek. Pismo Creek has a large watershed area. After a rainfall event there is a lag time of 2.2 hours at the mouth of the creek. The lag time for the Pismo Beach watershed tributary to the creek is 0.5 hours. Because of this difference in lag times, runoff generated within the City tributary to the creek should be conveyed as quickly as possible. The use of detention ponds in this area should be limited, as they tend to delay the local runoff and potentially combine with the peak flow of Pismo Creek. City of Pismo Beach Drainage Master Plan u 3-26 Chapter 3 Specific Site Evaluation CHAPTER 4 f' CAPITAL IMPROVEMENTS The results of this study are presented in this section as the recommended master plan and capital improvement program for storm drain system facilities for the Pismo Heights - and Downtown Area of the City of Pismo Beach. The master plan consists of staged improvements to correct existing deficiencies and for the expansion of the storm drain system. The proposed improvements are needed to correct existing storm drain system deficiencies, and to provide for future development. The proposed improvements should provide the capacity to adequately discharge stormwater runoff at build out. PRIORITIZATION Existing drainage facilities within the City of Pismo Beach were studied and evaluated as described in Chapter 3, "Evaluation of Specific Sites". From these studies, a capital improvement program (CIP) has been developed prioritizing the proposed projects into three categories: High Priority: Projects which are needed to improve existing significant drainage or flooding problems. Medium Priority: Projects which will address drainage problems of less severity. Low Priority: Projects which will address drainage problems of minimal severity that can be constructed in conjunction with future road or development projects. COST ESTIMATES Preliminary project cost estimates have been prepared for the proposed improvements. The costs estimates represent a total project cost appropriate for budgeting purposes. An allowance of approximately 40% has been included in the following unit costs to provide for expenses associated with administration, engineering, surveying, and testing. 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N U N> > a) S a m a m° a m 0 a° m° a m 'o a O) m C O) ` C N Y � a) m a) T 3U �o 3: 36 �33� m m = = In It a` 0) r m o) o) m 3 3 rn •0 S S _0) S S _o) S S J CD a) J S aai IL d m E m N 4 c m FL N m 00 o U � City of Pismo Beach Site 1: Wadsworth Culvert System Phase 1 No. Description POTENTIAL UNIT COSTS TOTAL COSTS Qty I Unit I Cost General Reouirements 1 Mobilization 1 LS $ 3,000.00 $ 3,000.00 2 Traffic Control 1 LS $ 2,000.00 $ 2,000.00 3 Com fiance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 Construction Survey 1 LS $ 2,000.00il $ 2,000.00 Surface Imorovements 5 Class 11 Aggregate Base 6" lift CY $ 65.00 $ 6 Class B Asphalt Concrete 2.5' lift ON $ 65.00 $ 7 Asphalt Concrete Traffic Berm LF $ 15.00 $ 8 Replace ExistingConcrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ Storm Drain System 10 Drop Inlet - 7.0 ft. Curb Opening 4 EA $ 5,000.00 $ 20,000.00 11 Drop Inlet - 10.0 ft. Curb Opening $ EA $ 7,000.00 $ - 12 Drop Inlet -14.0 ft. Curb Opening $ EA $ 9,000.00 $ 23,349.60 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ - 14 Energy Dissa ation Structure 1 EA $ 8,000.00 $ 8,000.00 15 12 -in Pipeline HDPE LF $ 80.00 $ - 16 18 -in Pipeline HDPE LF $ 90.00 $ 17 24 -in Pipeline HDPE 40 1 LF 1 $ 105.00 $ 4,200.00 18 36 -in Pipeline HDPE LF 1 $ 115.0011$ 19 42 -in Pipeline HDPE LF $ 120.00 $ - 20 48 -in Pipeline HDPE 230 1 LF $ 1 130.00 $ 29,900.00 21 48 -in Pipeline (HDPE) Cliff Construction 110 1 LF $ 1 $ 38,500.00 Subtotal $ 108,100.00 construction Estimate $ 129,720.00 Environmental Processing 15% $ 25,000.00 Construction Contingencies 10% $ 12,972.00 Contract Administration 10% $ 12,972.00 Testing 2% $ 2,594.40 Surveying and Design 18% $ 23,349.60 COST AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% Design Contingencies 20% JULY City of Pismo Beach Downtown Drainage Master Plan Environmental Processing Construction Contingencies 10% Contract Administration 15% Testing 2% Surveying and Design 18% 4-14 $2, WAMCE GROUP City of Pismo Beach Site 2: Wadsworth Culvert System Phase 2 General Requirements j No. Description POTENTIAL UNIT COSTS TOTAL COSTS Qty Unit Cost 1 Mobilization 1 1 LS $ 3,000.00 11 $ 3,000.00 2 Traffic Control 1 LS $ 4,000.00 $ 2,000.00 3 Compliance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 Construction Survey 1 LS 1 $ 2,000.00 $ 2,000.00 Surface Improvements I 5 Class 11 Aggregate Base 6" lift CY 1 $ 65.00 $ 6 Class B Asphalt Concrete 2.5" lift TON $ 65.00 $ 7 Asphalt Concrete Traffic Berm LF $ 15.00 $ 8 Replace Existing Concrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ 3 Storm Drain System 1 10 Drop Inlet - 7.0 ft. Curb Opening 4 EA $ 5,000.00 $ 20,000.00 11 Drop Inlet - 10.0 ft. Curb Opening EA $ 7,000.00 $ $ $ 12 Drop Inlet - 14.0 ft. Curb Opening EA $ 9,000.00 $ $2,400.00 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ 18% 14 Energy Dissa ation Structure EA $ 8,000.00 $ 163,000.00 15 12 -in Pipeline HDPE LF $ 80.00 $ 16 18 -in Pipeline HDPE LF $ 90.00 $ - 17 24 -in Pipeline HDPE 150 LF $ 105.00 $ 15,750.00 18 36 -in Pipeline HDPE LF $ 115.00 $ - 19 42 -in Pipeline HDPE LF $ 120.00 $ - 20 48 -in Pipeline HDPE 415 LF $ 130.00 $ 53,950.00 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ - AUGUST 2002 SUBTOTAL Subtotal $97,200.00 $ 97,200.00 $4,400.00 Design Contingencies 20% $ 19,440.00 Construction Estimate Construction Contingencies 10% $ $ 116,640.00 11,664.00 Contract Administration Contract Administration 10% $ 11,664.00 $2,400.00 Testing 2% $ 2,332.80 Surveying and Design 18% $ 20,995.20 TOTAL PROJECT COST $ 163,000.00 AUGUST 2002 SUBTOTAL $97,200.00 AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $4,400.00 Design Contingencies 20% $20,300.00 July 2005 Construction Estimate $121,900.00 Construction Contingencies 10% $12,200.00 Contract Administration 15% $18,300.00 Testing 2% $2,400.00 Surveying and Design 18% $22,000.00 JULY 2005 TOTAL PROJECT COST $176,800.00 City of Pismo Beach Downlown Drainage Master Plan 4-14 WAL CE GROUP City of Pismo Beach Site 3: Wadsworth Culvert System Phase 3 POTENTIAL UNIT COSTS No. Description Qty Unit Cost TOTAL COSTS General Requirements 1 Mobilization 1 LS 1 $ 3,000.00 11 $ 3,000.00 2 Traffic Control 1 LS $ 5,000-001 $ 5,000.00 3 Compliance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 Construction Survey 1 LS $ 2,000.00 1 $ 2,000.00 Surface Improvements 5 Class 11 Aggregate Base 6" lift CY $ 65.00 $ 6 Class B Asphalt Concrete 2.5 lift TON $ 65.00 $ 7 As halt Concrete Traffic Berm LF $ 15.00 $ 8 Replace Existing Concrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ Storm Drain Svstem 10 Drop Inlet - 7.0 ft. Curb Opening 4 EA $ 5,000.00 $ 20,000.00 11 Drop Inlet - 10.0 ft. Curb Opening EA $ 7,000.00 $ - 12 Drop Inlet - 14.0 ft. Curb Opening EA $ 9,000.00 $ Surveying and Design 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ 137,000.00 14 Energy Dissa ation Structure EA $ 8,000.00 $ 15 12 -in Pipeline HDPE LF $ 80.00 $ 16 18 -in Pipeline HDPE LF $ 90.00 $ - 17 24 -in Pipeline HDPE 50 LF $ 105.0011$ 5,250.00 18 36 -in Pipeline HDPE LF $ 115.00 $ - 19 42 -in Pipeline HDPE 380LF $ 120.00 $ 45,600.00 20 48 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ Suototal Design Contingencies 20% $ $ 81,350.00 16,270.00 Construction Estimate $3,700.00 $ 97,620.00 Construction Contingencies 10% $ 9,762.00 Contract Administration 10% $ 9,762.00 Testing 2% $ 1,952.40 Surveying and Design 18% $ 17,571.60 TOTAL PROJECT COST $ 137,000.00 AUGUST 2002 SUBTOTAL $81,350.00 AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $3,700.00 Design Contingencies 20% $17,000.00 July 2005 Construction Estimate $102,050.00 Construction Contingencies 10% $10,200.00 Contract Administration 15% $15,300.00 Testing 2% $2,000.00 Surveying and Design 18% $18,400.00 JULY 2005 TOTAL PROJECT COST $147,950.00 City of Pismo Beach Downtown Drainage Master Plan 4-14 F WWACE GROUP j Site 4: City of Pismo Beach POTENTIAL UNIT COSTS Wadsworth Culvert System Phase 4 JNo. 3,000.00 $ 3,000.00 Description Traffic Control 1 General Requirements j 1 1 Mobilization POTENTIAL UNIT COSTS TOTAL COSTS Qty Unit Cost 1 1 Mobilization 1 LS $ 3,000.00 $ 3,000.00 2 Traffic Control 1 LS $ 2,000.00 $ 2,000.00 3 Com liance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 lConstruction Survey 1 1 LS 1 $ 2,000.00 $ 2,000.00 Surface Improvements j 5 Class 11 Aggregate Base 6" lift CY $ 65.00 $ 6 Class B Asphalt Concrete 2.5 lift TON $ 65.00 $ 7 Asphalt Concrete Traffic Berm LF $ 15.00 $ 8 Replace ExistingConcrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ IStorm Drain System t . 10 Drop Inlet - 7.0 ft. Curb Opening 2 EA $ 5,000.00 $ 10,000.00 11 Drop Inlet - 10.0 ft. Curb Opening 1 EA $ 7,000.00 $ 7,000.00 12 Drop Inlet - 14.0 ft. Curb Opening Testing EA $ 9,000.00 $ - 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ 14 Energy Dissa ation Structure EA $ 8,000.00 $ 15 12 -in Pipeline HDPE LF $ 80.00 $ 16 18 -in Pipeline HDPE LF $ 90.00 $ - 17 24 -in Pipeline HDPE 50 LF $ 105.0011$ 5,250.00 18 36 -in Pipeline HDPE 540 LF $ 115.00 $ 62,100.00 19 42 -in Pipeline HDPE LF $ 120.00 $ - 20 48 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ 1 Subtotal AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. Design Contingencies $4,100.00 Construction Estimate Construction Contingencies 20% Contract Administration July 2005 Construction Estimate Testing $115,950.00 Construction Contingencies Surveying and Design $11,500.00 TOTAL PROJECT COST 10% 10% 2% 18% $ 91,850.00 $ 18,370.00 $ 110,220.00 $ 11,022.00 $ 11,022.00 $ 2,204.40 $ 19,839.60 $ 154,000.00 AUGUST 2002 SUBTOTAL $91,850.00 AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $4,100.00 Design Contingencies 20% $20,000.00 July 2005 Construction Estimate $115,950.00 Construction Contingencies 10% $11,500.00 Contract Administration 15% $17,300.00 Testing 2% $2,300.00 Survevina and Desian 18% $20.700.00 ! City of Pismo Beach Downtown Drainage Master Plan 4-14 WAL CE GROUP V e t Site 5: City of Pismo Beach Wadsworth Culvert System Phase 5 'J No. Description POTENTIAL UNIT COSTS p Qty I Unit I Cost TOTAL COSTS JGeneral Requirements J 1 Mobilization 1 1LS $ $ 3,000.00 $ 3,000.00 2 Traffic Control 1 LS $ 2,000.00 $ 2,000.00 3 Compliance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 Construction Survey 1 LS 1 $ 2.00 1 $ 2,000.00 JSurface Improvements J 5 Class 11 Aggregate Base 6" lift CY $ 65.00 $ 6 Class B Asphalt Concrete 2.5' lift TON $ 65.00 $ 7 Asphalt Concrete Traffic Berm LF $ 15.00 $ 8 Replace Existing Concrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase I CY $ 17.00 $ JStorm Drain System i r J( 10 Drop Inlet - 7.0 ft. Curb Opening 6 EA $ 5,000.00 $ 30,000.00 11 Drop Inlet - 10.0 ft. Curb Opening EA $ 7,000.00 $ - 12 Drop Inlet - 14.0 ft. Curb Opening EA $ 9,000.00 $ 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ - 14 Energy Dissa ation Structure EA $ 8,000.00 $ 15 12 -in Pipeline HDPE LF $ 80.00 $ 16 18 -in Pipeline HDPE LF $ 90.00 $ - 17 24 -in Pipeline HDPE 730 LF $ 105.00 $ 76,650.00 18 36 -in Pipeline HDPE LF $ 115.00 $ 19 42 -in Pipeline HDPE LF $ 120.00 $ 20 48 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF --$-350-00 $ Subtotal $ 114,150.00 Design Contingencies 20% $ 22,830.00 Construction Estimate $ 136,980.00 Construction Contingencies 10% $ 13,698.00 Contract Administration 10% $ 13,698.00 2% $ 2,739.60 JTesting Surveying and Design 18% $ 24,656.40 TOTAL PROJECT COST $ 192,000.00 AUGUST 2002 SUBTOTAL AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. July 2005 Construction Estimate Construction Contingencies Contract Administration Testing Survevina and Desian City of Pismo Beach Downtown Drainage Master Plan 4-14 4.50% 10% 15% 2% 18% $114,150.00 $5,100.00 $23,900.00 $21,500 $2,900 WA WE GROUP I Site 6: City of Pismo Beach Wadsworth Culvert System Phase 6 No. Description POTENTIAL UNIT COSTS TOTAL COSTS Qty I Unit I Cost t;PnPral ReauimmPnts 1 Mobilization 1 1 LS $ 5,000.00 11 $ 5,000.00 2 Traffic Control 1 LS$ 7 4,000.00 $ 4,000.00 3 Compliance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 Construction Survey 1 LS $ 3, 1 $ 3,000.00 Surface Improvements 5 Class 11 Aggregate Base 6" lift CY $ 65.0011$ $ 6 Class B Asphalt Concrete 2.5' lift TON 1 $ 65.00 $ 7 Asphalt Concrete Traffic Berm LF $ 15.00 $ 8 Replace Existing Concrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ Storm Drain Svstem 10 Drop Inlet - 7.0 ft. Curb Opening 5 EA $ 5,000.00 $ 25,000.00 11 Drop Inlet - 10.0 ft. Curb Opening EA $ 7,000.00 $ - 12 Drop Inlet - 14.0 ft. Curb Opening 2 EA $ 9,000.00 $ 18,000.00 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ - 14 Energy Dissa ation Structure EA $ 8,000.00 $ 15 12 -in Pipeline HDPE LF $ 80.00 $ 16 18 -in Pipeline HDPE LF $ 90.00 $ 17 24 -in Pipeline HDPE 1,810 LF $ 105.00 $ 190,050.00 18 36 -in Pipeline HDPE LF $ 115.00 Is - 19 42 -in Pipeline HDPE LF $ 120.00 $ 20 48 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ Subtotal $ 24b,bbUAU Design Contingencies 20% $ 49,110.00 Construction Estimate $ 294,660.00 Construction Contingencies 10% $ 29,466.00 Contract Administration 10% $ 29,466.00 Testing 2% $ 5,893.20 Surveying and Design 18% $ 53,038.80 $ 413,000.00 AUGUST 2002 SUBTOTAL $245,550.001 AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $11,100.00 Desion Contingencies 20% $51.300.00 July 2005 Construction Estimate $307,950.00 Construction Contingencies 10% $30,800.00 Contract Administration 15% $46,200.00 Testing 2% $6,200.00 Surveying and Design 18% $55,400.00 .Y 2005 TOTAL PROJECT COST $446,550.00 City of Pismo Beach Downtown Drainage Master Plan 4-14 City of Pismo Beach Site 7: Longview Street Inlet Upgrade at Merced Street No. Description POTENTIAL UNIT COSTS TOTAL COSTS Qty I Unit I Cost General Requirements 1 Mobilization 1 LS $ 1,000.00 $ 1,000.00 2 Traffic Control 1LS $ $ 500.00 $ 500.00 3 Compliance with OSHA requirements 1 LS $ 560.0011$ 35.00 500.00 4 Construction Survey 1 LS $ 500.00 $ 500.00 Surface Improvements 5 Class 11 Aggregate Base 6" lift CY I $ 65.0011$ $ 5,000.00 6 Class B Asphalt Concrete 2.5 lift TON $ 65.00 $ 7 Asphalt Concrete Traffic Berm LF $ 15.00 $ - 8 Replace Existing Concrete Surface Structures 20 1 LF$ $ 35.00 $ 700.00 9 Re -grade subbase. CY $ 17.00 $ - Storm Drain System 10 Drop Inlet - 7.0 ft. Curb Opening 1 EA $ 5,000.00 $ 5,000.00 11 Drop Inlet - 10.5 ft. Curb Opening EA $ 7,000.00 $ - 12 Drop Inlet - 14.0 ft. Curb Opening EA $ 9,000.00 $ 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ 14 Energy Dissa ation Structure EA $ 8,000.00 $ 15 12 -in Pipeline HDPE LF $ 80.00 $ 16 18 -in Pipeline HDPE LF $ 90.00 $ 17 24 -in Pipeline HDPE LF 1 $ 105.001IS 18 36 -in Pipeline HDPE LF 1 $ 115.00 $ 19142 -In Pipeline HDPE LF $ 120.00 $ 20148 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ auototai Design Contingencies 20% $ $ 8,200.00 1,640.00 Construction Estimate $400.00 $ 9,840.00 Construction Contingencies 10% $ 984.00 Contract Administration 10% $ 984.00 Testing 2% $ 196.80 Surveying and Design 18% $ 1,771.20 TOTAL PROJECT COST $ 14,000.00 AUGUST 2002 SUBTOTAL $8,200.00 AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $400.00 Design Contingencies 20% $1,700.00 July 2005 Construction Estimate 10,300.00 Construction Contingencies 10% $1,000.00 Contract Administration 15% $1,500.00 Testing 2% $200.00 Surveying and Design 18% $1,900.00 JULY 2005 TOTAL PROJECT COST $14,900.00 City of Pismo Beach Downtown Drainage Master Plan 4-14 WMACE GROUP i� City of Pismo Beach Site 8: Bakersfield Storm Drain Extension I� o. Description General Requirements N Mobilization POTENTIAL UNIT COSTSTOTAL COSTS Qty Unit Cost 1 Mobilization 1 I LS 1 $ 1,000.00-11 $ 1,000.00 2 Traffic Control 1 LS $ 1,000.00 $ 1,000.00 3 Compliance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 Construction Survey 1 1 LS $ 500.00 $ 500.00 1 Surface improvements j 5 Class 11 Aggregate Base 6" lift CY $ 65.00 $ 6 Class B Asphalt Concrete 2.5' lift TON $ 65.00 $ 7 Asphalt Concrete Traffic Berm LF $ 15.00 $ 8 Replace Existing Concrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY 1 $ 17.00 $ -, Storm Drain System i . k 10 Drop Inlet - 7.0 ft. Curb Opening 1 EA $ 5,000.00 $ 5,000.00 11 Drop Inlet - 10.5 ft. Curb Opening EA $ 7,000.00 $ - 12 Drop Inlet - 14.0 ft. Curb Opening 1 EA $ 9,000.00 $ 9,000.00 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ - 14 Energy Dissipation Structure EA $ 8,000.00 $ 15 12 -in Pipeline HDPE LF $ 80.00 $ - 16 18 -in Pipeline HDPE 270 LF $ 90.00 $ 24,300.00 17 24 -in Pipeline HDPE LF $ 105.00 $ - 18 36 -in Pipeline HDPE LF $ 115.00 $ 19 42 -in Pipeline HDPE LF $ 120.00 $ 20 48 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ ■ Subtotal $ 41,300.00 Design Contingencies 20% $ 8,260.00 Construction Estimate Construction Contingencies 10% $ $ 49,560.00 4,956.00 Contract Administration 10% $ 4,956.00 Testing Surveying and Design 2% 18% $ $ 991.20 8,920.80 TOTAL PROJECT COST $ 69,000.00 AUGUST 2002 SUBTOTAL $41,300.00 AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $1,900.00 Design Contingencies 20% $8,600.00 July 2005 Construction Estimate 51,800.00 Construction Contingencies 10% $5,200.00 Contract Administration 15% $7,800.00 Testing 2% $1,050.00 Surveyinq and Design 18% $9.300.00 a City of Pismo Beach Downtown Drainage Master Plan 4-14 —, WAUACE GROUP I r I City of Pismo Beach Site 9: Intersection of Selma and Lemoore Streets J No. Description General Requirements J 1 IMobilization POTENTIAL UNIT COSTS TOTAL COSTS Qty Unit Cost 1 IMobilization 1 LS 1 $ 2,000.00 $ 2,000.00 2 Traffic Control 1 LS $ 1,000.00 $ 1,000.00 3 Com liance with OSHA re uirements 1 LS $ 500.00 $ 500.00 4 lConstruction Survey 1 LS 1 $ 1,000.00 $ 1,000.00 JSurface Improvements J 5 Class 11 Aggregate Base 6" lift CY $ 65.00 $ 6 Class B Asphalt Concrete 2.5" lift TON $ 65.00 $ 7 Asphalt Concrete Traffic Berm 60 LF $ 15.00 $ 900.00 8 Replace Existing Concrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ JStorm Drain System J J 10 jDrop Inlet - 7.0 ft. Curb Opening EA $ 5,000.00 $ - 11 Drop Inlet - 10.5 ft. Curb Opening 1 EA $ 7,000.00 $ 7,000.00 12 Drop Inlet - 14.0 ft. Curb Opening EA $ 9,000.00 $ - 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ 14 Ener y Dissipation Structure EA $ 8,000.00 $ 15 12 -in Pipeline HDPE LF $ 80.00 $ - 16 18 -in Pipeline HDPE 180 LF $ 90.00 $ 16,200.00 17 24 -in Pipeline HDPE LF $ 105.00 $ - 18 36 -in Pipeline HDPE LF $ 115.00 $ 19 42 -in Pipeline HDPE LF $ 120.00 $ 20 48 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction S $ 350.00 $ Subtotal Design Contingencies Construction Estimate Construction Contingencies Contract Administration Testing Surveying and Design TOTAL PROJECT COST J AUGUST 2002 SUBTOTAL AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. Design Contingencies July 2005 Construction Estimate Construction Contingencies Contract Administration Testing Survevinq and Design JCity of Pismo Beach Downtown Drainage Master Plan 4-14 $ 28,600.00 $ 5.720.00 10% $ 3,432.00 10% $ 3,432.00 2% $ 686.40 18% $ 6.177.60 4.50% 20% $28,600.00 $1,300.00 $3,600.00 $5,400.00 $700.00 wntuce GROUP City of Pismo Beach Site 10: Price Canyon Culvert No. Description POTENTIAL UNIT COSTS TOTAL COSTS Qty Unit Cost General Requirements 1 IMobilization 1 1 1 LS $ 1,000.00 11 $ 1,000.00 2 TrafficControl 1 LS $ 1,000.00 $ 1,000.00 3 Com liance with OSHA requirements 1 LS $ 500.00 $ 500.00 4 lConstruction Survey 1 LS 1 $ 500.00 $ 500.00 Surface Improvements 5 Class 11 Aggregate Base 6" lift CY I $ 65.00 $ 6 Class B Asphalt Concrete 2.5 lift TON $ 65.00 $ 7 Asphalt Concrete Traffic BermLF EA $ 15.00 $ 8 Replace ExistingConcrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ Storm Drain Svstem 10 Drop Inlet - 7.0 ft. Curb Opening EA $ 5,000.00 $ 11 Drop Inlet -10.0 ft. Curb Opening EA $ 7,000.00 $ 12 Drop Inlet - 14.0 ft. Curb Opening EA $ 9,000.00 $ 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ - 14 Energy Dissipation Structure 1 EA $ 8,000.00 $ 8,000.00 15 12 -in Pipeline HDPE LF $ 80.00 $ - 16 18 -in Pipeline HDPE LF $ 90.00 $ 17 24 -in Pipeline HDPE LF $ 105.00 1 $ 18 36 -in Pipeline HDPE LF $ 115.00 $ 19 42 -in Pipeline HDPE LF $ 120.00 $ 20 48 -in Pipeline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ Subtotal Design Contingencies 20% $ $ 11,000.00 2,200.00 Construction Estimate $500.00' $ 13,200.00 Construction Contingencies 10% $ 1,320.00 Contract Administration 10% $ 1,320.00 Testing 2% $ 264.00 Surveying and Design 18% $ 2,376.00 TOTAL PROJECT COST $ 18,000.00 AUGUST 2002 SUBTOTAL $11,000.00', AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $500.00' Design Contingencies 20% $2,300.00 July 2005 Construction Estimate 13,800.00 Construction Contingencies 10% $1,400.00 Contract Administration 15% $2,000.00 Testing 2% $300.00 Surveying and Design 18% $2,500.00 JULY 2005 TOTAL PROJECT COST $20,000.00 City of Pismo Beach Downtown Drainage Master Plan 4-14 WAQ CE GROUP City of Pismo Beach Site 11: Intersection of Park Avenue & Cypress Street No. Description General Requirements 1 Mobilization POTENTIAL UNIT COSTS TOTAL COSTS Qty Unit Cost 1 Mobilization 1 1 LS $ 3,000.00 11 $ 3,000.00 2 Traffic Control 1 LS $ 2,000.00 11 $ 2,000.00 3 Compliance with OSHA requirements 1 LS 1 $ 500.Qqjj $ 500.00 4 Construction Survey 1 LS 1 $ 2,000.00 11 $ 2,000.00 Surface Improvements 5 Class IIAggregate Base 6" lift CY $ 65.00 $ 6 Class B As halt Concrete 2.5" lift TON $ 65.00 $ 7 As halt Concrete Traffic Berm LF $ 15.00 $ 8 Re lace ExistingConcrete Surface Structures LF $ 35.00 $ 9 Re -grade subbase CY $ 17.00 $ ■ Storm Drain System 10 Drop Inlet - 7.0 ft. Curb Opening 6 EA $ 5,000.00 $ 30,000.00 11 Drop Inlet - 10.0 ft. Curb Opening EA $ 7,000.00 $ - 12 Drop Inlet - 14.0 ft. Curb Opening EA $ 9,000.00 $ - 13 Drop Inlet - 21.0 ft. Curb Opening EA $ 14,000.00 $ - 14 Energy Dissipation Structure EA $ 8,000.00 $ - 15 12 -in Pipeline HDPE LF $ 80.00 $ - 16 18 -in Pipeline HDPE LF $ 90.00 $ - 17 24 -in Pipeline HDPE 610 LF 1 $ 105.00 $ 64,050.00 18 36 -in Pipeline HDPE LF $ 115.00 $ 19 42 -in Pipeline HDPE LF $ 120.00 $ 20 48 -in Pi eline HDPE LF $ 130.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 350.00 $ i j $ 101,550.00 20% 10% $ Subtotal 10% Design Contingencies 12,186.00 2% Construction Estimate 2,437.20 18% Construction Contingencies 21,934.80 Contract Administration $ 171,000.00 Testing 15% $19,100.00 Surveying and Design 2% TOTAL PROJECT COST Surveying and Design 18% i j $ 101,550.00 20% 10% $ 12,186.00 10% $ 12,186.00 2% $ 2,437.20 18% $ 21,934.80 Construction Contingencies $ 171,000.00 AUGUST 2002 SUBTOTAL $101,550.00 AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. 4.50% $4,600.00 Design Contingencies 20% $21,200.00 July 2005 Construction Estimate $127,350.06 Construction Contingencies 10% $12,700.00 Contract Administration 15% $19,100.00 Testing 2% $2,600.00 Surveying and Design 18% $22,900.00 JULY 2005 TOTAL PROJECT COST $184,650.00 City of Pismo Beach Downtown Drainage Master Plan 4-14 t n CY City of Pismo Beach L Site 12: 951 Hanford Street t Class B As halt Concrete 2.5' lift ntrol 1 LS $ 200.00 $ No. Description ETraffic e with OSHA re uirements 1 LS 1 General Requirements A TOTAL COSTS II Surface Improvements 5 n CY $ 6 Class B As halt Concrete 2.5' lift ntrol 1 LS $ 200.00 $ 200.00 TON ETraffic e with OSHA re uirements 1 LS 1 $ 200.00 $ 200.00 $ on Survey LS500.00 9 Re -grade subbase $ 500.00 35.00 $ 1 LS $ 500.00 $ 500.00 II Surface Improvements 5 Class II A re ate Base 6" lift CY $ 6 Class B As halt Concrete 2.5' lift Construction Estimate 65.00 $ 7 As halt Concrete Traffic Berm TON $ 65.00 $ 8 Re lace Existin Concrete Surtace Structures 70 LF $ 15.00 $ 1,050.00 9 Re -grade subbase LF $ 35.00 $ 15 12 -in Pi eline HDPE EA $ 8,000.00 $ IStorm Drain System 10 Dro Inlet - 7.0 ft. Curb O enin EA $ 11 Dro Inlet - 10.0 ft. Curb O enin Construction Estimate 5,000.00 $ 12 Dro Inlet - 14.0 ft. Curb Cleening EA $ 7,000.00 $ 13 Dro Inlet - 21.0 ft. Curb Opening EA $ 9,000.00 $ 14 Ener Dissi ation Structure EA $ 14,000.00 $ 15 12 -in Pi eline HDPE EA $ 8,000.00 $ 16 18 -in Pi .line HDPE LF $ 80.00 $ 17 24 -in Pi eline HDPE LF $ 90.00 $ 18 36 -in Pi eline HDPE LF $ 105.00 $ 19 42 -in Pi eline HDPE LF $ 115.00 $ 20 48 -in Pi eline HDPE LF $ 120.00 $ 21 48 -in Pipeline (HDPE) Cliff Construction LF $ 130.00 $ JULY 2005 TOTAL PROJECT COST S bt U otai Design Contingencies 20% $ $ 2,450.00 490.00 Construction Estimate $ 2,940.00 Construction Contingencies 10% $ 294.00 Contract Administration 10% $ 294.00 Testing 2% $ 58.80 Surveying and Design 18% $ 529.20 TOTAL PROJECT COST $ 4,000.00 AUGUST 2002 SUBTOTAL AUGUST 2002 TO JULY 2005 ENR COST INDEX AVG. $2,450.00 Design Contingencies 4.50% 20% $110.00 JUIy 2005 Construction Estimate $500.00 Construction Contingencies 10% 3,060.00 Contract Administration 15% $300.00 $500.00 Testing 2% $60.00 Surveying and Design 18% $550.00 JULY 2005 TOTAL PROJECT COST $4,470.00 City of Pismo Beach Downtown Drainage Master Plan 4-14 �� r WAMACE GROUP CHAPTER5 DRAINAGE WATER QUALITY Storm water runoff is part of a natural hydrologic process. However, human activities, both during and after construction, can alter natural drainage patterns, adding pollutants to rivers, lakes, and streams. BEST MANAGEMENT PRACTICES Municipalities typically address these concerns through the establishment of Best Management Practices (BMP) that relate to the issues of stormwater runoff and water quality. As described by the Environmental Protection Agency (EPA), Best Management Practices are directed towards five categories. These areas are described below along with the associated practices the City is recommended to follow: PUBLIC EDUCATION AND OUTREACH • Conduct informational presentations or distribute literature to the public to increase their awareness of the impacts of storm water pollution. ILLICIT DISCHARGE DETECTION AND ELIMINATION • Install informational signs at stormwater inlets and along drainage ways to increase public awareness of illegal dumping. • Require inspection of construction and development sites to prevent connections to the drainage system from non-stormwater systems. CONSTRUCTION SITE STORMWATER RUNOFF CONTROL • Require erosion control and sedimentation plans for all grading projects. • Require applicants for projects which disturb more than one acre of land to obtain a Storm Water Pollution Prevention Permit (SWPPP) from the California State Water Quality Control Board prior to approval of a grading permit. POST -CONSTRUCTION STORMWATER MANAGEMENT • Require property owners to maintain private drainage infrastructure after construction. Required activities should include street sweeping, cleaning of drop inlets, and removal of silt and debris from basins. Require project design to provide for maintenance access and disposal procedures. City of Pismo Beach DRAINAGE MASTER PLANChapter 5 5-1 Drainage Water Quality POLLUTION PREVENTION FOR MUNICIPAL OPERATIONS Continue existing maintenance programs for public areas and properties, including street sweeping and cleaning of drop inlets. • Establish schedules and procedures for maintaining stormwater inlet filters. • Require that developers utilize sound engineering practices in the design of drainage facilities through the implementation of existing City standards. A list of erosion and sedimentation mitigation control practices have been included in this chapter as guidelines during construction. r City of Pismo Beach Chapter 5 DRAINAGE MASTER PLAN 5-2 Drainage Water Quality pulpa': -1 e•nl poraI'v devices constructed around ;term drain, improve IIIc gnalirr of ware' being discharged to inlets or catch basin. ht- pondirn� sediment-lad(n runolf and increasing s(tding rime. A1lpropriare for small drainage arras onh. 1 pplirdtr.:Ic > \Vhcrr sediment laden sur15cc runot} plat' enter an tiller. > Where dl ainng areas have not been pernlanentiv stabilized. > \VIIcle the dr.1inaoc arca is 11.4 ha 1 ac nr les, > Appropriate during wet seasons. > Appropriate in open areas :uhjr:t to sheet Ilo1 .Ind I -,r flows not cweed- 111.,0-014 nr'i, 0.5 :f,,. > Block and oravel bag, barriers are apphc.lble tthcn sheet flows ol. cl,ucrn- tared flow, eSC(ed 0,01-1 n1' %s,0.5 iIS .'111d it IS Ilccc S' ;In to ,plow fol' overn?ppin,. to prevent flooding. > Gsc vawd drop inlet sediment taps arc appropriare inhere rclarn'clt' heart Ilox" arc exlxtitsd and overflow cap.lhilin is needed. l urrtonari' A Use only' when ponding will nor encroach incl hi, hwat' traffic or ,nto erodible sit] face. and slop(,. R Sedinn•nr renewal becomes note diffictllt m high flow Conditions. If' high 11111 condirions are rsp(crrd. nlher on-site snfimcnr rrappmg Iedulique, should be t,cd til cvxljuncrlon vrirh iulel plow Clioo. A 1 regncnl nl.linlcnancc i, required to minimize short-cirnliting .Ind to rcnulre s(dinlent dcposio and htildul,. City of Pismo Beach Drainage Master Plan 5-3 Chapter 5 Drainage Water Quality It City of Pismo Beach Drainage Master Plan 5-4 Chapter 5 Drainage Water Quality J J J A For drainage area, larger Than 0.4 ha I :IC:. runoAr;huuld be routed to a sediment napping device designed for larger floes. A Filter 4abric Should not be used to cover clic inlet orarc. 6iSprdron anti tiring the disrurbed area to ncc grade of rhe drop inler and smooth and ,Flumt,mrn�c compact it. Appropriarels'stabilize all bare AICIS erouud rhe inlet. Properly disposr of acetunuLned sediment. Inspect all inlet protection dericvs before and nicer rainfall events. and weekh' throughout the rainy Benson. Daring extended rainfall events. insrcct inlet protection drviccs at lea>I once cvcry 24 hours. Demme all inlet pron•crion devices within ihirn days after the >ne is sra- hilized. or when inlet protecrion i., no longer regUilCd. City of Pismo Beach Drainage Master Plan FILTER RUNOFF WATER WITH OVERFLOW FILTERED SEDIMENT WATER 7�'� .-. ' 1 illi �■ SEDIMENT ,r WIRE SCREEN \!MCU2B CROSS-SECTION INLET 5-5 Chapter 5 Drainage Water Quality Pminsr Slaw bales air rc llylolan' barriers aldiidi are ennrndied. anchoied.:md installed end a) Old across or at the rex of a slope. tivatt bale barflCIN :at'e toed ru intercept ;uhd renin sediment in storm atater nmoft from unprotected areas be Wdun111_1 ri le velvcin' of sheet lloxN� and reetinink sedinn'nt behind the barna'. Applinnnw: > Alono the penmen•[ of the site. Beneath flat areas which haat_ been disturbed and are subject to sheet and rill erosion. Anrallauar+ Slopes 50:1 :T',, or llatttr art Ill tcrrnl. If the slope c arcs 10:1 Cludrlinn: :; 104L.the Itrnrh of slope upsu'eam of rhe harrier mist Le Ics than LS m 50 11 Limir rhe drainake arca upsnram of the straw bale b:vriers m ll. ha/ 100 m: 0.2 5 ac i' 100 1 i :. Limit the slope Ieng tL draining to rhe [':artier Io , 0 m [ 100 ft l.irnitalien.s: A Limit the use to COn511'tlelioil activities that can Le completed in less [11.111 three months. A 00 not use in pa1'ed arra. or in arras 11111+"-( to cona:nn'ared flow. chan- nel flow. or in live snram,. Gulre,troa and Inspect after each siunificant rarnhall elrnt..rnd d.uhdl pIoloI sa)rnr ;1laintnntnrr, earnrs. Remove sediment lvhen accunndarrom reach 1 j3 bean•[ hci,ht. Remove straw bale dikes tahcn no lonoer nocrssart. t City of Pismo Beach Chapter 5 Drainage Master Plan 5-6 Drainage Water Quality r �S F� 4h Purptar: S.e l r M�Mss� N A silt Ince is it rentporare barrier of permeable fil6ric desicn ed to interceln _ and slots the flow of sedisrent laden shCCt holy runoll. Silt Ii•ncin11 ponds runoll. allows sediment to sctde. and releases 61rered hater ,IoNvll. Applhahen: > :Alonti rile perimeter of the site. > A10110, streams and challnclo , NOT dn'os snrams and damrrls . - > Lt low the we of exposed and erodible slopes. IAX,vnslopc Of Cspo.cd soil areas. > Around temporary oil srockpiles. :I pl,lrtation Aust be ionsn'licred a1011�1 .1 level contour or XVIII result in rhe ireatlUn -- Gwdrhnr:: of rills and � tellies and tonsnlurnr IailurC. Limit tributary draina,,C arra upsnr;nn ol- the silt fence to less than 0.3 Ila/ I00m0.25 1(/100It:of fence. Limit rile Ienkrh of slope draisin� to ally point along the silt fence to _ 3011, , 100 It i or less. "» 1-illlit length of any sim•le run of ICnee to 150111 500 ft . burn the Iasi 6 feet of ICniC up slope 111 "J" or •I: •shapes to allow for _ pondin,*. Silt Icncill, must pond runo(( to be Cflccriyc. 14•ntc C Tlllcsts should nor be tonnetted. Limit to locations suitable for rcs,porarX ponds,,• or deposition of NO,& stent. _ bijutanCns: A I)o not list- in streams. channels. or anN.Xvhnr Ilow is ct,n:rnn:uctl. A Do nor a>e silt knee to ,elven Ilow. A Iht not use silt Irmo on slol,Cs. City of Pismo Beach Chapter 5 Drainage Master Plan 5-7 Drainage Water Quality APPENDIX A DRAINAGE DEFINITIONS 1. Control Structure: A facility constructed to regulate the rate of discharge of storm water 2. Development: r Any man-made change to real estate or property, inlcuding buildings or other structures, streets, parking lots, mining, dredging, filling, grading, paving or excavating 3. Easement: Authorization by a property owner for use by another party or parties of all or any portion of his/her land for a specified purpose 4. Infiltration Basin: A volume designated to permanently accumulate excess storm water runoff 5. Natural Drainage: Waterwhich flows by gravity in channels formed bythe surface topography of the earth prior to changes made by the efforts of man C. Natural State: Land with soil and vegetation conditions that existed prior to any man-made activity on the land 7. Overland Escape Path: An open channel or swale design as an emergency coridor for storm water runoff if the design conveyance structures are exceeded or become partially plugged C. Retarding Basin: A volume designated to temporarily accumulate excess storm water runoff 9. Safe Storm Water Drainage Capacity: The quantity of storm water runoff that can be transported within a channel, passage, conduit, tube, duct, or a combination of these facilities in such a manner that the elevation of the water does not rise above the level of the adjacent ground surface so as to cause any damage to structures or facilities located thereon 10. Storm Water Management System: All facilities used to control storm water including storm water pipes, storm water retardation areas, berms, channels, swales, control structures, easements, overland escape passages, irrigation systems, improved watercourses, and any other facility or appurtenances used in the management of storm water City of Pismo Beach Appendix A Drainage Master Plan Drainage Definitions r d 11. Storm Water Runoff: Water that results from precipitation which is not absorbed by the soil, evaporated into the atompshere, or entrapped by ground surface depressions and vegetation, and which flows over the ground surface 12. Storm Water Runoff Release Rate: The rate (quantity per unit of time) at which storm water runoff is released from upstream to downstream land 13. Tributary Watershed: The entire catchment area that contributes storm water runoff to a given point 14. 10 -year Storm: A storm event that has a 10% chance of being reached or exceeded in any given year 15. 25 -year Storm: _ A storm even that has a 4% chance of being reached or exceeded in any given year 16. 100 -year Storm: A storm event that has a 1 % chance of being reached or exceeded in any given year City of Pismo Beach Appendix A Drainage Master Plan Drainage Definitions APPENDIX B PRELIMINARY RUNOFF CALCULATIONS The following drainage calculations refer to the Tributary Watershed Areas of Figure B-1. Wadsworth Culvert System Watershed: -The Wadsworth Street watershed area incorporates 83 acres from the beach to the top of the Pismo Heights subdivision as seen while studying the runoff pattern along Wadsworth. We concluded deficient collection of surface runoff at the following intersections with Wadsworth Avenue: at Longview Avenue, Price Street, and Dolliver Street. Concurrently, large storm flows are dispersed causing flood concern in areas tributary to these streets. -To improve surface runoff collection, we propose the Wadsworth Culvert System extending from the beach at Cypress Street to Longview Avenue. In addition, an arm to this culvert system is proposed on Bello Street to collect runoff that bypasses Wadsworth Avenue and flows down Price and Dolliver Streets to the downtown vicinity. Phases 2 through 6 would contribute to the flood control of the down town Pismo Beach area, while Phase 1 would solve difficult construction and permitting issues. In order to provide a uniform drainage system in the County of San Luis Obispo, flow computations for all open and closed conduits are made with the Manning's Formula with conduits flowing 75% full; and hydrologic computations were made with the Rational Method which is described as follows: RATIONAL METHOD -The Rational Method is a simple hydrology equation that includes basic runoff factors as: area, rainfall intensity, and percentage of rainfall resulting in runoff. The typical Rational Formula is: Q=CIA where: Q = discharge (rate of flow) in cubic feet per second(cfs) C = runoff coefficient (dimensionless) i = rainfall intensity (in/hr) A = area of the watershed (acres) Some basic limitations for use of the Rational Method for discharge determination are: (1) the watershed area should not exceed about 0.5 square miles (320 acres); (2) the peak City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations discharge on the runoff hydrograph is assumed to occur at a time equal to the duration of the storm. Area (A) the tributary area of the watershed expressed in acres. This tributary area is measured on the ground, from scaling contour maps, or scaling aerial photographs. Rainfall Intensity (i) is a function of the duration of the storm expressed in inches per hour for some specified return interval (storm frequency) and assumed to be the equal to the time of concentration for runoff. The rainfall intensity is derived from an intensity -du ration - frequency curve from the County of San Luis Obispo. Time of Concentration (tc) is the time of travel from the most remote part of the watershed to the outfall of the watershed. This time is measured by estimating average runoff velocities over the course of travel. The engineer will use guide tables, charts, references, and experience to estimate realistic flow velocities. Since the drainage facility to be designed should have some anticipated service life, the estimate of the velocity of runoff in the watershed must include consideration of the future watershed character. Determining tc may involve the division of length of travel through different areas of travel, since areas within the same watershed may exhibit varying types of ground cover, channel characteristics and slopes. Therefore, the engineer will develop a composite time of concentration. The County of San Luis Obispo recommends a minimum tc of ten (10) minutes for areas with slopes equal to, or flatter than ten (10) percent, and five (5) minutes for steeper slopes without surface storage. Runoff Coefficient (C) is a percentage of runoff resulting from a rainfall after many abstractions. The most important abstractions included in determining runoff coefficients for a rainfall event include: Infiltration, essentially the percolation of water into the soil; - interception, the initial "wetting" process by the rainfall; - evaporation, the return of water in the form of vapor to the atmosphere; - transpiration, water vapor released by vegetation into the atmosphere; - depression storage, intercepted accumulations of water (ultimately infiltrated or evaporated) - detention storage, the interim storage of runoff water in channels, sheet flow, etc. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Based upon an initial assumption in the Rational Method that storm runoff can be represented by a constant percentage of the precipitation intensity, the designer must assign a single relative percentage (the runoff coefficient'C') for each quantifiable segment of the watershed or the watershed as a whole based upon a consideration of current and future conditions. This simplistic assumption is for convenience of using the Rational Formula and tends to over-estimate the runoff from smaller, more frequent storms. The runoff coefficient assignment is a subjective exercise. While many guide charts and tables are available, the designer must decide how to characterize the watershed segment in question so that the characterization reasonably and adequately describes the land use, ground cover, vegetation, and other topographic features. That characterization must also correlate to descriptions which might be found in charts and tables of suggested runoff coefficients. A table of suggested runoff coefficients applicable in developed watersheds is found at the end of this appendix in exhibit D-2. -rhe presence of moisture in the soil (antecedent moisture conditions, or AMC) can significantly affect the amount of infiltration. The Rational Method does not really It accommodate this characteristic. If antecedent moisture conditions are assumed, soil infiltration will decrease, and the value for C, should be increased to as much as 0.16. Just as in the estimation of time of concentration, the assignment of an estimated runoff coefficient requires careful consideration of the future character of the watershed. Of course, as with so many things, experience is the best guideline for this activity. The Coefficient of Runoff was chosen as 0.65 in the Pismo Heights areas east of the freeway based upon the steep slopes greater than 10%, clay soil, and 6,000 Square Foot residential lots (see exhibit D-2 at the end of this appendix). The runoff coefficient on the west side of the freeway was chosen to be 0.65 based on the slope between 2% & 10%, on clay soil, with mixed commercial and apartments. San Luis Obispo County Specifications shows Pismo Beach receives 14 to 18 inches of rainfall annually and thus uses the Rainfall Intensity Duration Curve from County Specifications D-5. These documents are included at the end of this appendix. Combining the Time of Concentration nomograph (county specification D-3) with the Rainfall Intensity Duration Curves, the Intensity of each storm event was found. The intensity for each Rational Equation is as follows: i(10) = 2.2 in/hr i(25) = 2.5 in/hr i(100) = 3.2 in/hr -rhe initial decision about level of effort and degree of protection desired, determined that a storm drain system, meeting engineering criteria based upon a 25 -year frequency storm r will provide an acceptable level of protection. A 25 -year storm is appropriate if combined with conservative drainage structure sizing to mitigate heavy flooding. i City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations I "The Area component (A) in the Rational Method is determined by the existing tributary watershed area for each individual site. The curb opening inlets were placed based on the strategic locations to best intercept the runoff as it crosses major intersections. Gutter flow spread across the street and travel lanes will be determined during the actual design of each site; and more accurate inlet placement will occur when topographic surveying is included. The curb opening inlets are sized based on the form of the curb opening inlet in the Pismo Beach City Standard Detail 303, and assumed street sections with the following parameters: 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.016 = Manning's N (Part concrete, part asphalt) 5 inches = Drop Inlet Depression 18 feet = Width From Flowline to Crown 0.02 = Cross Slope of the Street The following computations are based on estimations of surface structures and topography. More accurate computations should be made when these sites are designed. City of Pismo Beach Drainage Master Plan Appendix B Preliminary Runoff Calculations Site No. 1: Wadsworth Culvert System at Cypress Street—Phase 1 t Cypress Street at the end of Wadsworth. l Tributary area: J 1) There is a direct 67.8 acre watershed at the intersection of Wadsworth and Cypress J (Drainage Area 3, 4 ,5, and 6 of Figure 13-1), less the amounts that are dispersed at the J intersections of Wadsworth & Price and Wadsworth & Dolliver. 1 Portions of the runoff values listed below will be conveyed to the Wadsworth & Cypress intersection. _Q(10) _ (0.65)(2.2)(67.8) = 97.0 cfs j 0(25) _ (0.65)(2.5)(67.8) = 110.2 cfs 1 Q(100) _ (0.65)(3.2)(67.8) = 141.0 cfs Portions of the runoff values listed below will be conveyed to the Wadsworth & Price intersection. Q(10) _ (0.65)(2.2)(15.2) = 21.8 cfs Q(25) _ (0.65)(2.5)(15.2) = 24.7 cfs Q(100) _ (0.65)(3.2)(15.2) = 31.6 cfs The above mentioned additional runoff to this site refers to the possibility that no otherwork will be performed beyond the Wadsworth Culvert System (WCS), and maximum overflow from other watershed areas will theoretically be collected here. However, if improvements are made at Sites 2, 3, 4, 5, & 6, the estimated runoff can be computed as follows: 24.3 CFS - Site 2 24.0 CFS - Site 3: 19.7 CFS - Site 4: 31.OCFS -Site 5: 23.5 CFS - Site 6: 122.5 CFS - Total collected from the above mentioned storm drainage sites. (110.2 CFS W.C.S.) + (24.7 CFS Sites 7&8) - (122.5 CFS collected) = 12.4 CFS to be collected by Site 1. If the complete Wadsworth Culvert System is built, most of the runoff will be collected by the time it reaches Site 1. However it is still recommended to use three curb opening inlets to catch runoff from all different directions and as a conservative catch-all before finally discharging over the cliff at the end of Cypress Street. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations J Curb Opening Inlet—Estimated Road Section ` 6 inches =Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.03 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street A 7 -foot opening will collect 4.3 CFS with a runoff 4.3 inches deep at the gutter flowline. 3 inlets x 4.3 CFS = 12.9 CFS 12.9 CFS > 12.4 CFS: OK Pipe Flow for a Q(25) = 110.6 + 24.7 = 134.9 CFS See the next page for a report of the pipe characteristics for 134.9 CFS flowing through the culvert. City of Pismo Beach Drainage Master Plan W Appendix B Preliminary Runoff Calculations Site No. 2: Wadsworth Culvert System at Dolliver Street—Phase 2 1. Intersection of Wadsworth & Dolliver. Tributary area: 1) There is a direct 60.2 acre watershed at the intersection of Wadsworth and Dolliver (Tributary Watershed Areas 3, 4, 5 ,6, and a portion of Area 1), less the amount that is dispersed at the intersections of Wadsworth & Price. The only way to effectively and economically collect this runoff is to implement all the phases of the Wadsworth Culvert System. Portions of the runoff values listed below will be conveyed to the Wadsworth & Dolliver intersection. Q(10) = (0.65)(2.2)(60.2) = 86.1 cfs Q(25) = (0.65)(2.5)(60.2) = 97.8 cfs Q(100) = (0.65)(3.2)(60.2) = 125.2 cfs Portions of the runoff values listed below will be conveyed to the Wadsworth & Price intersection. Q(10) = (0.65)(2.2)(15.2) = 21.8 cfs Q(25) = (0.65)(2.5)(15.2) = 24.7 cfs Q(100) = (0.65)(3.2)(15.2) = 31.6 cfs (97.8 CFS W.C.S.) + (24.7 CFS Pismo Hts.) = 122.5 CFS discharge at Site 2 The above mentioned runoff to this site refers to the possibility that no other work will be performed beyond the Wadsworth Culvert System, and maximum overflow from other watershed areas will theoretically be collected here . However, if improvements are made at Sites 3, 4, 5, & 6, the estimated runoff can be computed as follows: 24.0 CFS - Site 3: 19.7 CFS - Site 4: 31.0 CFS - Site 5: 23.5 CFS - Site 6: 98.2 CFS - Total collected from the above mentioned tributary watershed areas. 122.5 CFS - 98.2 CFS = 24.3 CFS to be collected iThe bypassed runoff from sites 3, 4, 5, & 6 are estimated to culminate at this site, either from Wadsworth Avenue or Dolliver Street. The excess runoff is incorporated in the 122.5 J CFS peak flowrate computed above. Sites with runoff in excess of their inlet capacities are discussed in their respect site analysis in this appendix. I JCity of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations I Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.03 (ft / ft) = Gutter Slope 0.017 = Manning's N 5 inches = Drop Inlet Depression 18 feet = Width From Flowline to Crown 0.02 = Cross Slope of the Street A 7 -foot opening will collect 6.2 CFS with a runoff depth 5.5 inches at the gutter flowline. 4 inlets x 6.2 CFS = 24.8 CFS 24.8 CFS > 24.3 CFS: OK See the next page fora report of the pipe characteristics for 122.5 CFS flowing through the culvert. City of Pismo Beach Drainage Master Plan Appendix B Preliminary Runoff Calculations i Site No. 3: Wadsworth Culvert System at Price Street—Phase 3 (_ Intersection of Wadsworth & Price. Tributary area: 1) There is a direct 15.0 acre water shed at Bello & Wadsworth (A portion of Drainage Area 4 of Figure B-1). Q00) _ (0.65)(2.2)(15.0) = 21.5 cfs Q(25) _ (0.65)(2.5)(15.0) = 24.4 cfs Q(100) _ (0.65)(3.2)(15.0) = 31.2 cfs Curb Opening Inlet It is estimated that half of the runoff flows to each of the two curb inlets at San Luis Avenue. Curb Opening Inlet—Estimated Road Section 6 inches= Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.03 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches = Drop Inlet Depression 18 feet = Width From Flowline to Crown 0.02 = Cross Slope of the Street A 7 -foot opening will collect 6.0 CFS with a runoff depth of 6.0 inches at the gutter flowline. 4 inlets x 6.0 CFS = 24.0 CFS 24.0 CFS < 24.4 CFS: Let by-pass 0.4 CFS The intersection at Price Street will most likely collect runoff from other watersheds that bypassed their respective inlets. Those deficits from Sites 4, 5, & 6 can be collected here at site 3, if bigger inlets are constructed. The following paragraphs will discuss the additional flow. Additional flow: 1) The storm run-off from Drainage Area 5 of Figure B-1 is collected at the end of San Luis Avenue on the East side of High Way 101 and is conveyed to the West side of the High Way. The storm run-off outlets onto San Luis Avenue and travels to the intersection of Price & San Luis Avenue. There is a bubbler system designed to convey storm flow under Price street and down San Luis Avenue. However the bubbler system does not have the capacity to convey very much flow; Therefor, a large amount of this runoff travels to the intersection City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations I I of Wadsworth & Price. 'r Portions of the runoff values listed below will be conveyed to the Wadsworth & Price intersection: Q(10) = (0.65)(2.2)(25.0) = 35.8 cfs Q(25) = (0.65)(2.5)(25.0) = 40.6 cfs 'r Q(100) = (0.65)(3.2)(25.0) = 52.0 cfs 2) All the runoff that reaches the intersection of Longview and Wadsworth either drains to Drainage Area 4 or 5; therefor, the runoff from Drainage Area 3 of Figure B-1 will travel to the intersection of Wadsworth and Price, less the amount dispersed at the intersection of San Luis Avenue & Price Street. Portions of the runoff values listed below will be conveyed to the Wadsworth & Price intersection. Q(10) = (0.65)(2.2)(6.6) = 9.4 cfs Q(25) = (0.65)(2.5)(6.6) = 10.7 cfs Q000) = (0.65)(3.2)(6.6) = 13.7 cfs 3) The portion of runoff from Drainage Areas 1 & 2 of Figure B-1 that pass the intersection of Bakersfield Street will continuing down Longview Avenue and travel to the intersection of Wadsworth and Price. 4 Portions of the runoff values listed below will be conveyed to the Wadsworth & Price intersection. Q(10) = (0.65)(2.2)(15.2) = 21.8 cfs Q(25) = (0.65)(2.5)(15.2) = 24.7 cfs Q(100) = (0.65)(3.2)(15.2) = 31.6 cfs The above mentioned runoff to this site refers to the possibility that no other work will be performed beyond the Wadsworth Culvert System, and maximum overflow from other watershed areas will theoretically be collected here. However, if improvements are made at Sites 4, 5, & 6, the estimated runoff can be computed as follows: Site 4:1.9 CFS Site 5: 1.6 CFS (3.2 CFS splits at Harlow St. and Price Street) Site 6: 4.5 CFS(11.9 CFS from Site 6 splitting at Harloe, San Luis, Price Streets) I (see the specific site for flow by-pass discussion) i The resulting runoff to Site 3 is then computed as follows: Runoff = 24.4 CFS + (1.9 +1.6 + 4.5 ) CFS = 32.4 CFS i City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.03 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street A 10.5 -foot opening will collect 8.7 CFS with a runoff depth at the gutter flowline of 6.0 inches. 4 inlets x 8.7 CFS = 34.8 CFS 34.8 CFS > 32.4 CFS OK It would be to the City's economical advantage to let water pass by the inlet and be caught further down the stream. Thus: it is recommended to construct the 7 -foot inlets and let Site 2 collect the runoff. 24.0 CFS <24.4 CFS: Let by-pass 0.4 CFS (as shown at the beginning of this discussion) See the next page for a report of the pipe characteristics for 98.2 CFS (runoff from sites 3, 4, 5, & 6) flowing through the culvert. City of Pismo Beach Drainage Master Plan Appendix B Preliminary Runoff Calculations k ( Site No. 4: Wadsworth Culvert System at Bello Street—Phase 4 Intersection at Wadsworth & Bello. Tributary area: 1) There is a direct 13.2 acre water shed at Bello & Wadsworth (A portion of Drainage Area 4 of Figure B-1). Q(10) _ (0.65)(2.2)(13.2) = 18.9 cfs Q(25) _ (0.65)(2.5)(13.2) = 21.5 cfs ' • Q(100) _ (0.65)(3.2)(13.2) = 27.5 cfs Additional flow: 2) There is a bubbler system at the intersection of Longview and Wadsworth having a tributaryarea of 6.6 acres (Drainage Area 3 of Figure B-1). The bubbler system collects and conveys runoff to Wadsworth adding runoff tothe above mentioned 13.2 acre tributary. Due to the bubbler system being undersized some of the runoff during large storm events will bypass Wadsworth and continue down Longview. Portions of the runoff values listed below will be conveyed to Wadsworth Street. Q(10) _ (0.65)(2.2)(6.6) = 9.4 cfs Q(25) _ (0.65)(2.5)(6.6) = 10.7 cfs Q(100) _ (0.65)(3.2)(6.6) = 13.7 cfs 3) The road improvements at the intersection Bakersfield Street & Longview Avenue are undersized, namely the cross gutter intercepting and conveying runoff from Longview Avenue to Bakersfield Street. Therefor, during large storm events the runoff generated by the 15.2 acre watershed tributary to Longview (above Bakersfield Street) will partially enter the Longview / Wadsworth intersection. Portions of the runoff values listed below will be conveyed to Wadsworth Street. Q(10) _ (0.65)(2.2)(15.2) = 21.8 cfs Q(25) _ (0.65)(2.5)(15.2) = 24.7 cfs Q(100) _ (0.65)(3.2)(15.2) = 31.6 cfs Curb Opening Inlets Though it has been mentioned how extra runoff may flow into this tributary watershed, the curb opening inlets for this site are designed based on the assumption that Sites 5 & 6 are to constructed at the same time. It is estimated that 90% of the run-off flows to the east side of the street due to a noticeable cross fall in this section of Wadsworth Avenue. Thus the curb opening inlets will be sized according to this criteria. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations ' Curb Opening Inlet -Estimated Road Section 6 inches = Curb Height (y 1.5 feet = Gutter Width ( 0.125 feet = Gutter Drop 0.06 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression E 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street East Inlet 21.5 CFS x 0.90 = 19.4 CFS to the east side of the street at the intersection. A 7 -foot opening will collect 6.1 CFS with a runoff depth of 6.0 inches at the gutter flowline, or a 14 -foot opening will collect 11.4 CFS with a runoff depth of 6.0 inches at the gutter flowline. 7 feet: 2 inlets x 6.1 CFS = 12.1 CFS 14 feet: 2 inlets x 11.4 CFS = 22.8 CFS 22.8 CFS > 19.4 CFS: OK It would be to the City's economic advantage if the upstream inlet be 7 feet wide and the downstream inlet be 14 feet wide to collect runoff from Wadsworth Avenue and from the eastern side of Bello Street. This will collect the majority of the runoff at a lesser cost. 6.1 CFS + 11.4 CFS = 17.5 CFS collected 19.4 CFS -17.5 CFS = 1.9 CFS passes by the curb opening inlet. West Inlet 21.5 CFS x0.10=2.2CFS A 3.5 -foot opening will collect 2.5 CFS with a runoff depth of 5.0 inches at the gutter flowline. However, a 7 -foot opening is recommended as a conservative solution. 2.5 CFS > 2.2. CFS: OK Total collected runoff = 17.5 + 2.2 = 19.7 CFS See the next page for a report of the pipe characteristics for 74.2 CFS (runoff from sites 4, 5, & 6) flowing through the culvert. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Site No. 5: Wadsworth Culvert System at Bello and San Luis Avenue—Phase 5 Intersection of Bello & San Luis Avenue and Intersection of Bello & Harloe Ave. Tributary area: ( San Luis Avenue i r 1) There is a direct 5.0 acre watershed at Bello & San Luis Avenue (a portion of drainage area 5 of Figure B-1). Q(10) _ (0.65)(2.2)(5.0) = 7.2 cfs Q(25) _ (0.65)(2.5)(5.0) = 8.1 cfs Q(100) _ (0.65)(3.2)(5.0) = 10.4 cfs Curb Opening Inlet It is estimated that half of the runoff flows to each of the two curb inlets at San Luis Avenue. Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.01 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street 8.1 CFS x 0.50 = 4.1 CFS to each inlet A 7 -foot opening will collect 4.3 CFS with a runoff depth of 5.0 inches at the gutter flowline. 4.3 CFS > 4.1 CFS: OK each inlet Total Collected = 2 x (4.1 CFS) = 8.2 CFS 2) Harloe Avenue at Bello Street 16.0 acres of tributary watershed area 5 drain to Bello Street and eventually to San Luis Avenue. However during large storm events some of the runoff will travel down Harloe Avenue. Portions of the runoff values listed below will drain to the intersection of Bello & San Luis Ave. Q(10) _ (0.65)(2.2)(16.0) = 22.9 Q(25) _ (0.65)(2.5)(16.0) = 26.0 City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Q(100) _ (0.65)(32)(16.0) = 33.3 cfs Curb Opening Inlets at Harloe and Bello Streets Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width F 0.125 feet = Gutter Drop 0.01 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street The intersection will see 26.0 CFS between the 4 drop inlets. Since more accurate topographic information is needed to see how much runoff enters each individual inlet. This report will match up the amount of inlet area needed to collect 26.0 CFS, and the future design will more accurately place the curb opening inlets as necessary. A 7 -foot opening will collect 5.7 CFS with a runoff depth at the gutter flowline of 6.0 inches. (4 inlets) x (5.7 CFS) = 22.8 CFS A 10.5 -foot opening will collect 6.9 CFS with a runoff depth at the gutter flowline of 5.5 inches. (4 inlets) x (6.9 CFS) = 27.6 CFS 27.6 CFS > 26.0 CFS: OK It would be to the City's economical advantage to construct the 7 -foot inlets and let runoff pass by to be caught further downstream. Thus, the following collection occurs: 26.0 CFS - 22.8 CFS = 3.2 CFS by-passes Total Collected = 8.2 CFS + 22,8 CFS = 31.0 CFS City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations F Additional Flow 3) 5 and 16 acre water sheds, along with some additional High Way 101 watershed, make up the 25 acre Drainage Area 5 of Figure B-1. The culvert system at the end of San Luis Avenue conveys all runoff under the High Way. Q(10) = (0.65)(2.2)(25.0) = 35.8 cfs Q(25) = (0.65)(2.5)(25.0) = 40.6 cfs Q(100) = (0.65)(3.2)(25.0) = 52.0 cfs 4) The bubbler system at the intersection of Longview and Wadsworth collects and conveys runoff to Wadsworth. Do to the bubbler system being undersized some of the runoff during large storm events will bypass Wadsworth and continue down Longview thus adding to the runoff to Drainage Area 5 of Figure B-1. Portions of the runoff values listed below will conveyed to Drainage Area 5: Q(10) = (0.65)(2.2)(6.6) = 9.4 cfs Q(25) = (0.65)(2.5)(6.6) = 10.7 cfs Q(100) = (0.65)(3.2)(6.6) = 13.7 cfs 5) The road improvements at the Bakersfield / Longview intersection are undersized, namely the cross gutter intercepting and conveying runoff from Longview Street to Bakersfield Street. Therefor, during large storm events, the runoff generated by the 16.2 acre watershed tributary to Longview (above Bakersfield Street) will partially enter the Longview / Wadsworth intersection. This will further impacting the bubbler system at this intersection and add runoff to Drainage Area 5. Portions of the runoff values listed below will be conveyed to Drainage Area 5: Q(10) = (0.65)(2.2)(15.2) = 21.8 cfs Q(25) = (0.65)(2.5)(15.2) = 24.7 cfs Q(100) = (0.65)(3.2)(15.2) = 31.6 cfs Much of this additional flow is collected at Site 2 if not collected at this site. See the next page for a report of the pipe characteristics for 31.0 CFS flowing through the culvert. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Site No. 6: Wadsworth Culvert System at Longview Street—Phase 6 Intersection of Wadsworth & Longview. Tributary Area: 1) The bubbler system at the intersection of Longview and Wadsworth collects and conveys runoff to Wadsworth Avenue. Due to the bubbler system being undersized some of the runoff during large storm events will bypass Wadsworth and continue down Longview thus adding to the runoff to Drainage Area 5 of Figure B-1. Portions of the runoff values listed below will be conveyed to Drainage Area 5: Q(10) _ (0.65)(2.2)(6.6) = 9.4 cfs Q(25) _ (0.65)(2.5)(6.6) = 10.7 cfs Q(100) _ (0.65)(3.2)(6.6) = 13.7 cfs 2) The road improvements at the Bakersfield / Longview intersection are undersized, namely the cross gutter intercepting and conveying runoff from Longview Street to Bakersfield Street. Therefor, during large storm events the runoff generated by the 16.2 acre watershed tributary to Longview (above Bakersfield Street) will partially enter the Longview / Wadsworth intersection. This will further impacting the bubbler system at this intersection and add runoff to Drainage Area 5. This site will be computed 2 ways: 1) Assuming that the improvements at Bakersfield Street (Site 7) and at Merced Street (Site 8) have been implemented. 2) Assuming the improvements at sites 7 & 8 were not Y implemented. Scenario 1) Assuming Site 7 & 8 have been improved with 100% success. Curb Opening Inlet Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.11 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street City of Pismo Beach Drainage Master Plan Appendix B Preliminary Runoff Calculations Due to existing site topography, an estimated 70% of the stormwater will enter the west drop inlet. 10.7 CFS x0.70=7.5CFS West Inlet: A 10.5 -foot opening will collect 8.0 CFS with a runoff depth of 5.50 inches at the gutter flowline. 8.0 CFS > 7.5 CFS: OK East Inlet: A 7 -foot opening will collect 3.3 CFS with a runoff depth of 4.0 inches at the gutter flowline. 10.7 CFS x 0.30 = 3.2 CFS discharge 3.3 CFS > 3.2 CFS: OK Scenario 2: Grate sizing without improvements at sites 7 & 8 Sites 1-5 in this master plan are designed according to Scenario 2. Portions of the runoff values listed below will be conveyed to Drainage Area 5 unless collected at this location of Wadsworth and Longview Avenues Q(10) _ (0.65)(2.2)(15.2) = 21.8 cfs Q(25) _ (0.65)(2.5)(15.2) = 24.7 cfs Q(100) _ (0.65)(3.2)(15.2) = 31.6 cfs West Inlet Q = (10.7 CFS + 24.7 CFS) x 0.70 = 24.8 CFS Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height r 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.11 (ft / ft)= Gutter Slope 0.017 = Manning's N 4 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations West Inlet: A 28 -foot opening will collect 25.8 CFS with a runoff depth of 6.0 inches at the gutter flowline. It would be to the City's economical advantage to let water pass by the inlet and be caught further down the stream. Thus, a 14 -foot drop inlet would collect 12.9 CFS and 11.9 CFS will flow past the drop inlet. It is estimated half of the by-pass will flow down Wadsworth Avenue, and half will flow down Longview Avenue. (24.7 CFS discharging) - (12.9 CFS collected) = 11.9 CFS passing by the inlet East Inlet Q = (10.7 CFS + 24.7 CFS) x 0.30 = 10.6 CFS A 14 -foot opening will collect 10.7 CFS with a runoff depth of 5.25 inches at the gutter flowline. 10.7 CFS > 10.6 CFS: OK Total Collected = 12.9 CFS (West) + 10.6 CFS (East) = 23.5 CFS See the next page for a report of the pipe characteristics for 23.5 CFS flowing through the culvert. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Site 7—Longview Inlet Upgrade at Merced Street Tributary Watershed Area 1 on Figure B-1 C = 0.65 A = 5.5 acres Q00) _ (.65)(2.2)(5.5) = 7.9 cfs Q(25) _ (.65)(2.5)(5.5) = 8.9 cfs Q(100) _ (.65)(3.2)(5.5) = 11.4 cfs Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.14 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street Due to existing site topography, an estimated 70% of the stormwater will enter the west r drop inlet. 8.9 CFS x0.70=6.2CFS West Inlet: A 7 -foot opening will collect 6.3 CFS with a runoff depth at the gutter flowline of 5.75 inches. 6.3 CFS > 6.2 CFS: OK East Inlet: A 3.5 -foot opening will collect 2.9 CFS with a runoff depth at the gutter flowline of 4.25 inches. 8.9 CFS x0.30=2.7CFS 2.9 CFS > 2.7 CFS: OK Therefore, an up-sized Curb Opening inlet on the East side of this site is not necessary. Total Collected = 6.2 CFS (West) + 2.7 CFS (East) = 8.9 CFS See the next page for a report of the pipe characteristics for 8.9 CFS flowing through the culvert. City of Pismo Beach Drainage Master Plan Appendix B Preliminary Runoff Calculations i Site 8—Bakersfield Storm Drain Extension Tributary Watershed Area 2 on Figure B-1 Area 2 C = 0.65 A = 9.7 acres Q(10) _ (.65)(2.2)(9.7) = 13.9 cfs Q(25) _ (.65)(2.5)(9.7) = 15.8 cis Q(100) _ (.65)(3.2)(9.7) = 20.2 cis Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.031 (ft / ft)= Gutter Slope 0.017 = Manning's N 5 inches= Drop Inlet Depression 18 feet= Width From Flowline to Crown 0.02= Cross Slope of the Street Due to existing site topography, an estimated 70% of the stormwater will enter the west drop inlet, and 30% of the stormwater will enter the east inlet. 15.8 CFS x 0.70 = 11.1 CFS West Inlet: A 14 -foot opening will collect 11.2 CFS with a runoff depth of 6.0 inches at the gutter flowline . 11.2 CFS > 11.1 CFS: OK East Inlet: A 7 -foot opening will collect 5.0 CFS with a runoff depth at the gutter flowline of 5.25 inches. 15.8 CFS x0.30=4.7CFS 5.0 CFS > 4.7 CFS: OK Total Collected = 11.1 CFS (West) + 4.7 CFS (East) = 15.8 CFS See the next page for a report of the pipe characteristics for 15.8 CFS flowing through the culvert. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Site No. 9: Intersection at Selma & Lemoore Tributary area: There is a direct 2.5 acre water shed at Selma & Lemoore (see Figure B-2). _ Q(10) _ (0.65)(2.2)(2.5) = 3.6 cfs Q(25) _ (0.65)(2.5)(2.5) = 4.1 cfs `.' Q000) _ (0.65)(3.2)(2.5) = 5.2 cfs Additional Flows: At the South East end of Stratford street there is evidence that runoff currently enters the Lemoore Street drainage system via a vacant lot between 690 & 710 Lemoore. The Strafford Street tributary water shed area is: 3.5 acres. Q(10) _ (0.65)(2.2)(3.5) = 5.0 cfs Q(25) _ (0.65)(2.5)(3.5) = 5.7 cfs ' Q000) _ (0.65)(3.2)(3.5) = 7.3 cfs At the intersection of Longview and Strafford the A.C. berm constructed to prevent • Longview runoff from entering Strafford Street may be over toped during large storm events. The Longview tributary area at Stratford is 20.1 acres. Curb Opening Inlet The following inlet is designed based on the assumption the existing berm at the i intersection of Strafford Street and Longview Avenue is built bigger or does not overflow. Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.24 (ft / ft) = Gutter Slope 0.017 = Manning's N 4 inches = Drop Inlet Depression 18 feet = Width From Flowline to Crown 0.02 = Cross Slope of the Street 4.1 CFS + 5.7 CFS = 9.8 CFS discharge A 10.5 -foot opening will collect 9.9 CFS with a runoff depth of 6.0 inches. at the gutter flowline. 9.9 CFS > 9.8 CFS: OK See the next page for a report of the pipe characteristics for 9.8 CFS flowing through the culvert. City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations Site No. 11: Intersection of Park Avenue & Cypress Street Tributary Area: There is a direct 11.5 acre water shed at the intersection of Park & Cypress (Drainage Area 11 and 12 of Figure B-3). Q00) _ (0.65)(2.2)(11.5) = 16.4 cfs Q(25) _ (0.65)(2.5)(11.5) = 18.7 cfs Q000) _ (0.65)(3.2)(11.5) = 23.9 cfs Additional Flow: Dolliver Street conveys runoff generated by a 14 acre water shed to Pismo creek (Drainage Area 10 of Figure B-3). However, during large storm events runoff will overtop Dolliver Street and flow to the intersection of Park & Cypress. Portions of the runoff values listed below will be conveyed to Wadsworth Street. Q00) _ (0.65)(2.2)(14.0) = 20.0 cfs Q(25) _ (0.65)(2.5)(14.0) = 22.8 cfs Q(100) _ (0.65)(3.2)(14.0) = 29.1 cfs It is estimated the 25% of the runoff from tributary watershed area 10 will spill over into t T Park Avenue & Cypress Street. This estimate assumes Dolliver Street has an even crown with half the runoff on one side of the street and half on the other. Then it is estimated half of the street will overtop. When this site is surveyed, actual street capacity can be derived. This report shall conservatively assume all inlets see the same tributary area. Discharge = 18.7 CFS + (22,8 1 4) CFS = 24.4 CFS Curb Opening Inlet Curb Opening Inlet—Estimated Road Section 6 inches = Curb Height 1.5 feet = Gutter Width 0.125 feet = Gutter Drop 0.02 (ft / ft) = Gutter Slope 0.017 = Manning's N 5 inches = Drop Inlet Depression 18 feet = Width From Flowline to Crown 0.02 = Cross Slope of the Street City of Pismo Beach Appendix B Drainage Master Plan Preliminary Runoff Calculations I 1 1 I A 7 -foot opening will collect 4.6 CFS with a runoff depth of 5.0 inches at the gutter flowline. Six curb opening inlets are planned for this site. (6 inlets) x (4.6 CFS) = 27.6 CFS 27.6 CFS > 24.4 CFS: OK Since flooding greatly impacts the vicinity of this site, 6 curb opening inlets will allow more interception in emergencies; and their placement around the 2 intersections allows for open travel lanes as opposed to a completely flooded street. See the next page for a report of the pipe characteristics for 24.4 CFS flowing through the culvert. City of Pismo Beach Drainage Master Plan Appendix B Preliminary Runoff Calculations ki MMV� mimm F 4kftil WD eut, OR