Chapter 5 Wastewater Master Plan

Transcription

1 Chapter 5 Wastewater Master Plan This chapter addresses the sewer collection system within the District. It includes a detailed description of the operation of the existing system and a capacity evaluation of the gravity sewer system and sewer lift stations to determine capacity needs. The District s newly calibrated hydraulic computer model is presented, as well as the findings of the collection system hydraulic analyses. Recommended sewer collection system improvements are included. 5.1 Existing Wastewater Collection System South Coast Water District collects the wastewater from homes and businesses and conveys it through miles of sewer mains and a series of lift stations and force mains. The collected wastewater is treated at two treatment plants. The Coastal Treatment Plant in Aliso Canyon, Laguna Niguel has a 6.7 MGD capacity and treats wastewater collected from the northern part of the District. The J.B. Latham Treatment Plant in Dana Point has a 13 MGD capacity and treats wastewater from the southern part of the District. Figure 5-1 graphically presents the regional wastewater collection system. The existing wastewater collection system consists of three separate service areas/systems: South Coast, Dana Point, and Capistrano Beach, which formerly were operated as the independent sewer districts of South Laguna Sanitary District, Dana Point Sanitary District, and Capistrano Beach Sanitary District, respectively. Figure 5-2 graphically displays the three systems. A portion of each system lies outside the current District boundary. In addition to the services provided to its residents, the District performs several levels of contract operations. In July of 1997, approximately 400 residential units in the communities of Laguna Sur and Monarch Point were transferred to the Moulton Niguel Water District (MNWD). The District continues to provide wastewater collection to these communities under contract with MNWD. In July of 1999, the District transferred the South Laguna area to the City of Laguna Beach. The South Laguna area begins at the community of Three Arch Bay and continues north to Nyes Place. The District continues to provide potable water, recycled water and wastewater collection to this area under contract with the City of Laguna Beach. Figure 5-3 illustrates the location of the gravity mains, trunk sewers, lift stations, and force mains that are owned, operated and maintained by the District. The District s sewer system includes approximately 140 miles of sewer ranging in size from 6 inch to 24 inch diameter, 14 lift stations and 3 miles of force mains. South Coast System The South Coast System service area generally includes the areas along Pacific Coast Highway (PCH) from south Laguna Beach to the northern part of the City of Dana Point. It is characterized by relatively short sewers conveying flows from the eastern hillsides to the PCH area. Sewer Lift Stations #1, and #3 through #7 are located along PCH to convey flows from sewer sub basins, to the north, to Lift Station #2 where the service area flows are pumped into the Coastal Plant. The South Coast System also includes a 10,500 foot gravity sewer tunnel (Tunnel Interceptor), stretching from the south tip of Three Arch Bay to Aliso State Beach. 5-1 South Coast Water District

2 TRABUCO CANYON WATER DISTRICT IRVINE RANCH WATER DISTRICT TCWD ROBINSONS RANCH WRP LAKE FOREST IRWD LOS ALISOS WRP RANCHO SANTA MARGARITA ETWD WWTP EL TORO WATER DISTRICT LAGUNA WOODS LAGUNA HILLS MOULTON NIGUEL WATER DISTRICT ALISO VIEJO EMERALD BAY SERVICE DISTRICT SMWD OSO CREEK WRP MNWD PLANT 3A WWTP ALICIA PARKWAY PS CITY OF LAGUNA BEACH LAGUNA BEACH PS MISSION VIEJO SANTA MARGARITA WATER DISTRICT SMWD CHIQUITA WRP LAGUNA BEACH BLUEBIRD PS NICHOLS INSTITUTE WRP REGIONAL TREATMENT PLANT (RTP) LAGUNA NIGUEL COASTAL TREATMENT PLANT (CTP) SAN JUAN CAPISTRANO DANA POINT SOUTH COAST WATER DISTRICT JB LATHAM TREATMENT PLANT (JBL) SAN CLEMENTE CITY OF SAN CLEMENTE CSC WRP LEGEND REGIONAL WASTEWATER COLLECTION SYSTEM FIGURE 5-1 Source: Cathcart Garcia von Langen Engineers, SOCWA, 2008 South Coast Water District Master Plan October 2008

3 Figure x17 Wastewater Systems Map 5-3 South Coast Water District

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5 Figure 5-3 Lift Stations and Temporary Flow Metering Map 11x South Coast Water District

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7 Dana Point and Capistrano Beach System The Dana Point and Capistrano Beach System sewer service areas are served by the Latham Plant. Dana Point System Lift Stations #8 through #11 convey flows from various smaller basins, such as the Harbor area, to gravity trunk sewers which drain to the Latham Plant. The Capistrano Beach System includes two smaller lift stations along the coast (#13 and #14). Flow from this service area is conveyed to Lift Station #12, where it is pumped to the Latham Plant Metered Sewer Basins The existing sewer collection system was temporarily metered in several strategic locations to provide accurate flow records to assist in hydraulic model calibration, as well as estimating peak dry weather sewer flows. The flow meter locations were strategically selected to quantify flows from portions of Dana Point and Laguna Beach. There were other areas of the District that were not metered because flow data was available from other District sources, such as permanent meters at the treatment plants and a majority of the sewer lift stations. For example, no new flow monitoring was conducted in the Capistrano Beach System because flow data was available from meter data at Lift Station #12. ADS Environmental Services was retained to provide flow meter data during a month long monitoring period at four locations during May Appendix C-1 includes the full report and analysis. Each meter captured weekday as well as weekend hourly flow data. No rainfall events occurred during the monitoring period. The metered locations and lift station drainage basins are described below and are shown graphically in Figure 5-3. Meter 1 Sewer Basin The Meter 1 Basin encompasses approximately 300 acres in the Dana Point System and extends from Calle La Primavera westerly to the street boundary of El Encanto Avenue. The Meter 1 Basin is bounded to the south by PCH and to the north by Stonehill Drive and is characterized as a predominately residential area, with a few schools and commercial areas. The Meter 1 Basin collects flow tributary to a 10 inch trunk sewer located on PCH, south of Golden Lantern. Basin sewers drain generally southeast to this trunk sewer, and then flow north along Del Obispo Street to the Latham Plant. Meter 2 Sewer Basin The Meter 2 Basin encompasses approximately 300 acres in the South Coast System and extends from Niguel Road easterly to Marlinspike Drive. The Meter 2 Basin includes the proposed Headlands Development and Lift Station #5. The Meter 2 Basin collects flows tributary to a 10 inch trunk sewer located on PCH north of Niguel Road and is characterized by a mix of residential and commercial land uses. Basin sewers drain generally to the northwest to the trunk sewer, which continues north along PCH and drains to Lift Station #6, west of PCH. These flows are eventually conveyed to the Coastal Plant. Meter 3 Sewer Basin The Meter 3 Basin encompasses approximately 25 acres in the middle of the South Coast System and extends from PCH easterly to Sunset Avenue. The Basin is bounded to the north by Second Avenue and to the south by Eastline Road. The Meter 2 Basin is directly to the south. The Meter 3 Basin collects flow tributary to a 10 inch trunk sewer that crosses PCH at Circle Drive and includes wastewater flows from the South Coast Medical Center. Basin sewers 5-7 South Coast Water District

8 drain generally southwest to the trunk sewer, which continues north along PCH and connects to the Interceptor Sewer Tunnel, west of PCH. Meter 4 Sewer Basin The Meter 4 Basin encompasses approximately 600 acres, also in the South Coast System, and extends from Aliso State Beach south along the coast, across the District boundary, to Via Siena. It is bounded to the east by Pacific Island Drive and to the west by the coastline. As with Meter 2, this basin includes a mix of residential and commercial land uses. The Meter 3 Basin lies to the southeast. The Meter 4 Basin includes Lift Station #6 and collects flow tributary to the Interceptor Sewer Tunnel. Basin sewers drain generally to the northwest to the Tunnel, which then conveys the wastewater north along the coast, where it drains to Lift Station # Wastewater Treatment Facilities The South Coast System is served by the 6.7 MGD Coastal Treatment Plant, owned and operated by the South Orange County Wastewater Authority (SOCWA). The Coastal Plant is located just outside of the District s northeast boundary in unincorporated Orange County (Aliso and Wood Canyons Wilderness Park) and is also owned and operated by SOCWA. The District currently owns 2.0 MGD of wastewater treatment capacity in the Coastal Plant. It is estimated that the District will sewer approximately 2.0 MGD to the Coastal Treatment Plant at buildout. It is recommended that the District closely monitor their capacity in the Coastal Treatment Plant. Effluent from the Coastal Plant is treated to secondary or tertiary levels dependent on disposal or reuse of the wastewater. Recycled water is treated to Title 22 standards at an Advanced Water Treatment Plant (AWT) located adjacent to the Coastal Plant. This facility is also owned and operated by SOCWA. Treated effluent that is not recycled is disposed through the Aliso Creek Ocean Outfall. During the summer months, over 2 MGD of recycled water can be produced by the AWT. Chapter 6 provides a discussion of the District s use of recycled water from the AWT. The Dana Point and Capistrano Beach Systems are served by the 13 MGD J.B. Latham Treatment Plant. Owned and operated by SOCWA, the Latham Plant has 3.75 MGD in capacity reserved for the District s wastewater flows. No recycled water is currently produced at the Latham Plant. Wastewater is treated to secondary levels and conveyed directly to the San Juan Creek Outfall. It is estimated that the District will sewer approximately 2.2 MGD to the J.B. Latham Treatment Plant at buildout Interconnections and Intra-Agency Service Due to the local topography, the District provides sewer service to some customers outside the District, but along its boundaries, to avoid the construction and operation of sewer lift stations in neighboring districts. There are currently five interconnections in the District s wastewater system. The District provides sewer collection services to the South Laguna area, via a service agreement with the City of Laguna Beach Approximately 400 customers within the MNWD sewer by gravity to the District s South Coast System. 5-8 South Coast Water District

9 Approximately 295 homes within the City of San Juan Capistrano north of the Latham Plant gravity flow to the District system near Stonehill Drive and Del Obispo. Approximately 20 homes just east of the Meter #1 and north of Meter #2 Basins flow to a Moulton Niguel lift station on Crown Valley Parkway west of Pacific Island Drive. Approximately 40 homes northeast of Lift Station #7 flow to the District s system at connections bordered by Pacific Island Drive, Isle Vista, and Sea Island Drive. Flows from approximately 300 homes in the City of San Clemente enter the District system, north of Camino El Molino and Calle Juanita Flow Diversions In order to comply with local stormwater quality regulations, the District has seen a large increase in the construction of flow diversion structures connected to its sanitary sewer system. There are currently 33 existing flow diversions in operation within the District and a proposed new flow diversion for Poche Creek. These flow diversions typically consist of (1) Culvert Diversion Structures (CDS), (2) Storm Drain Diversion, (3) Groundwater Diversion, and (4) Treatment Backwash. The most common being the CDS and storm drain diversions which are designed to convey nuisance or low flow runoff of poor quality from the storm drain system to the sanitary sewer system. The existing and proposed flow diversion locations are shown on Figure 5-4. Most of the units are located along the coastal area. Table 5-1 summarizes the name, location, type, flow and the organization responsible for maintenance for the existing and proposed flow diversions. Currently, most Diversion Agreements call for the systems to be shut down during the winter rainy months (October 15 April 15), or when chance of rain exceeds 50 percent. Most are also limited to maximum flows of 10,000 gallons per day. Proper operation is the responsibility of the individual owners, with activities reported to the District. These flow diversion structures present an inherent risk to the District s collection system if not properly operated. The District could experience high inflow rates into its sewer system if diversion structures are not operated properly. In addition, poor quality runoff could result in increased maintenance of the collection system. Since many of these facilities are dictated by local municipal land development codes, the District should work closely with local agencies to develop policy procedures for approved types of structures, replacement of existing nonconforming structures, and identify maintenance responsibilities. Table 5-1. Flow Diversions Ref. Number Name Index Map/ MH No. Type Contract (Max.) Inflow Average Inflow (1) Observed (Max.) Inflow (1) Maintained By 1 Montage (North) A-2 / S1513 CDS Unit unk unk Montage 2 Montage (South) B-3 / S1501 CDS Unit unk unk Montage 3 Montage (Public Parking) B-3 / S1470 CDS Unit unk unk City of Laguna Beach 4 5th Street & PCH C-5 / S1153 CDS Unit unk unk City of Laguna Beach 5 3 Arch Bay (North) - N. La D-7 / S991 CDS Unit 10,000 GPD unk unk 3 Arch Bay Senda 6 3 Arch Bay (South I) - Bay Drive D-8 / S981 CDS Unit 10,000 GPD unk unk 3 Arch Bay 7 3 Arch Bay (South II) - S. La Senda D-8 / S974 CDS Unit 10,000 GPD not yet operational not yet operational 3 Arch Bay 5-9 South Coast Water District

10 Ref. Number (1) Name Index Map/ MH No. Table 5-1 (continued) Type Contract (Max.) Inflow Average Inflow (1) Observed (Max.) Inflow (1) Maintained By 8 Salt Creek Ozone E-9 / S356A Treatment 144,000 GPD, 62, ,900 SCWD Treatment Backwash constant flow GPD GPD 9 Niguel Shores - Niguel G-11 / S153A Groundwater 10,000 GPD unk unk Niguel Shores HOA Shores Drive & Windlass Diversion 10 Niguel Shores - Magellan F-11 / near Storm Drain 10,000 GPD unk unk Niguel Shores HOA Isle S305 Diversion 11 Niguel Shores - Magellan F-11 / S303 Groundwater 10,000 GPD unk unk Niguel Shores HOA Isle & Niguel Shores Drive Diversion 12 Niguel Shores - Niguel F-11 / S267 Groundwater 10,000 GPD unk unk Niguel Shores HOA Shores Drive & Mercator Isle Diversion 13 Niguel Shores - Mercator F-11 / near Storm Drain 10,000 GPD unk unk Niguel Shores HOA Isle & Niguel Shores Drive S266 Diversion 14 Niguel Shores - Nauticus F-12 / near Storm Drain 10,000 GPD unk unk Niguel Shores HOA Isle & Niguel Shores Drive S264 Diversion 15 Niguel Shores Beach F-12 / S288E Storm Drain 10,000 GPD not yet not yet City of Dana Point Parking OC Storm Drain Diversion operational operational 16 Headlands CDS Unit 1 - F-12 / S4110 CDS Unit 10,000 GPD not yet not yet Headlands Reserve Strand Beach Drive operational operational 17 Headlands CDS Unit 2 - F-12 / S4095 CDS Unit 10,000 GPD not yet not yet Headlands Reserve Strand Beach Drive operational operational 18 Headlands CDS Unit 3 - F-13 / S4108 CDS Unit 10,000 GPD not yet not yet Headlands Reserve Strand Beach Drive operational operational 19 Baby Beach - Dana Point G-13 / D757 CDS Unit 10,000 GPD not yet not yet City of Dana Point Harbor operational operational 20 North Creek I-13 / D810 Storm Drain unk unk City of Dana Point Diversion 21 Del Obispo J-12 / C4002A Storm Drain 10,000 GPD 7,276 GPD 28,765 GPD City of Dana Point Diversion 22 Alipaz J-11 / D659 Storm Drain 72,000 GPD 44,958 85,143 GPD City of Dana Point Diversion GPD 23 GRF J-12 / C782 Treatment 120 gpm, constant not yet not yet SCWD Backwash flow (240 gpm w/ GRF Expansion) operational operational 24 Beach Road No. 1 J-14 / C715 Storm Drain 10,000 GPD unk unk City of Dana Point Diversion 25 Beach Road No. 2 K-14 / C710 Storm Drain 10,000 GPD unk unk City of Dana Point Diversion 26 Beach Road No. 3 K-14 / C684 Storm Drain 10,000 GPD <1000 unk City of Dana Point Diversion GPD 27 Capistrano Beach/ K-15 / C696 Storm Drain 10,000 GPD 10.6 GPD GPD City of Dana Point Palisades Diversion 28 Beach Road No. 4 K-15 / C681 Storm Drain 10,000 GPD < GPD City of Dana Point Diversion GPD 29 Camino de L-15 / C518 Storm Drain unk unk City of Dana Point Camino Capistrano Diversion 30 Beach Road No. 5 L-15 / C666A Storm Drain 10,000 GPD unk unk City of Dana Point Diversion 31 Beach Road No. 6 M-17 / C659 Storm Drain 10,000 GPD < GPD City of Dana Point Diversion GPD 32 Beach Road No. 7 M-17 / C658 Storm Drain 10,000 GPD <1000 unk City of Dana Point Diversion GPD 33 Beach Road No. 8 M-17 / C653 Storm Drain Diversion 10,000 GPD unk unk City of Dana Point 34 Poche Creek N-18 / near C651 Treatment Backwash 144,000 GPD, constant flow not yet operational Average Inflow is based on Average Daily Flow Reports from City of Dana Point, May - Sept 2007 not yet operational Undetermined (Proposed SCWD) 5-10 South Coast Water District

11 Figure 5-4 Flow Diversions 11x South Coast Water District

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13 5.1.5 Lift Stations There are currently 14 sewer lift stations in operation as shown in Figure 5-2. The lift stations are sequentially numbered from north to south, generally following the sewer service areas: South Coast System (Lift Stations #1 through #7) Dana Point System (Lift Stations #8 through #11) Capo Beach System (Lift Stations #12 through #14) The remaining section describes the location of the lift station, its service area, number of pumps and nominal capacity. Lift Station #1 Blue Lagoon The Blue Lagoon Lift Station is located within the Blue Lagoon condominium complex adjacent to the Montage Resort. Lift Station #1 has two operating and one spare Flygt pumps with a design capacity of 400 gpm at 105 feet of TDH. Two 30 hp Variable Frequency Drive (VFD) motors service the pumps with 1,755 rpm. The station lifts wastewater from the coastal section of Laguna Beach up to PCH. Lift Station #2 Aliso Creek / Maintenance Shop The Main Shop Lift Station is located on Country Club Road just east of Coast Highway. Lift Station #2 has two operating and one spare 1986 Centrifugal Allis Chalmers pumps with a design capacity of 2,200 gpm at 125 ft of TDH. Two 125 hp Variable Frequency Drive (VFD) motors service the pumps with 1,185 rpm. The station lifts all wastewater from the South Coast system of the District to the Coastal Treatment Plant. It is the District s largest lift station. Lift Station #3 Monarch Bay The Monarch Bay Lift Station is located west of Beach Club Drive. Lift Station #3 has two operating early 1980s Centrifugal Fairbanks Morse pumps with a design capacity of 520 gpm at 115 feet of TDH. Two 25 hp motors power the pumps at 1,755 rpm. The station lifts wastewater from the Meter #3 Basin (described previously) and the adjacent neighborhood, and pumps the wastewater to Lift Station #6. Lift Station #4 County Beach Lift Station The County Beach Lift Station is located on the beach west of Ritz Cove Drive. Lift Station #4 has two operating 2007 Flygt pumps with a design capacity of 150 gpm at 47 feet of TDH. Two 7.4 hp motors power the pumps at 1,750 rpm. The station primarily services two restrooms at the beach and pumps wastewater to Lift Station #3. Lift Station #5 Niguel Shores The Niguel Shores Lift Station is located at the beach parking lot on Breakers Isle. Lift Station #5 has two operating 1970 Centrifugal Fairbanks Morse pumps with a design capacity of 520 gpm at 115 feet of TDH. Two 25 hp motors power the pumps at 1,750 rpm. The station services Niguel Shores and surrounding neighborhoods and pumps wastewater to Lift Station # South Coast Water District

14 This lift station is scheduled for relocation as part of the Headlands Development improvements. The new lift station will operate two 2008 Flygt pumps with a design capacity of 825 gpm at 155 feet of TDH. Two 70 hp motors will power the pumps at 1775 rpm. Lift Station #6 Ritz Cove The Ritz Cove Lift Station is located on the Monarch Beach Golf Course west of Ritz Cove Drive. Lift Station #6 has three operating Centrifugal 1984 Crane Deming pumps with a capacity of 1,360 gpm at 95 feet of TDH each. Three 75 hp VFD motors power the pumps at 1,175 rpm. The station lifts wastewater from the Dana Point area of the District to the Tunnel Trunk Sewer ending up at Lift Station #2. This station also currently receives approximately 50 gpm of constant flow from the Salt Creek Ozone Treatment Plant s backwash, which is adjacent to the station. Lift Station #7 Circle Drive The Circle Drive Lift Station is located below Circle Drive. Lift Station #7 has one operating Submersible 2004 Barnes pump. One 1.5 hp motor powers the pump at 1,750 rpm. The station serves only three residences and pumps wastewater to the Tunnel Trunk Sewer ending up at Lift Station #2. Lift Station #8 Acapulco The Acapulco Lift Station is within the Dana Point system and is located at the intersection of Caracas Street and Santiago Drive. Lift Station #8 has recently been upgraded with two operating 2008 Flygt Dry Pit Submersible pumps that have a design capacity of 750 gpm at 90 feet of TDH. Two 30 hp motors power the pumps at 1,760 rpm. The station services the northern portion of Dana Point. The station pumps wastewater to Stonehill Drive, where it gravity flows through the Del Obispo Trunk Sewer into the Latham Treatment Plant. Lift Station #9 South Harbor Island Way The South Harbor Island Way Lift Station is located on the Dana Point Harbor at the intersection of Dana Drive and Island Way. Lift Station #9 has two operating Dry Pit Submersible 1990 WEMCO pumps with a design capacity of 275 gpm at 44 feet of TDH. Two 10 hp motors power the pumps at 1,170 rpm. Lift Station #9 total flows are then pumped to Lift Station #10. Lift Station #10 North Harbor Island Way The North Harbor Island Way Lift Station is located at the intersection of Dana Point Harbor and Island Way. Lift Station #10 has two operating Dry Pit Submersible 1990 WEMCO pumps with a design capacity of 350 gpm at 20 feet of TDH. Two 7.5 hp motors power the pumps at 1,170 rpm. The Marine Institute typically conveys flows during tank flushing operations, which can at times be scheduled or managed to minimize capacity impacts. The station also services the northwestern portion of Dana Point Harbor and pumps wastewater to Lift Station #11. Lift Station #11 Embarcadero The Embarcadero Lift Station is located near the intersection of Dana Point Harbor and Puerto Place. Lift Station #11 has two operating Dry Pit Submersible 1991 WEMCO pumps with a design capacity of 600 gpm at 34 feet of TDH. Two 15 hp motors power the pumps at 1,160 rpm. The station receives flow from the northeastern portion of Dana Point Harbor and pumps wastewater to the Latham Plant South Coast Water District

15 Lift Station #12 Victoria The Victoria Lift Station is within the Capo Beach system and is located near the intersection of Victoria Boulevard and Santa Fe Avenue. Lift Station #12 has three operating Submersible 2003 KSB pumps with a design capacity of 1,345 gpm at 39 feet of TDH. Three 25 hp VFD motors power the pumps at 1,170 rpm. The Station receives flow from Capo Beach and pumps wastewater to the Latham Plant. The station also currently receives approximately 120 gpm of constant flow from the GRF s Iron and Manganese removal and RO reject streams. It is anticipated that the station will receive approximately 240 gpm of flow from the GRF when it is expanded. Lift Station #13 State Park The State Park Lift Station is located along Beach Road in the State Park parking lot. Lift Station #13 has two operating Flygt submersible pumps with a design capacity of 500 gpm at 18 feet TDH. Two 7.5 hp motors power the pumps at 1,740 rpm. The station receives flow from Lift Station #14 and the northern Beach Road homes, and pumps across and down Beach Road. This lift station is also downstream of the future Poche Creek UV Treatment Plant. Lift Station #14 Beach Road The Beach Road Lift Station is located along Beach Road, south of Lift Station #13. The lift station has two operating Flygt submersible pumps with a design point of 200 gpm at 17 feet of TDH. Two 2.2 hp motors power the pumps at 1,670 rpm. The station receives flows from the homes along the southern portion of Beech Road and pumps to a gravity sewer main that drains to Lift Station #13. It is anticipated that LS #14 will receive approximately 100 gpm of treatment backwash from Poche Creek. This lift station is immediately downstream of the future Poche Creek UV Treatment Plant, and will receive approximately 100 gpm of backwash flows from the plant. 5.2 Wastewater System Design Criteria This section summarizes the wastewater system planning and design criteria used for the hydraulic capacity evaluation of wastewater facilities, as part of the wastewater master plan District Design Criteria The District s sewer system design criteria are summarized in Table 5-2. The criteria were reviewed and updated based on the following: Review of previous District planning studies and criteria Current District Standard Specifications Comparison to other sewer agency criteria Meetings and discussion with the District s engineering and operations staff The criteria also include standards for design capacity calculations, gravity sewer design, and force main and lift station design South Coast Water District

16 Gravity Main Criteria Minimum Pipe Diameter Minimum Velocity Item Table 5-2. Hydraulic Sewer Design Criteria 8 inches Manning's Roughness Coefficient Maximum Peak d/d Ratio for Existing Sewers 0.75 Maximum Peak d/d Ratio for New Sewers Force Main Criteria Minimum Pipe Diameter Minimum Velocity Maximum Velocity Pump Station Criteria Minimum Number of Pumps 2 Minimum Pump Capacity Standby Capacity Emergency Power Emergency Storage Capacity 2 fps at peak flow rate 0.50 for diameters < 12 inches 0.75 for diameters > 12 inches 4 inches 3 fps 8 fps Criteria Duty pumps capable of handling ultimate wet weather capacity 100% of largest pump capacity Required 6 hours of average flow To account for the daily variations in wastewater flow rates, the peak design flow rate within a specific reach of sewer is approximated by multiplying the total average flow rate in the pipe by a corresponding peaking factor. This peaking factor, especially under dry weather flows, is a function of the tributary average flow draining to the reach. This factor can be difficult to quantify and estimate at low flows. As part of this master plan, a peaking curve was developed by adjusting the standard Federov peaking curve to best fit the temporary sewer flow metering data collected. The new peaking curve and predicted peaking equation are shown in Figure 5-5, in comparison to the District s current peaking curve. It was recommended by the District, that the current peaking curve be used for steady-state analysis of the smaller collector sewers (8 inch and 10 inch). The major trunk sewers larger than 10 inches and larger were evaluated based on the calibrated dynamic sewer model Return-to-Sewer Capacity Methodology A return-to-sewer generation rate, based upon actual individual customer water billing records, was developed as the basis for estimating existing sewer flows in the District. Generally, a sewer system experiences between 65 and 85 percent return rates of water use to the sewer, depending on the type of land use and extent of outdoor water use. The return ratio can be as high as 90 percent or more during wet periods. Appendix C-2 summarizes the allocated potable water demands to their associated tributary sewer manhole. This methodology coupled with temporary sewer flow meter records and lift station records can produce fairly accurate sewer flow estimates for individual sewer basins in evaluating existing system capacities South Coast Water District

17 Peaking Factor District Peaking PF Eqn = 2.4 x Q ^ Modified Federov PF = 8.172/Q^.121 Note: Minimum Peaking Factor= AVERAGE WASTEWATER FLOW, gpd Modified Fedorov Equation District Peaking Equation Figure 5-5. Peaking Factor for Wastewater Flows As noted in Chapter 2, the District sewer service area does not anticipate large additional development, as it is predominately built-out. However, to assess the impacts of future development on the sewer system, unit generation rates by land use were developed based on the return-to-sewer rate and billing records based on water meter time data. Flows through all irrigation and non-permanent use meters such as temporary construction meters, interim service meters, and unmetered water losses in the system, were excluded. Table 5-3 summarizes the return-to-sewer rate and proposed unit generation rates by land use. 5.3 Wastewater Generation Forecasting The District is predominately built-out and therefore the review and evaluation of sewage generation is mostly focused on existing flows and patterns. This demand data is also important input for the development of a new hydraulic computer model, which simulates existing demands. This section reviews historic sewage generation within the District and also presents a basis for estimating future sewage generation South Coast Water District

18 Table 5-3. Sewer Unit Generation Rates Land Use Return-to-Sewer Rate Unit Generation Rate Single-Family Residential 65% 280 gpd/du Medium-Density Residential 65% 260 gpd/du Multi-Family Residential 65% 175 gpd/du Rec/Public Use Facilities 90% 1,000 gpd/ac Hotel / Motel 85% 75 gpd/room Commercial / Office 65% 1,800 gpd/ac School 65% 1,000 gpd/ac Note: Estimated based on water billing records, limited temporary sewer meters and sewer lift station meter data Historic and Existing Flows As presented in Chapter 4, existing water demands for the District were determined by analyzing actual water meter records for the past 5 years. However, during this process it was discovered that the billing data for years 2002 through 2004 was not reliable on a parcel by parcel basis as it was developed under a software system no longer used by the District. Moreover, a new accounting software program was implemented during 2005 and it was discovered that the data was incomplete for modeling purposes. Therefore, the 2006 data was used as the baseline for determining existing sewer flows, for use in the model, via a return-tosewer methodology. The District reports an existing sewer flow 4.0 mgd Buildout/Ultimate Forecast Ultimate or build-out sewer flow estimates were developed for the sewer system based upon known development projects and the historical growth pattern within the District, as presented in Chapter 2. Table 5-4 summarizes the buildout sewer flow estimates within the District by major proposed development. These future flows represent an increase of approximately 5 percent. Although new development and redevelopment are important to consider in future capacity needs, the District s sewer capacity needs will largely be driven by its peaked sewer flows typically seen during the influx of large weekend transient population. 5.4 Wastewater System Hydraulic Model As part of this Master Plan, the District has authorized the selection and preparation of a new GIS-based hydraulic computer model to analyze the existing capacity in the sewer collection system. The new model will be turned over to the District to be used as planning tools on future sewer system capacity needs. As part of the scope of services, PBS&J conducted a model selection workshop. It was recommended that the District utilize the InfoSewer dynamic modeling software by MWHSoft for its sewer system model. This section describes the development of the new hydraulic model South Coast Water District

19 Table 5-4. Buildout/Ultimate Sewer Flow Generation Project Name & Description Average Demand North Development 29 DUs 8,120 Aliso Creek Inn (2) 44,660 Adjacent Parcel to Aliso Creek Inn 15 DUs 4,200 Dana Point Harbor Revitalization (+/-) 40,000 sqft Retail (Eq ac) 3,312 (+/-) 40,000 sqft Restaurant (Eq ac) 3,312 Subtotal 6,624 Headlands 119 DUs 33, Room Hotel 6, Room Hostel 3,000 Restaurant 1,800 Commercial (1.6 AC) 2,880 Nature Interpretive Center 1,000 Subtotal 48,750 General District Growth 3% by 2030 (1) 120,000 Total 232,354 Existing Demand 4.0 MGD Buildout Demand 4.2 MGD (1) (2) Assumes to include Dana Point Town Center redevelopment. Assumed at 65% of Water Demand, see Table Hydraulic Model Development A detailed hydraulic computer model is required to analyze the complex operation of the City s wastewater system including collection system sub basins of gravity flow as well as the operation of 14 sewer lift stations and force mains. The steps of hydraulic model development include: obtaining the sewer system s physical data, translating the physical data into a network of pipes and nodes, determining basin boundaries and sewer flows, and calibrating the sewer model to known flow conditions to validate its use as a planning tool. The hydraulic model was developed using the District s new GIS database as the base information for pipes, manholes, and lift stations. The District s sewer system GIS was developed with a consultant and provided to PBS&J in early As part of the sewer 5-19 South Coast Water District

20 modeling effort, known system updates and corrections were tracked and provided to the District with the new sewer model. Lift Station information, including pump curve data and wet well control information, was obtained from District staff and input into the model. Manhole rim elevation data was taken from a digital terrain model developed from 5-meter aerial elevation extraction of the District s sewer service area. Missing information was either populated by the District or inferred from existing information within the GIS. There is an area of Capistrano Beach System that does not have record drawings available to populate manhole inverts, and the District provided updated invert elevations from CCTV inspections. The hydraulic model was populated with existing average sewer demands by applying the specific land-use-based return-to-sewer rate to the meter billing records for each parcel Sewer Model Calibration An integral part of developing and utilizing any hydraulic model for planning decisions involved a process of calibrating or validating the model. The new InfoSewer model was calibrated to meter data by comparing the simulated flow hydrographs to actual meter data at the four metered sites. Results of the model calibration are presented in Figures 5-6 through 5-9. In each of the four metered basins, May 2007 diurnal flow data was extracted for a typical day (shown in black), for weekdays (shown in red) and for weekend days (shown in blue). The results of the hydraulic model are shown in a thick pink line. The comparison allowed refinement of the estimated model parameters so that the simulated flow conditions reasonably approximated the measured flow conditions. These parameters generally include return to sewer rates, diurnal curve patterns, and peak to average flow ratios (peaking factors). Since the return to sewer rates were computed from actual flow data, the parameters adjusted to calibrate the model were primarily the peaking factors applied to the estimated diurnal patterns, input at each of the loading manhole by land use class. Model calibration was improved by assigning a specific diurnal curve to the land use classes. Typical sewer volume and peak flows range for sewer calibration is + or 10 percent for master planning. Table 5-5 summarizes the results of the model calibration. These results were sufficient to confidently approach hydraulic modeling to evaluate the District s system under existing and future conditions. Table 5-5. Model Calibration Table Meter Volume Calibration Peak Calibration Notes Meter 1-25% -18% Unable to calibrate to this meter. Flow was too low. Meter % 18% Calibrated to the volume to be conservative. High peak flow is the result of dual pump operation at LS #5 Meter 3 17% 0.10% Calibrated to match the peak if it occurred on a weekend, subsequently overestimating the volume. Meter 4-10% 11% Calibrated to both peak and volume South Coast Water District

21 Metered Discharge (mgd) :00 23:00 22:00 21:00 20:00 19:00 18:00 17:00 16:00 15:00 14:00 13:00 12:00 11:00 10:00 9:00 8:00 7:00 6:00 5:00 4:00 3:00 2:00 1:00 0:00 Time of Day 5/13/2007 Weekend Weekday Model Simulation Figure 5-6. Meter #1 DP Metered Discharge (mgd) :00 23:00 22:00 21:00 20:00 19:00 18:00 17:00 16:00 15:00 14:00 13:00 12:00 11:00 10:00 9:00 8:00 7:00 6:00 5:00 4:00 3:00 2:00 1:00 0:00 Time of Day 5/28/2007 Weekday Weekend Model Simulation Figure 5-7. Meter #2 SCS South Coast Water District

22 Metered Discharge (mgd) :00 23:00 22:00 21:00 20:00 19:00 18:00 17:00 16:00 15:00 14:00 13:00 12:00 11:00 10:00 9:00 8:00 7:00 6:00 5:00 4:00 3:00 2:00 1:00 0:00 Time of Day 5/3/2007 Weekend Weekday Model Simulation Figure 5-8. Meter #3 SCS Metered Discharge (mgd) :00 23:00 22:00 21:00 20:00 19:00 18:00 17:00 16:00 15:00 14:00 13:00 12:00 11:00 10:00 9:00 8:00 7:00 6:00 5:00 4:00 3:00 2:00 1:00 0:00 Time of Day 5/28/2007 Weekday Weekend Model Simulation Figure 5-9. Meter #4 SCS South Coast Water District

23 5.5 Wastewater System Analysis The hydraulic computer model (InfoSewer) and wastewater generation projections were utilized to analyze the capacity of the existing and ultimate wastewater systems. Lift station capacity requirements were analyzed based on model flow projections and the District s lift station and force main design criteria. Sewer collection system capacity was based on a review of the hydraulic modeling and design criteria. Appendix C-3 summarizes the hydraulic model simulation results. The coastal cities within the District are popular tourist destinations, which cause the District to experience seasonal and weekend increases in wastewater generation due to transient population influx. The District has observed that this seasonal influence increases wastewater flows more than rainfall events. Therefore, peak wet-weather flows are not a critical design parameter for the District. A transient model condition was therefore developed to assess maximum or peak wastewater flows within the District s collection system accounting for this seasonal variance. The transient model condition globally increased wastewater flows within the model by approximately 25 percent based upon a review of the historic maximum potable water month demands, which typically occurs during the busy summer months. The results of these analyzes were compiled below. The resulting sewer system improvements projects are consolidated and are further described in this chapter and the Capital Improvement Program (CIP), Chapter 7, of this master plan Lift Station Capacity Analysis The sewer lift stations were evaluated to determine surplus or deficient pump capacity. The District had previously analyzed the physical condition of each lift station; specific upgrades based on this conditions assessment are part of the current capital program. Typically, each sewer lift station includes a normal operating pump and a stand-by unit. These pumps are alternated for operation to ensure equal wear on each unit. Therefore, lift station pump capacity is based upon the largest pump (stand-by unit) being out of service. Table 5-6 summarizes the lift station capacity analysis for existing and future ultimate conditions in the District. Based upon Table 5-6 lift station capacity analysis and associated hydraulic model simulations the following lift station improvements are recommended: Additional pump capacity at Lift Station #2 through existing pump capacity upgrades. Review current pump operations at Lift Stations #10 and #11 Consider pump level setting changes at Lift Stations #10 and #11 to avoid dual pump operation. The hydraulic model also indicated that the downstream force mains from each sewer lift station have sufficient capacity and meet District design criteria. As part of the Lift Station #2 capacity upgrades, the force main velocities should be reviewed as part of pump selection South Coast Water District

24 Table 5-6. Lift Station Capacity Analysis Lift Stations Name No. of Pumps Pump Capacity (gpm) Firm Capacity (gpm) Existing Peak Inflow (gpm) Existing Transient Peak Inflow (gpm) Future Peak Inflow (gpm) Future Transient Peak Inflow (gpm) Surplus / (Deficit) (gpm) South Coast LS #1 Blue Lagoon LS #2 Main Shop 2 2,200 2,200 2,721 (1) 3,339 (1) 2,839 (1) 3,540 (1) (1,340) LS #3 Monarch Bay LS #4 County Beach LS #5 Niguel Shores (4) LS #6 Ritz Cove 3 1,360 2,720 1,842 (6) 2,114 (6) 1,893 (6) 2,283 (6) 437 (6) LS #7 Circle Drive Dana Point LS #8 Acapulco (5) LS #9 S Harbor Island Way LS #10 N Harbor Island Way (1) 211 (1) 208 (1) 212 (1) 138 LS #11 Embarcadero (1) 380 (1) 320 (1) 377 (1) 223 Capo Beach LS #12 Victoria 3 1,400 2,800 1,554 (2) 1,741 (2) 1,572 (2) 1,794 (2) 1,006 LS #13 State Park (3) 291 (3) 243 (3) 286 (3) 214 LS #14 Beach Road (3) 131 (3) 126 (3) 132 (3) 68 (1) Back up pump operated during model simulation (2) Includes 240 gpm from the GRF and 100 gpm from Poche Creek (3) Includes 100 gpm from Poche Creek (4) Future Headlands Lift Station (5) Upgraded Acapulco Lift Station (6) Includes 50 gpm from Salt Creek Ozone Treatment Plant Sewer Pipeline Capacity Assessment The hydraulic computer models for existing and ultimate flows were used to assess whether the existing collection system could convey wastewater flows within the District s design standard for depth-to-diameter ratios. A ratio (d/d) of less than 75 percent is appropriate for pipes, larger than 12 inches in diameter and less than 50 percent for pipes 12 inches in diameter and smaller. A d/d ratio of 75 percent was used to assess capacity for all diameters in the transient population model scenarios, which were considered the worse-case flow analysis. An extended period simulation using diurnal flow patterns was utilized to determine peak flow operating conditions. Table 5-7 lists the sewer pipelines that do not meet the District design criteria. A summary of the model findings includes the following: The existing condition model runs identified that 55 existing individual pipe segments, totaling approximately 10,500 feet, failed to meet the design criteria. The build out condition model runs identified that 6 additional existing individual pipe segments beyond the existing condition model scenario, totaling an additional approximately 1,600 feet, failed to meet the design criteria South Coast Water District

25 The existing transient condition model runs identified that 49 existing individual pipe segments, totaling approximately 8,000 feet, failed to meet the design criteria of 75 percent for all pipe line diameters The buildout transient condition model runs identified that 24 additional existing individual pipe segments beyond the existing transient condition model scenario, totaling approximately 3,600 feet, failed to meet the design criteria of 75 percent for all pipe line diameters. 5.6 Summary of Recommended Improvements Using Table 5-7 as a guide, recommended improvement projects were developed and phased based upon pipelines which failed to meet District criteria, and those with a high probability for a sanitary sewer overflow. This was determined by analyzing the degree of surcharging in the dynamic model and the potential risk for spill. These critical pipelines were defined as having a d/d of 0.90 or 0.75 for the transient and non-transient model conditions, respectively. Table 5-7. Model Identified Deficiencies Upstream MH ID Downstream MH ID Diameter (in) Length (ft) d/d Existing (d/d > 0.75) C696 C696A C696A C696B C696B C D745 D C684 CLS C793 CLS D728 D D729 D D790 D S3943 S S3919 S Existing Transient (d/d > 0.75) S1018 S S1158 S S3931 S S3937 S S3938 S D746 D751A C522 C S901 S S3917 S S1020 S S981 S S1166 S S3930 S S3932 S S1201 S S900 S South Coast Water District

26 Table 5-7 (continued) Upstream MH ID Downstream MH ID Diameter (in) Length (ft) d/d S1019 S S1170 S C703 C S3926 S S911 S S1000 S S995 S S3927 S S1016 S S3936 S S899 S S917 S D741 D D742 D S1168 S S3929 S D343 D S3925 S S3940 S D739 D D1097 D Existing (Dia. < 12" & d/d > 0.75) D740 D D792 D D703 D S650 S S902 S D788 D D743 D743A D743A D C187 C D706 D S203 S D731 D S1469 S D732 D C186 C D705 D S908 S D704 D S356A SLS S356A SLS S893 S C665 C S1477 S C666 C D744 D C667 C South Coast Water District

27 Table 5-7 (continued) Upstream MH ID Downstream MH ID Diameter (in) Length (ft) d/d C48 C D702 D D701 D D733 D C17 C CC47A C S1155 S C668 C Buildout Transient (d/d > 0.75) S1001 S S1015 S S999 S S3941 S S3948 S S3942 S S3145 S S3148 S S3944 S S3921 S S998 S S3920 S S1159 S S1167 S S3928 S S1160 S S3934 S S3933 S S3935 S S1192 S S1193 S S1188 S S1195 S S1189 S Buildout (Dia. < 12" & d/d > 0.75) S331 S C567A C D932 D S344 S D935 D Each sewer pipeline and lift station project was evaluated with the other improvements to determine whether some efficiency could be realized by combining certain improvements. The following recommended improvements are summarized below based upon their priority. It is recommended prior to any sewer pipeline replacement or up-grade that the District conduct sewer flow metering to confirm the model predictions and that the existing pipelines do exceed District criteria South Coast Water District

28 Phase I 5-Year Sewer Capacity CIP ( ) Project SLS 1 Sewer Lift Station #2 Upgrade. Under peak flows, the dynamic hydraulic model predicted the need for a second pump to operate over short periods. However, operations staff confirmed that unless there was a high rainfall event, this usually does not occur. It is further recommended that the District consider a detailed capacity study of the lift station. Due to the age of the lift station and its internal accessibility, the District has slated it for replacement. As part of the Aliso Creek Redevelopment, a new lift station location is being discussed. The District has also been in discussions with the City of Laguna Beach to convey pumped flows from the North Coast Interceptor. Project SP 1 Dana Point Harbor. Replace approximately 400 feet of existing 8 inch gravity main and 350 feet of existing 10 inch gravity main with 12 inch diameter. Figure 5-10 graphically presents the location of this replacement project. The existing 10 inch main did not exceed the replacement criteria, however was included as an upgraded because of its proximity and the fact that it exceeded the District s design criteria. Minor traffic control measures and utility conflicts are anticipated for this project. Coordination with Harbor businesses and general activity will need to be considered. This project may be constructed as part of the planned Harbor Redevelopment. Project SP 2 Del Obispo at Village Road. Replace approximately 600 feet of existing 12 inch gravity main with 18 inch diameter. Figure 5-11 graphically presents the location of this replacement project. Traffic control measures and utility conflicts are anticipated with this project. Project SP 3 Del Obispo at Stonehill Drive. Replace approximately 150 feet of existing 8 inch gravity main with 12 inch diameter. Figure 5-12 graphically presents the location of this replacement project. Traffic control measures and minor utility conflicts are anticipated with this project. Project SP 4 Headlands Off Site. As part of this Master Plan, a Technical Memorandum was submitted to the District evaluating the available existing capacity in the District s sewer system in PCH to serve the Headlands Development. The Headlands Development Technical Memorandum is included as Appendix A-1. The Technical Memorandum identified that an approximate 285 foot section of existing 12 inch gravity main needs to be replaced with a 15 inch diameter or paralleled with a 12 inch diameter relief sewer. Phase II 5-Year Sewer Capacity CIP ( ) Project SP 5 Camino Capistrano. Replace approximately 150 feet of existing 8 inch gravity main with 10 inch diameter. Figure 5-13 graphically presents the location of this replacement project. Minor traffic control measures and utility conflicts are anticipated for this project. Project SP 6 Links at Monarch Beach. Parallel approximately 150 feet of existing 8 inch gravity main with 8 inch diameter. Figure 5-14 graphically presents the location of this replacement project. No traffic control measures or utility conflicts are anticipated for this project. The project also appears to be highly accessible despite its location. Due to a landslide 5-28 South Coast Water District