Table of Contents. GWRS Final Expansion Engineer s Report Sept 2016

Transcription

1

2 Table of Contents Table of Contents... ii Chapter 1 Introduction Background Project Description and Objective... 1 Chapter 2 Source Water for the Final Expansion Project Source Water Orange County Sanitation District... 3 Chapter 3 Groundwater Replenishment System Final Expansion Description AWTF Process Expansion OCSD Improvements Chapter 4 GWRS Final Expansion Product Water Seawater Barrier (Talbert Barrier) Forebay Recharge Operations Mid Basin Injection Water Quality Monitoring Chapter 5 Financial Analysis Capital Cost of Project Annual Operation and Maintenance Costs Potential Sources of Financing Projected Unit Cost of GWRS FE Project Water Chapter 6 Project Implementation CEQA and NEPA Requirements Institutional Agreements Regulatory Approvals Sequencing of Project Activities and Schedule Financial Impact to OCWD Recommendation Appendix... A ii

3 Chapter 1 Introduction The Orange County Water District (OCWD) began operating the Groundwater Replenishment System (GWRS), located in Fountain Valley, California, in The 2008 GWRS facility consisted of a 70 million gallon per day (MGD) advanced water treatment facility (AWTF), a 13 mile GWRS pipeline, and an expansion of OCWD s Talbert Seawater Barrier Injection Wells. The original AWTF and pipeline projects were designed and constructed for an ultimate treatment and conveyance capacity of 130 MGD. The original GWRS design intent was to expand the GWRS facility in two phases an initial expansion of an additional 30 MGD of treatment capacity and a final expansion of another 30 MGD of treatment capacity. The GWRS Initial Expansion Project was completed in June 2015 and allows the AWTF to produce 100 MGD of purified water for groundwater injection and recharge. The GWRS Final Expansion project will include facilities required to upgrade the AWTF to produce 130 MGD of purified water as well as facilities required to convey the source water for GWRS treatment. This Engineer s Report evaluates this final expansion of the GWRS facility. 1.1 Background The OCWD manages the groundwater basin in northern and central Orange County, California by protecting, monitoring, and recharging the groundwater basin. Northern and central Orange County cities and water agencies (Producers) pump approximately 75% of their water demand from the groundwater basin to supply potable water to homes and businesses. The source water for OCWD s groundwater recharge currently comes from Santa Ana River base flows and storm flows, purified recycled water from GWRS, incidental recharge, and imported water from Metropolitan Water District (MWD). The 100 MGD AWTF as part of GWRS treats OCSD secondary effluent to drinking water standards and uses the purified water for both injection and percolation, through injection wells and recharge basins, as source water to replenish the groundwater basin s drinking water supplies. Figure 1 shows the GWRS existing facilities. 1.2 Project Description and Objective The existing AWTF has the capacity to receive 134 MGD of secondary effluent from the Orange County Sanitation District (OCSD) wastewater treatment plant and produce 100 MGD of purified water for recharge. The AWTF treats the secondary effluent with microfiltration, reverse osmosis and ultraviolet light to produce purified water for groundwater recharge. In order to increase the capacity of GWRS for the Final Expansion Project, the AWTF will require additional microfiltration cells, reverse osmosis units, ultraviolet vessels, and associated equipment in order to produce an additional 30 MGD of purified water. These improvements are referred to as the AWTF improvements. In addition to the AWTF improvements, for the GWRS Final Expansion Project, additional source water from OCSD s wastewater treatment 1

4 Figure 1 Existing OCWD Facilities

5 plants is required. With the treatment process efficiencies, approximately 40 MGD of secondary effluent is required from OCSD to produce the additional 30 MGD of purified water through GWRS. This additional 40 MGD of secondary effluent will be pumped to the GWRS facility from OCSD s Treatment Plant No. 2 located in Huntington Beach. The source water conveyance and AWTF treatment improvements will allow the GWRS facility to produce the total planned 130 MGD GWRS Final Expansion production capacity. The additional 30 MGD of purified water will be used as a new source of replenishment water for the Orange County groundwater basin Secondary Effluent Reuse Study, SP 173 The Secondary Effluent Reuse Study, (SP 173) is a jointly funded study by OCWD and OCSD to evaluate the feasibility of recycling the majority of OCSD s secondary effluent for GWRS Final Expansion Project. CDM Smith and Brown & Caldwell completed the study in July The SP 173 study evaluated numerous alternatives for obtaining the required secondary effluent for GWRS, to segregating non reclaimable flows at OCSD, to conveying the secondary effluent flows to GWRS, and to maximize the secondary effluent flow to GWRS. The study incorporated an alternatives analysis approach using Criteria Decision Plus to evaluate numerous alternatives in order to recommend the optimal project implementation plan for the GWRS Final Expansion. The recommended results from this study are summarized in this Engineer s Report. 2

6 Chapter 2 Source Water for the Final Expansion Project The OCSD operates two wastewater treatment plants that collect all of the wastewater from north and central Orange County for treatment. The OCWD & OCSD have worked together for over 40 years with OCSD providing secondary effluent free of charge to OCWD for further treatment for groundwater replenishment. This section describes the considerations for receiving an additional 40 MGD of secondary effluent at source water for the GWRS Final Expansion Project. 2.1 Source Water Orange County Sanitation District The OCSD owns and operates two treatment plants, Reclamation Plant No. 1 (Plant No. 1) in Fountain Valley and Treatment Plant No. 2 (Plant No. 2) in Huntington Beach. Currently to operate the GWRS AWTF to produce 100 MGD of purified water, OCWD receives all its secondary effluent from OCSD s Reclamation Plant No. 1. Figure 2 shows the locations of the GWRS facility, and OCSD s two treatment plants. In order for OCWD to reach the final capacity influent water requirement, OCWD will need effluent water from both of OCSD s treatment plants. 3

7 Figure 2 GWRS Final Expansion Project Area Map Reclamation Plant No. 1 Fountain Valley The OCSD owns and operates the Reclamation Plant No. 1, which is located in Fountain Valley. Reclamation Plant No. 1 (Plant No. 1) has a maximum capacity to treat approximately 180 MGD of raw wastewater to secondary effluent. All the raw wastewater is sent through the OCSD s headworks and primary treatment settling basins. The effluent from the primary settling basins is distributed to three various secondary treatment processes. The three processes are as follows: (1) Activated Sludge Plant 1 (AS1): Original activated sludge system optimized for BOD removal and converted with the addition of anoxic cells to a nitrification and partial denitrification (NDN) process. The process removes over 90% of tractable organic 4

8 material (BOD) and undissolved solids, and has removal of ammonia, partial removal of nitrate nitrogen, resulting in high quality secondary effluent for GWRS recycling. (2) Activated Sludge Plant 2 (AS2): Newer activated sludge system designed for nitrogen removal while providing equivalent removals of trace organics as AS1, producing high quality secondary effluent for GWRS recycling. (3) Trickling Filter (TF): Trickling filter system which removes similar amounts of tractable organic material and suspended material as AS1, however the TF process is less effective than the AS systems at removing suspended solids, ammonia and organics. The TF process provides a lesser quality effluent for GWRS recycling, although it does provide the ammonia necessary to form the necessary combined chlorine (chloramine) residual upon the addition of sodium hypochlorite for efficient AWTF operations Treatment Plant No. 2 Huntington Beach The OCSD also owns and operates the Treatment Plant No. 2 (Plant No. 2), which is located in Huntington Beach. Plant No. 2 has the capacity to treat 80 MGD of raw wastewater to secondary effluent. The wastewater comes into Plant No. 2 through the headworks and primary settling basins. The effluent from the primary settling basins is distributed to one of two secondary treatment processes. The two treatment processes are as follows: (1) Oxygen Activated Sludge (OAS): Uses pure oxygen instead of air to provide metabolic O2 for a conventional activated sludge system for BOD removals. The effluent produced is of lesser quality as compared to the Plant No. 1 AS1 and AS2 facilities NDN process, featuring greater suspended solids, ammonia, and organics. (2) Trickling Filter Solids Contact (TFSC): Similar to P1 TF except with an additional biological treatment step that increases removals of BOD over conventional TF systems and provides some additional removal of organics and suspended solids, but overall produces lesser quality than the Plant No. 1 AS1 and AS2 NDN processes, especially for ammonia. Approximately 60% of the Plant No. 2 primary treated effluent is sent to the TFSC facility for secondary treatment. The remaining 40% is sent to the OAS facility for secondary treatment. The TFSC plant receives peak wastewater flows that come into Plant No.2 and is therefore operated dynamically to manage the high and low flows Projected Secondary Effluent Flows The proposed source water for the GWRS Final Expansion Project is secondary effluent from OCSD s two wastewater treatment facilities. The current combined influent into OCSD s two wastewater treatment facilities is approximately 182 MGD. For the final expansion of GWRS, OCWD will require a total of approximately 174 MGD of secondary effluent to produce 130 5

9 MGD of purified water and produce 4 MGD of reclaimed water through OCWD s Green Acres Project (GAP) facility. This 174 MGD of recommended secondary effluent assumes that the AWTF microfiltration (MF) treatment process continues to operate at 90% efficiency, where 10% of the influent water returns to OCSD as Backwash Waste (BWW), and that the Reverse Osmosis (RO) treatment process operates at an 85% recovery rate, where 15% of the influent water returns to OCSD as RO concentrate for disposal in OCSD s ocean outfall. Figure 3 shows the projected secondary effluent recommended to produce the 130 MGD of GWRS product water with the associated treatment process wastes. Figure 3 Projected Secondary Effluent and Process Waste Flows for the GWRS Final Expansion Project Therefore, in order to receive 174 MGD of secondary effluent from OCSD, the flows from OCSD s Plant No. 2 will need to be considered OCSD Influent Flows In recent years there has been a steady decline in wastewater influent flows to OCSD. Figure 4 shows the average daily influent flows over the past 20 years. 6

10 OCSD Total Influent Flow OCSD Influent Flow, MGD Figure 4 OCSD Total Wastewater Inflow for both Plant No. 1 & 2 The economic recession, the ongoing drought and the water restriction mandates by the State of California are possible reasons for the decline in wastewater inflows in these recent years. Although, OCSD s treatment facilities have the ability to treat up to 260 MGD on average during non peak flow operations, in the most recent months the average daily influent has declined to 182 MGD. This 182 MGD average inflow is still more than the 174 MGD required for GWRS to produce 130 MGD of purified water, however a number of other factors must be considered to fully evaluate the availability of secondary effluent for GWRS Treatment Plant No. 2 Flows and SARI OCSD Plant No. 2 receives domestic wastewater from the coastal and central Orange County trunk lines. In addition to the local wastewater, Plant No. 2 also receives water from the Inland Empire Brine Line. The Inland Empire Brine Line, which is also known as the Santa Ana Regional Interceptor (SARI) pipeline, accepts desalter brine wastes from utilities and higher strength/sale waste from industries in the Upper Santa Ana Watershed. This water contains brine, concentrated waste streams, and effluent from the Stringfellow Hazardous Waste site in Riverside County and is currently not allowed to be used as source water for recycling through the AWTF by the Regional Water Quality Control Board permit to operate GWRS. The average SARI line flows into Plant No. 2 are 31 MGD. Approximately 30% of this flow is the brines, concentrated waste streams, and Stringfellow flows. The remaining 70% of the flows are local wastewater collected along the SARI pipeline alignment in Orange County. 7

11 Since these SARI flows are currently not allowed to be recycled through GWRS, they will have to be segregated and treated separately from the other domestic wastewater trunk sewer flows that flow into Plant No. 2, thereby allowing the remaining Plant No. 2 flows to be recycled. The improvements required to separately treat the SARI flows are discussed in more detail in Section of this report. Since the SARI line contains approximately 70% of local Orange County wastewater in addition to the SAWPA area flows, the SP 173 study evaluated the feasibility of diverting these Orange County raw wastewater flows out of the SARI line, so that the diverted flows could add additional secondary effluent for recycling through GWRS. Per the SP 173 study, there are three simple diversion projects that will be implemented by OCSD in the near future. These are referred to as SARI 1, SARI 2, and SARI 3 in the report. Implementing these three projects will divert an estimated 8 MGD of domestic wastewater out of the SARI trunkline and into adjacent Plant No. 1 trunklines that can be recycled by GWRS. Table 1 details the three OCSD diversion projects that are planned to be completed in Table 1 OCSD SARI Diversion Projects Project ID Description Predicted Domestic WW Diverted Out of SARI (MGD) SARI 1 SARI 2 Yorba Linda Pump Station Diversions into Newhope Placentia Trunkline Miller/Miraloma Diversions into Atwood Sub Trunk Sewer SARI 3 Gate Diversions into Atwood East Trunk 3.7 Sewer TOTAL With these diversions, 23 MGD will remain in the SARI Trunkline, approximately half of which is domestic wastewater and half of which is brine flows. These SARI flows will have to be segregated and treated separately at OCSD s Plant No Treatment Plant No. 2 Flows and Waste Streams During normal plant operations, OCSD produces on average 6 MGD of waste streams from their solids handling processes. These waste streams are made up of centrate/filtrate from thickening and dewatering processes, DAFT underflow, and OCWD RO Cleaning Wastes. This 6 MGD of waste streams is the average flow for OCSD s Plant No. 1 & Plant No. 2 combined. It is preferred to not recycle these flows through GWRS due to possible NDMA precursors in the 8

12 polymers used and concentrations of ammonia and organics they contain. Therefore, for these reasons, the 6 MGD of OCSD waste streams will also be segregated from secondary effluent for GWRS. These waste streams will be rerouted through the same segregated treatment train that is designated for the SARI flows discussed in the previous section. Therefore the proposed segregated flows for separate treatment at OCSD Plant No. 2 include the 23 MGD of SARI trunkline flows and 6 MGD of waste stream flows for a total of 29 MGD which will not be recycled through GWRS OCWD and OCSD Secondary Effluent Uses OCWD owns and operates a reclaimed water treatment facility referred to as the Green Acres Project (GAP) on the GWRS site. OCSD s secondary effluent is also used for source water for the GAP treatment system. On average, 4 MGD of OCSD secondary effluent is used to feed the GAP reclaimed water system. The GAP treatment process consists of a flocculation/mixing tank and dual media filters followed by a chlorine contact basin for disinfection to produce non potable tertiary treated water for reclaimed water endusers. Currently OCWD serves approximately 100 end users (including irrigation for parks, golf courses, schools) with GAP water. Discussions on the future of this system are on going, however for the purpose of this report it will be assumed that approximately 4 MGD of OCSD secondary effluent will go towards GAP. In addition to GAP, OCSD uses approximately 2 MGD of secondary effluent internally on average throughout OCSD s facilities as dilution water for various treatment processes. This 2 MGD of dilution water will be referred to as Plant Water and is the average plant water usage for both OCSD s Plant No. 1 & 2. Since the GAP and OCSD Plant Water have steady demands for secondary effluent, these flows cannot be used for GWRS Additional Secondary Effluent Flows for GWRSFE An additional source of treated wastewater used for recycling through GWRS is the backwash waste water produced from the Microfiltration (MF) Treatment Process at the AWTF. The MF process requires a 2 3 minute backwash flush of the MF modules every 22 minutes. This backwash water is MF filtered water combined with particles that have built up on the outside of the MF modules. This MF backwash waste water is suitable for recycling and is sent to OCSD s Plant No. 1 for treatment, and then returned to GWRS for recycling. The average backwash waste flows depend on how much water is being treated through the MF cells and the frequency of backwashes. Based on the current flow predictions for the GWRS Final Expansion Project, it was assumed that the MF backwash waste returning to GWRS would be approximately 16 MGD. Another source of wastewater for OCSD is the treatment of 0.6 MGD of MF cleaning wastes. After every 21 days of run time for each MF cell, the cell is cleaned through filling the cell with cleaning solutions (citric acid and sodium hydroxide) and recirculating these cleaning solutions 9

13 through the membranes. These cleaning wastes are currently piped to go to OCSD s waste streams and are therefore not recycled. However, these cleaning wastes can be safely recycled through GWRS with minimal piping improvements to allow these flows to comingle with the MF BWW flows. These flows would then be treated through OCSD s treatment processes at Plant No. 1 and counted as additional secondary effluent for GWRS. Another source of additional secondary effluent for the GWRS Final Expansion Project is the Extraction Wells for the North Basin Clean up Project. OCWD will begin construction in December 2016 on the Extraction Well No. 1 (EW 1) Project. The extraction well will be installed within the City of Placentia and the discharges from this extraction well will be routed into an OCSD sewer trunkline which feeds Plant No. 1. The project is scheduled to be complete in 2017 and it is estimated to discharge approximately 1.4 MGD to Plant No. 1 for treatment and eventual recycling through GWRS. In addition to the process waste streams mentioned above, there are potential urban runoff flows within Orange County that currently flow into storm drains/channels that could be diverted to OCSD for treatment. The OCSD Board of Directors adopted a resolution in 2000 to allow 10 MGD of urban runoff to be treated at OCSD free of charge to any parties interested. This incentive helps cities and agencies with urban runoff water quality issues develop new projects that would divert the urban runoff into OCSD s sewer trunklines for treatment. The cities/agencies responsible for the runoff would fund and manage these projects. Recently, the OCWD Board of Directors approved helping fund the Santa Ana Delhi Channel Diversion Project with City of Costa Mesa, Newport Beach, Santa Ana, and County of Orange which will divert approximately 1.4 MGD of urban runoff to OCSD Plant No. 1. This project is currently in design and is scheduled to be complete in Table 2 below shows the predicted flows to GWRS considering the segregated SARI, segregated waste stream flows, OCSD Plant Water Flows, GAP flows, and MF backwash waste (BWW) flows and new listed influent flows. 10

14 Table 2 Predicted Available OCSD Secondary Effluent for GWRS Water Type Average Flows (MGD) OCSD Wastewater Influent 182 Segregated SARI Trunkline Flows 31 Segregated OCSD Waste Stream Flows 6 GAP Flows 4 OCSD Plant Water Flows 2 MF Backwash Waste Flows 16 OCSD SARI Diversion Projects 8 MF Cleaning Waste Flows 0.6 EW 1 Flows 1.4 Urban Runoff Delhi Channel Flows 1.4 TOTAL The predicted secondary effluent of 166 MGD is 7 MGD less than the optimal 174 MGD of secondary effluent to produce 130 MGD of purified water through GWRS and 4 MGD of reclaimed water through GAP. However, the total 166 MGD reflected in Table 2 is an average predicted daily flow to OCSD. In OCSD s current inflow are peak and low flows throughout the day that can range between MGD in each direction. Therefore during peak flows, the production of 130 MGD of purified water with the GWRS Final Expansion can still be met. Also, with an average secondary effluent inflow of 166 MGD to the GWRS facility, OCWD will still be able to maintain a reliable annual yearly production average of 25,000 acre feet per year (AFY). The annual water production target is currently based on a 92% on line factor, however the GWRS facility has been operating at a more consistent 97% on line factor in recent years. With these considerations, the average 166 MGD of secondary effluent available for GWRS will still allow the annual production of 25,000 AFY to be met with an on line factor of 90%. This annual average production target will be compared with the annual costs for the GWRS Final Expansion project in the financial section of this report. It is with these considerations that OCWD recommends the GWRS Final Expansion Project despite lower than optimal average influent wastewater flows. However, if wastewater inflows for OCSD continue to decrease, there are additional outside sources of wastewater flows that can produce new influent for OCSD and provide water for GWRS. These potential projects are summarized in the section below. 11

15 Potential Future Secondary Effluent Flows for GWRSFE The SP 173 Study analyzed all projects that would be required to divert the entire domestic wastewater flows out of the SARI trunkline. However, the majority of these additional diversion projects included the requirement for new sewer lift stations within Orange County, which add significant operational and maintenance costs for these diversions. These diversions will not be further considered at this time. However there are four more diversion projects that would not require sewer lift stations and could be implemented if proven cost effective. The four additional potential domestic wastewater diversion projects are referred to as SARI 4, SARI 5.1, SARI 5.3, and SARI 5.7 in SP 173. Summarized descriptions of these projects are included in Table 3 below. Table 3 Potential OCWD Diversion Projects Project ID Description Predicted Domestic WW Diverted Out of SARI (MGD) SAR 4 SARI 5.1 SARI 5.3 Two New MHs & 200 feet of 15 inch Pipe Diversions into Taft Branch & Olive Sub Trunkline 2,800 feet of Pipe Diversions from Orange to Atwood West 11,000 feet of Pipe Diversion from Anaheim to Olive Trunkline SARI feet of Pipe from Brea to Atwood West 1.4 TOTAL OCSD s Treatment Plant No. 2 receives the SARI line flows in addition to domestic wastewater from trunk lines of OCSD s sewer system. As mentioned in Section 2.1.2, the continuous flow out of the advanced secondary treatment train at Treatment Plant No. 2 is approximately 55 MGD. The flow from this process could be pumped back to OCWD s AWPF to make up the total of 173 MGD of secondary effluent required for the source water for the final expansion. There are additional urban runoff projects that may add more influent to OCSD s Plant No. 1. The Peters Canyon Wash Groundwater Disposal and Reuse Pipeline Project is designed to capture groundwater dewatering or seepage related discharges from four locations in the lower Peters Canyon Wash. The anticipated diversion flow to OCSD will could be approximately 1.8 MGD. Another potential urban runoff project is the Santa Ana Santa Fe Channel Diversion Project. The City of Santa Ana is interested in diverting approximately 1 MGD of their Santa 12

16 Ana Santa Fe Channel and Lane Channel urban runoff flows to OCSD. If needed, OCWD would pursue the schedule for implementing these projects. The North Basin Groundwater Remediation Project is also recommending the installation of 4 more extraction wells. The four additional extraction well discharges could all be diverted into an OCSD trunk sewer main for treatment at OCSD s Plant No. 1. The flows from EW 2 through EW 5 are projected to total 2.8 MGD on average. These discharges would be treated through OCSD s Plant No. 1 free of charge with the GWRS Final Expansion Project. OCWD is also exploring the option of treating the GWRS RO concentrate flows and/or recovering more water via the RO process. It is predicted that the RO concentrate discharge flows will be approximately 23 MGD for the GWRS Final Expansion. These concentrate flows are sent to the OCSD ocean outfall. There are pilot systems that OCWD will be evaluating that would convey these concentrate flows through an additional specialized RO membrane stage with approximately 50% recovery and therefore producing approximately 11 MGD of additional GWRS product water. The cost to pilot such a system is included in the budget for the GWRS Final Expansion Project in order to determine if such a system would be a cost effective tool to boost water production OCSD Diurnal Flows Raw wastewater flows coming into Plant No. 1 and Plant No. 2 vary depending on the time of day. Night time flows into OCSD can be as low as a total of 100 MGD into both plants. Wastewater flows begin to lesson around midnight and gradually decrease until approximately 6am when wastewater influent flows begin to rise again. By 10am OCSD is typically back to their peak influent flows. In order to provide 133 MGD of secondary effluent continuously, for the GWRS Initial Expansion, OCWD constructed Secondary Effluent Flow Equalization (SEFE) tanks to capture peak flows from Plant No. 1. These peak flows are stored in the two 7.5 MG SEFE tanks and pumped back to OCWD at night to supplement night time low flows of secondary effluent. With this system, OCWD is able to capture the majority of the flows into OCSD s Plant No.1 for treatment at the Advanced Water Purification Facility. In 2015, two 7.5 million gallon Secondary Effluent Flow Equalization steel tanks (SEFE) were constructed on the AWTF site. These tanks store the secondary effluent peak flows from OCSD s Plant No. 1 during the day and at night this stored water is drained to supplement the low flows from OCSD s Plant No. 1. For the GWRS Final Expansion Project, the feasibility of capturing the peak secondary effluent flows and supplementing the low flows from OCSD s Plant No. 2 is being studied. This separate project may have the potential to enhance the overall water production through GWRS Final 13

17 Expansion. A final report analyzing the feasibility of this water production enhancement project for OCSD s Plant No. 2 will be completed in November of 2016 for further evaluation Projected Secondary Effluent Water Quality The AWTF of GWRS currently receives on average 25% secondary effluent from OCSD s Plant No. 1 Trickling Filter (TF) process. The remaining 75% of secondary effluent is from OCSD s Plant No. 1 Activated Sludge (AS) processes. The AS process at OCSD s Plant No. 1 (i.e. advanced secondary process) includes Nitrification Denitrification (NDN) and it greatly reduces the concentration of ammonia in the secondary effluent from OCSD. The NDN treatment process converts ammonia first into nitrite, then into nitrate, and then a denitrifying bacteria converts some of the nitrate into nitrogen gas. The low ammonia concentrations in the majority of the secondary effluent for GWRS allow the microfiltration treatment process efficiencies to remain high. The TF process at OCSD s Plant No. 1 consists of a fixed bed of media over which a microbial layer covers the outside of media. The primary effluent flows downward over the media for treatment. This form of treatment does not remove ammonia. Currently OCWD is receiving approximately 25% of OCSD s secondary effluent from the trickling filter treatment process. Since GWRS has been in operation, the more secondary effluent GWRS receives from the trickling filter system, i.e. the more ammonia in the feed water, the quicker the microfiltration membranes can foul, and require more frequent cleanings. The ammonia in the feed water does also provide a benefit for GWRS. OCWD uses sodium hypochlorite upstream of the microfiltration process to reduce biofouling of the microfiltration and RO membranes. The small ammonia concentration from the TF process binds with the hypochlorite to produce chloramines (combined chlorine), which act as a biocide to limit fouling, but prevents the formation of free chlorine that can damage the membranes. With the GWRS Final Expansion Project, secondary effluent from OCSD Plant No. 2 will be required. In addition, the entire Plant no. 2 Oxygen Activated Sludge treatment train will be isolated for SARI trunkflows and not available for GWRS source water. Therefore, the makeup of the secondary effluent for the GWRS Final Expansion Project will be different with respect to water quality. Table 4 below shows the predicted amount of secondary effluent from each treatment process at OCSD that will be available for GWRS. Table 4 estimates combined inflow of 182 MGD plus 3.4 MGD of new wastewater influent from MF cleaning wastes, OCWD extraction wells, and Delhi Channel urban runoff flows. 14

18 Table 4 Predicted OCSD Secondary Effluent Flows for GWRS Water Treatment Process/Source Predicted OCSD/GWRS Flows (MGD) Percent Plant No. 1 Activated Sludge (AS1) Treatment 37 22% Plant No. 1 Activated Sludge (AS2) Treatment 37 22% Plant No. 1 Trickling Filter Treatment (TF) 20 12% Plant No. 2 Oxygen Activated Sludge (OAS) SARI (1) 29 0% Plant No. 2 Trickling Filter Solids Contact (TFSC) 60 35% Recycled GWRS Flow MF Backwash Waste Flows 16 9% TOTAL 170 (1) These flows will be treated separately and not recycled through GWRS Table 4 shows that about 50% of the GWRS Final Expansion secondary effluent will come from OCSD s trickling filter treatment systems from both Plant No. 1 and 2. This will increase the ammonia concentration in the feed water for GWRS. In addition to the increase in ammonia, there are increases predicted in BOD, TOC, and TSS all of which also have the potential to foul the MF and RO membranes more quickly. There will also be an 80% predicted increase in GWRS feedwater TDS (from the saltier effluent from Plant No. 2 related to the infiltration of seawater into coastal sewer lines) which will increase feed pressure for the RO process. Alkalinity, boron and chloride concentrations are also predicted to increase. The higher concentrations of these constituents in the secondary effluent for GWRS Final Expansion will have to be evaluated in more detail. OCSD and OCWD are currently beginning a pilot study which will directly evaluate the effects of this new TFSC source water from OCSD s Plant No. 2 on the microfiltration membranes. OCWD has set up a pilot MF unit at OCSD s Plant No. 2 which will receive OCSD s Plant No. 2 effluent. The MF pilot unit will be evaluated for fouling and cleaning frequency. Pilot testing on 100% trickling filter flows, including SARI flows, represents a worst case scenario for fouling potential and actual fouling will likely be less. The unit will be run for approximately 6 months and the data from the study will be available for analysis prior to the design of this project to evaluate whether additional water quality improvements should be recommended for optimal GWRS operation Water Quality of SARI flows The current GWRS permit from the Regional Board (Order No. R ) has specified a requirement for OCWD s source water for GWRS. Specifically this order states: Only secondary treated wastewater from the OCSD Reclamation Plant No. 1 that does not include wastewater flows from the Santa Ana River Inceptor (SARI) line shall be used as influent source water for 15

19 advanced tertiary treatment at the interim WF21 and GWRS. The California Department of Public Health also noted that SARI flows should not be utilized as source water for GWRS given concerns related to unknown or potential risks from discharges to the SARI line. In order to consider allowing OCWD to use the SARI line as source water for the final expansion, OCWD has been asked to provide the following information: 1) Water quality characterization of the quantity and quality of discharges from the SARI. 2) A source control evaluation comparing the discharges of OCSD s Plant 1 (GWRS Source Water) and that of the SARI flows. OCWD has conducted a separate water study to assist with the implementation of the GWRS Final Expansion, which evaluated the water quality of the SARI trunkline, characterized the number, type and flow of the individual IEBL/SARI dischargers in the SAWPA area, and reviewed the SAWPA pre treatment (source control) program for IEBL/SARI. This study has concluded that the SAWPA area IEBL/SARI brine flows have TDS concentrations in excess of 5,000 mg/l as they enter Orange County. Recycling TDS water will add significant costs to operation GWRS. The brine flows into the SARI line are expected to increase and become more concentrated with increase in the use of groundwater and reclamation RO brine recovery processes. It has also been noted that some irregular discharges from dump stations that flow into the SARI trunkline are not adequately monitored for source water for water recycling. The SAWPA pretreatment program for the IEBL has also been revamped in recent years due to serious deficiencies uncovered by an OCSD audit. Additional SAWPA source control changes would be recommended in addition to address potential risks associated with SARI recycling. It is for these reasons that OCWD is currently not recommending to pursue actions that would allow the SARI flows to be recycled through GWRS. In turn, this requires OCWD and OCSD to recommend improvements that will treat the SARI flows separately and not allow these flows to be conveyed to GWRS. These improvements are described in the next chapter. 16

20 Chapter 3 Groundwater Replenishment System Final Expansion Description The current GWR System is made up of an advanced water treatment facility, a pipeline, injection wells and recharge basins. The original advanced water treatment facility (AWTF) incorporated the final expansion water production capacity of 130 MGD into the design of the process equipment spacing, pipeline sizes, number of pumps, and conveyance pipeline sizes. These improvements are detailed as part of the AWTF Improvement Project section. In addition to the added treatment capacity, a new pump station and pipeline at OCSD s Plant No. 2 will need to be constructed to convey additional source water to GWRS for treatment. With the exclusion of Inland Empire Brine Line flows for treatment at GWRS, a headworks bypass facility will also need to be constructed at OCSD Plant No. 2. These Plant No. 2 improvements recommended for the GWRS Final Expansion Project are detailed as part of the OCSD Improvements Section in this chapter. 3.1 AWTF Process Expansion The following sections describe the proposed improvements to the Advanced Water Treatment Facility in order to treat and produce 130 MGD of purified water Screening Facility The Screening Facility currently has all that screens that are needed for the final expansion. However current operations have shown that the screening facility storage tank may be undersized or pipe elevations into the tank are too high. In order to make sure OCWD receives the maximum flows, OCWD fills the screening facility tank in order to gravity flow the secondary effluent into the 96 inch Microfiltration Feed (MFF) pipe. There is a narrow water elevation that allows water to flow into the MFF pipe before reaching too high of an elevation to overflow the water to the ocean outfall (or SEJB 7). Therefore, when the screening facility storage reservoir water elevation reaches the overflow elevation secondary effluent is lost to the ocean. As part of the final expansion, OCWD would like this scenario evaluated to ensure that all the secondary effluent available is able to be captured and treated through the Advanced Water Purification Facility Microfiltration To expand the microfiltration system to its final ultimate capacity, 12 additional microfiltration cells will need to be added to the existing system. Train E will need to be expanded with 4 additional treatment cells. In addition, a new Train F will need to be constructed south of Train E and on the west side of the microfiltration process area. Train F will be made up of 8 new cells. The construction of the twelve new cells would occur by increasing the size of the microfiltration building and basement, which houses most of the actual MF equipment. The MF basement includes all piping, valves, pumps, instruments, and control panels. Figure 5 shows 17

21 the additional MF cells being added and the expanded building footprint. Figure 5 GWRS Final Expansion of Microfiltration Process During the backwash process, in addition to water running through the membranes the opposite direction to remove particulates that have accumulated on the membranes, the membranes are agitated with a high volume of air blown over them. The high volume of air is provided by the air blowers in the microfiltration basement. As part of the final expansion project, one additional air blower will need to be installed (along with all the piping, valves, appurtenances) that go along with feeding air to the new microfiltration cells. One additional backwash waste pump will also be required to send water from the backwash process to OCSD to be recycled as part of the final expansion. This waste is sent directly to OCSD s secondary treatment process Reverse Osmosis With exception of the equipment and piping, the Reverse Osmosis building is built out to full capacity. Therefore for the final expansion, only two new trains will need to be installed. The trains are made up of 3 units producing 5 MGD each, with 150 pressure vessels per unit. The 18

22 building also has room to house all the process equipment, piping, and electric cables for operating the trains. The treatment train equipment includes pressure vessels, RO membranes, RO feed pumps, and associated piping for each train. Figure 6 shows the location of the additional RO equipment units that are being added as part of the GWRS Final Expansion project. Figure 6 GWRS Final Expansion of Reverse Osmosis Process One additional RO Flush Feed Pump will need to be installed as part of the Final Expansion Project. This pump is a 50 hp horizontal end suction centrifugal pump which pumps RO permeate at 1000 gpm at a rated head of 120 feet. This pump provides RO permeate water to the RO membranes for flushing when a train is taken off line or for water when a train needs to be cleaned Ultraviolet Disinfection The advanced oxidation system currently part of the GWRS facility consists of hydrogen peroxide being injected upstream of the Trojan Ultraviolet (UV) processes. The system currently being used is the Trojan PHOX. In order to reach the final expansion capacity, three new trains 19

23 of the Trojan UV PHOX system will need to be installed. The piping leading up to the main influent and effluent headers is already installed. In addition to three new trains, there will be the three new electrical panels and PCS controllers. Figure 7 shows the layout of the existing and proposed UV trains. Figure 7 GWRS Final Expansion of the UV System In addition to the new trains, the UV canopy area is in need of a bridge crane system to allow the UV units to be disassembled and moved out of the area for service or future installation Decarbonation and Lime As part of the GWRS Final Expansion Project, one additional decarbonation tower and associated blower will need to be installed. The piping influent piping has already been constructed. In order to connect the decarbonation tower to the existing influent piping, an approximately 10 foot 24 inch diameter spool piece and valve will have to be installed. The effluent will drain into the Decarbonated Water Tank directly underneath the towers. Figure 8 shows the location of the proposed decarbonator tower. 20

24 Figure 8 GWRS Final Expansion of the Decarbonation System The lime system is currently built out to incorporate final capacity flow rates and therefore no additional work is required in this area Pump Stations For the Final Expansion Project, there will be one additional vertical diffusion vane pump required to be installed in the existing Product Water Pump Station building. The pump shall be rated at 20,140 gpm for 315 feet of head with a rated horsepower of 2,250 to match the four existing pumps in the building. The 30 inch discharge pipe and valve for the pump will be connected to an existing 30 inch pipe piece with a blind flange which connects to the common discharge header for all the product water pumps. For the Final Expansion two new Backwash Supply (BWS) pumps need to be installed. These pumps are provided by Siemens and have existing 20 inch discharge piping in the RO Transfer Pump Station Building assembled and ready to be connected to the new pumps. 21

25 3.1.7 Chemical For the Final Expansion Project, at least one additional 32,000 gallon steel sulfuric acid tank and dosing pump will need to be installed. Currently there is room for two new sulfuric acid tanks and pumps, however with developments in the use of new Threshold Inhibitors in the treatment process, the sulfuric acid usage for the AWPF has decreased significantly. Therefore, if the current operation of the AWTP is maintained, then only one sulfuric acid tank and pump will be required to meet the production requirements for the GWRS Final Expansion Project. During the design phase of the GWRS Final Expansion Project, the predicted sulfuric acid chemical usage will be calculated taking into account the different source water quality Electrical Each process component that is being expanded as part of the final expansion project (as mentioned in the above sections of this report), also has corresponding electrical work and equipment (cables, panels, conduit) that needs to be installed. 3.2 OCSD Improvements As mentioned in previous sections, OCWD requires 173 MGD of secondary effluent from OCSD to produce 130 MGD of purified water for the GWRS Final Expansion Project. In order to convey this volume of water to OCWD a few improvements on OCSD property will be required. An effluent pump station, conveyance pipeline, and a separate headworks facility for SARI flows will have to be constructed at OCSD s Plant No OCSD P2 Effluent Pump Station A secondary effluent pump station at OCSD s Plant No. 2 is being proposed to send between MGD of secondary effluent from Plant No. 2 to the GWRS facility. This pump station will be referred to as the OCSD P2 Effluent Pump Station. Figure 9 shows the location of this pump station. 22

26 Figure 9 OCSD P2 Effluent Pump Station Location Map The preliminary pump station layout is estimated to be approximately 47 feet by 100 feet with a three duty and one standby pump configuration. The four (4) pumps will be 500 hp vertical turbine pumps. The P2 Effluent Pump Station will take secondary effluent from the 120 inch TF SE pipeline and boost this flow into a new conveyance pipeline to GWRS OCSD Pipeline Rehabilitation OCSD owns an existing unused 66 inch gravity reinforced concrete pipeline (RCP) that connects Plant No. 2 to Plant No. 1. This pipeline was constructed prior to 1965 and is no longer in service. The pipeline alignment is 3.6 miles from Plant No. 2 to Plant No. 1. OCSD has surveyed the interior of this pipeline and determined that the pipeline is no longer usable with exposed rebar and deteriorating manholes. For the conveyance of secondary effluent from Plant No. 2 to the GWRS facility, OCSD will allow OCWD to use the 66 inch existing pipeline and construction easement. In order to convert this aging gravity RCP into a pressure pipeline to convey the effluent pump station discharge, it is being proposed to slip line the existing pipeline with a smaller diameter High Density Polyethylene (HDPE) pipe. The slip line repair entails excavation of access pits along the pipeline alignment to expose and enter into the existing pipeline. The new smaller diameter HDPE pipe will be pulled through the existing pipeline between the access pits. The new pipeline will be connected on the south to the 23

27 Effluent Pump Station at OCSD s Plant No. 2 and to the north to the existing 90 inch OCSD South East Junction Box No. 6 (SEJB6) influent pipeline. Figure 10 shows the pipeline alignment. Figure 10 P2 Secondary Effluent Conveyance Pipeline Alignment OCSD P2 Headworks Segregation/Modification In order to separate the SARI (brine) flows from comingling with domestic wastewater flows into OCSD s Plant No. 2, a separate headworks facility and bypass pipeline must be constructed. The SARI brine flows will have a dedicated flowmeter vault and screening and grit basins. After conveyance through the separate headworks, the SARI brine flows till be routed to the A side clarifiers of OCSD s Oxygen Activated Sludge treatment facility. The P2 OAS treatment facility will be entirely dedicated to the treatment of the SARI trunkline brine flows. Figure 11 shows the site plan for OCSD s Plant No. 2 headworks segregation project. 24

28 Figure 11 OCSD P2 Headworks Modification Project 25

29 Chapter 4 GWRS Final Expansion Product Water The 130 MGD purified water produced from the GWRS Final Expansion Project will be recharged into the groundwater basin through a combination of existing and new facilities. The two main sources for the GWRS product water are 1) the Talbert Seawater Barrier Injection wells and 2) the GWRS Pipeline to recharge basins in the Anaheim area (i.e. the forebay area of the groundwater basin). 4.1 Seawater Barrier (Talbert Barrier) OCWD owns and maintains the Talbert Seawater Barrier Injection Wells (Talbert Barrier).The Talbert Barrier was constructed to minimize early evidence of seawater intrusion into the groundwater basin. Currently, the Talbert Barrier contains 36 injection well sites, 32 of which are joined by a common pipeline which run along Ellis Avenue in the City of Fountain Valley and four along the Santa Ana River between Yorktown Ave. and Adams Ave. in Huntington Beach. Figure 12 shows the locations of the injection well sites. The annual Talbert Barrier capacity ranges from approximately 15 MGD to 36 MGD, with the lower flow rates occurring in the winter season and higher flow rates in the summer. The Talbert Barrier capacity is dependent on basin conditions, such as the degree of overdraft and seasonal water level fluctuations. However, over the past 8 years of operation, the average injection capacity for the Talbert Barrier has been 25 MGD (28,000 acre feet per year). 26

30 Figure 12 Talbert Barrier Injection Wells For the GWRS Final Expansion Project, to be more conservative in planning for necessary recharge capacities, the average Talbert Barrier demand will be decreased 10% to 22 MGD. During wet winter months, if the Talbert Barrier demands are temporarily below 22 MGD, the AWTF can be operated at a lower production during those wet months if needed. 4.2 Forebay Recharge Operations OCWD operates several recharge facilities in north Orange County with the purpose of percolating water via gravity into the ground. The majority of these recharge basins percolate Santa Ana River water that is diverted into them. However, there are currently four recharge basins that are dedicated for GWRS product water. These basins are Kraemer, Miller, Miraloma, and La Palma Basins. Figure 1 shows the existing GWRS pipeline and their connection to the GWRS recharge basins. These basins are filled with GWRS product water as needed. Overtime, as the water percolates into the ground, their fill rates decrease slowly until they require a cleaning. For cleaning operations, the basins are fully drained, dried, and then scraped with heavy equipment to 27

31 remove the clogging layer. Including these operational and maintenance activities, average recharge rates for these basins have been established and are summarized in Table 5 below. Table 5 Average Percolation Rates of Recharge Basins in Anaheim Recharge Basin Average Percolation Rate (MGD) Kraemer Basin 45 Miller Basin 20 Miraloma Basin 26 La Palma Basin* 45 TOTAL 136 *The percolation rate for La Palma is estimated and not based on a yearly average. The La Palma basin is currently being constructed and estimated to be completed in November OCWD began using Kraemer and Miller Basins in 1988 and 1963, respectively. Kraemer Basin is owned by OCWD. Miller Basin is owned by OC Flood Control District. During storm events, peak storm flows overflow into Miller Basin and when this occurs percolation into the groundwater basin stops. Miraloma Basin is located in Anaheim on E. Miraloma Ave. between N. Kraemer Blvd. and N. Miller Street. Miraloma Basin is owned and operated solely by OCWD and began operation in Miraloma Basin has received all of its influent water solely from the GWRS AWTF from the GWRS Pipeline. With this fully advanced treated influent water, Miraloma Basin has been able to percolate up to 50 cubic feet per second (CFS) or 32 MGD. However the average percolation rate, including down time for cleanings, since its operation has been 26 MGD. Geotechnical reports indicate that La Palma Basin should have a percolation rate similar to Miraloma Basin because of their similar sand material. La Palma Basin is going to be slightly larger than Miraloma Basin and therefore a percolation rate of 70 CFS or 45 MGD is predicted Pipeline Capacity Construction for the GWRS Pipeline was completed in The pipeline conveys water from the Advanced Water Purification Facility along the Santa Ana River for 13 miles to the Kraemer/Miller, Miraloma and La Palma Recharge Basins in Anaheim. The GWRS pipeline is concrete mortar lined and coated steel pipeline telescoping in diameter from 78 inch, 72 inch, 66 inch and 60 inch. During design of the pipeline, it was anticipated that there would be a significant volume of water recharged in the mid basin area. With this assumption, the pipeline 28