DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 1 Project Background
Project: EN25022.01 2
• Evaluated alternatives and identified a preferred site for the proposed pump station at the Rialto WWTP.
• Evaluated representative alternatives of pump conf igurations. • Presented civil, mechanical, structural, electrica l, and instrumentation design criteria for use in final design.
• Presented a Class IV opinion of probable construct ion cost (OPCC) for the Project.
The information presented in the PDR is used as a s tarting point for the alternatives analyses presented in this technical memorandum.
1.3.2 Rialto WWTP As-Builts
The Rialto WWTP serves the City of Rialto and portions of the City of Fontana, City of Colton, and unincorporated San Bernardino County. Water and was tewater systems in Rialto, including the Rialto WWTP, are managed by Rialto Water Services (RWS). R WS contracts with Veolia North America (Veolia) to operate its water and wastewater systems. The WW TP discharges treated effluent to the Rialto Flood Control Channel. The WWTP was originally constructe d in 1955 and has undergone several upgrades and expansions since its construction, the most recent of which was implemented in 2020 with the addition of a new Chlorine Contact Tank and apprutenances, design ed by AECOM.
As a part of Stantec Consulting Services Inc.’s (Stantec’s) research, AECOM’s record drawings of the Rialto WWTP were obtained from IEUA. Yard piping pl ans from the record drawings were used to determine approximate locations of existing buried utilities within the Rialto WWTP prior to location in the field via ground-penetrating radar and potholing.
1.3.3 Rialto Habitat Nature Center
The City of Rialto is currently designing the Rialto Habitat Nature Center project, located on the sou th side of the Rialto WWTP property. The project involves the construction of an approximately 8-acre lake and wetland area. The lake will be filled with dechlorinated effluent from the Rialto WWTP and will discharge to the existing WWTP discharge point via a pump station at the southeast corner of the Rialto Habitat Nature Center site. The project includes a retaining wall between the lake area and the planned Rialto Recycl ed Water Pump Station (pump station) site being designed as a part of this Project. This retaining wall establishes the boundary of the south and west sides of the pump station site.
Stantec has received the most recent design drawings for the retaining wall, dated March 12, 2024. The se drawings are used to inform the design and location of pump station components.
1.3.4 Utility Research
Utility research along the pipeline alignment was conducted by contacting utility owners listed on 811 Underground Service Alert and requesting as-builts/atlas maps of utilities in the area from each utility owner. A log of utility outreach correspondence and results is included in Appendix A . Information received from each utility owner is summarized in the subsections below.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 3 Pipeline
Project: EN25022.01
and the existing channel wall. Two additional options for crossing the I-10 freeway via a trenchless c rossing in the Alternative 2A/2B corridor are presented in Figure 5. CalTrans’ review of these options is pending.
Figure 5. Alternatives for crossing the I-10 freewa y adjacent to San Sevaine Flood Control Channel.
3.2.1.3 Union Pacific Railroad Crossings
All alternatives cross the UPRR on Santa Ana Ave. a t Live Oak Ave. Alternative 1 crosses the UPRR on Calabash Ave. Alternatives 2 and 2A cross the UPRR parallel to the San Sevaine Flood Control Channel.
Alternative 2A crosses a spur of the UPRR on Slover Ave. between Business Dr and Commerce Way.
Alternative 2B crosses a spur of the UPRR on Santa Ana Ave. between Business Dr and Commerce Way.
Alternative 1 crosses a spur of the UPRR on San Bernardino Ave. east of the San Sevaine Channel.
3.2.1.4 Alignment at Rialto WWTP
In addition to the preferred alignment within the Rialto WWTP developed during the PDR phase, Stantec has developed four additional alternative alignments.
The five alternatives evaluated (Figure 6) are:
• Alternative 1 (the alignment preferred in the PDR) – Alignment follows access road from proposed pump station location east to the Rialto Flood Control Channel, travels north parallel to the Rialto Flood Control Channel along the access road on the west side of the channel to Santa Ana Ave., and then proceeds east along Santa Ana Ave.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 3 Pipeline
Project: EN25022.01
• Alternative 2 – Alignment travels down the slope s outhwest of proposed pump station location to access road south of clarifiers in southwest corner of Rialto WWTP property, travels north along access road, travels around access road curve to the east, and then turns north up main plant access road to plant gate, then proceeds east along Santa Ana Ave. • Alternative 3 – Alignment travels west along south side of drying beds to main plant access road, then follows main plant access road north to Santa Ana Ave. • Alternative 4 – Alignment travels east along south side of drying beds to access road between Rialto WWTP and Rialto Bioenergy Facility, then follows access road to main plant access road, then follows main plant access road north to Santa Ana Ave. • Alternative 5 – Alignment travels east along south side of drying beds, under fence separating Rialto WWTP and Rialto Bioenergy Facility, east to eastern fence line of Rialto Bioenergy Facility, north along eastern side of fence to Santa Ana Ave.
Figure 6. Pipeline alignments evaluated at the Rial to WWTP.
Although Alternatives 3 and 4 follow shorter, more direct routes from the proposed pump station location to Santa Ana Ave., underground and aboveground utilities and yard piping are extremely congested in these areas. Therefore, Alternatives 3 and 4 were removed from further consideration. Alternative 5 was removed from consideration due to congestion of existing utilities and Rialto Bioenergy Facility equipment.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 3 Pipeline
Project: EN25022.01
Alternative 1 was removed from further consideration because SBCFCD will not grant permanent easement to IEUA within the Rialto Flood Control Channel. Therefore, Alternative 2 is considered to be the only viable alternative.
3.2.1.5 Alignment within SBCFCD Right of Way
In addition to the items mentioned in Section 3.2.1.2, discussions with SBCFCD highlighted the followi ng challenges:
• Construction activities that would inhibit access along channel maintenance roads may be restricted to the dry season (May–September).
• Existing utilities for the Rialto Bioenergy Facili ty are present in the SBCFCD right of way adjacent to the Rialto Flood Control Channel.
• The Rialto Flood Control Channel is listed as inte rim by SBCFCD, and there are plans for the U.S.
Army Corps of Engineers to construct permanent faci lities in the area. If the U.S. Army Corps of Engineers constructs or funds improvements to the Rialto Flood Control Channel, any construction within the channel zone of influence will likely require a Section 408 permit for modification to the existing facility.
• SBCFCD will not provide an easement or lease agree ment for the Rialto Channel portion of the alignment until the channel is built out to its ultimate condition. In the interim, an encroachment permit would be granted to IEUA for the pipeline. Therefore, SBCFCD would reserve the right to require IEUA to vacate its facilities from the SBCFCD right of way. • A new power service will be needed for the IEUA pu mp station at the Rialto WWTP, and SCE would need to apply for its own permit/easement from SBCFCD to secure its right to access for performing maintenance.
• The San Sevaine Flood Control Channel crosses thro ugh Caltrans right of way and a private property. Between the UPRR crossing and Caltrans right of way, the channel has an easement from a private property owner (Figure 7). Within the area where SBCFCD has easements from other property owners, IEUA would need to seek sepa rate easement from the owners-in-fee.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
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4.3 Tie-In to City of Rialto WWTP
Various options for the pump station tie-in method and location have been evaluated and discussed with IEUA, Veolia, and Dopudja & Wells. These options ar e presented below.
In order to deliver Title 22 water to IEUA’s AWPF at RP-4, the future pump station will receive effluent from the City of Rialto WWTP. Multiple options for connections between the existing WWTP and the future pum p station were analyzed. The selected option must be able to deliver required flows of Title 22 water reaches IEUA without restraining the WWTP from meeting its permit requirements.
The flow requirements are as follows: instantaneous environmental flows of 4.5 MGD must be discharged to the creek (based on conservative assumptions, as the city has not obtained its final permit), and IEUA will require 6.2 MGD, as a daily average of chlorinated effluent from the WWTP during the months of Ma y through October. Currently, fluctuation is leading to difficulty maintaining both 4.5 MGD of flow to the creek and 6.2 MGD to RP-4, as discussed previously in Section 2.
Regarding water quality, discharge to the creek must be dechlorinated while effluent diverted to the pump station must be chlorinated Title 22 water.
It is not possible to divert chlorinated water without disrupting the current sodium bisulfate dosing (SBS) dosing system, so changes to the dechlorination sys tem are required. Currently, a propeller flow meter, prior to the dechlorination chamber, measures all flow and is used to demonstrate contact time compliance.
Additionally, chlorine and SBS are dosed based on the flows at the dechlorination box. Therefore, if flows are diverted to the pump station prior to the flow meter, the water may be underchlorinated and chlori ne contact time (CT) requirements may not be able to be demonstrated.
The options must take into consideration plant hydraulics as well. A minimum hydraulic grade line must be maintained to divert flows to the pump station. All CCTs are currently hydraulically connected via the outlet of CCT 1.
A design criterion that was established during the development of these options is that all equipment that affects the diversion of water from the WWTP effluent to the pump station will be owned and operated b y the City of Rialto. IEUA will be the recipient of water from the City of Rialto, and control of that supply of water will be by the City of Rialto.
Each option also considers the location of ownership transition from the City of Rialto to IEUA. This location is proposed to be downstream of a flow control vault or the last control equipment between the WWTP an d IEUA pump station. The pump station operation shoul d not affect the amount of water received, as that will be controlled by the WWTP. Any equipment involved in operation will be in Veolia’s control postconstruction.
4.3.1 Description of Options
The following options were developed with input from IEUA, the City of Rialto, Veolia, and Dopudja & Wells in several workshops that were held specifically to discuss this tie-in method.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
Project: EN25022.01 51
4.3.1.1 Tie-In Option 1
Option 1 requires modifications to CCT 1 outlet and changes to SBS dosing at CCT 1 outlet, as seen on Figure 16. The outlet of CCT 3 would be modified with a tee fitting to divert water to the pump statio n. A new flow control vault would be constructed to control the diverted water, ensuring sufficient environmental flows are maintained. The SBS dosing system would b e relocated by several feet to the other side of the new weir that is constructed in the midpoint of the outlet box at CCT 1. It is assumed that the turbul ence post weir will provide sufficient mixing for the SBS, which matches the existing SBS dosing method. Th e flow meter at the dechlorination chamber would still be used to determine SBS dosing. New ultrasonic flow meters would be installed at each CCT weir to calculate contact time required for regulation.
Figure 16. Tie-In Option 1.
4.3.1.2 Tie-In Option 2
Option 2, shown in Figure 17, involves the relocation of the SBS dosing to a new vault with a static m ixing device.
Similar to Option 1, new ultrasonic flow meters at each of the CCT weirs would be required to determine sufficient CT. The proposed SBS dosing would occur in the pipeline between the CCT 1 outlet box and th e dechlorination chamber. A static mixer installed in a vault would ensure sufficient mixing of the SBS. This SBS dosing differs from Option 1, where SBS is dose d at the CCT 1 outlet box.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
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Additionally, the dechlorination chamber currently has baffles rather than weirs, so the hydraulic grade line is controlled by the weir at CCT 1. The baffles must be converted to a weir to create a hydraulic grade line that will drive diverted flow to the pump station while also ensuring sufficient flows are discharged to the creek. In addition to the static mixer in a vault, the difference between Options 1 and 2 is the alter ations to weirs to control the hydraulic grade line. For Option 1, the weir’s height at CCT 1 is increased. For Option 2, the baffles in the dechlorination box are converted into weirs.
Figure 17. Tie-In Option 2.
4.3.1.3 Tie-In Option 3
Option 3 would allow passive flow to the pump station and then rely on controls at the pump station to maintain environmental flows to the creek by regulating the flow rate of the pump station; see Figure 18.
With this option, IEUA would monitor flow signals at the dechlorination box and ramp the pumps up and down. Delayed signals to the pumps may cause difficulty maintaining the 4.5 MGD instantaneous flow to the creek in this case. This option would require more integration of metering equipment between Rialto and IEUA.
Due to the increased need for integration between R ialto and IEUA and added liability to IEUA to ensure environmental flows are met per Rialto’s permit, this option was discounted. Furthermore, the discussi on of this option helped establish the requirement that all equipment that effects or controls effluent from the WWTP must be owned and operated by the City of Rial to.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
Project: EN25022.01 53
Figure 18. Tie-In Option 3.
4.3.1.4 Tie-In Option 4
Option 4 diverts water at the dechlorination chamber; see Figure 19. With this option, the effluent that is diverted to the pump station will require re-chlorination. Veolia operations staff noted that an additional dosing point would be simple to install and operate by Veolia. The new chlorination dosing point would be owned and operated by Veolia/Rialto. The existing chlorine system is close to the required dosing area. A static mixer would be required after the dosing point.
Additionally, due to the re-chlorination, an airgap will be required to prevent backflow of chlorinated water.
This would require further coordination with the regulatory agencies overseeing the facility’s discharge permit. To account for the airgap, the pump station’s wetwell would need to be 6 ft to 8 ft deeper than previous options.
Additionally, this option may strip the effluent of its Title 22 compliance.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
Project: EN25022.01 54
Figure 19. Tie-In Option 4.
4.3.1.5 Tie-In Option 5
Rather than splitting the flows at the outlet of the CCTs, Option 5 would split flows at the inlet to the CCTs using the existing inlet structure; see Figure 20. CCT 3 would be dedicated to delivering flow to the pump station, and CCT 1 and CCT 2 would provide the 4.5 MGD minimum flow to the environment. Flow splitting control would be performed by motor-actuated weir g ates at the inlet structure. CCT 3 is an independen t system from the other two CCTs with its own chlorine dosing based on flows measured by an ultrasonic meter at CCT 3.
Based on existing operations and permitting requirements, all three CCTs are never required to be in operation at the same time. The maximum capacity of CCTs 1 and 2 combined is 11.7 MGD, and the capacity of CCT 3 alone is 11.7 MGD. If all CCTs were operating at the same time, permit discharge limits of 11.7 MGD could be exceeded.
Per Veolia, the only disruption expected in CCT operation would be a planned outage, which can be scheduled from the months of November to April when IEUA does not need water delivered. Therefore, CCT 3 could be dedicated to delivering water to the pump station without hindering operations at the WWTP.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
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Figure 20. Tie-In Option 5.
4.3.1.6 Tie-In Option 6
Rather than maintaining the 4.5 MGD environmental e ffluent flow via the inlet structure as seen in Option 5, Option 6 considers using a new flow control valve and vault near the CCT 1 outlet box; see Figure 21 a nd Figure 22. The flow control valve would control the minimum flow leaving the plant to maintain environmental flows, and the pump station would be passively connected to receive the remaining water, up to the maximum capacity of the pump station. This option would also include alteration to the weir height at the CCT 1 outlet to allow for sufficient flows to enter the valve vault. Chlorinated effluent will overtop the weir and travel through the below-grade concrete conduit that connects all three CCTs hydraulically back toward CCT 3 where the tie-in is located.
In this option, SBS dosing is moved from the CCT 1 outlet box to a point in the pipe after the valve box and will be mixed via a static mixer.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
Project: EN25022.01 56
Figure 21. Tie-In Option 6.
Figure 22. Detail of flow control vault required fo r Tie-In Option 6.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
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4.3.2 Preferred Options
Option 5 is preferred because minimal changes to operation and infrastructure are required. CCT 3 already has the capability to operate independently (process-wise) from CCT 1 and CCT 2. The alterations to the system would not exclude it from use by Rialto during the months when IEUA is not receiving deliveries .
Option 6 has more infrastructure required (valve vault).This option is the next preferred option after Option
5. Overall, both Options 5 and 6 ensure that 4.5 MGD of dechlorinated flow is prioritized and directed to the creek. Neither option requires effluent sent to the pump station to be dechlorinated and re-chlorinate d.
Option 5 is currently being considered by Veolia and Dopudja & Wells, and we are anticipating comments from them that either confirm that this is their preferred option or give the reasons not to proceed with Option 5 and instead proceed with Option 6.
Options 1 and 2 were not chosen because they provid e direct control of the flows to the pump station and maintain the environmental flows required by an ind irect method. Options 5 and 6 are preferred over these because the environmental flows are directly controlled and maintained by Veolia and the flow to the pump station is controlled indirectly, which aligns with the operational priority to maintain the environmental flows.
Option 3 was discounted as an option because it requires the operation of the pump station to maintain the environmental flows, which removes the City of Rialto’s ability to directly control and maintain the environmental flows required.
Option 4 was discounted because of the large amount of equipment required and the added depth to the wetwell to account for the airgap.
4.4 Wetwell Size
To determine the size of the wetwell, the pump stat ion wetwell was first sized per the guidelines for a rectangular intake structure per Hydraulic Institute Standard 9.8, Rotodynamic Pumps for Pump Intake Design. This standard gives minimum dimensions and recommended suction bay shape and size for a rectangular wetwell structure. The result of this analysis was a minimum wetwell structure size of 18' 6" wide and 23' 0" of length, with a pump spacing of approximately 3' 2". This minimum wetwell size is shown in Figure 23 below.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
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This pump station size results in a volume per foot of depth of 6,940 gallons. The design operating band has been selected as 2 ft, giving a total active volume of 13,880 gallons. The time required to pump this volume of water at various flow rates is given in Table 25 below.
Table 25. Pumping time for active volume at variou s flow rates.
Flow Rate (MGD) Flow Rate (gpm) Time Required to Pump
the Active Volume (minutes)
1.0 MGD 694 20.0
6.2 MGD 4,306 3.2
6.75 MGD 4,687 3.0
10.0 MGD 6,944 2.0
10.8 MGD 7,500 1.9
At the highest flow rate, the time required to empty the active volume is close to two minutes, which is sufficient time for the pumps to vary their speed and respond to changing incoming flow rates without allowing the wetwell to draw below or fill above the operating active volume.
4.5 Electrical Loads
A preliminary electrical load list was developed for the pump station site. The load list includes future loads and is based on pump sizing Option 2 as described in Section 4.2.2.3. This option includes the highest anticipated loads, so it is the most conservative estimate. The load list accounts for the following items:
• Four 450 HP Pumps (2 duty, 1 standby, 1 future)
• Two 75 HP Low-Flow Pumps (2 standby because they w ill not operate at the same time as the full- flow pumps)
• Air Compressor for Surge Tank
• Motor Control Center and Control Panels
• Redundant HVAC for Electrical Building
• Site and Building Lighting
The total estimated load is 1,483 kilovolt-amperes, 480 volts alternating current service. The electrical load lists are included in Appendix G.
A preliminary single-line diagram for the pump station has been developed, and that is included in Appendix H.
4.6 Pump Station Site Layout
The pump station site is south of the City of Rialto WWTP near the drying beds and is surrounded on th e south, west, and east sides by the future Habitat Nature Center. The plot of land dedicated to the pum p station is approximately 150 ft long in the east–west direction and 47 ft wide in the north–south direction.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
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There is a slope downward to a retaining wall directly south of the pump station. The retaining wall is part of the Rialto Habitat Nature Center project, and the design is by others.
The following has been considered or implemented in to the site layout:
• Access is anticipated to be along the north side b y entering through the WWTP and driving vehicles to the pump station site.
• All pipe is kept a minimum of 5 ft from fence line s, except where the pipe crosses perpendicularly to the fence line as it enters and leaves the site.
• The wetwell is located to avoid conflict with the geogrid that supports the retaining wall. A setback a minimum 5 ft from the closest geogrid has been assu med. • The pumps are located close to the north boundary of the site, with nothing between the pumps and the fence line to facilitate removing the pumps by crane from the access road along the south end of the WWTP.
• The site includes space for future equipment.
• A surge tank of the size required for the current project will be installed, arranged to allow for an additional surge tank to be added in parallel during future expansion. • There will be an electrical building to house the pump VFDs and a control panel. • The main switchboard will be located outside of th e electrical room. • The main utility transformer will be located towar d the north of the site, with nothing between it and the fence line to facilitate access by the local utility.
A preliminary pump station site layout is included below on Figure 25. The pump station site will be bordered by chain link fencing on all sides with adequate space between the fence and structures for pickup trucks to navigate. From west to east, the pump station site will include space for a future generator, the utility service transformer, the pump station power panel, an electrical building housing VFDs and control panels, a parking area, a surge tank (including one additional future surge tank), and the pum p station and wetwell.
The site will be graded to drain from south to north so that any spills of recycled water or washdown water do not flow to the Habitat Nature Center. Preliminary elevations for the southern corners of the site will require some revisions to the retaining wall design and geogrid layout but these are not anticipated to conflict with the wetwell layout. Constructability analysis including work sequencing, detailed excava tion footprints, and staging areas will be discussed in a future TM.
DRAFT TECHNICAL MEMORANDUM 1 – RIALTO PIPELINE CONV EYANCE SYSTEM OPTIMIZATION 4 Pump Station
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Figure 25. Rialto pump station site layout.
DRAFT TECHNICAL MEMORANDUM 1 – CONVEYANCE SYSTEM OP TIMIZATION Appendix E Preliminary Alignments
Project: EN25022.01 E- 1
Appendix E Preliminary Alignments
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