TE4.docx

Pre-Final Submittal Operation and Maintenance Guide for Central Vehicle Wash Facility Schofield Barracks, Oahu, Hawaii

Prepared For:

U.S. Army Corps of Engineers Honolulu District

Prepared by:

HDR Engineering, Inc.

Contract No. W9128A-10-D-0006 HDR Project No. 155557 October 2014

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OPERATION AND MAINTENANCE GUIDE FOR CENTRAL VEHICLE WASH FACILITY, SCHOFIELD BARRACKS

TABLE OF CONTENTS

O&M Guide for Central Vehicle Wash Facility, Schofield Barracks i

10. Vehicle Maintenance Wash Facility and Hot Water Pressure

October 2014 ii

LIST OF TABLES

Table 1 Vehicle Undercarriage Height and Slide Gate Depth 3

Table 2 Wash Station Fixtures 4

Table 3 Slurry Pump and Air Compressor Characteristics 7

Table 4 Equalization Basin Pump Characteristics 9

Table 5 Equalization Basin Pump Station Activation Levels 10

Table 6 Filtrate Pump Characteristics 12

Table 7 Filtrate Pump Station Activation Levels. 13

Table 8 Water Storage Tank 1 Piping Connections 14

Table 9 Water Storage Tank 2 Piping Connections 15

Table 10 Prewash Booster Pump Characteristics 16

Table 11 Wash Station Booster Pump Characteristics 17

Table 12 Pressure Washer Pump Characteristics 18

Table 13 Detergents Allowed at the Vehicle Maintenance Wash Facility 19

Table 14 Hot Water Pressure Washer Pump Characteristics 21

Table 15 Process Piping Characteristics 30

Table 16 Process Equipment Alarm Events 36

Table 17 Wash Procedures for Military Personnel 67

Table 18 Maintenance Tasks for Military Personnel 69

Table 19 General Rules for Military Personnel 71

LIST OF FIGURES

Figure 1 Facility Plan

LIST OF FIGURES (CONTINUED)

Figure 23 Vehicle Maintenance Wash Facility Plan

Figure 24 Vehicle Maintenance Wash Facility Oil/Water Separator Figure 25 Sediment Drying Bed Plan

APPENDIX

Inspection and Maintenance Forms vii viii

OPERATION AND MAINTENANCE GUIDE FOR

CENTRAL VEHICLE WASH FACILITY (CVWF), SCHOFIELD BARRACKS

A. OVERVIEW OF THIS MANUAL

This Operations and Maintenance (O&M) Guide is provided to give the Facility Operations Personnel a generalized overview of typical operational procedures and maintenance work required to keep the Central Vehicle Wash Facility in proper operating condition. The manual is written assuming that the processes and equipment selected for the project are consistent with the originally specified processes and equipment. This O&M Guide is not intended to replace equipment manufacturers’ O&M manuals that are provided with the purchased equipment. In the event of conflict between this O&M Guide and the equipment manufacturer supplied O&M Manual, the equipment manufacturer supplied O&M Manual shall govern. All activities must be conducted in accordance with the Facility Operations Personnel’s Safety Plan. In the event of a conflict between this O&M Guide and the Facility Operations Personnel’s Safety Plan, the Facility Operations Personnel’s Safety Plan shall govern.

This O&M Guide is structured as follows:

1) Overview of This Manual

2) General Description of the Facility

3) Description of Individual Process Components

4) Facility Startup

5) Typical Operation of Facility During a Wash Event

6) Facility Shutdown

7) Operation of Facility Before and After a Storm Event

8) Typical Maintenance of Facility

9) Standard Operating Instructions for Military Personnel

B. GENERAL DESCRIPTION OF THE FACILITY

The Central Vehicle Wash Facility (CVWF), Schofield Barracks, is used to wash soil from the outside of tactical vehicles after returning from training. The primary purpose of the facility is to provide expedient, cost-effective vehicle cleaning for tactical vehicles, while incorporating water conservation and recycling techniques. Washing is intended to clean vehicles sufficiently for inspection and reduce the potential migration of mud and plant seeds.

The Central Vehicle Wash Facility recycles spent vehicle washwater for reuse to minimize consumption of potable water. The recycled washwater is non-potable and is not appropriate for human consumption. The facility utilizes sedimentation (settling), oil/water separation, equalization, intermittent sand filtration, disinfection (chlorination), and water storage tanks to recycle the washwater. Vehicles are washed in a prewash bath or wash stations. There is a separate four bay vehicle maintenance wash facility to provide detailed washing of vehicles prior to maintenance.

Heavily soiled vehicles must utilize the prewash bath. Lightly soiled vehicles can bypass the prewash bath and proceed directly to the wash stations. Estimated wash time at the prewash bath is ten minutes per vehicle for heavily soiled vehicles. An additional two minutes per vehicle is assumed for vehicle maneuvering into and out of the prewash bath. Estimated wash times at the wash stations are 20 minutes for vehicles that used the prewash bath first, and 30 minutes for lightly soiled vehicles, that bypassed the prewash bath. Wash times at the wash stations include time for vehicle maneuvering into and out of the wash stations.

Vehicles must be washed in the prewash bath or at the wash stations prior to entering the vehicle maintenance wash facility.

The facility utilizes potable water for pressure washers; make up water lost due to vehicle carry-off and evaporation; for the control building restrooms; and for wash down of the equalization basin to meet storm water discharge requirements.

The facility was designed for three wash scenarios: a peak wash event, normal wash event, and daily wash event.

For a peak wash event, the facility was designed to wash 800 vehicles over a three-day period, at 24 hours per day. The peak wash event is expected to occur no more than three times per year.

For a normal wash event, 200 vehicles are expected over a two-day period, at ten hours per day. The normal wash event occurs weekly, and is not expected to occur during the same week as a peak wash event.

For a daily wash event, ten vehicles are expected per day. Daily wash events occur during the remaining days.

A physical layout of the facility is shown on Figure 1. A process flow diagram is shown on Figure 2. Design data for individual processes is shown on Figure 3. Specific processes are described in detail in the following sections.

C. DESCRIPTION OF INDIVIDUAL PROCESS COMPONENTS

1. Prewash Bath and Trench Drain

The prewash bath consists of a reinforced concrete bath with entrance and exit ramps to accommodate heavily soiled vehicles during a wash event. The prewash bath is used to loosen soil and debris from vehicle wheels and undercarriage. Lightly soiled vehicles can bypass the prewash bath and proceed directly to the wash stations. A plot plan of the prewash bath is shown on Figure 4.

The prewash bath has a level control structure to adjust the water level in the bath. The level control structure is located at the end of the exit ramp. Slide gates of varying depths are used in the level control structure to control the water level in the bath.

Three interchangeable slide gates adjust water depths to one foot, 1.5 feet, and two feet. The water level selected is based on the undercarriage height of the vehicles expected to utilize the prewash bath. The vehicles expected to utilize the prewash bath are listed in Table 1 with undercarriage height and corresponding slide gate depth.

Table 1 Vehicle Undercarriage Height and Slide Gate Depth

Vehicle Type

The prewash bath has four water cannons to clean vehicles in the prewash bath. A water cannon is located at each corner of the bath. Each water cannon has a flow rate of 80 gallons per minute (gpm) at a pressure of 100 pounds per square inch (psi). A maximum flow rate of 320 gpm is anticipated when all four water cannons are in use.

A prewash trench flush vault is located on the north side of the prewash bath as shown on Figure 4. The prewash trench flush vault contains a manually operated gate valve, PB-V1, and backpressure regulating valve as shown on Figure 5. The trench flush is used when draining and flushing the prewash bath and trench drain. Valve PB-V1 is used to isolate the trench flush. Valve PB-V1 must be opened manually prior to flushing the prewash bath and trench drain. Valve PB-V1 must be manually closed after flushing the prewash bath and trench drain.

A hose bibb is located on the south side of the prewash bath as shown on Figure 4. The hose bibb can be used with a hose to wash down the prewash bath entrance and exit ramps and bath during draining and cleaning.

Spent washwater enters a concrete trench drain, Trench Drain A, and flows into the Sedimentation Basin. Trench Drain A intersects with Trench Drain C before flowing to the Sedimentation Basin as shown on Figure 1. The trench drain has a U-shaped invert sloped at two percent to optimize hydraulic efficiency and to minimize accumulation of settled solids. The trench drain has a removable traffic-rated, heavy-duty metal grating. If the trench drain becomes clogged, hoses can be used to flush the trench drain. In addition, the metal grating can be removed by hand to facilitate flushing.

The prewash bath is emptied after approximately 200 vehicles have been washed. However, the operator can vary the frequency that the bath is emptied based on soiling of vehicles. Draining, cleaning, and refilling the prewash bath takes approximately one hour. During this time, the bath will be out of service. The bath is flushed by removing the slide gate in the level control structure and opening Valve PB-V1 in the prewash trench flush vault. The water cannons and a hose can be used to clean the prewash bath after draining. The bath is filled by opening the plug valve, PB-V2, located on the south side of the prewash bath. The bath is filled directly from the water storage tanks using the available head in the water storage tanks.

The prewash booster pumps at the Pump Building supply the water cannons and the prewash trench flush. Refer to Section C10 for a description of the Prewash Booster Pumps.

2. Wash Stations and Trench Drain

The wash stations consist of a reinforced concrete pad with low-pressure hoses and high pressure washers. A plot plan of the concrete wash stations is shown on Figure 6. There are ten wash stations (WA). There are two tandem stalls to accommodate trucks with trailers and six individual stalls. Each wash station has two low-pressure hose connections and four high-pressure washer quick connections. The ten wash stations are equipped with the fixtures listed in Table 2:

Table 2 Wash Station Fixtures

Fixture

Spent washwater enters a concrete trench drain and flows into the Sedimentation Basin. Each wash station is sloped to a center trench drain, Trench Drain C, which runs perpendicular to the wash pads. The trench drain has a U-shaped invert sloped at two percent to optimize hydraulic efficiency and to minimize accumulation of settled solids.

The trench drain has a removable traffic-rated, heavy-duty metal grating. If the trench drain becomes clogged, the low-pressure hoses can be used to flush the trench drain. In addition, the metal grating can be removed by hand to facilitate flushing.

Square pits are centered over the trench drains between each wash station as shown on Figure 6. The square pits are used to capture gravel to reduce the potential for clogging the trench drain. The gravel pits have a removable traffic-rated, heavy-duty metal grating. Grating can be removed with equipment as needed.

Do not wash any vehicle that is NOT PARKED ENTIRELY on the concrete wash station area within the painted dashed lines as shown on Figure 6 because spent washwater will not be captured and directed to the Sedimentation Basin.

A trench flush nozzle is located in a trench flush vault connected at the upstream end of Trench Drain C as shown on Figure 6 and Figure 7. The trench drain flush nozzle is used to flush Trench Drain C. The trench drain is flushed approximately every eight hours during a peak wash event. Flushing the trench drain takes approximately 15 minutes. However, the operator can vary the trench drain flushing frequency and duration based on soiling conditions. During trench drain flushing, all low-pressure hose connections at the wash stations must be closed.

The trench flush nozzle is connected to Process Line “C” and flow is controlled by a back pressure regulating valve. When all washing has stopped, the back pressure regulating valve maintains a back pressure, providing flow to flush the trench drain.

The back pressure regulating valve is adjacent to a gate valve, WS-V1. Valve WS-V1 is used to isolate the trench flush nozzle. Valve WS-V1 must be opened manually prior to beginning a wash event. Valve WS-V1 must be manually closed after a wash event is complete.

The wash station booster pumps at the Pump Building supply the low-pressure hose connections and the wash station trench flush nozzle. Refer to Section C11 for a description of the Wash Station Booster Pumps. Wash station pressure washer pumps at the Pump Building supply water to the high-pressure connections. Refer to Section C12 for a description of the Wash Station Pressure Washer Pumps. A design flow rate of 66 gpm is anticipated from the wash process per wash station. A maximum flow rate of 660 gpm is anticipated when all ten wash stations are in use.

Trench Drain Junction Box

The Trench Drain Junction Box consists of a reinforced concrete box with slide gates to direct trench drain flow to either the Sedimentation Basin or the Equalization Basin.

Typically, water will flow to the Sedimentation Basin via Trench Drain C. However, prior to a severe weather event, water must be directed to the Equalization Basin via Trench Drain D. Wash events shall not be scheduled during a severe weather event. The Trench Drain Junction Box is located west of the Sedimentation Basin.

3. Sedimentation Basin, Slurry Pumps, and Air Compressor

Sedimentation Basin

The Sedimentation Basin, as shown on Figure 8, is a large concrete tank used to settle out larger clumps of mud, small rocks and pebbles, and other soil particles washed from the vehicles. These particles settle to the bottom of the tank as the washwater flows from the inlet side to the outlet side of the tank. The Sedimentation Basin was designed to remove silt and clay particles. The Sedimentation Basin has two compartments, each with a length of approximately 135 feet and width of approximately 45 feet. The total depth of the outlet end of the Sedimentation Basin is approximately 6.7 feet. The bottom one foot depth of the Sedimentation Basin is used for sediment storage, while the upper 1.5 feet of the Sedimentation Basin is used for freeboard.

Design characteristics of the Sedimentation Basin are as follows:

1) Maximum flow rate into basin:

· Four water cannons at 80 gpm = 320 gpm

· 20 low-pressure hoses at 25 gpm = 500 gpm

· 40 high-pressure wands at 4 gpm = 160 gpm

· Total maximum inflow = 980 gpm

2) Detention time at maximum inflow (with two compartments) = 4.0 hours

3) Water volume provided = 438,507 gallons

4) Sediment storage provided = 12,150 ft3

The Sedimentation Basin is partially below grade and is rectangular-shaped in plan view. Trench Drain C discharges to the Sedimentation Basin Junction Box as shown on Figure 8. Two openings in the Sedimentation Basin Junction Box direct flow to Sedimentation Basin Compartments A and B. During normal operation, both compartments are operational and flow enters Compartment A and B. Stainless steel slide gates, SB-G1 and SB-G2, mounted within the Sedimentation Basin Junction Box allow either compartment to be isolated for maintenance.

Washwater enters the Sedimentation Basin through the Sedimentation Basin Junction Box, flows through the Sedimentation Basin to the opposite end, over a v-notch weir into an effluent launder. The Sedimentation Basin compartments are covered by a geomembrane cover to prevent excessive evaporation due to high winds and low humidity and to reduce the growth rate of algae in the Sedimentation Basin. The geomembrane cover also assists in preventing the propagation of frogs, toads, and mosquitoes. The geomembrane covers are equipped with “windows,” which can be opened for ventilation prior to entering the Sedimentation Basin.

The effluent launder is a rectangular shaped concrete channel as shown on Figure 9. The effluent launder in Compartment A is connected to the Aboveground Oil/Water Separators through a 10-inch DI pipe connection. The effluent launder in Compartment B is connected to the Aboveground Oil/Water Separators through a 12-inch DI pipe connection.

The bottom of each Sedimentation Basin compartment was sized to provide sediment storage for approximately one year. If wash activity exceeds the design criteria, sediment is expected to accumulate more rapidly and will require cleaning more frequently.

Slurry Pumps and Air Compressor

There are two air-operated, double diaphragm, positive displacement slurry pumps at the Sedimentation Basin. An air compressor housed in the Pump Building provides compressed air for the slurry pumps. Each Sedimentation Basin compartment has a dedicated slurry pump to remove sediment slurry. The slurry is pumped from the Sedimentation Basin to the Sediment Drying Bed weekly or as necessary. Sediment Slurry Pump 1 pumps Sedimentation Basin Compartment B and Sediment Slurry Pump 2 pumps Sedimentation Basin Compartment A. The slurry pump suction piping enters the Sedimentation Basin near the sump in each compartment.

Design characteristics of the slurry pumps and air compressor are listed in Table 3:

Table 3 Slurry Pump and Air Compressor Characteristics

Max Pressure: 100 psi Air Flow at Max Pressure: 78 CFM

It is recommended that sediment slurry be pumped from the Sedimentation Basin weekly with the slurry pump. To remove accumulated sediment, the Sedimentation Basin can be drained and cleaned annually. To facilitate Sedimentation Basin draining during sediment removal, a telescoping valve system allows water levels to be drawn down. A telescoping valve in compartment A and compartment B, Telescoping Valves SB-V1 and SB-V2, respectively, allows water to be decanted from a normal operating depth of approximately 5.2 feet down to a depth of approximately 1.2 feet. The telescoping valve allows the operator to manually draw down the water in the Sedimentation Basin and maintain control over the amount of silt-laden water discharging to the Equalization Basin.

After the water level reaches a depth of approximately 1.2 feet, the accumulated sediment should be left for several days in the Sedimentation Basin, if possible, to facilitate additional dewatering via evaporation.

4. Aboveground Oil/Water Separator

The Aboveground Oil/Water Separator is a prefabricated steel rectangular “in-line” device used to remove oil and grease as shown on Figure 10. There are two Aboveground Oil/Water Separators east of the Sedimentation Basin, which receive water from the Sedimentation Basin effluent launder via a 10-inch DI pipe. The Aboveground Oil/Water Separator discharge outlets are connected to the Equalization Basin through Process Line “I”. Process Line “I” includes a 12-inch PVC pipe connected to three manholes. The Aboveground Oil/Water Separator is equipped with internal baffles and coalescers to facilitate the oil/water separation process. Oil and grease accumulate on the water surface within the Aboveground Oil/Water Separator while effluent is discharged by gravity to the Equalization Basin.

Prior to a severe weather event, the Aboveground Oil/Water Separator would be isolated using the slide gates in the Trench Drain Junction Box. Closing the trench drain slide gate to the Sedimentation Basin, TD-G1, and opening the slide gate for Trench Drain D, TD-G2, as shown on Figure 8 will direct storm water to the Equalization Basin. Inflatable pipe plugs would be placed into the Sedimentation Basin Effluent Line located in the effluent launder of each Sedimentation Basin compartment to prepare for a storm event.

A third oil/water separator is located in a below grade vault west of the Vehicle Maintenance Wash Facility. Refer to Section C13 for a description of the Oil/Water Separator at the Vehicle Maintenance Wash Facility.

5. Equalization Basin and Equalization Basin Pump Station

The Equalization Basin, as shown on Figure 11, is a large concrete tank used to provide storage to allow wash water to be delivered at a controlled rate to the intermittent sand filter. The wash water generated during a peak wash event is stored in the Equalization Basin and pumped to the intermittent sand filter at regular intervals over a seven-day period. The Equalization Basin has a compartment located in the northeast corner, which operates as a smaller basin during normal wash events and daily wash events.

The Equalization Basin has a length of approximately 250 feet and a width of approximately 200 feet. The depth in the Equalization Basin varies. The bottom of the basin is sloped towards the compartment. The depth outside the compartment wall is approximately 20 feet. The upper 2.5 feet of the Equalization Basin is used for freeboard.

The compartment has dimensions of 50 feet by 50 feet. The compartment contains a slide gate, EQ-G1, in the west wall to isolate the compartment from the rest of the basin. The entire Equalization Basin must be emptied and washed down after each wash event to assure the State of Hawaii Department of Health that storm water generated durin g a storm event will not be mixed with wash water prior to discharge in the bioswale. There are four hose bibbs connected to Water Line “A” located around the Equalization Basin as shown on Figure 11. Hoses can be connected to the hose bibbs to wash down the Equalization Basin. Storm water from large storm events would be isolated and stored in the Equalization Basin. Storm water would be pumped to the Intermittent Sand Filter and discharged at a controlled rate into the bioswale using Valve DL-V1. The bioswale is located to the east of the Intermittent Sand Filter.

DO NOT schedule a wash event until after captured storm water has been discharged from the Equalization Basin. Refer to Section G for instructions on operating the facility after a storm event. If the water level in the Water Storage Tanks is low, filtered storm water can be used to fill the Water Storage Tanks. Design characteristics of the Equalization Basin are as follows:

1) Effective water storage volume provided = 4,488,000 gallons

2) Volume of compartment = 205,700 gallons

Most of the Equalization Basin is below grade and is rectangular-shaped in plan view. Flow from Process Line “I” and Process Line “M” discharge into the Equalization Basin compartment as shown on the Equalization Basin plan view on Figure 11. Trench Drain D, Drain Line D, and Drain Line E also discharge to the Equalization Basin.

The Equalization Basin Pump Station is a rectangular sump located in the northeast corner of the Equalization Basin compartment and functions similarly to a pump station wet well. A plan view of the compartment is shown on Figure 12. There are two pumps in the Equalization Basin Pump Station as shown on Figure 13. Pump discharge piping and valves are located in the Equalization Basin vault, a concrete vault, as shown on Figure 12 and 13. A socket base for a portable davit crane is located adjacent to the Equalization Basin vault. The portable davit crane can be used to remove the Equalization Basin pumps for maintenance. Water from the Aboveground Oil/Water Separator and filtrate from the sediment drying bed discharge into the Equalization Basin Pump Station and is pumped to the Intermittent Sand Filter at a controlled rate.

The Equalization Basin Pump Station is equipped with two submersible non-clog pumps, normally operated with one pump in operation and the other in standby. The pumps are equipped with an auto-alternator to automatically alternate operating and standby modes between the two pumps. Equalization basin pump characteristics are listed in Table 4.

Table 4 Equalization Basin Pump Characteristics

The pumps are normally always activated and will operate during a storm event if water levels in the Equalization Basin Pump Station rise. Pump operation is activated by a level transducer at water levels in the sump listed in Table 5. Pumps can be operated manually for maintenance or as necessary.

Table 5 Equalization Basin Pump Station Activation Levels

Action

Notes

The pumps are wired for five alarm conditions: Level Alarm High, Level Alarm Low, motor overload, Emergency Shutdown, and power failure. Each of the alarm conditions activate a red light on the equalization basin pump station control panel mounted in the Pump Building Electrical Room. The control panel alarm signals are also transmitted to the Emergency Shutdown/Alarm Cabinet mounted on the outside face of the Pump Building and Control Building. Alarm conditions will activate a red light and audible horn at the Control Building. A plan view of the Pump Building is shown on Figure 14. The equalization basin pumps are connected to the Emergency Shutdown/Alarm Cabinet.

The push button at the Emergency Shutdown/Alarm Cabinet can be used to shut down all processes automatically in the event of an emergency.

6. Intermittent Sand Filter

The Intermittent Sand Filter is a large concrete structure containing separate layers of sand and support gravel to remove the solid particles, which did not settle in the Sedimentation Basin. The Intermittent Sand Filter is divided into four cells as shown on Figure 15. Each cell is divided by a concrete wall and has a length of approximately 135 feet and width of approximately 94 feet. The depth of the sand layer is approximately three feet. Each cell contains a concrete distribution box, concrete distribution channel with metal grating, and PVC distribution piping. An access ramp into each filter cell is provided for cleaning operations.

Water pumped from the Equalization Basin is applied to the Intermittent Sand Filter at controlled rates. Each cell is dosed in eight hour intervals to allow the cell to drain and “breathe” between doses. Improper dosing may result in the filter surface becoming plugged. Electric motor operated valves, MOV-1, MOV-2, MOV-3, and MOV-4, are used with a programmable logic controller (PLC) to apply wash water to the filters.

Dosing intervals are alternated from cell to cell.

Two operating modes have been programmed into the PLC: “Peak Wash” and “Normal Wash.” The “Peak Wash” mode is selected for a peak wash event. The “Normal Wash” mode is selected for normal wash events and daily wash events. The initial sequences for the “Peak Wash” and “Normal Wash” modes are shown below. However, the sequences in the PLC are field adjustable and can be reprogrammed as necessary.

"Peak Wash" Sequence

Electric Motor Operated Valve 1 opens Enable Equalization Basin Pump Controller

Disable Equalization Basin Pump Controller t = 8 hrs 40 mins Sequence Repeats

"Normal Wash" Sequence

Enable Equalization Basin Pump Controller

Disable Equalization Basin Pump Controller t = 8 hrs 40 mins Sequence Repeats

Underdrain piping in each filter cell as shown on Figure 16 collects the filtrate. Filtrate flows by gravity to the Filtrate Pump Station.

A slimy layer of sediment will collect on the filter surface over time. The slimy layer will become tightly matted and block flow through the filter and eventually cause ponding. After a slimy mat has formed on the surface of the filter, the filter cell must be taken offline to allow the filter cell to dewater. After the surface mat is dry enough, rake the filter surface to break up any material clogging the filter surface. Accumulated sediment may be removed annually or more frequently depending on sediment accumulation.

Do not take a filter cell offline during a peak wash event. During a peak wash event, four filter cells are needed to dewater the volume of water generated. A filter cell may be taken offline during a normal wash event or a daily wash event. However, the electric motor operated valves are not programmed to automatically dose the filter cells when a filter cell is offline. If a filter cell is offline, manually dose the remaining intermittent sand filter cells. Each filter cell should be dosed for 40 minutes. Dose each cell in eight hour intervals to allow the cell to drain and “breathe” between doses.

7. Filtrate Pump Station and Filtrate Pumps

The Filtrate Pump Station is a rectangular concrete structure that functions as a pump station wet well. There are two filtrate pumps in the Filtrate Pump Station as shown on Figure 17. Pump discharge piping and valves are located in a concrete vault as shown on Figure 17. A socket base for a portable davit crane is located adjacent to the Filtrate Pump Station vault. The portable davit crane can be used to remove the filtrate pumps for maintenance. Filtered water from the Intermittent Sand Filter discharges into the Filtrate Pump Station and is pumped into the Water Storage Tanks.

The Filtrate Pump Station is equipped with two submersible non-clog pumps, normally operated with one pump in operation and the other in standby. The pumps are equipped with an auto-alternator to automatically alternate operating and standby modes between the two pumps. Filtrate pump characteristics are listed in Table 6.

Table 6 Filtrate Pump Characteristics

The pumps are normally always activated and will operate during a storm event if water levels in the Filtrate Pump Station rise. Pump operation is activated by a level transducer at water levels in the sump listed in Table 7. Pumps can be operated manually for maintenance or as necessary.

Table 7 Filtrate Pump Station Activation Levels

Action

Notes

The pumps are wired for five alarm conditions: Level Alarm High, Level Alarm Low, motor overload, Emergency Shutdown, and power failure. Each of the alarm conditions activate a red light on the filtrate pump station control panel mounted in the Pump Building Electrical Room. The control panel alarm signals are also transmitted to the Emergency Shutdown/Alarm Cabinet mounted on the outside face of the Pump Building and Control Building. Alarm conditions will activate a red light and audible horn at the Control Building. A plan view of the Pump Building is shown on Figure 14. The filtrate pumps are connected to the Emergency Shutdown/Alarm Cabinet. The push button at the Emergency Shutdown/Alarm Cabinet can be used to shut down all processes automatically in the event of an emergency.

8. Chlorination Unit

There is a skid-mounted hypochlorite mixing and feed system in the Pump Building Chlorination Room to chlorinate the filtered washwater prior to storage. The chlorination unit uses solid calcium hypochlorite tablets stacked in a storage canister above a mixing chamber. A 1-1/2 inch water line feeds the mixing chamber, causing the tablets to dissolve and release hypochlorite. The hypochlorite solution is stored in a solution tank below the mixing chamber. When water is added to calcium hypochlorite, it combines to form hypochlorous acid, a weak acid, which is the primary disinfecting agent and calcium hydroxide, a strong base.

There are two feed pumps on the chlorination skid. One feed pump is used to inject the

0.25 percent hypochlorite solution at the chlorine injection point on the 10-inch DI pipe as shown on Figure 18. The second feed pump is a backup pump. The chlorination unit feed pump injects hypochlorite into the water prior to storage in the Water Storage Tanks.

The chlorination unit is controlled using a process logic controller (PLC) and chlorine residual analyzer. A sample is drawn from the chlorine residual sample point inside the

Pump Building as shown on Figure 14. The sample is conveyed to a wall mounted chlorine residual analyzer via a 0.25 inch PVC tube. The chlorine residual analyzer sends a 4 to 20 mA signal that varies in proportion to the chlorine concentration to the process controller to control the variable speed injection feed pumps. The pump speed is controlled to increase or decrease the hypochlorite solution feed rate to maintain a typical chlorine residual of 1.0 mg/L.

A three-day peak wash event would consume approximately 244 pounds of tablets per day. For the design three-day peak wash event, approximately 732 pounds of tablets would be consumed. The storage canister has a capacity of 280 pounds, which would require re-filling after every peak wash event day. DO NOT store more than 2300 pounds of calcium hypochlorite tablets in the Pump Building Chlorination Room.

A flow meter and sampling port are provided at the facility to monitor water quantity and quality. The flow meter is located in a below grade vault on the south side of the Pump Building. The sampling port is located inside the Pump Room of the Pump Building.

9. Water Storage Tanks

There are two aboveground steel tanks that provide storage for the finished water as shown on Figure 1. Each tank has a diameter of 74.27 feet and its height is 28 feet as shown on Figure 19 through Figure 22. Each tank has a capacity of 761,500 gallons. The total capacity of the two tanks is 1,523,000 gallons, which provides storage for one day of a peak wash event. The Water Storage Tanks are supplied by potable water to make up for water losses due to evaporation, overspray, and vehicle carry-off. The Water Storage Tanks supply the prewash bath, wash station low-pressure hoses, and trench flush nozzles. The water in the Water Storage Tanks is chlorinated to maintain a chlorine residual of 1.0 mg/L. The tanks have piping connections as listed in Table 8 and Table 9:

Table 8 Water Storage Tank 1 Piping Connections

Table 9 Water Storage Tank 2 Piping Connections

To fill the tank with potable water to makeup for water losses, a 4-inch gate valve, T1-V1 on Water Storage Tank 1 and valve T2-V1 on Water Storage Tank 2 is manually opened. A 4-inch float valve is connected on the interior of each tank to the inlet from Water Line “A1” to reduce potential for overflows during tank filling. The 4-inch float valve is shown on Figure 20 and Figure 22. When the float valve reaches the maximum water level, the valve closes, stopping the flow of potable water into the tank. However, if water is withdrawn from the tank during filling, the water level in the tank will drop and the float valve will open. Valve T1-V1 and T2-V1 must be manually closed after filling the tank.

The interior of the tanks have an overflow assembly connected to an exterior 6-inch pipe that drains to grade. The overflow pipes are located along the east sides of the tanks and daylights at a concrete splash block. The tanks have exterior gage board indicators mounted on the west faces, adjacent to the 10-inch connection to Process Line “E”. The exterior gage board indicator is connected to a float inside the tank and indicates the water level in the tank.

During a peak wash event, the tank operating levels would range between 25 feet - full and 5 feet. During a peak wash event, after approximately 24 hours of washing, approximately 4.6 feet of water will need to be added to each water tank to replenish the tank’s water supply for the remaining 48 hours of wash activity.

10. Prewash Booster Pumps

The skid-mounted prewash booster pump system has three pumps in the Pump Building and draws water from the Water Storage Tanks to provide water to two sources at the Prewash Bath: 1) water cannons, and 2) prewash trench flush. The prewash booster pumps are also used to recirculate the water in the Water Storage Tanks. A 4-inch recirculation line from the prewash booster pump discharge piping is connected to a 10-inch DI pipe, which is connected to Process Line “F.” The recirculation line is shown on Figure 18.

The skid-mounted booster system contains the three pumps, intake and discharge piping header, valving, pressure gauges, and control panel. The prewash booster pump system has variable frequency drives and uses a pressure transducer to regulate the flow rates and discharge pressures for the water cannons. The prewash booster pumps are shown on Figure 14.

The prewash booster pumps are configured in a triplex system in an operating/standby mode and are operated in auto alternation mode for even wear of the pumps. The prewash booster pumps have the design characteristics listed in Table 10:

Table 10 Prewash Booster Pump Characteristics

The prewash booster pumps are MANUALLY activated prior to beginning a wash event. The pumps have the following alarm conditions: motor overload, low suction pressure, and high system pressure. All alarm conditions are indicated at the prewash booster pump control panel and activate an alarm condition at the Emergency Shutdown/Alarm Cabinet at the Pump Building and Control Building. Alarm conditions will activate a red light and audible horn at the Control Building.

11. Wash Station Booster Pumps

The skid-mounted wash station booster pump system has three pumps in the Pump Building and draws water from the Water Storage Tanks to provide water to three sources at the wash stations: 1) low-pressure hose connections at the wash stations,

2) trench flush nozzle on Trench Drain C, and 3) wash down hose bibbs.

The skid-mounted booster system contains the three pumps, intake and discharge piping header, valving, pressure gauges, and control panel. The booster pump system has variable frequency drives and uses a pressure transducer to supply the required flow rates and discharge pressures to the wash stations. The wash station booster pumps are shown on Figure 14.

The wash station booster pumps are configured in a triplex system in an operating/standby mode and are operated in auto alternation mode for even wear of the pumps. The wash station booster pumps have the design characteristics listed in Table 11:

Table 11 Wash Station Booster Pump Characteristics

The wash station booster pumps are MANUALLY activated prior to beginning a wash event. The pumps have the following alarm conditions: motor overload, low suction pressure, and high system pressure. All alarm conditions are indicated at the wash station booster pump control panel and activate an alarm condition at the Emergency Shutdown/Alarm Cabinet at the Pump Building and Control Building. Alarm conditions will activate a red light and audible horn at the Control Building.

12. Wash Station Pressure Washer Pumps

There are eight skid-mounted pressure washer pumps arranged in tandem in the Pump Building. Four pressure washer pumps can be operated concurrently to provide water to forty pressure washer wands at the wash stations. The remaining four pressure washer pumps are provided as standby pumps. The pressure washer pumps are supplied by potable water and provide water for the high-pressure connections at the wash stations. Each tandem set of pressure washer pumps supplies water to ten pressure washers at the wash stations.

The skid-mounted booster pump system contains a pump, intake and discharge piping, pulsation dampener, valving, pressure gauges, and control panel. The pressure washer pump system has variable frequency drives and a pressure regulator to supply the required flow rates and discharge pressures to the wash station pressure washer wands. The pressure washer pumps are shown on Figure 14. The wash station pressure washer pumps are configured in an operating/standby mode. The control panel allows pumps to be selected manually or operate in auto alternation mode to alternate pumps after each wash event.

The pressure washer pumps are connected to four black steel pipes that traverses to the wash area. The four individual steel pipes are referred to as Process Line “D” as shown on Figure 1. At the wash stations, each high pressure connection has a quick-connect coupler to allow easy connection and disconnection of the individual pressure washer hoses.

Design characteristics of the pressure washer pumps are listed in Table 12:

Table 12 Pressure Washer Pump Characteristics

The wash station pressure washer pumps are MANUALLY activated prior to beginning a wash event. The pumps have the following alarm conditions: motor overload, low suction pressure, and high system pressure. All alarm conditions are indicated at the wash station pressure washer pump control panel and activate an alarm condition at the Emergency Shutdown/Alarm Cabinet at the Pump Building and Control Building. Alarm conditions will activate a red light and audible horn at the Control Building.

13. Vehicle Maintenance Wash Facility and Hot Water Pressure Washer Pumps

The Vehicle Maintenance Wash Facility is a separate four bay facility used to provide detailed washing of vehicles prior to maintenance. Detergents and chemical cleaners may be used at the Vehicle Maintenance Wash Facility. A plan of the Vehicle Maintenance Wash Facility is shown on Figure 23. Each wash bay has two hot water high-pressure washer quick connections.

The Vehicle Maintenance Wash Facility has a trench drain, Trench Drain B, centered perpendicular to the wash bays. The trench drain has a removable traffic-rated, heavy-duty metal grating. If the trench drain becomes clogged, the pressure washers can be used to flush the trench drain. In addition, the metal grating can be removed by hand to facilitate flushing.

Spent washwater captured on the concrete wash bays enters a concrete trench drain and flows into an Oil/Water Separator. The Oil/Water Separator is located in a below grade vault west of the Vehicle Maintenance Wash Facility. The oil/water separator is shown on Figure 24.

The washwater from the Vehicle Maintenance Wash Facility oil/water separator discharges to the sewer system. Flow from the Vehicle Maintenance Wash Facility is discharged to the sewer because detergents or chemical cleaners are used in the facility. The detergents listed in Table 13 are allowed at the Vehicle Maintenance Wash Facility.

Table 13 Detergents Allowed at the Vehicle Maintenance Wash Facility

(1:50).

Multipurpose cleaner.

Biodegradable and o/w separator compatible.

(1:64).

parts water (1:8).

450- 9805/9810/9813 Cleaner/Degreaser

(1:20).

engine/turbine engine flush and gas path cleaner only.

Biodegradable.

engine/turbine engine flush and gas path cleaner only.

Biodegradable.

Jadco Chemical Ltd, Aqua Mate 1

& 60 (AM-1 & AM- 60)

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