Introduction
The Chevron Oil Refinery (Plant #A0010) occupies an approximately 2,500 acre site in Richmond, California. This refinery has a typical daily throughput of 225,000 barrels (1 barrel = 42 gallons) of crude oil, primarily from the Alaskan north slope. Crude oil is refined at the facility to produce gasoline, marine fuel oil, jet fuel, diesel, home and industrial fuels, propylene/polymer base stocks and 14,000 barrels of lube oils. In addition, Plant #A0010 also produces 350 tons of sulfur daily as a by-product of the on-site processes.

As part of the Bay Area Air Quality Management Districts' (the District) 2001 Clean Air Plan, the District, in cooperation with the California Air Resources Board (ARB) and the United States Environmental Protection Agency (U.S. EPA), is examining process wastewater systems for each of the Bay Area refineries. This effort is directed at determining whether there are significant potential emission reductions from the control of any remaining uncontrolled components of the process wastewater systems, or through other measures. Most components of refinery wastewater systems are already controlled through compliance with District Regulation 8, Rule 8 (8-8), District New Source Review requirements, and EPA's National Emission Standard for Benzene Waste Operations (40 CFR Part 61, Subpart FF).

As part of this project, a two day site visit (4/10/02 and 4/11/02) was conducted at Plant #A0010 to assess the availability of information related to the process wastewater system, and to review the on-site collection and treatment of water management processes which may have Volatile Organic Compounds (VOC) emissions impacts.

Site History
Plant #A0010 has been located in Richmond since the beginning of the 20th Century. Initially established in 1901. The Richmond site was ideal because of its natural deepwater port. Initially the facility engaged in the production of kerosene, tar and fuel oil. This production occurred in large horizontal batteries located in what is now known as the "south yard" area of the refinery. This is the oldest area of the facility and with the exception of tank storage, blending and shipping areas, it has for the most part been decommissioned. In the 1920's the refining capacity of the facility was expanded to include gasoline production for the expanding automobile markets.

During the war years of the 1940's that the initial elements of today's modern refinery processes began to take shape. The early development of distillation process and thermolytic cracking meant replacement of horizontal batteries in the south yard area of the refinery with four modern distillate column crude units, and the addition of a number of steam plants. This greatly increased the gasoline production capacity of the site.

The 1950's saw the construction of the fluid catalytic (cat.) cracker and related process units. While the majority of these were retrofitted in the mid-199O's to accommodate State-mandated fuels programs, a number of these units are still functioning in the "central yard."

The major addition to the site in the 1960's was the construction of the "ISOMAX" complex in the "north yard" area. This unit consists of a number of hydro-processing units, a catalytic hydrogen plant and solvent-deasphalting unit that was modified in the early 1990's.

Increased demand for low sulfur fuels in the 1970's drove the need to construct the Low Sulfur Fuel Oils (LSFO) complex. The LSFO project consisted of a new crude unit in addition to jet and gasoline hydro-treaters, sulfur plants and a Rheniformer.

In the 1980's, Plant #A0010 further expanded the ISOMAX complex by approximately 20% with a modernized lube oil production facility. The lube oil facility, RLOP, is currently in operation manufacturing high grade base oil products, however, part of the facility, which received waxy feed from a number of different operations, was shutdown in 1999.

The final iteration of the current construction occurred in the mid 1990's with imposition of California clean fuels requirements for gasoline. This necessitated the modernization of the fluid catalytic cracking unit (FCCU) in the north yard area of the refinery. This construction also included building a new alkylation plant, TAME and MTBE plant.

On-site Waste Water Treatment
At Plant #A0010, the process wastewater treatment system is segregated into three collection areas, along the lines of the facility's own nominal division system, north yard, central yard and south yard. Each of these denominations accepts flows from the process units in their area and routes them via three separate oil water separators to the 165 million gallon biological treatment unit. Temperatures at each of the separators are estimated at approximately 26.7 0C (80 0F) year round while temperatures in the bioreactor vary from 26.7 0C (80 0F) in the aggressive treatment area to between 15.6 0C (60 0F) and 18.3 0C (65 0F) in the settling basin area.

The Aggressive Biological Treatment Unit (ABTU) has approximately 900 subsurface air aerators operated by two compressors that deliver approximately 17,000 CFM of air to the bio-mass. From the bioreator treatment segment, there are two options for effluent treatment. Effluent can either be routed directly to the deepwater outfall point (DWOP) sump for discharge to the bay via the granular activated carbon (GAC) unit or a portion may be routed through the three tier constructed wetlands for secondary polishing and selenium removal. Effluent from the wetlands rejoins the main waste water stream at the DWOP sump and these commingled streams are discharged via the GAC unit to a 36" diffuser outfall at an average depth of 30-50 feet into San Pablo Bay, approximately 2000 feet offshore to the north of Point San Pablo.

North Yard Collection System
The North Yard collection system is responsible for the conveyance of process water effluent from the catalytic cracking and hydroprocessing areas. This effluent consists specifically of outfall from the following: Alkylation plants, polypropylene unit, sulfur recovery unit, stripped sour water, and a small amount of ground water, MTBE plant, FCC plant, TAME plant, ISOMAX plant and the Richmond Lube Oil Plant (RLOP).

Flows from these process collect into three main inputs to an oil water separator (13 Separator). These inputs are the 27" SRU line which flows at 190 gallons per minute (gpm) from the decommissioned alkylation plant, and operating sulfur recovery units, the 36" FCC line which flows at 765 gpm from the FCC and polypropylene units and the 60" Hydro line which flows at 845 gpm from the ISOMAX and RLOP plants.

At 13 Separator, these flows are commingled in an underground two-cell separator system. Solids are settled out by gravity and the effluent is piped via 60" line to the Bioreactor. The temperature at 13 separator is estimated at 26.7 0C (80 0F). This separator is covered and complies with existing regulation for VOC fugitive emmissions control and design. It has three pressure ventilation (PV) valves, a debris removal system and an oil removal system. The outflow from 13 separator is estimated at 1,870 gpm or 2.6 million gallons per day (mgd) and comprises approximately 50% of the effluent produced at the facility.

Central Yard Collection System
This system routes process flows primarily from the low sulfur fuel oil (LSFO) complex and its associated process units to an oil water separator (2A separator). The effluent consists specifically of outfall from the following: hydrotreating plants, crude desalter plant, rheniformer plants, DEBRU unit and crude process units.

Flows are routed via three main trunk lines to 2A separator. However, unlike at the 13 Separator, in this case the three streams are combined prior to entering the 2A Separator. Flows are input to this point by the 48" D&R North line at 35 gpm from the DHT unit, from the 12" LSFO line at 71 gpm from LSFO rheniformers and cat crackers, and the 18" Foundation Street line at 793 gpm from LSFO cat. cracker process.

The total flow to 2A separator is estimated at approximately 1,160 gpm. 2A separator consists of a two-cell oil water separator supplied by two 4.3 mgd pumps. This separator is above ground and has both debris removal and oil recycling facilities as well as standard gravity solids settlement. The separator is completely covered and is only opened twice daily for approximately 1 hour at an approximately 2'X2' gasketed area to remove gross debris. The separator is covered as required, and is equipped with three PV (pressure-vacuum) valves. This unit also has the capability to accept vacuum truck input. This unit may also accept storm waters from a co-located sump associated with the 50-100 foot storm water impoundment area.

The temperature at 2A separator is estimated at 26.7 0C (80 0F) and the outflow is estimated at 1,160 gpm or 1.6 million gallons per day (mgd).

South Yard Collection System
This collection system is by far the most complicated at the facility and routes process flows from tank areas, the research center, marketing and distribution operations and miscellaneous operations to an oil water separator (1A separator) via a diversion box. The effluent consists specifically of wastewater from the following: lube tanks, general tank storage areas, the blending area, stormwater retention areas, Altamont loading racks and boiler blow down.

These flows are routed via five main lines to a flow splitter (five cell diversion box) and lifted via four pumps into the 1A separator. These lines are as follows: a 36" main line that inputs boiler blow down and tank run off at 30 gpm, a 48" center line which inputs tank and blending area effluent at 415 gpm, a 48" line that runs along Pipe Street and that routes process sewer water from the main tank field (stormwater retention areas) at 115 gpm, a 60" line that runs along Division Street and inputs various effluents and tank draw effluents at 385 gpm and finally, the 36" CALOL line which inputs various tank effluents at 337 gpm.

Following the diversion box these flows are joined by three additional trunk lines prior to the flow splitter at 1A separator. These lines are as follows: a 38" sewer line from the south yard, a 12" line that runs along Channel Street and a 24" line from the PETROLITE area of the south yard at 85 to 225 gpm.

From each portion of the flow splitter effluent can be pumped via four 4.3 mgd pumps to the above ground oil water separator. 1A separator is a four cell "in train" separator similar to 2A separator. Both have debris removal and oil recycling facilities as well as standard gravity solids settlement. The separator is completely covered and is only opened twice daily for approximately 1 hour at an approximately 2'X2' gasketed area to remove gross debris. The separator is covered as required by current regulations and is equipped with three PV valves. This unit also has the capability to accept vacuum truck input.

The temperature at 1A separator is estimated at 26.7 0C (80 0F) and the outflow is estimated at 1,435 gpm or 2.0 million gallons per day (mgd).

Aggressive Biological Treatment Unit and Bioreactor
Effluent from each of the three on-site effluent collection systems is hard piped to a single junction point and then this commingled flow is sent via a 60" line to the Aggressive Biological Treatment Unit and bioreactor.

The bioreactor consists of a 165 million gallon pond varying in depth to between 24 and 26 feet. This pond has four distinct regions further divided by a curtain wall into the Aggressive Biological Treatment Unit (ABTU) and the settling basin. It is estimated that the total retention time of the bioreactor ranges from as low as 3 - 7 days to a high of 2-3 weeks depending on operational conditions and weather conditions.

The Aggressive Biological Treatment Unit contains approximately 85 millions gallons of effluent that is aerated by 900 subsurface aerators. These aerators receive air flow from two compressors that produce between 17,000 to a maximum 23,000 CFM. Temperature for this area is estimated to be constant at 26.7 0C (80 0F).

The settling basin portion of the bioreactor is designed to polish the effluent which flows from the Aggressive Biological Treatment Unit at the end of the curtain wall where the 2nd and 3rd quadrants meet. This area lets the biomass settle out of the effluent. This area contains approximately 80 millions gallons of effluent and varies in temperature between 15.6 0C (60 0F) to 18.3 0C (65 0F) seasonally. As this area precipitates solids from the aggressive biotreatment area, dredging operations must be conducted on an as-needed periodic basis.

The finished effluent from this activity, is estimated at an annual average flow of 6.8 mgd and is primarily directed to the DWOP sump or may be directed to the Water Enhancement Wetlands Treatment Area for further polishing prior to carbon treatment (GAC), and discharge to San Pablo Bay.

Wetlands
Plant #A0010's Water Enhancement Wetland project (an explicit treatment option) is an experimental natural treatment and polishing system primarily for solids and metals removal. This system consists of three passes containing approximately 30 million gallons of effluent. This effluent is supplied from the bioreactor at approximately 1.5 mgd, however, this flow may be increased depending on seasonal conditions and Department of Fish and Game requirements. The flow is supplied to the first pass via a hardpipe system directly from bioreactor settling area. The majority of growth in the passes consists of cattails and bulrushes that remain unharvested to assist in biotreatment. The system is claimed to effect up to a 60% reduction of selenium from bioreactor effluent. Effluent from the wetlands is pumped to the DWOP sump to rejoin outfall from the Bioreactor.

DWOP Sump and GAC Unit
Effluent from the bioreactor and wetlands are commingled at the DWOP sump before being pumped to the Granular Activated Carbon (GAC) facility for final treatment.

This sump is 8' deep and is designed to remove any gross debris and biomaterial

The GAC facility is the final step of onsite treatment for Plant #A0010's effluent. It consists of 24 GAC units on 12 skids and serves to remove turbidity, hydrocarbons, and aquatic toxicity from the final effluent. From here the final effluent is pumped to the bay via a 36" line to a diffuser at an average depth of 30-50 feet into San Pablo Bay, approximately 2000 feet offshore to the north of Point San Pablo.

Oil/Water Separator Solids
In addition to the effluent treatment onsite, solids from both the bioreactor and the three onsite separators are treated prior to disposal.

Solids that precipitate out of the effluent in each of the three API oil-water separators are removed periodically by vacuum truck. This material is transported to the hazardous waste annex on-site and dewatered using two centrifuges. Vapors from this process are controlled via a caustic solution wet scrubber, vapor chiller, and carbon bed. Wastewater from this process is disposed via an open sump to the head works for 1A separator. This effluent is stated to be at ambient temperature.

As previously stated solids from the bioreactor are dredged from the settling area periodically. It is assumed that this material is de-watered and than landfilled after meeting all hazardous waste regulatory specifications. This matter is currently undergoing further investigation.

Storm Water
Due to the nature and size of this site there are numerous discharge points and impoundment areas; these were identified by Chevron and in their Regional Water Quality Control Board NPDES (RWQCB) permit. Permitted (SF-RWQCB Order 01-067) stormwater discharge can occur in many instances either directly to the waters of SF/San Pablo Bay(s), and may be routed through the refinery Effluent Treatment System at the facilities discretion, and dependent upon analytical qualitative factors.

Prior to any direct discharge of impound basins to SF Bay, or San Pablo Bay, the NPDES permit specifies sampling programs and qualitative permit limits. Sheetflow runoff areas have specific sampling plans, but due to the very nature of this discharge, it's flow to the Bay(s) is monitored, but not controlled.

In addition to the stormwater water collected by the on-site wastewater treatment system, some stormwater runoff from the ChevronTexaco Energy Research and Technology Center is also processed. The final discharge of this system is through a deepwater outfall at an average depth of 30-50 feet into San Pablo Bay, approximately 2000 feet offshore to the north of Point San Pablo. This discharge point is referred to as E-001.

Stormwater runoff from an area of approximately 4 acres located in a former Point Orient Tankfield discharges into San Francisco Bay at outfall location E-005.

Runoff from an area of approximately 48 acres located in a former Point Orient Tankfield area, the 12-Basin area (approximately 3 acres) and from the Horse Pasture area (approximately 17 acres) discharges into San Francisco Bay at outfall location E-006.

In addition, stormwater runoff from the Horse Pasture (approximately 17 acres) located in a former Point Orient Tankfield area discharges into San Francisco Bay at outfall location E-007.

Stormwater runoff may commingled with incidental amounts of steam condensate, groundwater seepage, and water from the fire protection systems from the 496 acres in and around the Main Tankfield, Distillation and Reforming facilities, Main and South Yard areas, rail car loading areas, Asphalt Plant, and Cogeneration Facility may discharge into San Pablo Bay at outfall location E-008, or may be transferred to the North Yard Impound Basin for discharge as part of the North Yard Impound Basin discharge operation.

Runoff commingled with steam condensate and water from the fire protection systems that originates from an area of approximately 26 acres within the Quarry Tankfield may discharge into San Francisco Bay at outfall location E-009.

Sheetflow stormwater runoff from an area of approximately 6 acres which is a portion of the Reclamation Yard area discharges into Wildcat Creek via the Gertrude Street Ditch, which then drains to Castro Creek and San Pablo Bay. The discharge of Waste 010 is monitored at outfall E-010.

Stormwater runoff commingled with groundwater (both seepage and extracted from various subsurface hydraulic containment systems), steam condensate, and potable water used in the facility's fire protection systems and facility washdown originates from an area of approximately 28.4 acres from areas within the Chevron Chemical Company LLC Hensley Street facility is collected in the Castro Acres surge pond (located along the east side of Castro Street) prior to being pumped into sections of Chevron Chemical Company LLC's Integrated Wastewater Pond System (IWPS) or it can be pumped directly to the IWPS, located at the Castro Street facility.

The Castro Acres surge pond is not permitted to discharge to surface waters under typical rainfall conditions as it may contain trace contaminants. Typically, this water is discharged to the IWPS, which provides necessary surge capacity before discharge to the City of Richmond sanitary sewer system (POTW). However, during periods of high intensity rainfall (in excess of a 25-year, 24-hour rainfall event), this pond may discharge into Castro Creek via a drainage ditch on the east side of Castro Street, identified as Outfall E-011.

Stormwater runoff commingled with groundwater (both seepage and extracted from various subsurface hydraulic containment systems), steam condensate, and potable water used in the facility's fire protection systems and for facility washdown originates from an area of approximately 19 acres within the Chevron Chemical Company LLC's Castro Street facility which was formerly used to manufacture fertilizer. This runoff is collected in evaporation ponds located along the west side of Castro Street.

This runoff, which collects in the fertilizer ponds, is not permitted to discharge to surface waters under typical rainfall conditions as it may contain trace contaminants. Typically, it is discharged to the fertilizer ponds, which provide necessary surge capacity before discharge to the City of Richmond POTW. However, during periods of high intensity rainfall (in excess of a 25-year, 24-hour rainfall event), Waste 012 may be discharged into Castro Creek at an outfall identified as E-012.

Runoff from direct rainfall onto sections of Chevron Chemical Company LLC's IWPS, an area of approximately 81 acres of synthetically lined surface impoundments, is accumulated. Depending on annual precipitation, various sections of the IWPS receive water from other on-site surface impoundments. When this occurs, these sections are no longer considered as solely containing storm water runoff and the accumulated water is discharged to the City of Richmond's POTW. This area also receives rainfall runoff from an adjacent 4 acre capped Class II waste management unit (Soil Management Unit No.1) and may be discharged into Castro Creek, at a point approximately 1000 feet upstream of its confluence with Wildcat Creek at an outfall identified as E-013.

Stormwater runoff from an area of approximately 4 acres in a former tankfield area of the Office Hill Tankfield discharges to San Pablo Bay via the City of Richmond's stormwater management system. This system routes stormwater from storm sewers to the Castro Street Pump Station. The Pump Station pumps water to Chevron's 38-Foot Channel, which discharges into Castro Creek.

Stormwater runoff from an area of approximately 5 acres in a former tankfield area of the Office Hill Tankfield discharges to San Pablo Bay via the City of Richmond's stormwater management system. This system routes water from storm-sewers to the Castro Street Pump Station. The Pump Station pumps water to Chevron's 38-Foot Channel, which discharges into Castro Creek. Stormwater runoff from an area of approximately 7 acres in a former tankfield area of the Office Hill Tankfield may discharge into San Francisco Bay.

Stormwater runoff commingled with steam condensate and water from the fire protection systems from approximately 20 acres in the SP Hill Tankfield may discharge into San Francisco Bay or be returned to the process water system. Stormwater runoff commingled with steam condensate and water from the fire protection systems from approximately 29 acres in the Quarry Tankfield may discharge to San Francisco Bay or be returned to the process water system. Stormwater runoff from an area of approximately 3 acres in the former Point Orient Tankfield discharges to San Francisco Bay. This runoff may also be transferred and discharged at E-006.

Runoff from the City of Richmond's stormwater management system drains an area of approximately 260 acres (encompassing City owned property on the Castro Street Roadway, North Richmond, and Point Richmond suburban areas) and routes water from City of Richmond storm sewers to the Castro Street Pump Station. The Pump Station pumps water to Chevron's 38-Foot Channel, which discharges into Castro Creek, which flows to San Pablo Bay.

Stormwater sheetflow runoff from a capped waste management unit area of approximately 5 acres is discharged to Castro Creek. Castro Creek flows into San Pablo Bay.

Stormwater sheetflow runoff from a capped waste management unit area of approximately 3 acres is routed to the Gertrude Street ditch which drains to Wildcat Creek. Wildcat Creek flows to Castro Creek then to San Pablo Bay.

Stormwater sheetflow runoff from a capped waste management unit area of approximately 41 acres discharges to Castro Creek, which flows to San Pablo Bay.

The North Yard Impound Basin (formerly 1st Pass #1 Oxidation Pond) discharge consists of stormwater commingled with steam condensate, groundwater seepage, and water from fire protection systems. The North Yard Impound Basin is a remediated containment basin formerly used in wastewater treatment. Runoff originates from an area of approximately 341 acres from areas within the: Poleyard and Alkane Tankfields and adjacent hill sides; LPG and Ammonia Storage Facilities; Cracking and Hydroprocessing facilities; Petrochemical facilities; FCC, RLOP, Isomax, MTBE/TAME cooling water towers; Hydrogen Plant; former Alkane and HF Plant areas; Sulfur Recovery Unit and sulfur sales facilities; and Hydropits Cap. The North Yard Impound Basin discharges may contain transferred stormwater W-008, and may discharge to Castro Creek or may be processed through the Refinery effluent treatment system. Castro Creek flows into San Pablo Bay. Stormwater sheetflow runoff from a capped waste management unit area of approximately 7 acres of the Parr-Richmond Site discharges to Wildcat Creek and Gertrude Street ditch (which drains to Wildcat Creek). Wildcat Creek drains to Castro Creek, which flows to San Pablo Bay.

Drains and Junction Boxes
During the course of the site visit to Plant #A0010, a number of different drain formations were observed in the process areas. The formations observed were generally consistent with the phases of construction at the site.

Drains in the LSFO area with the more modern construction (1990's cat. crackers and rheniformers) had P-trap water seal drains and Chevron box-type water seal drains. The older areas of construction such as 1970's rhenofirmer #5 tended to have a mixture of P-trap water seal drains, Chevron box-type water seal drains and what appeared to be unsealed drains. These apparently unsealed drains were for the most part associated with pump stands and were in the minority of the drains observed. This was also the case at 1950's rheniformer #4, where the same mixture of sealed drains and occurrence of apparently unsealed drains repeated itself. This was again the case at the #4 crude unit. Junction boxes observed in this area were linked to vent pipes which opened in most cases approximately 20 to 30 feet above the ground surface exceeding current BAAQMD minimum standards.

In other areas of Plant #A0010 this scenario replayed itself. Newer construction such as the "new alkylation plant" and FCC units were observed to have P-trap water seal drains and Chevron box-type water seal drains. In the older areas of the facility such as the "old alkylation plant" and polypropylene unit apparently uncontrolled drains were located on the outer "older" edges of the construction.

Investigation is currently being conducted into the format of the pump stand drains and other drains from the 1940's, 1950's and 1970's to confirm their configuration. The site visit also indicated that the older 1940's drains at the site had, for the most part, been blinded.

Inspection of the ISOMAX process area revealed two sets of distinct drain constructions corresponding to distinct phase of development at that site. Both the north and south ISOMAX complexes were developed in the 1960's with later construction in the southside ISOMAX in the 1990's. Pump stand drains for the north and south 1960's construction appeared for the most part to be open and varied in size from 2" to 4". Box seals were observed in a number of areas and junction boxes were for the most part under water seals. Also, one area of open surface drains was observed in the south ISOMAX complex. In the newer area only three inch drains were observed and all were covered with steel plates. Also, a number of 1' x1' box seal drains were observed.

Drains in the RLOP area date from the mid to late 1980's and it appears that this construction mirrored the 1960's construction at the site. A number of what appear to be 4" open drains were observed at pump stands within the complex and a number of 1' x1' box seal drains were also observed. This complex also included some 6" drains that also appeared to be open.