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Site Visit Report

Valero—Delaware City Refinery

2000 Wrangle Hill Road

Delaware City, DE 09706

July 15, 2009

1.0 Background and Objectives

The Environmental Protection Agency (EPA) is in the process of developing 

316(b) cooling water intake structure requirements that reflect the best technology

available (BTA) for minimizing adverse environmental impact for all existing 

power plants and manufacturing facilities. As part of this process, EPA staff is

visiting electric generators and manufacturers to better understand the cooling 

water intake structure (CWIS) technologies in use at typical facilities, including 

the site-specific characteristics of each facility and how these affect the selection 

and performance of CWIS technologies. EPA is also visiting facilities to better 

understand cooling water use and specific issues or technologies that can affect 

316(b) compliance. Valero’s Delaware City Refinery was selected for a site visit 

because it utilizes cooling water in its petroleum refining processes and in 

electricity generation.

1,2

2.0 Facility Description

Valero’s Delaware City Refinery is located on approximately 5,000 acres3along 

the Delaware River south of Wilmington, DE. The refinery was built in 1956 and 

employs approximately 760 Valero personnel.4 The facility has two NPDES 

permits, one for the refinery and the other for a cogeneration power plant5

(NPDES permit numbers DE0000256 and DE0050601, respectively). The 

permits have expired (August 31, 2002 and June 30, 2007, respectively) and are in 

the process of being renewed.6

 

1 EPA provided a draft of this report to Valero but did not receive any comments from the facility.

2 According to online news reports, Valero announced in late 2009 that it would close the Delaware City 

Refinery, eventually selling it to PBF Energy, who plans to reopen the refinery in 2011.

3 Approximately 500 acres are dedicated to the refinery and power plant and 800 acres for the petroleum 

storage tanks. Another 1800 acres are leased as farmland and 1700 acres have been designated as 

conservation easements.

4 There are often large numbers of contractors on-site; the number varies according to construction projects 

and other operations. Valero purchased the facility from Premcor in 2005. Premcor purchased the facility 

from Motiva in 2004.

5 The refinery complex includes a 280 megawatt cogeneration facility. See Section 6.0.

6 Valero is also working the Delaware Department of Natural Resources and Environmental Control 

(DNREC) to merge the two permits.
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3.0 Manufacturing Information

The facility processes heavy, high-sulfur crude oil to produce conventional and 

reformulated gasoline, low-sulfur and ultra low-sulfur diesel, and home heating 

oil as well as liquid natural gas and propane. Crude is received by ship at the 

facility’s dock and offloaded to storage tanks.

Production is approximately 180,000 barrels per day (production was 160,000 

barrels per day the day prior to the site visit). Facility representatives noted that 

production is at or near historic levels, but that profits are currently much lower 

than before.

Cooling water usage at the facility includes trim cooling via heat exchangers, 

overhead condensers on distillation columns, and the firewater system. Water 

used for non-contact once-through cooling undergoes little pretreatment and is 

typically dosed with small amounts of sodium hypochlorite prior to being 

discharged back to the Delaware River. Process water and contact cooling water 

is comprised of a combination of source waters (nine onsite groundwater wells, 

municipal water systems, and freshwater streams) and undergoes water treatment 

prior to use.7

4.0 Cooling Water System and Intake Structure

The Valero Delaware City Refinery operates one CWIS that withdraws from the 

Delaware River. The CWIS is located at the end of an intake canal and is 

approximately 1⁄2 mile downstream of the main discharge outfall for the refinery

and cogeneration plant. The CWIS is comprised of a concrete structure with a 

trash rack8 with nine circulating water pumps and one one-half capacity pump. 

The design intake flow (DIF) is 465 million gallons per day (mgd)9but the facility

is limited by its water use permit with the Delaware River Basin Commission 

(DRBC)10 to a maximum withdrawal rate of 452 mgd. The actual intake flow 

(AIF) varies throughout the year; in the summer, the facility generally operates all 

nine pumps. The facility does not know the through screen velocity. Each pump 

has a dedicated 10-foot travelling screen which is rotated and rinsed for 20 

minutes three times per day. The screens are of different mesh sizes and are being 

replaced at the rate of one per year. The combined fish and debris return (an open 

concrete trough) is routed back to the canal outside of the initial trash rack. 

Downstream of the screens, there are three bays and two six foot headers.

 

7 Boiler feed water is softened and demineralized, while contact cooling water is treated by reverse osmosis 

or ion exchange to remove Total Solids and TDS.

8

 A second trash rack is installed across the width of the canal approximately 100 feet in front of the 

CWIS.

9 Each full capacity pump operates at 34,000 gallons per minute (49 mgd).

10 The DRBC is a collaborative stave-level regulatory agency for dischargers on the Delaware River. As 

part of its duties, it assesses a fee for water withdrawals.
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The refinery’s fire suppression system is comprised of a single pump located at 

the CWIS and a holding tank at the refinery. The pump operates intermittently to 

maintain an adequate water level in the tank, but can also directly supply water to 

the fire suppression system if needed.

This portion of the Delaware River is tidal and brackish in nature. The canal is 

dredged twice per year (spring and fall). Since the Delaware River is tidal in this 

segment, the facility’s intake can entrain warm water from the discharge outfall 

depending on tidal direction.11

The refinery discharges through a 13 MGD water treatment plant and into two 

holding ponds (aka “guard basins”). These basins provide additional evaporative 

cooling and also serve as a safety factor in case of catastrophic failures or leaks at 

the facility. The power plant effluent discharges just downstream of the basins; 

the combined effluent cascades down a series of steps (for aeration and cooling) 

before entering the river.

5.0 Flow Diagram

Based on information provided in the facility’s detailed industry questionnaire 

and from the site visit, EPA has constructed a water flow diagram. Virtually all 

water withdrawn at the refinery and power plant is for non-contact cooling water. 

A small amount of pipe washing occurs but generally uses treated freshwater from 

other sources. Some contact water is used in other processes and the coker unit 

uses some quench water, but much of the process water (and any heat produced)

at the refinery is recycled. Contact water is treated at the facility’s wastewater 

treatment plant before discharge. See Attachment C for the diagram.

As noted above, the DRBC limits the amount of water Valero can withdraw. In 

an effort to reduce water withdrawals as it grew and added processes and to 

recover as much heat as possible, the facility began installing dry and wet cooling 

systems in the 70s12 and 90s, respectively.

6.0 Electricity Generation and Transmission

The refinery has a 280 MW cogeneration facility located onsite. The 

cogeneration facility was originally designed to use the refinery’s petroleum coke 

production as the fuel source. In 1998, the power plant was repowered with a 

combined cycle turbine to increase the generating capacity and now uses gasified 

petroleum coke as its fuel.13 The power plant supplies electricity and steam to the 

 

11 In the summer, changes in the direction of the tide may require the facility to also operate the halfcapacity pump to ensure sufficient heat rejection.

12 The fin fans (radiators) were installed as a response to rising energy costs at that time. Facility 

representatives noted that many refineries are shifting to air cooled processes when possible; however, due 

to the reliance on ambient air temperatures (in the case of Valero, no more than a 20 degree differential 

may be available), air cooling may be limited to processes with small circulating flows.

13 The power plant can also burn #2 fuel oil.
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refinery and accounts for approximately 33% of the cooling water needs for the 

complex (refinery and cogeneration plant).

7.0 Impingement and Entrainment Information

Impingement and entrainment studies were conducted in the 1990s – 2000 time 

period. 

8.0 Cooling Tower Feasibility

Valero has several cooling towers, several of which are process-dependant.14 One 

was constructed for a process that is no longer in operation and is not currently

being used. The cogeneration facility has a 3-cell helper cooling tower which is 

used approximately 4 months per year to provide supplemental cooling in the 

warmer summer months. All of the cooling towers are wooden and many are 

only operated seasonally. Typically, the towers using the untreated saline river 

water have 1.5 cycles of concentration.

15

 An onsite vendor maintains standard 

antifouling and antiscaling chemical feeds for all the towers. 

The facility has considered retrofitting additional closed-cycle cooling at the site, 

but has concluded that closed-cycle cooling is not the most appropriate solution.

16

 

Facility representatives discussed the limitations of both dry and wet cooling and 

the difficulties with the use of existing cooling towers at both the refinery and 

cogeneration plant. Specifically, they noted that the brackish nature of the 

Delaware River may influence the metallurgy within the cooling system and limit 

the cycles of concentration that can be achieved without pretreatment. They

added that the existing wastewater treatment capacity at the refinery might not be 

able to treat the increased flows that would be generated by closed-cycle cooling 

systems.17 In addition, groundwater or municipal sources are unlikely to be 

available for makeup water. Facility representatives also noted that closed-cycle 

cooling systems are limited by the ambient air temperature and humidity, 

requiring that the cooling towers be overdesigned to perform in worst case 

conditions.

Facility personnel also mentioned potential drift or plume from the towers;

however, no mention was made of any problems from current towers on-site. 

 

14 The facility began to install cooling towers in the 1990s in order to maintain a relatively constant rate of 

water withdrawal and heat rejection while increasing production. Increased production requires additional 

cooling capacity and the facility was already withdrawing nearly the full volume allowed under its DRBC 

permit. The facility also discharges at or near its thermal limit in summer months; the installation of 

cooling towers helped to mitigate any additional heat load.

15 Facility representatives noted other facilities withdrawing freshwater achieve up to 8 cycles of 

concentration. 

16 A 25 to 30 cell cooling tower was estimated to be required to convert the facility to closed-cycle cooling.

17 Facility representatives were concerned about the ability to the existing treatment plant to handle the 

additional volume from cooling tower blowdown, which may require treatment for solids or other 

pollutants. The treatment plant has a capacity of approximately 13 mgd and currently treats about 10 mgd.
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Lastly, facility representatives noted that the refinery had made significant capital 

investments in improving the metal tubing throughout the facility18 in an effort to 

improve process efficiency and reduce the concentration of metals in the effluent; 

if closed-cycle cooling were installed, the cost-effectiveness of these upgrades 

may be lost or significantly reduced.

9.0 Future Activities

As part of its discussions with DNREC concerning the renewal of the facility’s 

two NPDES permits, Valero may be required to reduce water usage at the 

facility.

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 Facility personnel are also continuing to investigate reusing treated 

effluent and redistributing the heat load throughout the facility as ways to reduce 

cooling water requirements.20

10.0 Cooling Ponds

There are no recirculating cooling ponds on-site.

11.0 316(a)

The NPDES permit contains temperature discharge limits including a daily

maximum withdrawal volume. During portions of the summer, the facility has 

problems meeting the thermal limits, occasionally resulting in a reduction of 

production capacity.

12.0 Ash Handling

There is no ash produced onsite.

13.0 Air Emissions Controls

The facility is currently constructing a scrubber system on the cracking unit and is 

retrofitting the boilers at the power plant to low NOx burners. EPA did not 

collect any further data on air emissions.

 

18 The facility has installed several million feet of titanium tubing.

19 Valero has studied a wide variety of intake technologies for reducing impingement and entrainment at the 

facility. However, DNREC and Valero have largely concluded that intake technologies are not sufficiently 

protective of the aquatic ecosystem (especially with regards to entrainment) and may adversely affect the 

refining process. (See Section 14.0.) As a result, the refinery may be required to reduce its 12 month 

rolling average water intake by 33% over each of the next three permit terms. Facility representatives 

indicated they prefer a percent reduction requirement in the permits as opposed to specific technologies 

(e.g., cooling towers) being required.

20 Such options might include re-routing some portion of the effluent back to the CWIS or optimizing the 

usage of existing cooling towers (including winter operations).
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13.0 Issues with Debris

The Delaware River carries a high debris load, especially after large storms. 

Other than the dredging of the cooling water canal due to silt and sediment 

buildup, the facility did not identify any problems with handling the debris 

loading. Periodic cleaning of the area directly in front of the CWIS (and behind 

the canal bar rack) also occurs to remove material.

15.0 Additional Information

The facility considered several intake technology options. A 2007 fine mesh 

wedgewire screen feasibility study concluded that a large number of screens 

would be required and that locating the screens in an area of sufficient depth 

would be difficult. Obtaining permits and ongoing maintenance (such as 

dredging) would also be difficult and expensive. Other technologies were 

examined, but were largely not considered due to poor performance in 

entrainment reduction.

The facility’s NPDES permit does not contain any requirements for 316(b). As 

noted in Section 4.0, however, the facility does have a maximum permitted flow 

of 452 mgd. During portions of the summer, the facility occasionally has to 

curtail production as it approaches the withdrawal limit.

The facility had a 3-month shutdown earlier this year; this was the first time the 

entire plant had been closed in its history (nearly 60 years).

A small rail line within the property is owned by Valero, but a second rail line 

(separating the refinery from the power plant) is not.

Attachments

Attachment A List of Attendees

Attachment B Aerial Photo

Attachment C Flow Balance Diagram
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Attachment A--List of Attendees

Paul Shriner, USEPA

Jan Matuszko, USEPA

Steve Geil, Tetra Tech

Kelly Meadows, Tetra Tech

Mike Gudgeon, Valero

Eric Jacobs, Valero

Joe Greenfield, Valero

John Gillespie, Valero

Brian Muldowney, Valero

Mike Seaner, Valero

Bob Wojewodski, Valero

Attachment B--Aerial Photo

Please see DCN 10-6553A accompanying this document.
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Attachment C--Flow Balance Diagram

Intake Cooling Water 

(Delaware River)

Once Through Cooling 

Water

Trim Cooling - Heat 

Exchangers

Distallation Towers -

Condensers

Cogeneration Facility

Cooling Towers and 

Makeup Water