US Army Corps of Engineers
Fort Worth District

Former Laredo Air Force Base

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Site and Project History

Site History
The former LAFB (previously called Laredo Army Air Corps Base) was acquired by the U.S. Government on May 7, 1942. The LAFB had a total 2,085 acres. The government constructed runways and other facilities at LAFB between 1942 and 1974. The LAFB was initially deactivated in June 1947; however, it was reactivated during the Korean conflict. In 1974, the LAFB was deactivated again. Approximately 309 acres were either deeded or sold to other federal, state and county agencies, or private firms. The rest was transferred to the City of Laredo. The City of Laredo presently operates a portion of the former LAFB as the Laredo International Airport (LIA).

Background Investigation
E&E, contracted by the USACE-Tulsa District, performed a Background Investigation during April 2003. Malcolm Pirnie observed the field activity which consisted of 10 soil borings. Malcolm Pirnie also collected three soil samples for a series of geotechnical analyses. The purpose of the investigation was to determine the site specific background valves for 24 metals in soil and groundwater. The average Total Dissolved Solids (TDS) in background groundwater is of particular importance when defining certain regulatory limits in the State of Texas.

Background Well Sampling:
Ten groundwater monitoring wells were installed in March of 2003 on the airfield west of the airport. These wells were installed in areas not affected by other sites. The results will establish background concentrations for metals and other chemicals of concern. The quarterly sampling of these wells is ongoing and may extend until the beginning of 2004.

SCAPS in Sanitary Landfill:
Soil and groundwater samples were collected in the Sanitary Landfill (SLF) area utilizing the USACE Site Characterization and Analysis Penetrometer System (SCAPS) Rig. The SCAPS utilizes direct push sampling techniques and is mounted on a 20-ton truck equipped with two hydraulic rams capable of exerting 38,000 pounds of combined force. The system is capable of pushing 1.75" (44-mm) diameter rods into the subsurface to a up to a depth of approximately 150 feet below ground surface (bgs) in suitable geological formations. The SCAPS rig was utilized for this project because it is quick and economical compared to other technologiesand it produces much less investigation-derived waste to store and dispose compared to traditional drilling and sampling methods. Additionally, the SCAPS rig provides a less invasive investigation technique that minimizes disturbance to the private properties and public rights of way where sampling was performed.

A total of 39 soil sampling locations were selected to be in suspected landfill cells and also adjacent to landfill cells, as observed on historical aerial photographs and a magnetometer survey. At each pre-determined location, the SCAPS Rig would first push a cone penetrometer into the soil to classify types of soils at the sanitary landfill area. Next, if the penetrometer log indicated the possible presence of the landfill, soil samples were collected above the cell, in the cell, and below the cell to determine the contents of the landfill and presence of any potential chemicals of concern. At some sampling locations where landfill contents were found, water was found entrapped in the cells. When possible, the entrapped water was collected with a disposable bailer and submitted for analysis for all potential chemicals of concern. In addition to the collection of soil and water samples from landfill cells, soil gas was screened in the landfill cells for the presence of methane with a flame ionization detector (FID). If methane was detected, an air sample was collected and submitted for analysis of methane. In locations where the SCAPS Rig did not detect landfill cells, or the pre-determined location was adjacent to a landfill cell, the soil was sampled at three intervals and analyzed for all potential chemicals of concern.

Sediment Sampling:
Six sediments samples were collected from the drainage ditch north east of the SLF area. The purpose of these samples was to determine if any potential chemicals of concern from the SLF have leached or drained into the ditch. The samples were collected utilizing stainless steel hand tools (scoop and bowl). Each of the sediment samples was analyzed for all potential chemicals of concern. The six sampling locations were chosen to target the inflow from a large drainage pipe and areas upstream and downstream of this pipe. Three sample locations were selected at 200-foot intervals downstream of the influent pipe, one sample 10 feet downstream of the influent pipe, and two samples at 150-foot spacing upstream of the influent pipe.

Press Conference (April 25th):
At 9:30 AM on Friday, April 25th, the United States Army Corps of Engineers conducted a media briefing on the environmental studies currently being performed at the site of the Former Laredo Air Force Base and offered a tour to the Site Characterization and Analysis Penetrometer System (SCAPS) site. The briefing was held at the City of Laredo Public Works Conference Room, 5512 Thomas Avenue and included the announcement of an upcoming public meeting scheduled for May 1, 2003.

Representing the Army Corps of Engineers was Mr. Dan Davis, Senior Environmental Engineer. Mr. Davis was accompanied by Mr. Jonathan Greene, project manager for Malcolm Pirnie, environmental consultant to the United States Army Corps of Engineers.

Public Meeting (May 1st):
The public meeting was held at the City of Laredo public Works Service Center 5512 Thomas Avenue, regarding its ongoing environmental studies performed at the Formerly Used Defense Site (FUDS) of Former Laredo Air Force Base. The purpose of this meeting was to inform citizens of current activities and to allow citizens the opportunity to discuss environmental studies with the U.S. Army Corps of Engineers. The meeting was attended by 250 citizens and city officials.

Public Meeting (September 2003):
This public meeting will also be held at the City of Laredo public Works Service Center 5512 Thomas Avenue. The meeting will discuss the results of the investigations and environmental studies performed at the Formerly Used Defense Site (FUDS) of Former Laredo Air Force Base.

Jet Engine Test Area and Paint Shop Preliminary Investigation
The Jet Engine Test Area is on a tract of vacant land located north of the City of Laredo Water Utilities. The property has been partially cleared with some remaining grass, shrubs and trees. The former Jet Engine Testing Area is located on this land. The Paint Shop is just north of the Industrial Water Treatment Area.

A Site visit was performed in April of 2003 to the Jet Testing Area. After examining the jet testing structures in the fenced area, the injection wells were located on the north side of the fenced area. Pictures were taken of the jet testing structures and injection wells.

A visual site inspection of the Paint Shop occurred in April of 2003. The Paint Shop appeared to be clean at this time.

IWTP Investigation
The property upon which the IWTP was constructed had formerly been mostly vacant. The General Plan map (USACE, 1946) indicates a small fenced storage yard approximately on the area just east of the present IWTP building and clarifier. Another fenced storage yard is indicated further southwest partially located on the southwestern portion of the IWTP site. Information regarding the materials that may have been stored in the areas is not indicated.

The General Plan map also indicates facilities on adjacent and nearby areas. The base fuel farm was located east and northeast of the IWTP site. Several warehouses are indicated along the west side of present day Jarvis Avenue. A motor pool facility with USTs and motor repair facilities are located about 100 yards northwest of the IWTP site. The Storm Drainage Plan Map (USACE, 1969) indicates that the drainage ditch along the western side of the IWTP site collects surface water runoff from the southern end of the flight line area.

IWTP was constructed by the Air Force in 1969. Effluent from the IWTP was discharged to the base sanitary sewer system. The IWTP was taken out of service in 1974 when LAFB was closed. No information is available regarding the influent/effluent water quality, the amounts of waste processed by the system, or sludge disposal amounts or practices.

Remains of the former IWTP include the control building, clarifier, sanitary sewer manhole structure, and a former sludge drying bed.

CH2MHill Investigation
In May 1999 CH2MHill, contracted by the USACE-Tulsa District, performed an initial investigation at the IWTP. In this study, soil and groundwater samples were collected and analyzed for VOCs, SVOCs, TPH, pesticides, PCBs, and metals. Results of this investigation are presented in the report titled "Site Inspection Report Industrial Waste Treatment Plant", dated September 2000. Please refer to online library to view a copy of this report.

Deerinwater Environmental Management Services Investigation
In January 2001, Deerinwater Environmental Management Services, Inc., contracted by the USACE-Tulsa District, performed a second investigation. The results of a geophysical survey outlined the influent/effluent pipes as well as the former sludge lagoon. Three soil samples were taken from the former lagoon area and tested for VOCs, PCBs, BTEX, and various metals (total arsenic, mercury, selenium). Results of this investigation are presented in the report titled "Industrial Waste Treatment Plant Investigation", dated April 2001. Please refer to online library to view a copy of this report.

Malcolm Pirnie
Malcolm Pirnie, under contract by the USACE-Tulsa District, performed an Environmental Investigation in April through June 2003. Malcolm Pirnie installed three soil borings, three monitoring wells, took 12 soil samples, and six water samples in the IWTP area. Malcolm Pirnie also observed the SCAPS rig as it drilled nine borings, four deep and five shallow, with 27 soil samples extracted from the boring excavations. These borings were created in a probable sludge bed area. Groundwater samples were tested for VOCs, SVOCs, TPH, pesticides, herbicides, metals, PCBs, and TDS. Soil samples will be tested for VOCs, SVOCs, TPH, metals, and in some cases pesticides, herbicides, and PCBs.

Sanitary Landfill Investigation
The area west-northwest of the base was used for landfill activities beginning in the mid 1950s and apparently continuing until the early 1970s. The landfill was reportedly used as a sanitary landfill for the former LAFB. After the base was deactivated in 1974, the (Sanitary Landfill) SLF area was sold along with the base golf course to a developer, but it remained undeveloped until the early 1980s.

Beginning in the early 1980s, residential development of the SLF area began. Housing developments and an elementary school (Newman Elementary School) were constructed within the SLF area. A number of homes and a portion of the elementary school were apparently constructed over the locations of the former landfill trenches. In 1988, the engineering firm of Raba-Kistner Consultants, Inc. discovered sanitary refuse in a foundation boring drilled during an investigation for construction of an addition to the elementary school. Recent excavations in the neighborhood for swimming pools and utility connections for new homes indicate that the refuse consisted of old bottles, cans, clothing and other similar types of sanitary refuse.

Land use prior to the current development on the properties surrounding the SLF area were primarily agricultural and military. Land west and north of the SLF site appears to have been utilized for agricultural purposes until the late 1970s. McPherson Road, along with residential development west of McPherson Road, is visible for the first time in a 1979 aerial photograph. Land use south and east of the SLF was military. Residential development of the area immediately south of the SLF area appears to have begun in the late 1970s. Land north of the SLF appears to have been developed for industrial use beginning in the early 1980's. Land east of the SLF area has appeared generally unchanged or industrial since the closing of former LAFB.

CH2MHill
Previous Site Investigations of the Sanitary Landfill (SLF) from 1997 through 1999 included collecting and analyzing groundwater, soil, soil gas, and sediment samples for VOCs, SVOCs, metals, pesticides, PCBs and herbicides. The data for the soil, groundwater, and sediment samples, however, were later invalidated by the USACE due to irregularities at the analytical laboratory. The data from the soil gas survey were validated. Results of this investigation are presented in the report titled "Revised Site Investigation Report Sanitary Landfill Site", dated May 2000. Please refer to online library to view a copy of this report.

Malcolm Pirnie
The USACE conducted an investigation using SCAPS during April 2003. The investigation included a soil gas survey and soil sampling from an estimated 50 locations. Malcolm Pirnie observed this rig as it performed the investigation.

Malcolm Pirnie, under contract by the USACE-Tulsa District, performed an Expanded Site Investigation in June 2003. The work included the installation of eight monitoring wells and eight soil borings. The sampling plan required the collection of eight groundwater samples, 32 soil samples, and three geotechnical samples. Groundwater and soil samples were tested for VOCs, SVOCs, TPH, pesticides, herbicides, metals, PCBs, explosives, and TDS.

Shotgun Range Investigation
The Shotgun Range (SGR) was part of the original base construction and was operated as a gunnery training area. At the SGR, crews were trained to shoot skeet. Based upon historical aerial photography, the original firing line was located along present-day Hillside Road, with the weapons firing northward. The firing line extended from present-day McPherson Road on the west to north of present-day Bartlett Avenue, on the east.

The use of the SGR during the period of 1946 through 1952, while the base was operated as Laredo's Municipal Airport, is unknown. However historical aerial photography from 1952 indicates that the SGR was either unused during that time period or possibly used as a public firing range, as no obvious changes in land use are visible between the 1952 and earlier photographs.

During the 1960's much of the SGR area was developed as a golf course for the air force. A 1973 aerial photograph indicates that the original firing line areas had been incorporated into the golf course and another pistol range had been constructed further north, approximately the present-day location of the intersection between Poinsetta Drive and Hemlock Drive. The direction of fire for the new firing line was apparently toward the north-northeast.

The residential development of the southern portion of the SGR began in the early 1980s with the construction of the Vista Hermosa subdivision. Development of the Alta Vista subdivision apparently began approximately in the mid-1980's. Maps and a more detailed description of the history can be found on the Document Library page of this website or in the Laredo Public Library.

CH2MHill
In May and June of 1999, 33 soil samples from 0.5 and 2-ft bgs were collected and analyzed for lead. Groundwater sampling for the SGR was not conducted. Results of this investigation are presented in the report titled "Site Inspection Report Shotgun Range Site", dated July 2000. Please refer to online library to view a copy of this report.

Malcolm Pirnie
The SCAPs rig work drilled eight soil borings and took 24 soil samples. These samples were tested for lead only. Malcolm Pirnie observed this SCAPS rig and also installed four soil borings, taking 16 soil samples. The 16 soil samples were tested for lead, mercury, and arsenic, and four were also analyzed for PAHs. The four soil borings were turned into monitoring wells, where four groundwater samples were tested for lead, mercury, arsenic, PAHs, and TDS.

In July of 2003, Malcolm Pirnie will perform yard sampling in as many as 50 residences lawns. All samples will be surface soil samples, with two samples taken per yard for a maximum total of 100 samples. 75 of these samples will be tested for lead only, and the remaining 25 will be tested for lead, mercury and arsenic.

Reporting
Three reports will be generated from Malcolm Pirnie to interpret the analytical findings as well as recommend a solution. Once these reports are complete and approved by USACE an TCEQ, copies will be available both on this website and at the Laredo Public Library.

Project Schedule...