Sediment control measures, including straw bales, silt fences, sediment traps and/or sediment basins

Transcription

1 During final design, additional efforts will be taken to minimize wetland impacts, such as minimizing culvert lengths and the use of riprap for bridge abutment protection and stormwater outfalls. Wetland mitigation will be provided by purchasing banking credits from the Mile High Wetland Bank. Temporary and indirect impacts to wetlands will be mitigated through the use of construction BMPs, which would ensure that all work will minimize impacts to wetland areas and include the following: Erosion prevention, including temporary soil stabilization measures (surface roughening, terracing, mulching, and blankets) and structures such as berms or swales, with or without a diversion channel, to prevent and/or slow runoff across disturbed areas and/or divert runoff to sediment basins Sediment control measures, including straw bales, silt fences, sediment traps and/or sediment basins Water quality treatment measures to capture and treat runoff and to prevent runoff from entering the Toll Gate Creek and associated wetlands (See Section 4.9 Water Quality) Use of designated areas for vehicle staging to minimize disturbance of wetlands and vegetated areas Revegetation of disturbed areas as quickly as possible with native vegetation throughout construction Installation of temporary fencing to prevent construction access to wetland areas Dewatering activities would avoid wetland areas Keep cranes and other equipment for bridge demolition out of the creek or streambank area to the greatest extent practicable Where construction equipment must be positioned on or cross over wetlands, place a protective layer of geotextile/straw/soil to be removed after construction HAZARDOUS WASTE SITES This section discusses the potential for soil and groundwater contamination to be encountered in the project area. Areas of potential soil and groundwater contamination must be identified so that they can be avoided or mitigated, if reasonably possible. Encountering soil and groundwater contamination during construction without prior knowledge can potentially affect the project in terms of worker safety, mitigation, cost and schedule. Due diligence is required when investigating for acquisition in order to protect the City of Aurora and CDOT from liability from existing contamination that they may unknowingly acquire. Therefore, the assessment and investigation of contamination concerns in the project area is an integral part of the CDOT project planning process. Page 4-79

2 The term hazardous materials is an all-inclusive term for materials that are regulated as solid waste, hazardous waste, and other wastes contaminated with hazardous substances, radioactive materials, petroleum fuels, toxic substances, and pollutants. Due to their contaminated nature, hazardous materials require specific materials management, handling, worker health and safety, and disposal procedures. As part of this EA, a Modified Environmental Site Assessment (MESA) was conducted to identify sites with known and potential soil and groundwater contamination that are located adjacent to or within the I-225/Colfax Project area (FHU 2005e). The MESA was performed in accordance with a methodology based on the American Society for Testing and Materials (ASTM) Standard Practice for Environmental Site Assessments E and CDOT Modified Environmental Site Assessment Guidance (CDOT 2003) Current Conditions Methodology The MESA was performed in support of the EA to identify potential and recognized environmental conditions in the project area. ASTM defines recognized environmental conditions as the presence or likely presence of any hazardous substances or petroleum products on a property under conditions that indicate an existing release, a past release, or a material threat of a release of any hazardous substances or petroleum products into structures on the property or into the ground, groundwater, or surface water of the property. The term potential environmental condition has been used to identify properties where recognized environmental conditions may be present but could not be confirmed without additional inspection or investigation. The methodology for this MESA included: Performing a limited site reconnaissance, windshield survey, of sites associated with the I-225/Colfax project area for readily identifiable site activities Reviewing readily available documents identifying historical uses of the sites associated with the I-225/Colfax project area Reviewing readily available local, state, and federal environmental agency databases within a maximum distance of one mile of the centerline of the I-225/Colfax Project area as dictated by the CDOT guidance and ASTM Standard E Screening the sites identified in the local, state, and federal environmental agency databases by distance and estimated groundwater flow and ranking the sites based on known environmental site conditions Reviewing previous City of Aurora and CDOT investigations and other available records from local, state, and federal agency records for sites associated with the I-225/Colfax project area based on the site ranking Page 4-80

3 Conducting interviews with relevant agencies and regulatory staff regarding the potential for historical releases of hazardous substances or petroleum products on sites associated with the I-225/Colfax project area Identifying sites requiring additional evaluation or investigation to assist in right-of-way acquisition, project design, and specific-materials management or institutional controls required during construction The limited site reconnaissance focused on visual areas of chemical and petroleum usage, storage, and discharges. A visual inspection of sites within the project area was conducted from public right-of-way. The interior of buildings, fenced areas, and rear lots were not inspected during the site inspection. FHU contracted Environmental Data Resources, Inc. (EDR) to conduct a review of local, state, and federal environmental agency database records. Approximately 525 sites were identified by EDR within one mile of the centerline of the project area. These sites were screened to determine if they were likely to have had an adverse impact on the project area. The initial screening process consisted of distance from the project area (within 1,000 feet) and expected direction of groundwater flow. Although groundwater flow was not confirmed as part of the MESA, shallow groundwater tends to flow in the same general direction as surface drainage (USGS 1996). Groundwater flow direction for the segments of the project located east of Toll Gate Creek is expected to be toward the north/northwest, and groundwater flow direction for the segments of the project located west of Toll Gate Creek is expected to be toward the north/northeast. Sites that were located within 1,000 feet, potentially upgradient or cross-gradient to the combined project footprint, or with a high possibility of having impacted the project area based on site conditions were included in the screening and ranking process. Following the initial site screening, 43 sites were identified with the possibility of having impacted the project area based on distance and expected groundwater flow. These sites were ranked based on known site conditions. Sites with no to minimal indications of a potential existing release, past release, or material threat of a release of any hazardous substances or petroleum products into the ground (soil), groundwater, or surface water were ranked as low. Sites with moderate indications of a potential existing release, past release, or material threat of a release of any hazardous substances or petroleum products into the ground (soil), groundwater, or surface water were ranked as medium. Sites with a medium environmental condition ranking include Resource Conservation and Recovery Act (RCRA) generators with violations, Emergency Response Notification System (ERNS) sites, and leaking underground storage tank (LUST) sites. Sites with the potential for large-scale contaminant migration and a known existing or past release of a hazardous substance or petroleum product were ranked as high. Of the 43 sites identified with the possibility of having impacted the project area, 24 sites were ranked as low; 18 sites were ranked as medium; and one site was ranked as high. Following the site ranking based on known environmental conditions, the sites were screened again based on distance. Sites were identified within 100 feet, from 100 feet to 500 feet, from 500 feet to 1,000 feet, and greater than 1,000 feet from the project area. Five sites were located within 100 feet of the project area. Eleven sites were located from 100 feet to 500 feet from the project area, and two sites were located from 500 feet to 1,000 feet from the project area. Twenty-five Page 4-81

4 sites were located potentially upgradient of the project area but greater than 1,000 feet from the project area. The hazardous sites screening that was conducted is described in detail in the MESA (FHU 2005e). A detailed review was conducted for sites located within 100 feet of the project footprint with an environmental condition ranking of either high or medium and sites from 100 feet to 500 feet with a high environmental ranking. Three sites, including the Fitzsimons Redevelopment Area, were recommended for a detailed review, which consisted of researching agency records, reviewing previous CDOT investigations, and conducting interviews with relevant local and state environmental regulatory staff, as appropriate. Historical Land Use The project area has a long history of industrial, commercial, and residential land uses. The Fitzsimons (former Fitzsimons Army Medical Center) site is located west of the project area, north of Colfax Avenue between Potomac and Peoria Streets. Prior to the 1950s, the primary land uses in the area consisted of the Fitzsimons Army Medical Center, agricultural land, scattered residences, and some commercial use along Colfax Avenue. The Fitzsimons Army Medical Center opened in The Fitzsimons Army Medical Center operated for approximately 77 years from 1918 to In 1995, the Fitzsimons Army Medical Center was designated for closure under the Department of Defense Base Realignment and Closure Act. A site investigation was initiated in 1996 to identify potential environmental concerns associated with the site. The site is currently being redeveloped as a biosciences center under the Fitzsimons Redevelopment Authority and will be the future home of the University of Colorado Health Sciences Center, Children s Hospital, and potentially Veteran s Hospital. Toll Gate Creek parallels the west side of the project area until approximately 17 th Place, where it trends toward the northwest. A U-Haul truck and trailer facility, Conoco gasoline service station, vacant lumber yard, and Archery Adventures retail shop are located west of the I-225/Colfax interchange along Colfax Avenue. Residences, a mobile home park, and a single commercial property, Action Pools, are located between I-225 and Toll Gate Creek. The areas east of the project area consist of suburban residential land use, and commercial properties, including gasoline service stations and automotive repair shops along Colfax Avenue. The area northeast of the project area along Billings Street consists of single and multi-family residences. A closed, former gasoline service station is located at the northeastern corner of Billings Street and Colfax Avenue, and the Regional Transportation District (RTD) East Metropolitan facility is located south of Colfax Avenue and southeast of the interchange. Sites with Potential and Recognized Environmental Conditions Figure 4-18 shows sites identified as having potential or recognized environmental conditions. Three sites, a Conoco gasoline service station, Archery Adventures and A-AAA key mini storage, were identified during the site reconnaissance as sites with potential environmental conditions. Three sites - the Fitzsimons Redevelopment Area, RTD East Metro facility, and the former gasoline service station at E. Colfax Avenue, were identified as sites with known recognized environmental conditions. This section discusses each of these sites. Page 4-82

5 Conoco Station E. Colfax Avenue The Conoco Station is located at E. Colfax Avenue on the northside of Colfax Avenue, west of the I-225/Colfax interchange. According to Colorado Department of Labor and Employment Division of Oil and Public Safety (OPS) records, the Conoco Station has four 8,000-gallon underground storage tanks (USTs) for diesel and one liquid petroleum gas (LPG) tank. No spills or leaks related to this site have been reported. This site has been reportedly a gasoline station since the 1970s. Although no spills or leaks have been reported at this site, this is a site with potential environmental conditions. Archery Adventures E. Colfax Avenue Archery Adventures, a retail sporting business, is located at E. Colfax Avenue on the south side of Colfax Avenue, west of the I-225/Colfax interchange. According to OPS records, this site was a former gasoline station. Although no spills or leaks have been reported at this site, this is a site with potential environmental conditions due to its history as a gasoline service station. A-AAA Key Mini Storage 1530 Potomac Street Storage unit facilities, such as A-AAA Key Mini Storage, can be associated with hazardous material spills or methamphetamine laboratory residues and materials. Although no spills were reported, this site has potential environmental conditions. Fitzsimons Redevelopment Area The former Fitzsimons Army Medical Center was built on approximately 575 acres and provided health services to U.S. Department of Defense active duty, retired personnel, and dependents; conducted research and development activities; and provided residential housing for staff. Due to the size of the Fitzsimons Redevelopment Area, only the area near the intersection of 17 th Avenue and Potomac Street was investigated. Five facilities are located in the vicinity of the project and included the former incinerator [Fitzsimons Army Medical Center (FAMC) Building 616], the Officers Club (FAMC Building 642), Post Exchange (FAMC Building 817), Sentry Station (FAMC Building 819), and the demolished Fitzsimons Credit Union (FAMC Building 823). In addition, a former landfill (Landfill #5) and an existing landfill (Landfill #4) are located north of the intersection. The former FAMC buildings and landfills are identified on Figure No known soil and groundwater contamination has been identified associated with the incinerator, Post Exchange, Officers Club, former Sentry Station, or former Fitzsimons Credit Union buildings. Groundwater in the area has been impacted by petroleum releases from upgradient sources on the former Fitzsimons Army Medical Center site. Known petroleum releases have been mitigated; however, low levels of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) may remain in the groundwater (Smith Environmental 2003). Page 4-83

6 Landfill #4 is located directly east of the incinerator and consists of approximately 1.6 acres. The landfill was used from approximately 1918 to 1950 and contains burnt medical waste and ash from the incinerator (Matrix 2003). Prior to construction of Fitzsimons Parkway, which will occur before the actions evaluated in this EA, landfill 1, 2, 3 and 4 will be excavated and the material disposed of (Matrix 2003). Confirmation soil sampling will be conducted to determine the extent of the excavation. Groundwater upgradient and downgradient of the landfill is contaminated with SVOCs. Landfill #5 was located directly north of the intersection of 17 th Place and Potomac Street and consisted of a series of shallow pits. The landfill contained radioactive waste generated by the U.S. Army Medical Research and Nutrition Laboratory between 1961 and The landfill was excavated in 1997, and the material was disposed of at the Hanford Disposal Facility in Hanford, Washington (Allied Technology Group 1997). Confirmation sampling was conducted in the excavation, and sampling results were below the limits of 5 picocuries per gram (pci/gm) for tritium and 10 pci/gm for carbon-14 (Allied Technology Group 1997). No detectable quantities for toxicity characteristic leaching procedure (TCLP) analysis of SVOCs, VOCS, pesticides, herbicides, or heavy metals were identified in the surrounding soils. Groundwater was not encountered in the excavation. RTD East Metro Facility E. Colfax Avenue The RTD East Metro Operating Facility is a 22-acre parcel located southeast of the I-225/Colfax Avenue interchange at E. Colfax Avenue. RTD vehicle fueling and maintenance activities are conducted at the site. Eight petroleum releases from the tank farm on the east side of the facility have been documented. The site is an active leaking underground storage tank (LUST) site and is currently implementing a Corrective Action Plan (CAP). The CAP consists of manual removal of any remaining free product with natural attenuation and quarterly groundwater monitoring (RTD 2002). Monitoring wells on the western side of the property were sampled for benzene, toluene, ethylbenzene, xylenes (BTEX) and diesel range organics (DRO). Groundwater samples on the western side of the RTD facility were not detected above the laboratory reporting limit for BTEX and DRO. Elevated concentrations of BTEX and DRO are present on the eastern side of the facility in the vicinity of the tank farm. Residual petroleum contaminated soil may also be present on the property. Shell Oil/Equilon Enterprises LLC E. Colfax Avenue The former gasoline service station at E. Colfax Avenue is an active LUST site and is implementing a CAP. The CAP consists of natural attenuation of free product and quarterly groundwater monitoring. Elevated concentrations of BTEX, methyl tertiary butyl ether (MTBE), gasoline range organics (GRO) are present on the property. The property is currently for sale, and prior to divestiture of the property, approximately 100 to 200 cubic yards of petroleum contaminated soil will be removed from the property (LT Environmental 2004). Petroleum impacted groundwater and soil are present on the property and may be present in the vicinity of the project area. Page 4-85

7 Consequences The project is located in an area with a long history of industrial and commercial land use. Although residential areas are located throughout the area, historical industrial and commercial processes have influenced the project area. Several areas of known groundwater contamination were identified in the vicinity of Potomac Street and 17 th Place and along Colfax Avenue east of the existing I-225/Colfax Avenue interchange. Given these known sources of groundwater contamination and the size of the project area, groundwater contamination may be present throughout the project area. Consequences of the No-Action Alternative The No-Action Alternative would result in no impacts to or from sites with recognized or potential environmental conditions. Consequences of the Proposed Action Contaminated soil and/or groundwater, which could pose a risk to worker and/or public health and safety, may be encountered during excavation for construction of the Proposed Action in the area of the existing I-225/Colfax interchange. Structural excavations for retaining walls and caissons related to the proposed ramps and bridges, potentially would encounter contaminated soil and groundwater. Structural excavation on the west side of Toll Gate Creek will be limited to shallow excavations for the bridge abutments for the new local connection south of the existing Potomac Street bridge and the new 17 th Place bridge. These excavations will be located east of Potomac Street and the eastern boundary of the former Fitzsimons Army Medical Center. The Fitzsimons Parkway project, which will be constructed prior to this project, will reconstruct Potomac Street, excavate Landfill #4, and will encounter Landfill #5. Although not expected to be encountered in the excavations for the bridge abutments, radioactive materials, undocumented landfill areas, buried-in-place buildings, and transite or asbestos-containing piping are concerns on the former Fitzsimons Army Medical Center. The Proposed Action would involve the acquisition of seven properties. None of the properties to be acquired for right-of-way were identified as a site with recognized or potential environmental conditions. An asbestos survey was not conducted on structures to be demolished following right-of-way acquisition. Asbestos is a worker and public safety and materials management concern. A lead-based paint survey was not conducted on the structures to be demolished following right-ofway acquisition. Lead-based paint is a worker health and safety and materials management concern. Replacement of the I-225 bridge over Colfax Avenue is not included in the Proposed Action; however, the bridge structure will be modified. A heavy-metal based paint survey was not conducted. Given the age of the structure, heavy-metal based paint may be a concern when the structure is modified. Page 4-86

8 Mitigation Structural excavation may require the dewatering of contaminated groundwater. If dewatering is necessary, groundwater brought to the surface will be managed according to Section Water Quality Control of the CDOT Standard Specifications for Road and Bridge Construction (CDOT 1999). Contaminated soil may be encountered during project construction. The Fitzsimons Parkway project, which will be constructed prior to this project, will excavate Landfill #4 and potentially encounter hazardous materials during construction. Potential hazardous material concerns associated with the former Fitzsimons Army Medical Center include radioactive materials, undocumented fill areas, buried-in-place buildings, and transite or other asbestos-containing piping. Prior to construction of this project, all reports related to hazardous materials that are prepared as a result of construction of the Fitzsimons Parkway project will be reviewed to identify any additional hazardous material concerns. A material handling plan and health and safety plan, as required by Section of the CDOT Standard Specifications for Roadway and Bridge Construction, will be prepared and a Health and Safety Officer or their representative will be on site during activities that could encounter hazardous materials to evaluate the risks and to ensure proper worker protection and hazardous materials handling and disposal. The materials management plan should include provision for a radioactive materials licensed contractor, if radioactive materials are encountered. Prior to demolition of all structures required for right-of-way, an asbestos and miscellaneous hazardous materials survey will be conducted at each property. Materials abatement will be conducted, as necessary, according to Section of the CDOT Standard Specifications for Road and Bridge Construction and relevant Occupational Safety and Health Administration (OSHA) and regulatory requirements. In addition, the residences will be checked for the presence of methamphetamine lab residues prior to acquisition. The residences to be demolished following right-of-way acquisition may contain lead-based paint. The relevant OSHA requirements to protect workers health and safety will be followed during demolition. The demolition debris will be assessed to determine its appropriate handling and disposal. The demolition debris assessment methodology, handling, and disposal will be included in the materials management plan. A heavy-metal based paint survey will be performed on the bridge structure prior to any demolition or modification. If lead or heavy-metal based paint is identified, heavy-metal based paint abatement will be conducted, as necessary, according to Section of the CDOT Standard Specifications for Road and Bridge Construction and relevant OSHA and regulatory requirements. The mitigation measures identified above will be implemented to ensure proper management of contaminated material. Page 4-87