Asarco Smelter Chimney Demolition Plan

Texas Custodial Trust
2013-04-05
Texas Commission on Environmental Quality

1.1          INTRODUCTION

This document describes the methods, procedures and control measures used by the Texas Custodial Trust (Trust) to perform explosive demolition of two concrete chimneys at the former Asarco Smelter in El Paso, Texas. The explosive demolition will be conducted under the direction of Brandenburg Industrial Service Company (Brandenburg) by Dykon Explosive Demolition Corporation (Dykon). This document will serve as the Trust’s central location to communicate blast event plans. Specifically, the document will provide information regarding:

•              Explosive demolition approach;

•              Potential vibration impacts;

•              Potential dust generation evaluations and control mechanisms;

•              Security controls;

•              Public traffic controls; and

•              Stakeholder engagement activities.

Many details of the events will continue to be developed ahead of the blast and as a result, this document will be updated as details are developed.

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1.2          Background

As part of site demolition, remediation and restoration activities, the Trust is demolishing the two concrete chimneys at the former Asarco smelter.  The two chimneys consist of an 828-foot continuous poured concrete chimney constructed in 1966 and a 612-foot chimney constructed in 1950. The 828-foot chimney serviced the copper smelter and consists of an outside concrete shell approximately 62.5 feet in outside diameter at the base with a 35.5-foot diameter concrete liner. This effectively forms a chimney within a chimney.  The 612-foot chimney serviced the lead smelter and is approximately 46 feet in outside diameter at the base.

 

1.3          Project Team

The Trust selected Environmental Resources Management (ERM) to manage demolition and asset recovery operations at the former smelter. The demolition contractor has been Brandenburg. This team has demolished most site features and has operated safely on the site with nearly 200,000 project man-hours without any Occupational Safety Health Administration (OSHA) recordable injuries or illnesses.

The ERM / Brandenburg team having significant site experience will perform demolition of the concrete chimneys. Brandenburg has selected Dykon to design and execute the explosive demolition plan. Dykon is led by Mr. Jim Redyke, a Bureau of Alcohol, Tobacco, Firearms and Explosives-licensed blaster with over 40 years of experience.

Brandenburg and Dykon have significant large-scale demolition and explosive demolition experiences including:

•              Dykon is responsible for the felling of more than 100 chimneys around the world.

•              Dykon recently executed the successful implosion of Cowboy Stadium in Irving, TX.

•              Brandenburg is responsible for the felling of smelter chimneys in San Manuel, AZ and Silver City, NM, and numerous other chimneys throughout the US.

•              Brandenburg executed the successful explosive demolition of Veteran's Stadium in Philadelphia, PA.

•              Brandenburg and ERM have been involved in the management, planning, oversight and implementation of many explosive demolitions, several of which have been chimney demolitions.

•              Brandenburg and ERM also have experience in coordinating such events with local authorities and external stakeholders.

•              Brandenburg, ERM and Dykon have a long working relationship.

As the demolition contractor, Brandenburg is responsible for developing the Blast Event Coordination Plan. As with this summary document, Brandenburg’s plan will be continuously updated as details are finalized. Brandenburg’s event plan is included as Appendix A.

 

2.0          BLAST EVENT SCHEDULE

The chimney demolition is scheduled for April 13, 2013 near sunrise. The exact time will be determined by the blaster the day of the blast depending on the completion of blast preparations, traffic control implementation, and weather conditions.

The demolition date was set based on timing to facilitate overall site remediation and restoration. City of El Paso officials were consulted in addition to reviewing planned public events in the city. Because of the high level of coordination with multiple stakeholders and public inconveniences due to traffic controls, the work was scheduled on a Saturday with a backup day on Sunday in case the demolition must be re- scheduled.

 

3.0          EXPLOSIVE DEMOLITION APPROACH

The explosive demolition approach is being designed and executed by Dykon. Dykon has subcontracted the structural analysis of the blast plan to Mr. Paul Rose, PE (Texas) of Phillips Slaughter Rose. The Dykon Blast Plan and the structural analysis are included as Appendix B. A summary of the information provided in Appendix B is presented below for ease of use.

The general approach to demolish the chimneys is to fall the structures like a tree letting gravity do the work. Prior to the demolition, the area is prepared, and a circular fall exclusion zone equal to 1.5 times the height of each chimney is established along with other items described in this document. During the blast event, no personnel will be allowed in the fall exclusion zone.

First, a small portion of the bottom of the chimney on the fall side is removed. The back side (side opposite of the direction of fall) reinforcing steel is cut to allow the chimney to rotate over like a tree in the direction of fall along two hinge points. Second, explosives are used to remove a section on a side where the chimney will fall. And, third, the chimney will fall like a tree in the target fall zone set by the engineers.            A general summary of this approach is illustrated in Figure 1.

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Figure 1: Chimney Explosive Demolition

 

The targeted fall zone for the chimneys is to the east, toward the center of the site (see Figure 2). The fall exclusion zone area is based on guidelines provided by the National Demolition Association’s Safety Manual and provides a sufficient safety buffer for debris and dust control around the area as well as a control zone for any unlikely change in the intended fall direction.

Explosives will be managed under the direction of the licensed blaster. Under El Paso City ordinances, the El Paso Fire Marshall is the permitting authority for the work.

The structural analysis indicates that the chimneys in their “prepared for demolition state” will remain stable and the fall of the structures will not be affected in sustained winds of 15 mph and in wind gusts of 30 mph. Consequently, weather conditions will be monitored, and if steady winds of 15 mph or more, or wind gusts of 30 mph or more are predicted for the site at the time of the demolition, the demolition will be delayed. The Weather Monitoring Plan is included in Appendix B. The blaster will be monitoring the weather conditions via the on-site weather station and available computer-based weather data.

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Figure 2: Fall Zone Preparations

 

4.0          POTENTIAL VIBRATION IMPACTS

Vibrations from explosive demolition events can potentially impact nearby structures. Protec Documentation Services (Protec) was contracted to evaluate the potential for vibration impacts.  Protec used site-specific data provided by Brandenburg and Dykon to prepare a vibration model simulating the effects of discharge of the explosives or vibrations due to the chimneys hitting the ground. The model results were compared to thresholds developed by the United States Bureau of Mines (USBM) for vibration damage and were found to be within acceptable limits for the remaining on-site structures (i.e. the Powerhouse and Administration Building). The study assessed structures within a half-mile radius of the chimneys, and no damage is expected to structures.  Protec’s summary report is included in Appendix C.

Ahead of the blast, field seismographs will be placed at several locations, both on and off site. Exact monitoring locations are being determined by the project team and will be identified in Appendix C when finalized. The monitoring stations include field seismographs that measure peak particle velocity vibration levels on horizontal, longitudinal and transverse channels.  A fourth channel will measure air overpressure.

A report summarizing the vibration data observed during the demolition event will be prepared by Protec after the event.

 

5.1          POTENTIAL DUST GENERATION EVALUATIONS AND CONTROL MECHANISMS

Predictive Evaluation

Dust can be generated during explosive demolition of concrete chimneys from two primary sources.  One is ground dust “pushed” into the air from the force of the structures hitting the ground. The other source is from the breaking of the concrete by the explosives and by the chimneys hitting the ground.   At the request of the Trust, ERM performed air dispersion modeling to assess potential impacts to ambient air quality at the site property boundaries. Applicable site-specific compounds were evaluated. The approximate ambient air concentration of each modeled compound was compared against the compound’s defined National Ambient Air Quality (NAAQS) standard or TCEQ Effects Screening Level (ESL) limit, as applicable. The model will be revised based on analytical data from concrete cores collected from each chimney. The modeling summary report is included in Appendix D.  Based on the modeled conditions, there are no exceedances expected at the property boundaries of the NAAQS or ESL limits for the evaluated constituents.

Blast Event Monitoring

On the day of the blast, ambient air dust monitoring will be conducted at the perimeter of the site. This approach is similar to the ongoing ambient air monitoring program that was established when field work began in 2011. Visible dust from the event will be monitored and Brandenburg response crews will be deployed as necessary to address areas where significant dust cloud movement is observed off-site.

Dust Control Mechanisms

Several redundant dust control measures are being implemented before and during the blast event to reduce the potential for dust generation during the blast. This cautious “belt and suspenders” approach to dust control is outlined below and several components of this approach are depicted in Figure 2:

•              Removal of the accumulated dust within and at the base of each chimney. This has already been done for the 828-foot chimney. Dust from the 612-foot chimney is being removed and will be completed prior to demolition. This material will be staged on site for future disposal in the on-site waste cell.

•              Insulation material on the outside of the interior chimney for the 828-foot chimney will be removed. The insulation consists of 3-inch thick fiberglass material extending from the ground surface to approximately 110 feet upward from the base of the chimney.  This material will be staged on site for future disposal in the onsite waste cell.

•              Application of tackifier (adhesive-like material) on the inside surface of each chimney. Based on ground observations and pictures from recent visual observations of the chimneys, the inside walls do not have significant visible accumulations of dust. However, the application of a tackifier, where safely possible, will further reduce the potential for dust from being dispersed into the air. The tackifier will be applied by positioning a water mist applicator at the bottom of the chimney to spray the mixture around the inside surfaces.

•              Construction of berms along the target fall zones is designed to reduce the lateral extent of the dust cloud and contain dust in the fall zone.

•              Construction of berms and a hardened “backstop” around the sides and back side of the chimneys to reduce the potential for fly-rock generation and redirect generated dust toward the site.

•              Installation of a cover over approximately a 400-foot section of the American Canal near the site. This cover is designed to prevent small fly-rock fragments and gross dust from landing in the canal.

•              Installation of a three-part ground cover dust control system in the target fall zone that consists of:

1.            Installing a geotextile liner on top of the existing site soil.

2.            Placing one-foot of imported clean soil fill over the target fall zone. Coverage will be from the inside of each berm extending approximately 30% beyond the length of each chimney’s height (e.g., for the 828-foot chimney, imported soil fill will extend out to approximately 1076 feet from the base)

3.            Spraying a soil binder on top of the imported soil fill. A similar material is used by the US military to reduce dust at helicopter landing zones.

•              Installation of one of the largest water mist dust control applications attempted for a chimney fall. As shown in Figure 2, a minimum of 21 articulated water mist application units will be installed around the target fall zones.  These units provide a fine mist of water and will come in two sizes.  One type generates a mist at a rate of about 140 gallons/minute/unit for a distance of up to 300 feet, and the other generates a mist at a rate of about 80 gallons/minute/unit for a distance of up to 150 feet.  This “mist curtain” is designed to reduce the amount of dust particulates in the air.

The water mist system will be started 15-20 minutes before the start of demolition, and it is planned to operate for about 15 minutes after the chimneys have made impact with ground surface.  Most of the water from the mist system is expected to be absorbed by dry soil and chimney debris, but there may be some ponding of water into onsite sumps. Thesumps are part of a robust storm water management system at the former ASARCO plant site. The chimneys, the fall zones, water mist system, and sump areas are located within what is considered a zero-discharge facility. Water is collected in sumps and directed to two onsite storm water ponds with approximately 12,000,000 gallons of capacity. Sampling of the captured storm water and/or discharge will be in accordance with the site storm water management plan that has been in place since the beginning of the Trust’s on-site work. The water quality limits are set in a TPDES Multi- Sector General Permit.

After demolition of the chimneys, the fall zone materials and chimney debris will be managed on site. Rebar from the concrete will be removed and recycled.  It is anticipated that some of the chimney concrete will be intermingled with the fall-zone soils and surrounding berm material. The Trust’s environmental team has evaluated the stack concrete by collecting concrete core samples and submitting the samples to a laboratory for analysis of metals, volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). The concentrations of metals in the concrete are substantially less than the concentrations found in Category II and III materials on site. VOC and SVOC concentrations are negligible (see Recastingthesmelter.com, frequently asked questions for sample results).

In accordance with the approval letter from the Texas Commission on Environmental Quality (see letter dated March 22, 2013), post-demolition sampling of debris (e.g. stack concrete and the surrounding fall-zone soil materials) will take place prior to in-site disposal. Stack and fall zone materials are anticipated to be managed as Category II materials (e.g. under the planned soil cover) based on the results of the pre-demolition sampling. However, final categorization and management of the materials will be based on post-demolition sampling results.

 

6.0          SECURITY CONTROLS

Security is a very important component of this event, especially given the location relative to the international border. Once explosives arrive on site, 24-hr per day security will be provided to monitor the explosives. Detailed security plans are being developed by the demolition team in coordination with the El Paso Police and Fire Departments and the US Border Patrol. Security will be provided through the El Paso Police Department and other law enforcement agencies as needed. Security details including any information about the transport and storage of explosives are limited to authorized personnel only. Site security the day the event will be strictly enforced and trespassing will not be tolerated.

 

7.0          PUBLIC TRAFFIC CONTROLS

Select public roadways will be closed for public safety and to facilitate site security. Only one public street in the United States, West Paisano Drive, is in the potential fall zone if the chimneys fall in an unintended direction. Interstate 10 is more than 1,800 feet away from the base of the nearest chimney and is being closed to reduce the potential for traffic accidents to occur during the event.

Road closures will vary from approximately 3 hours before and up to 3 hours after the blast. The road closures are summarized on Figures 3 through 6.  The closures will be permitted through the Texas Department of Transportation (TxDOT) and the City of El Paso Transportation Department, as applicable. Detailed traffic control plans are included in Appendix 2 of Appendix A.

In addition to public roadways, railroads operated by Union Pacific and Burlington Northern Santa Fe are located adjacent to the site. Both operators have been contacted and train movement will be prevented in the area during the event. After demolition, railroad-provided teams will inspect each track prior to reopening for rail service.

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Figure 3: Road Closures Approximately 3 Hours Before the Blast

 

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Figure 4: Road Closures Approximately 15 Minutes Before the Blast

 

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Figure 5: Road Closures Approximately 15 Minutes After the Blast

 

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Figure 6: Road Closures Approximately 1 Hour After the Blast

( The remainder of W. Paisano Dr. will open Approximately 2-1/2 hrs After the Blast)

 

Contingency Planning

The targeted fall zone for the chimneys is located well inside the site property, away from the property boundaries. As previously described, a potential fall zone (i.e., the fall exclusion zone) equal to 1.5 times the height of each chimney has been established in a circle around each chimney. Most of this area is located on site in which case, fall in an unintended direction will result in the chimneys landing in vacant site property, the dust control berms, or site buildings that will be unoccupied at the time of the blast. The largest safety concern is for an unintended chimney fall backward, toward the west. In this scenario, the chimneys would fall outside of the site boundary, across West Paisano Drive.  The 612-foot chimney could also have the potential to fall across the Rio Grande River. West Paisano Drive will be closed prior to the blast to prevent the public from being the fall exclusion zone. The City of Juarez, Mexico officials are being asked to close streets in Juarez that are within the fall exclusion zone.

In the remote event that one or both chimneys fall to the west across West Paisano Drive, the demolition contractor will coordinate response activities with the City of El Paso Office of Emergency Response (EPOER). Because the public will be kept out of the fall exclusion zone, it is anticipated the response will consist mainly of providing heavy equipment to remove debris from the roadway.  In addition, if impacts occur at the international border, response activities will be coordinated by the US Border Patrol. Since EPOER will have the lead, they will assess the situation, coordinate with all affected stakeholders, establish priorities for action, and initiate corrective action on a priority basis. The demolition team will work with EPOER and provide available resources.

 

8.1          STAKEHOLDER ENGAGEMENT ACTIVITIES

Blast event planning has focused on engaging applicable stakeholders to seek their input and keep them informed throughout the process. Starting in January 2013, the Trust has hosted biweekly meetings with the Trust’s demolition team and City of El Paso representatives including the El Paso City Construction Manager, Fire Marshall, Office of Emergency Management and the Police Department. As plans have developed, additional stakeholders have been included in those meetings including representatives from City of El Paso Transportation Department and TxDOT. Additional meetings have been held with governmental agency stakeholders, including the TCEQ, USEPA, FAA, US Border Patrol, International Boundary Water Commission (IBWC), and the City of Juarez.

Non-governmental stakeholders that have been or will be contacted prior to the event include Union Pacific Railroad, Burlington Northern Santa Fe Railroad, the University of Texas at El Paso (UTEP), and businesses located on or near road closures (primarily on West Paisano Drive). In addition, the Catholic Diocese of El Paso who is the caretaker for a historic Smelter Cemetery near the site will be consulted. Due to the potential inconvenience caused by road closures on Executive Center Boulevard, the residents in the La Calavera subdivision will be given the opportunity to stay in a hotel on the weekend of the blast event.

In addition to the agency and one-on-one stakeholder engagement and coordination meetings, a public meeting was held by the Trustee to provide an overview of the blast event. The Trust will continue to work with the City of El Paso and print / electronic media outlets to provide the community with important information related to the chimney demolition. Additional information will also be communicated via the Trust’s website at www.recastingthesmelter.com.

 

APPENDIX A

Brandenburg Demolition Plan

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Appendix 1

Work Area Extents

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Appendix 2

Road Closure Design

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Appendix 3

Pre-Demolition Surveys

TO BE PROVIDED AS COMPLETED

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Appendix 4

Permits and Notifications

TO BE PROVIDED AS COMPLETED AND ISSUED

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Appendix 5

Stakeholder List

INTERNAL DOCUMENT ONLY

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Appendix 6

Project Specific Health and Safety Plan

INTERNAL DOCUMENT ONLY

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Appendix 7

Project Schedule

INTERNAL DOCUMENT ONLY

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Appendix 8

Water Misting System Design

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Appendix 9

Canal Dust Cover Design

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Appendix 10

Vibration Monitoring Plan

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Appendix 11

Blasting Plan and Design

DETAILED PROJECT SPECIFIC PLAN IS AN INTERNAL DOCUMENT ONLY

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APPENDIX B

Dykon Blast Plan

 

APPENDIX C

Vibration Modeling and Monitoring

 

Attachment 1:

Instantel Portable Field Seismograph Specifications

 

Attachment 2:

USBM Report of Investigations RI-8507 S-Graph

 

Attachment 3:

Blast Impact Calculations, Calc’s at Adjacent Liabilities Previous Vibration Report for Bangor, PA stack blast

 

APPENDIX D

Air Modeling and Monitoring

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APPENDIX E

Traffic Control Plans

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