Robin Rickel Vroegop145 Avenue C

Apalachicola, Florida 32320

June 23, 2014

Via Email - michael.spaits@us.af.milMike SpaitsEglin AFB Public Affairs Office96 TW/PA, 101 West D Avenue, Room 238Eglin AFB, FL 32572-5499

RE: ! Gulf Regional Airspace Strategic Initiative! Environmental Impact Study: Comments to ! Draft EIS

Dear Mr. Spaits,

Enclosed please find my comments on the subject enironmental impact study (EIS).Please ensure that these comments are addressed by the Air Force as part of any final EIS which may be prepared.

Sincerely,

Robin Rickel Vroegop

Citizen Comments: US Air Force Proposal for the GRASI Landscape Initiative Page 1 of 2 with two reference documents

My name is Robin Rickel Vroegop and I have been a resident of Franklin County for over 20 years. For the past ten years I have frequented many of the public lands in Northwest Florida, including Tate’s Hell S. F. and Blackwater S.F., as a volunteer, as a student, as a teacher, for personal recreation and study, and more recently, as a guide. My husband and I operate Florida Geotourism Associates, LLC, located at 118 Commerce St. Apalachicola, Florida.

My specific comments will address my concerns regarding ES. 4.1.2.2 Fixed-Wing Aircraft Landing Sites and also ES.4.1.2.1 Helicopter Landing Zones/Drop Zones in Tate’s Hell S. F., the area with which I am most familiar. Currently Tactical Map ES-5 shows three proposed FWALS for T.H.S.F. in TA-2, TA-6, and TA-8. I am familar with those dirt roadways that are proposed in support of aircraft operations, such as CV-22 landing zones. According to the two reference documents that I have attached to these comments, I do not think the proposed areas can be utilized within the restriction parameters listed in Tables ES-2 and ES-1. I have attached as reference an article from Air Force Civil Engineer, Vol. 21, No.3, 2013 regarding improvement of unimproved landing area on Melrose Air Force Range, N.M. to provide suitability for repeated take-offs and landings of CV-22 Osprey aircraft. The article indicates that to meet training requirements, the landing area must be a minimum 240-foot diameter circle. I question whether that criteria can be met at the locations proposed for FWALS in Tate’s Hell State Forest, without additional clearing, or disturbance of wetlands or floodplains as stated in Tables ES-2 and ES-1.

In addition, I note that the tables state, “no new impervious surfaces”. I would like the Air Force to define impervious as it relates to the construction materials/methods allowed in LZ/DZs as well as FWALS. Specifically, will the Air Force or Florida Forest Service be employing the use of aggregates or synthetic fluid soil treatments to stablize these areas against structural and heat damage on roads from CV-22 exhaust and downwash as described in detail in the Air Force Civil Engineer article about the MAFR landing pad construction? I am concerned that these construction methods and landings/takeoff/hover operations will result in significant adverse and irreversible impacts to the hydrology, water, and soil quality to the immediate area, and cumulatively, to the water table, leaving sterile zones that will persist for decades and be nearly impossible to mitigate.

From a military fact-sheet published online, I have learned that the CV-22 Osprey aircraft purportedly has a maximum downwash speed above 80 knots, more that the 64 knots lower limit of a hurricane. Video that I have viewed of these machines in operation appears to bear this out.

Furthermore, footnoted information found elsewhere states the following:

! Heat from the V-22's engines can potentially damage the flight deck on some ! amphibious ships of the U.S. Navy. Naval Air Systems Command devised a ! temporary fix of portable heat shields placed under the engines, and determined ! that a long-term solution would require redesigning the decks with heat resistant ! coating, passive thermal barriers, and changes in ship structure, similar changes ! are required for F-35B operations. In 2009, DARPA requested solutions for ! installing robust flight deck cooling.

That information has led me to ask the Air Force to address my second Environmental Impact Statement concern: the potential hazards created by the heat and petroleum, oil, and lubricants (POL) from aircraft engines. Please refer to my second attached reference document, dated April 2, 2014, from the Department of the Air Force, Air Force Civil Engineer Center on Tyndall Air Force Base Florida. This is an Engineering Technical letter (ETL) providing guidance to Air Force and Naval engineers on surface treatments to alleviate damage to portland cement concrete caused by extreme exhaust heat and POVs from CV-22 landing, take-off, and hover operations. According to the letter, at times, the concrete can become so hot that the water inside becomes vaporized, causing scaling of the concrete. While the roads in Tate’s Hell are not concrete, they do contain some of the same chemical compounds found in concrete, such as calcium carbonate, but in a more permeable form.

Such intense aircraft exhaust heat poses a serious fire risk in times of drought. Even though Tate’s Hell is mostly wetlands, the open, grassy and weedy areas along roadsides are often the first to dry out. On other public lands, such as St. Vincent NWR, wildfires have been known to start from just the contact of high, dry, roadside grass with the hot underside of truck chassis. For that reason, I am very concerned about the compatibility of military aircraft and ground training operations with the sylvaculture and management missions of these state Forests. For example, when others are under a “no fire or fireworks” red flag condition, would these high-risk operations and manuevers with pyrotechnics continue, and under what provisions?

Likewise, I am concerned that the permeability of present road surfaces in Tate’s Hell will not provide an effective barrier to retard the migration of POVs into the water table during rainfall events, while the extreme heat from the engine exhaust will likely hasten the process. As such, CV-22 operations in T.H.S.F. would seem to pose an unacceptable risk of significant adverse and irreversible impacts to the hydrology, water, and soil quality to the immediate area the entire basin which drains to Apalachicola Bay. The costs to mitigate those impacts would likely be high both in economic terms, and in terms of further damage to the ecosystem.

In conclusion, due to my above-outlined concerns regarding the environmental impacts of this proposed action, I must recommend that no action be taken to implement the GRASI Landscape Initiative.

Finding ways to reduce aircraft maintenance costs is a criti-cal step in saving money and time.

This is especially true for the CV-22 Osprey, whose primary mission is the in!ltration and ex!ltration of special opera-tions forces and cargo in austere locations. These locations frequently come with a lot of dust, which can cause a huge aircraft maintenance problem for the Osprey.

Because of its resemblance to Afghanistan, Melrose Air Force Range, located 20 miles west of Cannon Air Force Base, N.M., provides some of the most realistic training available to special operations forces. But the dust condi-tions there reduce engine "ight hours to 140 to 250 as opposed to the designed 500 in normal conditions. Once the limit is reached both engines are removed from the aircraft and rebuilt — a maintenance cost of approximately $1.6 million a year.

Due to these high costs, Air Force Special Operations Com-mand tasked the 27th Special Operations Civil Engineer Squadron to engineer a solution — a low-dust landing pad — that could extend the lifecycle of the CV-22’s engines while maintaining realistic training on MAFR.

Design

While there are many commercial methods for dust con-trol, none are capable of withstanding the intense heat of the CV-22 engine’s exhaust. Options considered for the problem included a full-depth concrete pad, large river rock and a liquid polymer or synthetic "uid soil treatment. The soil treatment method was ultimately selected as the most cost-e#ective and expedient.

Having never constructed such a project, 27 SOCES engi-neers consulted experts from the U.S. Marine Corps as well as the U.S. Army Dust Control Field Handbook. Marine Wing Support Squadron 374 has used the soil treatment method in constructing several helicopter landing zones and a short !eld runway for heavy aircraft. There was major concern about the limited amount of data on the durability of the chosen technique.

Choosing the right commercially available dust control product was crucial. There are two main types of products on the market: synthetic "uids and liquid polymers. Syn-thetic "uids are oil-based and control dust by binding soil particles together. However, this can cause large chunks of soil to stick to aircraft landing gear, a safety issue that immediately excluded synthetic "uids from consideration. This left liquid polymers, which are water-based and con-trol dust by gluing particles together. Once dry, the liquid polymer doesn’t stick to aircraft tires.

Our application needed a product with polymer content greater than the 20 to 30 percent in most commercial products. The MWSS 374 recommended the SoilWORKS product called SoilTAC, with a polymer content of 50 to 60 percent that allows for greater strength while reducing the amount of product required. Using data from the U.S. Army Dust Control Field Handbook and information provided by the MWSS 374, 27 SOCES engineers developed a mix-ture using SoilTAC, Portland cement, recycled asphalt and water.

To meet training requirements, the landing pad is a 340-foot diameter circle with an inner 240-foot-diameter landing area and an outer 100-foot-diameter dust control

1st Lt. Matthew Buscemi 27 SOCES/CEO

28 Air Force Civil Engineer Vol. $% No. &, $'%&

A CV-22 Osprey makes a test landing on the low dust landing pad con-structed by the 27th Special Operations Civil Engineer Squadron. (U.S. Air Force photo by Senior Airman Ericka Engblom)

(1.) Grading the recycled asphalt after it was placed on the site.

(2.) Placing portland cement before the SoilTAC and water was applied.

(3.) A grader mixes the SoilTAC, water, Portland cement, and recycled asphalt together. At the same time a water truck sprays the SoilTAC and water onto the center of the pad.

(4.) The Steel Wheel roller compacts the pad. (U.S. Air Force photos by 1st Lt. Matthew Buscemi)

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zone (see !gure). The landing area consists of six inches of recycled asphalt, Portland cement, SoilTAC and water. The dust control zone was created by applying a SoilTAC and water mix to the graded surface, in quantities determined by following the recommendations of both MWSS 374 and SoilWORKS engineers.

Construction

The landing pad construction area was an existing unim-proved heavy landing zone. The heavy equipment shop spent three weeks excavating and hauling soil from a bor-row pit, and then back!lling to bring the site up to grade. Recycled asphalt (840 cubic yards) was used to further improve the soil. With the site prepped, the !nal mixture of SoilTAC, water, recycled asphalt and Portland cement was placed and mixed in under two days.

The manufacturer recommended an asphalt reclaimer or tractor with disk plows to mix the materials, but such unique equipment was unavailable in the local area and

sourcing from a larger metropolis wasn’t cost e"ective. So, the 27 SOCES improvised and used a grader for mixing.

With the pad complete in less than a month it was time to test it. The initial assumption of the 20th Special Opera-tions Squadron at Cannon was that the pad wouldn’t be able to withstand the loading of a CV-22. An Air Force CV-22 completed nine test landings, including several low hovers a few feet over the pad. The pad showed no sign of structural or heat damage.

Five months and more than 100 landings later, the pad is holding strong with no signs of damage. Leadership from AFSOC and the 27th Special Operations Wing was so impressed that the 27 SOCES was tasked to construct three additional pads before the end of the calendar year.

1Lt Buscemi was the o"cer-in-charge, Operations Engineer-ing, 27 SOCES, Cannon AFB, N.M. He is now the Energy Manager, 8 CES, Kunsan AB, Republic of Korea.

Air Force Civil Engineer Vol. #$ No. %, #&$% 29

2 APR 2014

DEPARTMENT OF THE AIR FORCE AIR FORCE CIVIL ENGINEER CENTER

TYNDALL AIR FORCE BASE FLORIDA

FROM: AFCEC/DD 139 Barnes Drive Suite 1 Tyndall AFB FL 32403-5319

SUBJECT: Engineering Technical Letter (ETL) 14-2: Preventing and Repairing

Concrete Deterioration Under MV-22 and CV-22 Aircraft 1. Purpose. This ETL provides guidance on (1) Portland cement concrete (PCC) surface treatments to reduce or eliminate spalling, scaling, and other surface damage caused by heat and petroleum, oil, and lubricants (POL) from aircraft engines; and (2) repairing PCC damaged by CV-22 or MV-22 operations. Note: Use of the name or mark of a specific manufacturer, commercial product, commodity, or service in this ETL does not imply endorsement by the Air Force. 2. Application: All bases supporting MV-22 or CV-22 operations on PCC pavements.

2.1. Authority: x Unified Facilities Criteria (UFC) 3-260-02, Pavement Design for Airfields x Air Force Policy Directive (AFPD) 32-10, Installations and Facilities x AFPD 10-2, Readiness

2.2. Effective Date: Immediately. 2.3. Intended Users:

x Major Command (MAJCOM) engineers x Base Civil Engineers (BCE)

2.4. Coordination:

x Naval Facilities Engineering Command Engineering and Expeditionary Warfare Center (NAVFAC EXWC)

3. Acronyms and Glossary: APU - auxiliary power unit BCE - Base Civil Engineer °C - degrees Celsius °F - degrees Fahrenheit FOD - foreign object debris MAJCOM - Major Command

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

NAVFAC EXWC - Naval Facilities Engineering Command Engineering and Expeditionary Warfare Center

NFESC - Naval Facilities Engineering Service Center PCC - Portland cement concrete pH - measure of the acidity or basicity of an aqueous solution POL - petroleum, oil, and lubricants PPE - personal protective equipment TDS - Technical Data Sheet TSP - trisodium phosphate UFC - Unified Facilities Criteria UFGS - Unified Facilities Guide Specification 4. References.

4.1. Air Force: x AFPD 10-2, Readiness, http://www.e-publishing.af.mil/ x AFPD 32-10, Installations and Facilities, http://www.e-publishing.af.mil/ x ETL 02-7, Preventing Concrete Deterioration Under B-1 and F/A-18 Aircraft,

http://www.wbdg.org/ccb/browse_cat.php?o=33&c=125 4.2. Navy:

x Naval Facilities Engineering Service Center (NFESC) Technical Data Sheet (TDS) 2058-SHR, A Concrete Solution to the F/A-18 Parking Apron Problem, September 1998

x TDS NAVFAC EXWC-CI-1403, Mitigating Concrete Damage Caused by Engine Exhaust Surface Temperature below 500ºF, December 2013 (supersedes TDS-2058-SHR)209 208 6144

x Malvar, L.J., Rossetti, P., Technical Report TR-2344-SHR, Naval Facilities Engineering Service Center, Port Hueneme, California, October 2010

4.3. Joint:

x UFC 3-260-02, Pavement Design for Airfields, http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

x UFC 3-270-03, Concrete Crack and Partial-Depth Spall Repair, http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

x UFC 3-270-04, Concrete Repair, http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

x UFGS 32 13 99, High Temperature Concrete for Airfields, http://www.wbdg.org/ccb/browse_org.php?o=70

4.4. New York State Department of Transportation Materials Bureau:

x NY 703-19 E (2008), Moisture Content of Lightweight Fine Aggregate

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4.5. Industry: x Anderson, John R., Marian P. Rollings, Michael Ayers, and Raymond S.

Rollings, Auxiliary Power Unit (APU) Resistant Concrete: State-Of-The-Art. Transportation Systems 2000 Conference, San Antonio, Texas, 1 March 2000

x Hironaka, M.C., Malvar, L.J., “Jet Exhaust Damaged Concrete,” Concrete International, vol. 20, no. 10, October 1998, pp. 32-35

x McVay, Michael, Jeff Rish III, Chris Sakezles, Shaik Mohseen, and Charles Beatty, “Cements Resistant to Synthetic Oil, Hydraulic Fluid, and Elevated Temperature Environments,” ACI Materials Journal, March-April 1995, pp. 155-163

5. Background.

5.1. MV-22 or CV-22 engine exhaust can damage ordinary PCC pavements. The damage occurs in the form of scaling or spalling of the top 1 to 2 inches (25 to 50 millimeters) of the pavement. Pavement fragments from these surface scales have the potential to produce foreign object damage (FOD) to aircraft engines. The exhaust temperatures, coupled with spilled fluids (POL), damage ordinary PCC airfield pavements. The damage occurs progressively to the pavement surface under repeated thermal cycling and chemical reaction of the spilled aircraft fluids with the cement paste. 5.2. Testing by NAVFAC EXWC and the Air Force Research Laboratory (AFRL) (reference report, paragraph 4.2) has shown that there are three primary mechanisms causing the damage: thermal fatigue, vapor pressure, and chemical degradation. Thermal fatigue has produced failures without the presence of POL. Damage due to vapor pressure has also been observed when the water vapor pressure cannot be relieved fast enough during the heating phase. Chemical degradation results in a significant loss of strength — up to 50 percent in some cases — which accelerates the failure. Chemical degradation by itself can result in raveling of the concrete, which has been observed under the auxiliary power units (APU) for the B-1 and F-18. It does not produce scaling, but accelerates scaling. 5.3. There are three techniques to reduce damage from MV-22 or CV-22 exhaust.

5.3.1. Applying sodium silicate dramatically improves a concrete pavement’s ability to resist damage from exhaust temperatures below 500 °F (260 °C). Appling sodium silicate is the most affordable way to reduce damage to existing undamaged pavement because reconstruction is not required. 5.3.2. When new construction is planned, a high-temperature aggregate such as an igneous traprock, expanded shale, or expanded slate should be used as the coarse aggregate in the concrete mix design. Unlike a concrete mix for an F-35 vertical landing pad (see UFGS 32 13 99, High Temperature Concrete for Airfields), the fine aggregate can be a natural sand. For best results, sodium silicate must also be applied; however, the sealant must not be applied any earlier than 70 days after placement of the concrete.

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5.3.3. Multifilament polypropylene fibers at a dosage of 3 pounds per cubic yard of concrete further improves concrete durability when subjected to exhaust.

5.4. In cases where existing pavement has been damaged, repairs in accordance with ETL 02-7, Preventing Concrete Deterioration Under B-1 and F/A-18 Aircraft, will provide a level of protection against further damage to the affected areas. For best results, a sealant must also be applied; however, the sealant must not be applied any earlier than 70 days after placement of the repair material.

6. PCC Surface Treatment.

6.1. Sealing with Sodium Silicate. (Note: Do not apply to asphalt pavement).

6.1.1. The sodium silicate surface sealer is absorbed into the top 0.125 inch (3 millimeters) of the concrete, providing resistance to high exhaust temperatures and preventing POL stains. The sodium silicate will need to be reapplied if surface wear occurs. 6.1.2. The sodium silicate surface sealer needs to be a colorless, water-based solution containing 9 percent sodium silicate. Many manufacturers provide a product with this concentration. Higher-concentration products need to be diluted to 9 percent sodium silicate. The 9 percent sodium silicate provides optimum concrete penetration with three applications. Eucosil (Euclid Chemical Company), Woodeze 5RU-146 (Rutland), or CARS Liquid Glass (Hubbard-Hall) are sodium silicate products that can be used to seal the concrete surface; however, the concentrations may need to be diluted. The sodium silicate sealer is applied to PCC subject to the heat and POL from MV-22 and CV-22 engines. 6.1.3. Before application, clean the concrete with a rotary power washer/scrubber to remove tire rubber, curing compound, and POL. If heavy POL contamination is present, follow the procedures in paragraph 6.2 before applying the pavement sealant. 6.1.4. Apply the sodium silicate no earlier than 70 days after the pavement has been placed. Testing has determined that sodium silicate applications prior to 70 days result in surface flaking of the PCC. The pavement joints must be properly sealed before applying the sodium silicate. If the joint seals are not in good condition, repair or replace them before applying the sodium silicate. All paint markings (including shadow markings) must be in place, in good condition, and contain no cracks or chips before applying the sodium silicate. Damaged markings must be repaired or replaced before applying the sodium silicate. The concrete surface must be dry for 24 hours before applying the sodium silicate and after the pavement markings have been applied. Air temperature must be 40 °F (4.4 °C) or higher, and relative humidity must be 80 percent or lower, both

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during application and for 48 hours after application. It is acceptable to apply the sodium silicate over pavement markings and glass beads. 6.1.5. Recommend sealing only those areas most susceptible to POL and direct exhaust: a circular area 5 to 7 feet (1.5 to 2.1 meters) in radius, centered where the engine exhaust is directed at parking, maintenance, and preflight check areas. For taxiway and taxilane hold points, the sodium silicate should be applied in two stripes 90 to 360 feet (27.4 to 109.7 meters) long and 10 to 14 feet (3.0 to 4.2 meters) wide, centered 24 feet (7.3 meters) on either side of the taxiway centerline. The length of the treated area is determined by the number of aircraft anticipated to hold at a time. 6.1.6. Apply three coats of the sodium silicate solution with low-pressure airless spraying equipment to ensure uniform application. Start applying the solution at the highest point in the pavement and continue downgrade. Each coat must cover not more than 200 square feet per gallon (4.9 square meters per liter). Avoid excessive application, as it will cause efflorescence and reduce friction. Allow the sodium silicate to penetrate for two hours, then wash off any visible excess (ponded) solution. Allow the area to dry for at least 24 hours between each coat. 6.1.7. After allowing the last coat to dry for 24 hours, evaluate the surface for any excess silica or dusting. Wash off any excess silica or dusting as needed. Protect the application from any pedestrian or vehicular traffic until the last coat has dried.

6.2. Cleaning Heavy POL Contamination of PCC and PCC Joints. 6.2.1. If POL stains are present, treat the entire stain before sealing the pavement. Several methods to remove POL stains and, in the case of POL stains on joints, improve the bond to the joint surface are described below. Most stains require several applications and may require the use of more than one treatment method. By implementing all of these steps, maximum removal will be achieved; however, one or more of the steps can be omitted to achieve acceptable results. Steam may be used; however, steam alone will provide some cleansing of the immediate surface but will not penetrate deep enough to provide a long-term result.

6.2.1.1. Dawn (or Simple Green) Dishwashing Detergent and Hot Water. Apply to the stained area and scrub to develop a thick lather. Let set for several minutes then rinse with warm/hot water. Use of steam to pretreat the area and rinse may aid removal. 6.2.1.2. Trisodium Phosphate (TSP). TSP (also called sodium orthophosphate) is available in many hardware stores. Note: Some states have banned this product because the phosphate can cause problems with nearby waterways. Check with the environmental office before

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using. Mix one measure of TSP with six measures of water. Apply over the stain with a paintbrush and allow it to dry completely before scraping off the dried paste. Rinse the concrete surface and scrub with a stiff brush and clean water. WARNING: DO NOT MIX TSP WITH ANY ACID! A violent reaction can occur and release noxious gas. You can use both products but they must be used separately, with a thorough rinsing with water between applications. Alternate application method: Dissolve 1 pound, 6 ounces of TSP in a gallon of water. Add enough finely ground calcium carbonate (also called whiting or agricultural lime) to make a thick paste. (Agricultural lime is available at garden supply stores.) Spread the paste over the stain and allow it to dry for a day, if possible. Brush off the dry paste with a stiff brush and scrub the concrete with water. The paste has a high pH so personal protective equipment (PPE) must be used and the paste should be kept away from aircraft. If it is windy, protect the treated area until the area is cleaned and rinsed to keep the caustic material from blowing around the apron. 6.2.1.3. Sodium Hyroxide. If TSP is not available or not allowed, use sodium hydroxide, such as Morado Super Cleaner (Zep® Superior Solutions, http://www.zep.com/ZepSearch/singleproduct.aspx?search=0856&num=1&match=Exact&country=U?iframe=true&width=620&height=400). Make a solution of 5 percent sodium hydroxide (caustic soda: NaOH). Apply it over the stain with a paintbrush and allow it to dry for at least 24 hours. Rinse and scrub with clean water then repeat as required. This has a high pH, so PPE must be used and the solution should be kept away from aircraft. If it is windy, protect the treated area until the area is cleaned and rinsed to keep the caustic material from blowing around the apron. 6.2.1.4. T.S.P. Substitute. T.S.P. Substitute (DAP® Products, http://www.dap.com/product_details.aspx?product_id=317), a sodium carbonate (washing soda) plus other chemicals, can be used as a substitute for TSP or sodium hydroxide; however, it does not work as well and may take more applications to remove the POL. Apply as directed. Rinse well with water. This is an organic salt. If it is windy, you need to protect the treated area until the area is cleaned and rinsed to keep the salt from blowing around the apron. 6.2.1.5. Phosphoric Acid Cleaner. Apply Phosphoric Acid Cleaner (Miracle Sealants Company, http://www.miraclesealants.com/c_pre_cast_concrete_clean.html) as directed. Rinse well with water and sodium carbonate (washing soda or soda ash) to neutralize the pH, then rinse with clear water. This product will etch the concrete so do not leave it on too long and ensure the area is rinsed well to ensure no acid is left on the concrete.

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6.2.1.6. Eximo® or G Force. Eximo® (CAF® Environmental Solutions, http://mycaf.com/eximo.php) or G Force (Winsol Laboratories, http://www.winsol.com/G-Force.htm) are biological materials (bacteria) that consume POL. No matter what method is used to remove the stains, use of one of these products is recommended as a final treatment because the bacteria stays in the concrete and will eliminate any remaining POL over time. Follow the product directions. 6.2.1.7. Concrete Sealant. Once the POL stain is removed, joints sealed, and markings added, the PCC surface should be sealed to minimize future POL contamination (see paragraph 6.1). For areas not subject to direct or prolonged exposure to MV-22 or CV-22 exhaust, a silane- or siloxane-based concrete sealer that contains no silicone can be used in lieu of sodium silicate (with the approval of the MAJCOM pavements engineer), but it must be reapplied every 12 to 24 months. Products that allow the concrete to breathe work best. Available products include, but are not limited to, Aquapel (L&M Construction Chemicals), MasonrySaver (SaverSystems®, http://www.saversystems.com/products/masonry-water-repellent-products.html), and Prote-crete® Densifier plus Repeller™ (Applied Concrete Technology, http://concretesbestsolution.com/densifier-plus-repeller.html). Sodium siliconate products such as SealGreen® concrete sealers (http://sealgreen.com/concrete-sealer.aspx) may also be used (with the approval of the MAJCOM pavements engineer) but require reapplication every 24 to 48 months.

6.2.2. If the contamination is too heavy then removal/repair of the area may be required.

7. PCC Repair. Repairs to PCC damaged by MV-22 or CV-22 exhaust should be accomplished in accordance with ETL 02-7. In the event that an entire slab must be replaced, a high-temperature aggregate such as an igneous traprock, expanded shale, or expanded slate should be used as the coarse aggregate in the concrete mix design. Unlike a concrete mix for an F-35 vertical landing pad (see UFGS 32 13 99), the fine aggregate can be a natural sand. For best results, sodium silicate must also be applied; however, the sealant must not be applied any earlier than 70 days after placement of the concrete repair material. 8. Point Of Contact. Questions or comments about this ETL are encouraged and should be directed to the Pavements Subject Matter Expert, AFCEC/COSC, DSN 523-6439, commercial (850) 283-6439, afcec.rbc@tyndall.af.mil. ANTHONY A. HIGDON, Colonel, USAF 1 Atch Deputy Director 1. Distribution List

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