Metro Waste Authority (MWA) conducted a shingles recycling demonstration project from September to November 2009 in conjunction with Des Moines Asphalt & Paving.

The project included the following recycling components:

• Securing a clean supply of tear-off roofing scrap from selected roofing companies;
• Sorting out the non-shingle debris (e.g., plastic, metal, wood);
• Grinding and screening asphalt shingles to produce a finished product of recycled asphalt shingles (RAS); and
• End use of the RAS into hot mix asphalt (HMA) under a project partnership agreement with Des Moines Asphalt & Paving.

 

“I’m a firm believer recycling programs are effective when there is an end market for the material being collected. It only makes sense that we would start a shingle recycling program because 100% of the material (shingles) is recyclable and we have found a local outlet to take the ground shingles,” said Thomas Hadden III, executive director, MWA.

The demonstration project resulted in a little more than 300 tons of shingles being ground for use in constructing local asphalt pavement projects in and around the City of Des Moines. The initial use of the RAS was incorporated at about 5% by weight of aggregate into the HMA in a road paving project in South Des Moines at SE 34 Avenue and Evergreen on October 20, 2009.

Procedures
The following procedures were implemented as part of this demonstration project. Based on the success of the pilot, MWA expects to continue these procedures for use in the shingle recycling project for the foreseeable future.

MWA proactively worked with the roofing companies that partnered with the company to educate them on asbestos containing material (ACM) to try to minimize the chance of ACM being delivered to the MWA recycling facility. This education included a roofer training workshop, phone calls and on-site discussions. Only clean asphalt shingles were allowed. No other types of roofing or siding materials were included in the demonstration project. All other roofing materials was prohibited from this project including: flashings, other materials heavily contaminated with mastic, cedar shakes, rolled or flat roofing, plastic or metal roofing, slate tile, ceramic or clay tiles, etc.

Only roofing materials from non-NESHAP regulated facilities allowed. Private, residential “single family” homes were allowed. Multi-family buildings up through four-plexes were considered eligible. No public buildings owned by a government agency or institution (e.g., subsidized housing) were allowed for the purposes of the demonstration. Going forward, MWA would be interested in accepting material from these organizations as long as they provided appropriate written certification from an asbestos testing lab that the material is free of any known ACM. Roofing companies that partnered with MWA were required to sign a certification form that the homes where the asphalt shingles came from are not NESHAP-regulated facilities. This form was provided in both English and Spanish to accommodate the diverse roofing workforce.

Roofing loads were required to be “source separated”—asphalt shingles were presorted by the roofer at the job site. MWA provided roll-off boxes near the shingle area for wood, metal and trash so roofers could dispose of the “related roofing material” conveniently and easily. MWA offered a $15 rebate to roofers who brought in clean loads (meaning those that were primarily shingles only). MWA recommended to roofers they place the asphalt shingles at the bottom of the trailer or roll-off box and put non-shingle debris on top so it could be easily thrown into the roll-offs provided. Non-shingle debris included items such as plastic wrap, wood and metal flashings.

MWA provided a handout on the rebate and associated acceptable and non-acceptable items to roofing companies and their haulers. This handout was given to every roofer who brought shingles for disposal. It was also provided in advance to roofers the company contacted that wanted to participate in the pilot program. MWA staff visually inspected each incoming load to ensure prohibited materials (e.g., suspect ACM) as listed in the MWA’s supply instructions were not included to the extent possible. MWA staff attended the roofer training and were given hands-on training to identify suspect ACM. Any load containing prohibited materials (either suspect ACM or a contaminated load) was redirected for disposal at the landfill. Ideally, loads were visually inspected by a quick check of the open box or trailer before unloading. If not, loads were inspected after unloading. If loads are tipped and prohibited material was identified, the entire load was reloaded for disposal at the landfill.

MWA kept a record of all incoming loads that supplied the recycling demonstration project. This log included date; time; supplier company name (e.g., roofing or hauling company); weight of load in tons; general description of material type (e.g., mixed roofing material vs. source separated shingles only); any other notes helpful in recording the specifics of the load. This log was very useful in identifying which roofers were providing “clean” material and which were blatantly ignoring the company’s requests for source-separation.

Sorting by MWA staff took place at the tipping area after roofers sorted and unloaded the asphalt shingles. Any additional non-shingle debris was manually hand sorted from the clean asphalt shingles with the assistance of a Bobcat equipped with a grapple bucket. MWA used a “dump and pick” operation. Roll-off boxes were placed near the sorting area for storage and hauling of recyclable metal, recyclable wood and mixed waste for disposal.

MWA contracted with an independent environmental laboratory, EMSL of Minneapolis, Minn., to test the shingle samples. The shingles were kept in smaller piles (e.g., daily loads) in individually marked bunkers until results from the lab demonstrated the materials did not contain ACM. Once inspected and cleared as free of ACM, MWA staff pushed the shingles into a larger stockpile.

For testing, one sample was taken per load from every type of shingle (i.e., for every re-roof job) as well as roof paper in the load. A 3-in. square sample was cut from a randomly selected, representative shingle. This sample was clearly labeled, packaged and then sent to EMSL for asbestos analysis using the polarized light microscopy (PLM) method as prescribed by NESHAP. If the laboratory analysis indicated the sample was free of ACM, the load was processed. If laboratory analysis indicated ACM the load was handled and disposed as hazardous material in accordance with MWA protocols as per federal, state and county regulations.

MWA’s protocol called for landfilling any load that had a sample come back with trace asbestos. Even if the ACM detect is lower than NESHAP limits (less than 1%), MWA landfilled the entire load. MWA wanted to err on the side of safety and caution.

Dust Control
The dust control plan included the following elements:

• All shingle recycling operations were conducted on a concrete pad. This included the tipping area, stockpiling of sorted shingles, grinding/screening and RAS stockpile storage.
• All truck traffic to and from the shingle recycling area was directed via facility roads with paved surfaces.
• The roads and active working areas within the shingle recycling operations were swept on a regular basis as needed to keep dirt from accumulating.
• Workers involved directly with the shingles sorting were required to wear OSHA-specified dust masks.

The shingle grinding machine was equipped with a hose and spray nozzles to provide continuous watering of the whole shingles just before entering into the grinding chamber. The incoming shingles were sprinkled wet (just enough to reduce dust and cool the grinding chamber), but not soaked. The front end loader was equipped with an enclosed operator’s cab to prevent dust from reaching the operator.

Des Moines Asphalt & Paving contracted with Dem-Conn to grind the shingles October 26-27, 2009. MWA contracted for a one-time, air quality test for asbestos conducted in the area of the operators of the shingle grinding equipment to demonstrate all OSHA asbestos standards were met. This air quality asbestos test was conducted by an independent, environmental and industrial hygiene testing lab (IES). Following the grind, Des Moines Asphalt & Paving loaded out the ground shingles at the Metro Park East Landfill and were weighed out at the scalehouse.

All shingle recycling operations were managed according to MWA’s storm water management plans and permit approvals, including stockpiling of feedstock shingles and finished RAS product. Detailed procedures included:

• Conducting all shingle recycling operations on a paved surface; and
• Managing storm water run off from the shingles recycling area the same as other run off from adjacent operations (compost pad and recycling areas).

MWA invited the Iowa Department of Natural Resources and other local stakeholders to the facility to observe the shingles recycling operations and grinding. MWA also requested Iowa DOT come take samples of the ground shingles to see how the ground product fit its draft specifications for use in DOT roadways. “The only way we know how to make a new program work is to bring everyone to the table at the beginning,” said Hadden. “We hosted meetings with Iowa IDNR, Iowa Department of Transportation, the hot mix asphalt producer and our staff to discuss all possible needs and potential issues with shingles recycling.”

Sampling
For testing, one sample was taken per load from every type of shingle (i.e., for every roof job) as well as roof paper in the load a 3-in. square sample was cut from a randomly selected, representative shingle. MWA sent one sample to the lab and pulled a second sample to be archived. The samples were put into individual bags and clearly labeled “lab” or “archive.” The lab samples were packaged and sent overnight to MWA’s contract laboratory for asbestos analysis using the polarized light microscopy (PLM) method as prescribed by NESHAP. The samples were sent overnight so testing could be completed in a timely manner, and loads free of ACM could be pushed into the larger pile, freeing bunker space for incoming loads. If laboratory analysis indicated ACM, the load was handled and disposed as hazardous material in accordance with MWA protocols per federal, state and county regulations.

It was originally intended MWA would conduct three tiers of sampling to cost-effectively determine if any ACM was present in the clean asphalt shingles.

• Tier 1: Sample and test every load, every separate layer of asphalt shingles (for the first 50 tons of shingles)
• Tier 2: Random sample loads and test once every 10 tons (for the second 50 tons of shingles)
• Tier 3: Random sample loads and test once every 50 tons (for the next 100 tons of shingles)

As it turned out, MWA tested every load and every layer of shingles for the demonstration project. This means the company stayed with the Tier 1 regimen and did not move to the more random approach during the demonstration. This decision was made because MWA had two asbestos “hits” while in the first tier of testing. This led MWA to continue further testing to develop a baseline for the type of material it was receiving. MWA wanted to feel confident the material received was consistently non-asbestos containing, before moving to the next tier. Sampling of every load and every layer did cause a backlog at times. MWA found that on busy days the bunkers would fill up, even with sending samples overnight to the lab, new loads would be coming in before approved loads could be pushed out of the way. The company dealt with this situation by creating additional receiving areas on the back side of the bunkers. This helped, but during peak times, the sampling of every layer and every load did limit MWA’s ability to accept large volumes of material. This was not only frustrating for the staff, but also for roofers who were source-separating loads specifically so the material could be recycled and they could receive the rebate.

Findings
MWA tested every load and every layer of shingles we received in the pilot project (even though the materials being received did not fall under NESHAP.) This resulted in MWA submitting 237 samples during the demonstration project, with two trace hits from roof paper (both at .25%) and one 18.6% hit on a shingle sample. Below is the sample information and corresponding results:

• Sample 092809014A was <1% chrysotile asbestos
• Sample 092809017A was 4% chrysotile asbestos
• Sample 100209007A was 18.6% chrysotile asbestos

As described in the sampling procedures, all of these loads were immediately disposed of in the landfill. MWA resubmitted samples taken from the archive samples to both EMSL as a blind sample and a separate, independent lab, IES. All six of these samples came back as non-asbestos containing. MWA then shared with EMSL how it conducted a blind sample that had come back non-asbestos containing the second time, but 18.6% ACM the first time. EMSL pulled the original sample and upon closer inspection found the shingle had a strip of tar on the top that was highly positive. The asbestos was not evenly distributed in the shingle, and was only present in the strip of tar. This explained the very high asbestos detect on part of the shingle, but not on the other samples resubmitted for re-testing. The company was told the trace asbestos found on the first samples of roof paper was likely operator error. No other explanation could be identified for the trace findings.

Air Testing Results
MWA contracted with IES to conduct air monitoring during the grinding of the shingles to make sure we were well below OSHA guidelines. The permissible level is .1 f/ee on a time weighted average. All of the air samples collected were below the permissible exposure level.

Summary
Feedback from all of the partners in this project has been very positive. Based on the success of the pilot project, MWA has decided to continue recycling shingles in 2010. The roofers are excited to have a place to recycle shingles and receive a rebate for their product. They have asked MWA to help them promote that they are a contractor who recycles shingles. As customers become more interested, MWA will work with roofers to develop marketing that is mutually-beneficial.

Dem-Conn, the company Des Moines Asphalt & Paving contracted with to do the grinding, was impressed by MWA’s product. Des Moines Asphalt & Paving was also pleased with the product and the resulting paving that was done in the City of Des Moines. It has decided to work with MWA for another year, through the fall of 2010. Many public works directors, the Iowa DOT and others were also excited about the possibilities and what this product can do for Central Iowa. MWA is working with Polk County Air Quality to modify its air permit to allow for more random asbestos sampling based on the results of this pilot project.

MWA is excited about the pilot project and expanding shingle recycling in 2010. “After completing the pilot, the results of the program showed us that we could continue to meet our IDNR permits and the stringent IDOT specs, while still operating a successful shingles recycling program at our landfill,” said  Hadden.

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