I asked the folks at Withers & Ravenel to give share more about their project, how it was conceived, and how it was designed.
Why Swine Farms? What was the genesis of this Project?
North Carolina is “pork proud”, with approximately 9 million hogs on farms scattered throughout the eastern part of the State. These farms rely on open pit lagoons and land application for the treatment and disposal of animal waste. However, open-air treatment lagoons have a poor reputation among some lawmakers, residents and environmentalists. They are accused of creating sickening odors, allowing methane to escape into the atmosphere, and contaminating groundwater and streams.
Because of environmental concerns, the State temporarily suspended permitting the construction and operation on any new swine farms utilizing lagoon treatment systems in 1997, and required new farms to meet “environmentally superior technology” (EST) standards. Since the enactment of the suspension, there have been no new hog farms introduced in North Carolina.
Tax Credits, Legislation, and Funding
In 2007, the State passed Senate Bill 3, which pushes the use and development of renewable energy standards, the State took a big step toward encouraging innovative treatment technologies for swine waste by mandating utilities to purchase Renewable Energy Credits (REC) generated from swine waste. The Bill also provides a 35% State tax credit in addition to the Federal 30% tax credit.
Spurred by the availability of the NC Green Business Fund grants from the 2009 American Resource Recovery Act, Withers & Ravenel conceived the 600kW renewable energy project and assembled the project team, which included developer AgPower Partner, Withers & Ravenel engineers, and Barnhill General Contractors.
The project was able to receive over $2 million dollars in grants and tax credits, including a $500,000 grant from the NC Department of Energy and $1.5 million grant from the US Treasury. The Owner, Billy Storms, was able to finance the balance of the project cost through a loan with the Cape Fear Farm Credit Association.
Engineering a Plan for the System
In North Carolina, swine farms flush the houses with water in a closed system with a lagoon providing storage and treatment of waste which is then applied to crops. With this process, the waste is diluted to around 1-2% solids. However, in order to reduce the water content for more efficient temperature control of the anaerobic digestion, the waste needs to be between 5-10% solids.
With the implementation of scraper technology, swine waste volume was significantly reduced by eliminating the added liquid from the flushing system. This made the Storms Farm much less reliant on the volume required in the existing lagoons, reduced the required size of the anaerobic digester, providing benefits to both the waste handling concerns and to energy production. The scraper system also reduced the amount of ammonia gas in the barns, which is beneficial to animal and human worker health.
Most digester systems for swine manure in North Carolina have relied on ambient covered lagoons. However, at Storms Farm, with the scale of a 600 acre farm and swine houses separated by as much as a mile, it was not cost-effective to build and cover a new lagoon to treat the waste using anaerobic digestion. The distance between the 23 barn complex made it problematic to pump waste because of build-up in the pipe known to cause maintenance and failure problems.
After review of viable technologies, Withers & Ravenel recommended DVO Anaerobic Digesters to supply the digester technology for Storms Farm. DVO has an extensive tract record using their patented mixed plug-flow digester technology on dairy farms, but there was no comparable swine waste facilities using mesophilic digestion in the US. Europe has a substantial number of facilities that use swine manure mixed with other substrates, but there was no reliable source of data for the gas yield using solely swine waste substrate.
As a result, Withers & Ravenel took multiple manure samples from local farms and had them tested to help estimate the biogas yield. Even with this data, there was very little information to collaborate the projected biogas yield. After all alternatives were evaluated, the most cost-effective, efficient option was to construct a heated mesophilic digester system with cogeneration and to convert the barns to scraper manure removal systems.
Geotechnical borings were done and revealed the need to raise the digester above grade due to a high ground water table. This required sloping the backfill around the tank as insulation to maintain the needed 95 degree temperature in the mesophilic process. The report also revealed the need to pre-load the site to avoid potential settling of the digester and cogeneration building. This additional grading and site work was necessary from the original conceptual site plan.
The Digester Operation
The scraper system scraps the waste to a gravity collection system and storage tanks behind each barn. Two vacuum trucks and drivers empty each of the 23 tanks daily to collect the manure collected from each of the barns, drive to the digester facility and empty the manure into the influent pump station.
Manure is pumped into the 1.1 million gallon in-ground concrete digester where the temperatures are maintained above 95 degrees (mesophilic) and the natural occurring anaerobic bacteria destroy the volatile solids, produce the bio-gas containing 65% methane, kill pathogens, and produce a high quality inorganic waste product virtually pathogen and odor free for storage and, eventually, land application as fertilizer. At Storms Farms, about 60,000 gallons of swine waste is processed each day. The biogas is “scrubbed” of corrosive components and combusted in an 845 HP gas driven engine/generator integrated system provided by Martin Machinery, from Latham, Missouri.
The digester produces wastewater that is free of pathogens and odors and removes 90% of the phosphorus and 75% of ammonia nitrogen. The electricity – enough to power over 300 homes – is sold to North Carolina Electric Membership Corp.’s grid network.
Through this design, Withers & Ravenel was able to develop Storms Farm into the largest swine biogas renewable facility in North Carolina, generating 600kW of power with an operating capacity of 95%.
The volume reduction due to the implementation of the scraper system and digestion process has allowed the treated effluent to be returned to one of the existing lagoons, reducing the dependence on the original six lagoons on the site.
Future projects to remove the inorganic solids remaining in the effluent by dewatering and to treat for additional phosphorous and ammonia nitrogen removal are in the planning stages in order to meet the additional requirements of an EST standard farm.
What was the Owner’s involvement?
Billy Storms, owner of Storms Farms was instrumental in getting the Project off the ground, through financing the project, through the willingness to change the method of manure management and by accepting the technological challenge of running what is, essentially, a small wastewater treatment and power plant. He was a true partner in the project and was directly responsible for the selection and installation of the manure scraper system in all of the barns, implementing the operations of the truck collection system, the digester and generator systems as part of the farm operations.
What can we learn from this project?
This project demonstrates a method to economically build new swine farms without total dependence on the historical open air lagoon treatment system, and flushing system collection methods, a conversion that is necessary to meet the State EST standards. The system also develops renewable energy meeting the goals in Senate Bill 3 requiring swine waste to be utilized in a percent of the production of renewable energy.
However, because of the cost, risk, and complexity of the project, its applicability may be limited to a handful of existing farms in North Carolina. Larger farms, preferably more than 50,000 animals, are required in order to have the scale to produce the amount of energy to have an economical rate of return on investment.
Thanks, Withers & Ravenel, for the detailed project description. Your turn: Thoughts? Comments? Questions for the team? Shoot me an email or post in the comments below.
Photos (c) Withers & Ravenel; Pig outline courtesy Pixabay.
As I noted earlier this week, the ACEC of North Carolina’s Engineering Excellence Awards gala was held last month. 13 amazing projects were awarded recognition, including projects involving environmental and coastal issues, higher education facilities, and government projects.
Each project was important, unique, or challenging in some manner. In my next post, I will highlight one of the most unusual– the Swine Farm Biogas project by Withers & Ravenel. In the meantime, here are all of the winners, which I’ve loosely sorted into categories:
Coastal & Environmental projects
Sea Bright to Manasquan Profile Survey, NJ (McKim & Creed)
American Tobacco Trail Pedestrian Bridge, Durham, NC (Parsons Brinckerhoff)
Town of Hillsborough Riverwalk, Hillsborough, NC (Summit Design and Engineering Services)
Swine Farms Biogas Renewable Energy Project, Bladenboro, NC (Withers & Ravenel)
Campus & Higher Education projects
South Halls Renovation, Penn State, University Park, PA (Clark Nexsen)
Science & Technology Building, Fayetteville State University, Fayetteville, NC (McKim & Creed)
Marsico Hall, University of North Carolina, Chapel Hill, NC (Mulkey Engineers & Consultants)
Military, Municipal, & Highway projects
Carolina Field of Honor War Memorial, Kernersville, NC (Woolpert)
Broad Avenue Bus Terminal, High Point, NC (Mulkey Engineers & Consultants)
The diversity of the award-winning projects was very clear, as even a cursory review of the projects demonstrates. I recommend you follow the links to the specific projects to see some great photos and hear more about the projects in detail.
In the meantime, tell me what project you would have given the “best in show” award to if you were the judge. Or, was a project left out of the awards that you thought superior to some of these? Share your thoughts about both these projects, and any others that you think should have made the cut, in the comments section.
Want to know how bats may effect your engineering plans? Want to hear about cool new bridges? Read on.
Over the past month, I’ve had the pleasure of attending two events hosted by the North Carolina Chapter of the ACEC (American Council of Engineering Companies). The first of these was the Joint Transportation Conference, held in conjunction with the NC DOT. The second was the annual ACEC Engineering Excellence Awards. At both events, I learned interesting information that engineers should know. Today, I will discuss the Transportation Conference, including some new regulations and unusual design methods. I will save the highlights from the Excellence Awards for later this week.
1. It’s a cave, it’s a bat, it’s bats, man! Did you know that your future bridge project may be effected by the Northern Long-Eared Bat? It’s true. Right now, the federal government is considering listing the bat on the Endangered Species List, due to the 98-99% mortality rate the bats are experiencing due to “white nose syndrome”. Over 1,700 projects in North Carolina could be impacted, including work on bridges, culverts, abandoned buildings, and guardrails–essentially, any activity involving tree clearing, structure demolition/removal, or structure maintenance. On November 26th, 2014, the US Fish and Wildlife Service extended the comment period to discuss the implications of listing the bat on the endangered species list. If the bat is listed, there is no grandfathering of projects. All projects will immediately be required to engage in protective activities. Stay tuned, but be aware that your transportation projects could be effected starting sometime next year.
2. Is that a pirate on your map or is it worse–soil contamination?
At the conference, we also heard from the GeoEnvironmental Section of NC DOT on their geologic symbols for known or potential contamination. Known contamination consists of soil or ground water samples that have been analyzed; or by evidence of such contamination as cracked transformers, battery casings, unusual odors while excavating, or new anecdotal information about past use. Potential contamination, in contrast, is for areas where there is no data, but historical maps or photos which indicate current or assumed past uses of possible contamination, such as gas stations, dry cleaner facilities, auto body facilities, chemical manufacturers, landfills, and manufacturing plants. Both known and potential contamination sites are important for designers, as they consider:
- large cuts, drainage, utilities, or stream relocations in contaminated areas
- selecting chemical resistant construction materials
- additional costs for materials, remediation
- other unanticipated costs or complications
3. Water, water everywhere! We also heard what’s new with the Highway Stormwater Program, including the updated Post-Construction Stormwater Program and the companion Stormwater BMP Toolbox manual. To learn more about these programs, check out:
- The NCDOT Stormwater website, which contains useful links; and
- The Highway Stormwater youtube chancel of training videos, which is still in development but will include environmental sensitivity maps, nutrient load accounting tools, and stormwater management plans.
4. Cool, cool bridges One of the highlights of the conference was hearing about some truly unique bridge designs, including:
- The Tappan Zee Hudson River Crossing, in New York, featuring twin-tower cable stayed structures and all electronic toll collection
- Vietnam’s Dragon Bridge, a truly working piece of art; and
- The Milton-Madison Bridge Slide, (Indiana/Kentucky) the longest bridge slide in North America. The Milton-Madison Bridge Slide was a feat of engineering design. Using “truss sliding” a new 2,427 foot long truss was moved along steel rails and plates and “slid” into place atop the existing, rehabilitated, bridge piers.
What about you? Did you attend the conference? If so, what insight did you take away? Share in the comments, below.
To start our week off right, today we have another important article from guest blogger Christopher G. Hill, LEED AP. Chris is a Virginia Supreme Court certified mediator, construction lawyer and owner of the Richmond, VA firm, The Law Office of Christopher G. Hill, PC. He authors the Construction Law Musings blog where he discusses legal and policy issues relevant to construction professionals. His practice concentrates on mechanic’s liens, contract review and consulting, occupational safety issues (VOSH and OSHA), and risk management for construction professionals. [His blog was also one of the first construction law blogs I found and followed, even if he is a Duke alum!] Take it away, Chris!
First and foremost, thanks to Melissa for inviting me back to post here at her great blog. She continues to invite me back despite my being a Blue Devil (and I try not to hold her Tar Heel status against her).
So much of discussion relating to construction law and construction lawyers centers on the litigation of disputes. This discussion comes in many forms from avoidance of such litigation through the early intervention of good counsel prior to getting into a project to what sort of resolution mechanism to use. Another branch of this discussion is essentially the right way to pursue your claim (or as some may read it start the dispute ball rolling). Sometimes a payment bond claim is the best method while others a straight up contractual suit is the best way to go.
Of course, all of this discussion presumes that there will be disputes. While I agree to some degree that in the Murphy’s Law riddled world of commercial construction, problems will arise. These problems need not rise to the level of a dispute that requires outside (read court or arbitrator) intervention. A few tips that are easy to write, but admittedly hard to practice at times can hopefully keep problems from blossoming into disputes. I’ve listed a three big ones here:
- Use “in house counsel.” Yes, I know that most of you engineers, architects, commercial general contractors and subcontractors out there aren’t big enough to either want or need a full time attorney on the payroll. What I mean by this is that when problems occur (or preferably before doing so), give your friendly local construction lawyer a call. As I learned from my dad, an ounce of prevention and all that. That 10 minute phone call may help avoid many hours of time and bills from your attorney later down the road.
- Build Relationships. This seems like more of a marketing tip, but it is also a risk prevention strategy. I have seen many a potential dispute get resolved with minimal or no intervention on my part simply because the general and subcontractor had a good working relationship. With the right team oriented approach and communication many a jobsite problem can be resolved in the pre-dispute stage. If the two companies don’t know each other, this is less likely to occur.
- Communicate Up Front. I know, I beat this drum a lot. Why? Because it’s a big deal. Setting the right expectations through proper communication and negotiation on the front end will set the terms of the “deal” and give all involved a guide for how to deal with problems as they occur.
Following these three tips will help you avoid construction disputes and the hefty attorney fees that come with the prosecution of those disputes.
Can you think of other tips that we can add to the list? Let Melissa and me know.
Thanks Chris! As always, you hit the nail on the head (pun intended). For those that don’t already follow Chris’ blog (and why don’t you???), do check it out and show him some blog love. You’ll learn a lot, and be glad you did.
Yesterday evening, I had the privilege of attending the Triangle USGBC’s “Talk & Walk” at the Wake County Justice Center. The 576,996 square foot Justice Center was completed 6 months early and over 30 million under budget. (The final cost, including soft costs, came in at ~$141,000,000). Now that’s what I call a LEED project done right!
Interestingly, the County did not endeavor for a LEED Silver rating– the plan was to aim for a Certification. However, as the process unfolded, the Team kept meeting the goals and points for a Silver certification without any appreciable additional costs.
The end result? An “iconic but energy efficient building,” according to Tim Ashby, current Wake County Facilities Project Manager. Tim was initially involved in the Project while working at O’Brien Atkins, which served as the architecture firm for the Project under the direction of Architect Andrew Zwiacher.
The Project was a Construction Manager at Risk project, involving a joint venture between Balfour Beatty Construction and Barnhill Contracting Company. Did the contract type contribute to the success of the Project? According to Project representatives, it likely was responsible for the 6 month early completion due to the high level of coordination.
Energy efficiency in the Building comes from the low flow plumbing (total water savings of 45%, 15% more than LEED requires), programmable and natural daylighting, and almost 98% construction waste diversion.
Another interesting legal factoid: BIM (Building Information Modeling) was utilized. Through BIM, a conflict was discovered in the space allocated for the air handling units versus the planned size of those units. This discovery enabled a change to the AHU units (to make them wider and shorter) prior to manufacturer, saving untold delays in time and increases in cost. We’ll talk more later about the pros (and cons) of BIM, but suffice it to say it worked very well on this Project.
If you haven’t been by to see the Justice Center yet, please do. It’s a great design (17 elevators!), and a great change from the old Courthouse across the street.
Have you seen the Justice Center yet? Thoughts on the design? Share in the comments below.