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by Stuart Toraason, PE, LEED AP
Friday Mar 5, 2010
Sustainable…LEED…green…LID…these terms have become industry marketing buzzwords, but what are their true meanings? Many who have pondered the importance of these concepts will quickly understand that urban re-development and urban infill development are, by their nature, the most low impact types of land development available.
Rehabilitation of an existing structure or the re-development of property that has already undergone some use will decrease the need for urban sprawl, deforestation and other impacts to our natural surroundings.
I’ll use two examples:
- In a dense urban setting sits a half-acre infill lot. The site is slated for a 30-unit apartment building with a large retaining wall. Due to the infill nature of the site, it will never provide substantial wildlife habitat or public recreation opportunities. This site is a prime candidate for a low impact development project. By putting 30 units on this parcel, the demand for a new green-field suburban apartment complex is decreased, replaced instead by a housing option that does not require deforestation or impacts to farmland.
- A five-acre site in an existing urban industrial park has a creek running right through the middle of it. The owner desires to impact the creek by installing 200 linear feet of culvert pipe in order to create vehicular access to the opposite half of the site, which is currently inaccessible.
Allowing the owner to improve his already developed site in the City helps reduce the demand for a new suburban industrial complex outside of the City’s current development footprint.
Land development is necessary for the growth of society, yet any new development that is not re-development or urban infill development will require deforestation and/or other negative impacts to previously untouched natural environments. Using every possible opportunity to recycle land that has already undergone some type of development allows us to continue development without increasing our impact on the natural environments that we cherish.
Tags: infill, land development, redevelopment
Posted in Urban Redevelopment
by John Russell, PG
Monday Mar 1, 2010
So you’ve had a Phase I ESA completed and the lousy environmental professional you retained is recommending the completion of a Phase II ESA because of some dark episode in the history of the property – let’s say a gas station occupied a corner of the property in the 1950’s. Your initial thoughts probably focus on unnecessary spending and meeting the deadline of your due diligence period – after all, this project was supposed to be easy right? But let’s revisit what due diligence is; yes, it’s required by the bank to make sure that the money they’re lending you won’t be at risk, however, and perhaps more importantly, jumping through the due diligence hoops also serves to protect you from incurring unnecessary liability – for example, when you hit that patch of petroleum contaminated soil while digging your footers and the construction workers suddenly and collectively swear that they show signs of benzene poisoning. Or better yet, tenants, in the future, start smelling petroleum vapors and you never even considered installing a vapor barrier beneath the foundation slab. It all comes down to up-front spending for long-term security, and the assurance of knowing that the property is free of environmental issues by collecting soil and/or groundwater samples for analysis, is well worth the time and money. Trust us on this – ‘cause we’ve likely seen more contaminated property than you have.
Tags: Due Diligence, Phase I Environmental Site Assessments, Phase II ESA
Posted in Environmental
by Stuart Toraason, PE, LEED AP
Friday Feb 19, 2010
Urban infill and re-development projects require special means of minimizing increases in stormwater flow is to implement innovative sustainable design techniques to increase pervious area and improve rainwater retention. Projects like Timmons Group’s LEED® Gold certified 1050 K Street project in DC use green roofs, planter beds and rainwater harvesting to meet city code and minimize impact to the combined sewer system.
Projects that involve large-scale infrastructure updates are often required to separate the storm and sanitary sewers as the project progresses. Rocketts Landing in Richmond, Virginia, is a good example of this. In this case, the existing combined sewer system was designated solely for stormwater runoff, and a separate sanitary sewer system was created by constructing new sanitary mains and connections. Stormwater runoff was treated on site and discharged directly to the James River, while the sanitary sewage was directed to the treatment plant.
Combined sewer systems do have one benefit from a development standpoint, in that most local jurisdictions, as well as state and federal codes, do not require stormwater quality control since the stormwater runoff flows to a municipal treatment plant. In addition, for projects in localities that control stormwater quantity, previously mentioned sustainable design techniques may be implemented to eliminate any stormwater increases; thus, the end result can be that stormwater management is not required at all.
Tags: combined sewer, infill, land development, sanitary sewer, Stormwater Management
Posted in Urban Redevelopment
by Lu Gay Lanier, LA, FASLA, LEED AP
Wednesday Feb 10, 2010
The integration of stormwater treatment for quality and quantity is always challenging on an urban site where traditional treatments require acreage that is simply not available. To meet current regulations, the design team needs to look at creative options for removal of pollutants and detention of rainfall within a restricted area.
The flow through planter has become a regular tool utilized in conjunction with green roofs, cisterns, bio-retention and traditional basins. The close coordination between civil engineers, architects and landscape architects from inception of the project enables the team to:
- Correctly size the planter according to capture area and quantities,
- Incorporate design with architecture for optimum aesthetics,
- Utilize required buffer and foundation plantings for uptake of nutrients, and
- Specify plantings that are tolerant of wet feet for up to 24 hours.
In designing DASH, an infill maintenance facility in Alexandria, Virginia, Timmons Group was challenged by the minimal space available for stormwater treatment. To design an effective solution within this limited area, a flow through planter was used to capture the first inch of rainfall for pre-treatment and detention prior to entering a traditional basin. The basin was able to be greatly reduced in size due to the successful design and fit of the planter in a tight space between the sidewalk and building.
The typical detail was updated to obtain enhanced horizontal flow of water from the roof drains to ensure that all plantings were getting equal saturation. Emergency overflow measures were specifically designed to accommodate any additional precipitation.
Let us know your experiences both positive and lessons learned. Continue to follow this thread for more on flow through planters; future discussions will focus on specifying planter components, mid-Atlantic plantings for use with flow through planters and long term maintenance requirements.
Tags: bio-rentention, Landscape Architecture, planters, Stormwater Management
Posted in Landscape Architecture, Stormwater Management
by Clint Smith, PE
Wednesday Feb 3, 2010
If you’re driving around and see a yellow sign with arrows forming a counter-clockwise circle, don’t worry — you haven’t fallen asleep and woken up in the United Kingdom. Virginia is undergoing a bit of a renaissance in urban roadway design in an effort to calm traffic and greatly reduce the severity of accidents at intersections. Since you’re going to see more of them in the coming years, it’s important to understand why roundabouts are a benefit to your community and, most importantly, how to use one (coming in the next post).
Proposals to retrofit existing intersections with roundabouts routinely face community scorn. While roundabouts are not appropriate for all crossroads, they are often misunderstood and unfairly criticized. If you picture a common intersection, there are typically approaches from four directions, with lanes marked for certain traffic movements, and a governing traffic signal. The signal is timed to provide drivers ample time to reduce their speed and stop following a change from green to amber, followed by a moment of “all-red” time before the next movement can occur. When drivers obey the signals, there is very little that can go wrong. Unfortunately, motorists may either misjudge the color of the signal or, often, deliberately continue speeding on towards an amber signal, forging ahead through an intersection and potentially colliding with other vehicles.
A roundabout’s greatest asset is its pledge to safety. As motorists approach the first curve, they are required to reduce their speed to approximately 15 miles per hour, as opposed to a typical intersection where drivers maintain their current speed or even accelerate to “make the green.” The drivers’ speed remains reduced throughout the roundabout, ensuring calm actions from all vehicles. Pedestrian safety is also maximized, as pedestrian crossings are positioned at the legs of the roundabout, where drivers have already decelerated to make their first maneuver. Should an accident occur in a roundabout, it is typically far less severe than that of a typical intersection, where T-bone, rear-end, and even head-on collisions are common. While side-swipe incidents can occur inside multi-lane roundabouts, the severity of these accidents is typically very low due to the demand for increased driver awareness and relatively low speeds within the roundabout..
Other benefits of roundabouts include simpler U-turns, reduced waiting time for drivers, full operation during power outages, reduced energy use, and aesthetic landscaping opportunities in the center island. In residential areas, roundabouts’ traffic-calming design reduces traffic noise as well, since motorists are hitting the breaks rather than revving their engines or honking their horns. Once resistant citizens give roundabouts a chance, they typically change their opinion – going from as much as 68 percent opposed to 73 percent in support, according to a 1998 study by Georges Jacquemart and the Transportation Research Board of the National Research Council.
Tags: intersections, pedestrian safety, roundabouts, traffic
Posted in Transportation
by Charlene Harper, PE, LEED AP
Monday Feb 1, 2010
It may not be glamorous, but erosion control design is a critical component to managing water quality both during and after site construction. The transition between a manmade drainage system and a natural channel is one area of potential erosion that must be given special attention during design. A structure is needed at this point to dissipate both the velocity and the energy of the concentrated storm flows and to protect the downstream channel from scour. 
Although it is not the only measure available, the most typical transition to alleviate potential erosion is a riprap outfall protection (ROP) apron.
The process of designing and specifying ROP is well detailed in every state erosion control manual; however, one requirement that is often overlooked is the need to install the apron at a zero percent slope. It may seem like a small detail; however, the absence of slope is absolutely essential for the ROP to function properly. The pictures below show a drainage system failure resulting from the installation of ROP at a slope greater than zero percent.
Timmons Group was asked to investigate the cause of the issue and identify potential solutions. The original riprap apron was installed at a slope of approximately three percent at an outfall which drained into a stormwater management basin. Stormwater began to scour the downstream end of the riprap and then undercut the entire section, causing it to drop over three feet in less than five years. 
After consideration of several possible alternatives, the sandy soils and failure magnitude led us to make the following recommendation: install a drop manhole with a new outfall pipe, construct a flat (zero percent slope) riprap apron with a cutoff wall at the downstream end, and re-grade and stabilize the failed slopes.
The problem shown above is not uncommon, but it is easily avoidable. Whether using riprap outfall protection or alternative methods (e.g., concrete or gabion aprons or reinforced turf mats), designing this delicate transition from manmade elements to natural systems is vital to the protection of water quality in our receiving waters and the overall success of your project.
Tags: erosion control, ROP, water quality
Posted in Stormwater Management
by John Russell, PG
Thursday Jan 28, 2010
The completion of ASTM E 1527-05 due diligence requirements in property acquisition is a critical issue that is widely underrated and often overlooked in property development. Evaluating the environmental condition of a property is an important factor in understanding the limitations that could inhibit construction; however, many times, I have received requests to complete a Phase I Environmental Site Assessment after conceptual site plans have already been prepared. In fact, on occasion, I sometimes receive the conceptual details with the deed or title search information as part of the background documentation. Or even worse, I can think of one occasion where the construction schedule had already been set (talk about putting the cart before the horse!).
Yes, no one likes to hear bad news and, trust me, environmental consultants don’t gain any great joy conveying it either. Yet while Phase I Environmental Site Assessments are necessary, they are not evil. Evaluating and recognizing the presence of the environmental conditions that have impacted, or have the potential to impact, your property of choice is a critical issue that plays into both your lender’s liability as the financier and your future liability as the property owner. Therefore, one of the first professionals you should contact after conjuring the idea of how great your building would look at that downtown intersection is an environmental consultant – and the sooner the better. For if issues are identified, a certain time element will be required to quantify the risks and negotiate the regulatory waters: however, rest assured that those of us who have been in this business for any substantial length of time can steer you safely through the rocks.
Always remember that there is a logical stepwise approach to this business that is intended to protect the interests of all parties concerned before too much money is dropped into the deal, and whenever you start haphazardly pursuing the elements of a project out of order (e.g., by delaying the completion of the required due diligence) you run the risk of wasting time and money, both of which could be spent better elsewhere.
Tags: ASTM E 1527-05, Due Diligence, Phase I Environmental Site Assessments
Posted in Environmental
