New Contruction Turbidity Standards

Land and Water Magazine: Reducing Turbidity, ELG’s, and Compost-Based BMPs

Summary

The final rule for the US EPA Effluent Limitation Guideline for the Construction and Development Industry (40 CFR Part 450 of the Federal Register) went into effect in February 2010. The new rule creates storm water quality performance standards for soil disturbance on construction sites 10 acres or greater. The land owner will be required to monitor and report the daily average nephelometric turbidity (NTU) from waters discharged from the construction site. The turbidity standard (numerical limit) to trigger a violation was originally 280 NTUs.

Under the current rule, the US EPA will begin enforcement on construction sites with a total active soil disturbance of 20 acres of 20 acres or greater as of August 2011. Sites that disturb 10 acres or greater will undergo active enforcement starting February 2014. For large developments this includes the sum total area of disturbance at any given time, including small sections under the acre limit.

Effluent Limitation Guideline (ELG) states the permitted party must report the daily average turbidity from all site storm water discharge areas. A violation will only occur if the daily average exceeds the NTU threshold, whereas, one reading in breach of the NTU limit does not constitute a violation. Also, if the 2yr 24hr storm event is surpassed for the local area where the construction site is located, the turbidity standard will not be enforced.

Storm water sampling frequency, number of daily samples required, sampling methodology, sampling equipment, method of measurement, and reporting method is up to the local permitting authority. Although, the US EPA will likely release a guidance document which will likely steer the permitting authorities.

The Final Rule does not dictate what type of best management practices can be used as the US EPA does not want to limit strategies that may help permitted parties comply with the new rule. They estimate that full enforcement and compliance with the new rule will encompass 73% of construction site soil disturbance nationally and should reduce annual sediment discharges from construction sites by 77%

For those with sites of 20 acres or greater, this rule will be effecting you very soon. The new standards have been described as strict and depending on the site type may be difficult to comply with. Remember that the owner is in-charge of reporting the daily average NTU, and should also be considering ways to reduce the turbidity level to keep it under limitations. The link below gives an article which includes suggestions for reducing turbidity levels: http://viewer.zmags.com/publication/f15cb27c#/f15cb27c/24

EPA Launches Green Infrastructure Strategy

WASHINGTON – The U.S. Environmental Protection Agency (EPA) is launching a new strategy to promote the use of green infrastructure by cities and towns to reduce stormwater runoff that pollutes our nation’s streams, creeks, rivers, lakes and coastal waters. Green infrastructure decreases pollution to local waterways by treating rain where it falls and keeping polluted stormwater from entering sewer systems. In addition to protecting Americans’ health by decreasing water pollution, green infrastructure provides many community benefits including increased economic activity and neighborhood revitalization, job creation, energy savings and increased recreational and green space.

“Through this agenda, we’ll help cities and towns across the nation clean up their waters and strengthen their communities by supporting and expanding green infrastructure,” said Deputy Administrator Bob Perciasepe, who announced the agenda at a Green Street, Green Jobs conference focused on fostering green infrastructure in the Washington, DC metropolitan area. “Green infrastructure changes improve the health of our waters while creating local jobs, saving communities money and making them healthier and more prosperous places to raise a family and start a business.”

Stormwater is one of the most widespread challenges to water quality in the nation. Large volumes of polluted stormwater degrade our nation’s rivers, lakes and aquatic habitats and contribute to downstream flooding. Green infrastructure captures and filters pollutants by passing stormwater through soils and retaining it on site. Effective green infrastructure tools and techniques include green roofs, permeable materials, alternative designs for streets and buildings, trees, rain gardens and rain harvesting systems.

As part of the strategy, EPA will work with partners including local governments, watershed groups, tribes and others in 10 cities that have utilized green infrastructure and have plans for additional projects. EPA will encourage and support expanded use of green infrastructure in these cities and highlight them as models for other municipalities around the country. The 10 cities are: Austin, Texas; Boston, Mass.; Cleveland, Ohio; Denver, Colo.; Jacksonville, Fla.; Kansas City, Mo.; Los Angeles, Calif.; Puyallup, Wash.; Syracuse, N.Y.; and Washington, DC and neighboring Anacostia Watershed communities.

Energy savings is one of the greatest benefits of green infrastructure. On and around buildings, green infrastructure can reduce heating and cooling costs. For example, green roofs reduce a building’s energy costs by 10 to 15 percent, and an additional 10 percent of urban tree canopy can provide 5 to 10 percent energy savings from shading and windblocking. Green infrastructure also conserves energy by reducing the amount of stormwater entering combined collection and treatment systems, which reduces the amount of wastewater processed at treatment plants.

EPA will continue to work with other federal agencies, state and local governments, tribes, municipalities, and the private sector to identify opportunities for using green infrastructure and provide assistance to communities implementing green approaches to control stormwater. EPA will also provide additional tools to help states and communities leverage green infrastructure opportunities within other innovative environmental projects.

For more information on EPA’s green infrastructure agenda: http://epa.gov/greeninfrastructure

Green Roof for Tulsa City-County Central Library!

The Tulsa City-County Central Library, constructed in 1965, formerly included two reflecting pools flanking the main library entrance.  The reflecting pools were built over an underground parking structure - and over time -the pools began to leak, damaging cars and creating a hazard.  And so, the pools were emptied and sat abandoned for years.  They became an eyesore, and a maintenance issue. 

The library evaluate using the former pools as landscaping, but faced challenges due to soil loads on the parking structure roof.  But, observing rooftop gardens, they began to see other opportunities for reuse. 

After consultation with structural engineers, the library confirmed that a roof system would be feasible.  The project was fully funded by the American Recovery and Reinvestment Act "Green Project Reserve" adminstered by the Oklahoma Water Resources Board. 

The first step was to remove the old terrazzo and install a new waterproof membrane to correct leakage problems.  The next step was to add insulation and a root-stop barrier.  The bottom white later is styrofoam insulation, which was also helped to raise the bed.

Next, a moisture retention layer was added.  This was critical due to the long, hot, dry summer in Tulsa as well as the garden's location on a southern exposure.  Roof top gardens often also have moisture loss from constant winds.  Rather than using soil, LiteTop(r) growing media was utilized to help minimize weight. 

Plants were chosen to minimize the need for irrigation and maintenance.  A drip irrigation system was installed to assure plant survival while minimizing water consumption.  The landscaping design was developed specifically to deter misuse or vandalism of the beds.  The final installation is an attractive as well as educational addition to the library.  Along with overall beautification, the library has seen a decrease in the amount of abuse and litter in the surrounding plaza. 

Last year the Tulsa City-County Library System received two grants to install green stormwater management systems.  We have recieved a presentation from the Library showing the sites, design elements, and final products for both installations and will be posting them here.  Go by and check these out yourself!

The first is at the Judy Z. Kishner Library, located in a Sperry, OK. The library was completed in 2008 and lies in a two acre lot adjacent to the Osage Trail. Nearly the entire town, along with areas to the north, is prone to flooding. The contours and elevations of the library property did not allow positive drainage off the site and were a mosquito haven.

Since draining the water was not an option for this property, the idea of a rain garden took shape.To fund this project, the Library applied for a grant from the Amercina Recovery and Reinvestment ‘Project Green Reserve’ administred by the Oklahoma Water Resources Board. Due to the innovative nature of this problem resolution, the project was fully funded with the Green Reserve Grant Funds.

During construction, the existing surface depression was excavated further and the soil amended.  New vegetation, selected to enjoy the wet conditions, was planted. The finished result is an amenity for the library and the nearby trail as well as a stormwater management feature.

TulsaPartners Raingarden - Plant Selection

 Shown to the left are plant descriptions for several of the varieties we used in the TulsaPartners' raingarden.  You'll notice most of the descriptions feature a butterfly sticker, which indicates that they attach pollinators, like butterflies.  You may also notice that we generally selected 1 gallon (1#) container sizes, which are lower priced, but generally fill out well within a season or two. 

 

Color.  Because the building is a light yellow and there are already lavender flowing plants present (a lilac bush sits just behind the raingarden), we kept with that theme and selected plants that would have lavender or yellow flowers.  Because the building is surrounded by an evergreen hedge, which also forms the garden's backdrop, we didn't invest in additional evergreen material.

Moisture Tolerance.  In general, plants in the deepest section of the garden will have the greatest depth and duration of inundation, so these plants should be water-loving or wetland-type plants.  For this garden, we looked around the building for plants that were already present and found an overgrown clump of purple irises, which do well in wet soil.  In addition, they are vertical plant and wouldn't get lost due to height.  Some of these were transplanted into the deepest part of the garden.  In the middle zone, we planted another popular lavender flowing plant, garden phlox, along with a yellow flowering plant, Helianthus.  Both tolerate moderate levels of inundation but also do well with direct sun and periods of drought.  In the back, which is the driest part of the garden, we planted Russian sage and Little Joe Pye Weed.  The "Little" is important because a normal Joe Pye Weed would  take up almost all of a garden this size!

Russian sage has a nice silvery green color and texture that indicates it takes drought well.  The lawn and plantings at TulsaPartners are not irrigated, so these plants need to be able to take a beating.  

With Spring just around the corner, I'm looking forward to seeing how these plants have handled the long dry fall that followed their installation.  Stay tuned for more photos!

Raingarden Irony

The wonderful irony of the raingarden featured below, which we installed at the TulsaPartners, Inc. office in September 2010, is that it HAS NOT RAINED significantly since then.  And we always get the question - "Do I need to water my raingarden?"  The short answer is "Yes", especially in the first year or if it hasn't rained for a while.  Raingardens should be designed to feature water-loving plants as well as plants that can handle both dry heat and periodic flooding.   And this means that they do need to be watered, especially for the first growing season.  Come Spring, we'll see what of this garden survives. My bet is on the Russian sage.

Building a Raingarden for Tulsa Partners

As part of the kickoff of Tulsa Partner's Green Building Resource Library on September 24th, we will be installing a raingarden at the TPi office! There's a good bit of prep work that goes into building a raingarden, so I thought I would use the blog as repository of everything we can't get into the short on-site workshop we'll conduct that evening.

I went by today and took few photos of the office. The downspouts are already disconnected, so that is one thing we won't have to do. There is one downspout on the southeast corner of the building that discharges to a sunny, grassy spot. Its visible from the street and building entrance, which is great from an educational perspective. Its also in a nice sunny spot, which gives us a good range of plants to work with.  See the downspout on the right side of the roof overhang.

I then walked off the area of the roof handled by this downspout.  Its about 20' across and 25' long, or 500 sf.  I'll do a field check of infiltration later, but just as a starting point we could assume 6" of infiltration/24 hours, resulting in a 6" deep garden. For a garden that would handle the first 1" of runoff, that would require 500/6 = 83 sf of garden.  The space available is 80sf, max.  So, let's say we get more infiltration, say 8"/24hours.  That would make our garden 500/8 = 62.5 sf.  Probably more likely to fit the space, but we'll check the infiltration to be sure the soil can handle it.

What if we don't have the infiltration needed for this size roof?  Just size the garden depth for the infiltration (depth = infiltration in 24 hours but 12" maximum).  A smaller garden than your runoff volume requires just means you'll be capturing less than the first 1", and the first 0.5" is typically the most important, so that gives you a good range for the available space.

Here's another look at our site.