LA Course #GCE-1-1801
Tree Planting in the 21st Century
by Len Phillips, edited by Richard W Gibney RLA/ISA
Sections Go directly to the Section by clicking on the title below
Tree Planting in the 21st Century
by Len Phillips, edited by Richard W Gibney RLA/ISA
Sections Go directly to the Section by clicking on the title below
The way we should be planting trees in our cities today has changed. Researchers have determined that there are better ways to plant city trees in the typical tree pit of a city sidewalk. Gone is the digging of a 3 x 3 x 2 feet (1x1x0.6 meter) hole between the sidewalk and the street curb or a missing section of sidewalk. Also gone are the above ground stakes to hold the tree from tipping over. The following three case studies represent some of the latest research efforts to grow trees in our cities.
Kensico Dam Plaza Case Study
Edited by Len Phillips and Richard Gibney
The Kensico Dam Plaza is a 20-acre part of the 98 acre Kensico Reservoir property. The Plaza is located at the base of the Kensico Dam. The reservoir is located in Valhalla, Westchester County, New York, in the Catskill Mountains, 15 miles north of New York City. The dam was built on the site of an old earth and gravel dam built in 1885, which impounded the Bronx and Byram Rivers to supply water for the residents of New York City. The construction of a new masonry dam in 1915, replaced the old dam, and expanded the water supply. The dam was completed in 1917. It is 307 feet high and 1,843 feet long, and forms the Kensico reservoir. The entire property was acquired as parkland in 1963 from the New York City Watershed Commission and remains the property of the New York City Department of Environmental Protection. It is listed on the National Register of Historic Places as part of the Bronx River Parkway Reservation.
In 2005 the New York City Department of Environmental Protection (DEP) commenced a $31.4 million project to rehabilitate the Kensico Dam infrastructure. The rehabilitation project included new tree planting, reconstructing portions of the dam, the spillway, stone masonry surfaces, and reconstructing the dam’s downstream Plaza, which included beautification, regrading, and landscaping.
The Kensico Dam Plaza, enhanced by the northeast native trees planted (photo Ostrya Quercus) at the base of the dam including White Oak, Hop Hornbeam, American Hornbeam and Hackberry. It provides a unique setting for a wide variety of public amenities and activities including ethnic celebrations, concerts, shows including arts and craft shows, as well as areas for picnicking, playgrounds, in-line skating, walking trails, and nature study. This is the start of the bike and jogging trail that winds along the Bronx River Parkway. Also on the plaza is “The Rising”, Westchester's monument to the county residents who perished in the World Trade Center on 9/11. The City occasionally has movies on a large screen in the summertime. The 4th of July fireworks are here along with a lot of festivals such as the annual “Best of Westchester” celebration.
Landscape Work on the Plaza
However, all of this activity was likely to have a major detrimental effect on the existing and proposed tree plantings. With this concern in mind the landscape work on the Plaza began in 2006 and involved the installation of granite posts and pipe railings, (see photo) seating areas with benches, and four brick plazas totaling about 15,000 sq. ft. including 42 new trees. About 5 acres of lawn was renovated. The brick pavement area is used for vendors and flea market type fairs in the summer requiring solid paving, The landscape architect specified excavation of the entire area between 2 – 3’ deep and replacement of the soil with CU-Structural Soil® for the trees that were to be planted throughout the entire Plaza.
The CU-Structural Soil® was intended to provide a stable soil for root growth while allowing for the compaction necessary for the brick pavement area. This soil treatment is expected to last for the entire life expectancy of the trees. The CU soil was selected so the trees would have a suitable medium for root growth while the surface could be paved and used for the wide variety of park and community activities that occur at the Plaza. The CU Soil mixture contained crushed stone and soil with a small amount of a hydrogel to prevent the soil and stone from separating during the mixing and installation process (see photo). The stone was crushed to approximately one inch in diameter, with no fine particles, and to provide a large void space. The specified soil was a loam to clay loam mix containing at least 20% clay to maximize water and nutrient holding capacity. The proportion of soil to stone was approximately 80% stone to 20% soil by dry weight, with a small amount of hydrogel aiding in the uniform blending of the two materials. This proportion insured that each stone touched another stone, creating a rigid skeleton, while the soil almost filled the large pore spaces that were created by the stone. This way, when compacted, any load on the plaza surface was carried from stone to stone, while the soil in between the stones remained uncompacted and acceptable for tree root growth. The entire installation process was overseen by Cornell University and its licensed representatives to be sure the process was done correctly and in the best interest of the newly planted trees.
The installation process for the CU-Structural Soil® required the stone, coated with hydrogel and mixed with the soil, installed in layers that was compacted after each layer was added. This process continued to the final grade just before a layer of stone dust was applied. After the CU-Structural Soil® was installed, the new trees were planted with regular soil immediately around the root balls and the clay brick pavers were set with no mortar joints on stone dust over the CU-Structural Soil®. This allowed water to infiltrate into the CU-Structural Soil®, so no automatic irrigation was necessary.
Tree Planting
The trees that were planted were all New England natives (see photo) including White Oak (Quercus alba), Red Oak (Quercus rubra), American Hornbeam (Carpinus caroliniana), Hackberry (Celtis occidentalis), and Hop Hornbeam (Ostrya virginiana). Many of the existing trees surrounding the plaza were evaluated for hazard tree mitigation as a part of the rehabilitation project.
Kensico Dam Plaza rehabilitation project was completed in 2007 in time for the New York State Summer Empire State Games (mini-Olympics in NYS). A new electrical system upgrade added permanent park lighting in 2014, so Kensico Dam Plaza is now open after dark. Today, the park provides a unique setting for a wide variety of activities including cultural heritage celebrations and concerts, fitness classes and a fitness course, as well as areas for picnicking, a renovated playground with safety surfaces, in-line skating, widened walking and nature study trails, and opportunities to study nature and the trees. All of the newly planted trees are likely to survive the plaza environment and live for a normal lifespan.
Editor's Note: CU-Structural Soil® continues to be a cost effective product for growing trees in harmony with paved surfaces.
Edited by Len Phillips and Richard Gibney
The Kensico Dam Plaza is a 20-acre part of the 98 acre Kensico Reservoir property. The Plaza is located at the base of the Kensico Dam. The reservoir is located in Valhalla, Westchester County, New York, in the Catskill Mountains, 15 miles north of New York City. The dam was built on the site of an old earth and gravel dam built in 1885, which impounded the Bronx and Byram Rivers to supply water for the residents of New York City. The construction of a new masonry dam in 1915, replaced the old dam, and expanded the water supply. The dam was completed in 1917. It is 307 feet high and 1,843 feet long, and forms the Kensico reservoir. The entire property was acquired as parkland in 1963 from the New York City Watershed Commission and remains the property of the New York City Department of Environmental Protection. It is listed on the National Register of Historic Places as part of the Bronx River Parkway Reservation.
In 2005 the New York City Department of Environmental Protection (DEP) commenced a $31.4 million project to rehabilitate the Kensico Dam infrastructure. The rehabilitation project included new tree planting, reconstructing portions of the dam, the spillway, stone masonry surfaces, and reconstructing the dam’s downstream Plaza, which included beautification, regrading, and landscaping.
The Kensico Dam Plaza, enhanced by the northeast native trees planted (photo Ostrya Quercus) at the base of the dam including White Oak, Hop Hornbeam, American Hornbeam and Hackberry. It provides a unique setting for a wide variety of public amenities and activities including ethnic celebrations, concerts, shows including arts and craft shows, as well as areas for picnicking, playgrounds, in-line skating, walking trails, and nature study. This is the start of the bike and jogging trail that winds along the Bronx River Parkway. Also on the plaza is “The Rising”, Westchester's monument to the county residents who perished in the World Trade Center on 9/11. The City occasionally has movies on a large screen in the summertime. The 4th of July fireworks are here along with a lot of festivals such as the annual “Best of Westchester” celebration.
Landscape Work on the Plaza
However, all of this activity was likely to have a major detrimental effect on the existing and proposed tree plantings. With this concern in mind the landscape work on the Plaza began in 2006 and involved the installation of granite posts and pipe railings, (see photo) seating areas with benches, and four brick plazas totaling about 15,000 sq. ft. including 42 new trees. About 5 acres of lawn was renovated. The brick pavement area is used for vendors and flea market type fairs in the summer requiring solid paving, The landscape architect specified excavation of the entire area between 2 – 3’ deep and replacement of the soil with CU-Structural Soil® for the trees that were to be planted throughout the entire Plaza.
The CU-Structural Soil® was intended to provide a stable soil for root growth while allowing for the compaction necessary for the brick pavement area. This soil treatment is expected to last for the entire life expectancy of the trees. The CU soil was selected so the trees would have a suitable medium for root growth while the surface could be paved and used for the wide variety of park and community activities that occur at the Plaza. The CU Soil mixture contained crushed stone and soil with a small amount of a hydrogel to prevent the soil and stone from separating during the mixing and installation process (see photo). The stone was crushed to approximately one inch in diameter, with no fine particles, and to provide a large void space. The specified soil was a loam to clay loam mix containing at least 20% clay to maximize water and nutrient holding capacity. The proportion of soil to stone was approximately 80% stone to 20% soil by dry weight, with a small amount of hydrogel aiding in the uniform blending of the two materials. This proportion insured that each stone touched another stone, creating a rigid skeleton, while the soil almost filled the large pore spaces that were created by the stone. This way, when compacted, any load on the plaza surface was carried from stone to stone, while the soil in between the stones remained uncompacted and acceptable for tree root growth. The entire installation process was overseen by Cornell University and its licensed representatives to be sure the process was done correctly and in the best interest of the newly planted trees.
The installation process for the CU-Structural Soil® required the stone, coated with hydrogel and mixed with the soil, installed in layers that was compacted after each layer was added. This process continued to the final grade just before a layer of stone dust was applied. After the CU-Structural Soil® was installed, the new trees were planted with regular soil immediately around the root balls and the clay brick pavers were set with no mortar joints on stone dust over the CU-Structural Soil®. This allowed water to infiltrate into the CU-Structural Soil®, so no automatic irrigation was necessary.
Tree Planting
The trees that were planted were all New England natives (see photo) including White Oak (Quercus alba), Red Oak (Quercus rubra), American Hornbeam (Carpinus caroliniana), Hackberry (Celtis occidentalis), and Hop Hornbeam (Ostrya virginiana). Many of the existing trees surrounding the plaza were evaluated for hazard tree mitigation as a part of the rehabilitation project.
Kensico Dam Plaza rehabilitation project was completed in 2007 in time for the New York State Summer Empire State Games (mini-Olympics in NYS). A new electrical system upgrade added permanent park lighting in 2014, so Kensico Dam Plaza is now open after dark. Today, the park provides a unique setting for a wide variety of activities including cultural heritage celebrations and concerts, fitness classes and a fitness course, as well as areas for picnicking, a renovated playground with safety surfaces, in-line skating, widened walking and nature study trails, and opportunities to study nature and the trees. All of the newly planted trees are likely to survive the plaza environment and live for a normal lifespan.
Editor's Note: CU-Structural Soil® continues to be a cost effective product for growing trees in harmony with paved surfaces.
Trees on the Toronto Waterfront Case Study
Edited by Len Phillips
The City of Toronto, Ontario, Canada, has been undergoing a massive effort to refurbish the City's shoreline on Lake Ontario. It is one of the largest waterfront revitalization efforts ever undertaken in the world. The work has been divided into 8 separate projects consisting of street reconstructions, park developments, new buildings, and most importantly, new trees. The projects all required that trees be provided soil areas that will meet the city's minimum soil volume requirements to ensure the long term growth of the urban trees. The high water table, near the Lake, was also a problem that was solved by providing adequate soil volume over a wider area, rather than the deeper area that is normal. The projects were also intended to improve the quality of ground water, reduce flooding, improve the beaches, provide shady areas, and encourage recreation uses on the waterfront.
Soil Cell Testing
Soil cells provided the answer to many of these concerns. Soil cells are used in many cities as a system to provide large volumes of un-compacted planting soil for trees in the dense urban center. Lesser known, but equally important, are that most, but not all soil cells have the ability to manage stormwater runoff as the source control.
The Queensway
Toronto Water, the city’s water authority, wanted to test the soil cells' capacity to manage surface water runoff. So in the spring of 2008, the city installed a proof-of-concept installation on the Queensway, a commercial street
(see photo) in the east end of the city. The soil cell contractor excavated trenches for two soil cell systems, each two cells deep (see Photo) and with spots for two tree openings that straddled the sidewalk and parking bays.
The soil cells were filled with a bioretention soil mix that has a 20% water holding capacity. All of the rainwater runoff is collected in the city’s standard stormwater catch basin. In effect, the soil cell is being used to create a giant rain garden underneath the sidewalks and parking bays that serves two purposes: one to reduce peak-flow runoff and the second to filter out pollutants. The soil cell selected by the city provided more soil and water holding capacity than other types of soil cells.
A typical rain event in Toronto is 0.09-0.12 in. (2-3 mm) in 24 hours, and 50% of Toronto’s annual precipitation events are less than 0.19” (5 mm). The soil cell system was laid out and sized to manage the runoff from a 2” (5 cm) per 24 hour rain event.
An 8” (20 cm) PVC pipe runs from the street catch basin into the top layer of the soil cell system, delivering all of
the surface runoff from the roadway and adjacent sidewalks into the bioretention soil. A perforated PVC pipe (see Photo) then distributes the surface runoff evenly throughout the soil, and the water infiltrates through the soil until it reaches the bottom of the system where a perforated drain line carries any excess overflow into the existing stormwater system. Depending on the site, the runoff that percolates to the bottom of the soil cell system can be infiltrated into the subsoil to help replenish the aquifer. All of the runoff water is cleansed and held by the bioretention soil.
The system also meets AASHTO H-20 loading requirements to support parking on the surface over the root zone. The entire project took three days to completely install and provides a total of almost 600 cubic feet (16 cubic meters) of soil per tree.
Stormwater Flow and Quality
Just before the Queensway project began, the City decided it wanted to track the volume of infiltration and quality of water in and out of the soil cells. To do this, the trees were planted in pairs. After four years, one set of trees were disconnected from the associated catch basin so it only receives whatever surface water that happens to flow into the tree opening. This created a control. The other tree was left connected. The pollutant reduction concentration results, and well as other interim findings, will be included in a report issued by the city. The system will continue to be monitored throughout 2016, and a full report should be completed later this year. The preliminary reports show significant peak flow reductions and as well as increased water quality.
As the two trees in each of the trenches mature, they significantly increase the efficiency of the system, by transpiring large volumes of rainwater out of the soil through their roots systems and evaporating much of the rainfall with their canopies.
Queens Quay-Revitalizing Toronto’s Waterfront
Following the success of The Queensway project (see Photo), the City undertook the construction of several other projects using the soil cell system that worked out so well on The Queensway. One typical project was a different street called the Queens Quay which is located on the waterfront. Stormwater bioretention was a major factor in this project because of its proximity to the Lake and past flooding issues.
Queens Quay, Toronto’s main waterfront street, stretches over 1 mi (1.7km). Before this reconstruction, the street was defined by four lanes of vehicle traffic with narrow sidewalks, and outdated public transit facilities. Dominated by delivery vehicles and used primarily as a loading zone and for the businesses and condominiums that lined the street, Queens Quay acted as a barrier to the City’s waterfront.
The revitalization of Queens Quay consisted of transforming the busy roadway into a pedestrian promenade (see Photo) and was one of the most complex street reconstruction projects in Toronto’s history. The project has transformed the central waterfront into a vibrant new landmark and destination for the City. The re-envisioned Queens Quay (see Photo) now serves as a linear park connecting various parts of the city.
A key element of the design is the 232 new trees that line the north and south sides of the street and the Martin Goodman Trail (see Photo), a multi-use recreational trail that is now, for the first time, continuous along the full length of the City’s waterfront.
On the north side of the street (Photo 159), a mix of maples (Acer), honey locusts (Gleditsia), elms (Ulmus), and lindens (Tilia) are planted in continuous trenches with 4 ft. (1.2m) diameter sidewalk openings, meeting the city’s standard requirement of 500 cu. ft. (15 cu. m.) of soil per tree. The promenade trees on the south side of the street (see Photo) are London plane (Platanus) trees arranged in two alternating rows with 5 ft. (1.5m) diameter openings, planted within wide continuous trenches. The soil cells were used to allow the soil volume to span beneath the Martin Goodman Trail and were essential in meeting and exceeding the city’s target soil volume of 1,000 cu. ft. (30 cu. m.) per tree.
Stormwater is also being managed on-site. While the use of soil cells and the collection of stormwater was initially designed with tree growth in mind, early in the design process the design team recognized that the system had the potential to manage stormwater on a broader scale through interception, absorption, and evapo-transpiration. The design for the irrigation system (see Photo) was fully integrated into the storm water system for the street, with input from the City, to ensure that performance and maintenance requirements were met.
Prior to the reconstruction, the existing storm system on the street surcharged and was over-capacity during most rain events. The new integrated system showed important positive impacts on the overall stormwater calculations for the site. Surface runoff, flowing water from the Martin Goodman Trail, and boulevard surfaces, now enters the system via custom designed catch basins that capture and store the first flush of runoff, and allows stormwater to enter the soil cells through a network of perforated pipes that passively irrigate the trees. In total, 47% of surface runoff is being diverted into the soil cells and the entire system is designed to handle a 100-year rain event. The stormwater results achieved on these projects are directly related to the specific type of soil cell used. Not all soil cells have stormwater capabilities and will not necessarily provide the same results.
In addition to the low-impact features of the site, landscape materials were selected to be sustainable, robust, and durable. The granite cobbles that pave the street with a maple leaf mosaic hail from Quebec and the yellow cedar (Cupressus nootkatensis) for the custom wood street light poles are harvested sustainably in British Columbia. Wood benches line the promenade and add a splash of color with their bright red cast aluminum supports that also sport the abstracted maple leaf. The project as a whole comes together as a street that welcomes not only residents of the City, but visitors from around the country, and the world.
People look at this street as a long public square, according to Michael James of DeepRoot Canada Corp. who supplied the soil cells. The street now has all the amenities of a central, public square with transit stops, places to sit, and eat, and shop, and places where things slow down and become pedestrian in scale. And it is much easier to connect to and enjoy the waterfront.
Edited by Len Phillips
The City of Toronto, Ontario, Canada, has been undergoing a massive effort to refurbish the City's shoreline on Lake Ontario. It is one of the largest waterfront revitalization efforts ever undertaken in the world. The work has been divided into 8 separate projects consisting of street reconstructions, park developments, new buildings, and most importantly, new trees. The projects all required that trees be provided soil areas that will meet the city's minimum soil volume requirements to ensure the long term growth of the urban trees. The high water table, near the Lake, was also a problem that was solved by providing adequate soil volume over a wider area, rather than the deeper area that is normal. The projects were also intended to improve the quality of ground water, reduce flooding, improve the beaches, provide shady areas, and encourage recreation uses on the waterfront.
Soil Cell Testing
Soil cells provided the answer to many of these concerns. Soil cells are used in many cities as a system to provide large volumes of un-compacted planting soil for trees in the dense urban center. Lesser known, but equally important, are that most, but not all soil cells have the ability to manage stormwater runoff as the source control.
The Queensway
Toronto Water, the city’s water authority, wanted to test the soil cells' capacity to manage surface water runoff. So in the spring of 2008, the city installed a proof-of-concept installation on the Queensway, a commercial street
(see photo) in the east end of the city. The soil cell contractor excavated trenches for two soil cell systems, each two cells deep (see Photo) and with spots for two tree openings that straddled the sidewalk and parking bays.
The soil cells were filled with a bioretention soil mix that has a 20% water holding capacity. All of the rainwater runoff is collected in the city’s standard stormwater catch basin. In effect, the soil cell is being used to create a giant rain garden underneath the sidewalks and parking bays that serves two purposes: one to reduce peak-flow runoff and the second to filter out pollutants. The soil cell selected by the city provided more soil and water holding capacity than other types of soil cells.
A typical rain event in Toronto is 0.09-0.12 in. (2-3 mm) in 24 hours, and 50% of Toronto’s annual precipitation events are less than 0.19” (5 mm). The soil cell system was laid out and sized to manage the runoff from a 2” (5 cm) per 24 hour rain event.
An 8” (20 cm) PVC pipe runs from the street catch basin into the top layer of the soil cell system, delivering all of
the surface runoff from the roadway and adjacent sidewalks into the bioretention soil. A perforated PVC pipe (see Photo) then distributes the surface runoff evenly throughout the soil, and the water infiltrates through the soil until it reaches the bottom of the system where a perforated drain line carries any excess overflow into the existing stormwater system. Depending on the site, the runoff that percolates to the bottom of the soil cell system can be infiltrated into the subsoil to help replenish the aquifer. All of the runoff water is cleansed and held by the bioretention soil.
The system also meets AASHTO H-20 loading requirements to support parking on the surface over the root zone. The entire project took three days to completely install and provides a total of almost 600 cubic feet (16 cubic meters) of soil per tree.
Stormwater Flow and Quality
Just before the Queensway project began, the City decided it wanted to track the volume of infiltration and quality of water in and out of the soil cells. To do this, the trees were planted in pairs. After four years, one set of trees were disconnected from the associated catch basin so it only receives whatever surface water that happens to flow into the tree opening. This created a control. The other tree was left connected. The pollutant reduction concentration results, and well as other interim findings, will be included in a report issued by the city. The system will continue to be monitored throughout 2016, and a full report should be completed later this year. The preliminary reports show significant peak flow reductions and as well as increased water quality.
As the two trees in each of the trenches mature, they significantly increase the efficiency of the system, by transpiring large volumes of rainwater out of the soil through their roots systems and evaporating much of the rainfall with their canopies.
Queens Quay-Revitalizing Toronto’s Waterfront
Following the success of The Queensway project (see Photo), the City undertook the construction of several other projects using the soil cell system that worked out so well on The Queensway. One typical project was a different street called the Queens Quay which is located on the waterfront. Stormwater bioretention was a major factor in this project because of its proximity to the Lake and past flooding issues.
Queens Quay, Toronto’s main waterfront street, stretches over 1 mi (1.7km). Before this reconstruction, the street was defined by four lanes of vehicle traffic with narrow sidewalks, and outdated public transit facilities. Dominated by delivery vehicles and used primarily as a loading zone and for the businesses and condominiums that lined the street, Queens Quay acted as a barrier to the City’s waterfront.
The revitalization of Queens Quay consisted of transforming the busy roadway into a pedestrian promenade (see Photo) and was one of the most complex street reconstruction projects in Toronto’s history. The project has transformed the central waterfront into a vibrant new landmark and destination for the City. The re-envisioned Queens Quay (see Photo) now serves as a linear park connecting various parts of the city.
A key element of the design is the 232 new trees that line the north and south sides of the street and the Martin Goodman Trail (see Photo), a multi-use recreational trail that is now, for the first time, continuous along the full length of the City’s waterfront.
On the north side of the street (Photo 159), a mix of maples (Acer), honey locusts (Gleditsia), elms (Ulmus), and lindens (Tilia) are planted in continuous trenches with 4 ft. (1.2m) diameter sidewalk openings, meeting the city’s standard requirement of 500 cu. ft. (15 cu. m.) of soil per tree. The promenade trees on the south side of the street (see Photo) are London plane (Platanus) trees arranged in two alternating rows with 5 ft. (1.5m) diameter openings, planted within wide continuous trenches. The soil cells were used to allow the soil volume to span beneath the Martin Goodman Trail and were essential in meeting and exceeding the city’s target soil volume of 1,000 cu. ft. (30 cu. m.) per tree.
Stormwater is also being managed on-site. While the use of soil cells and the collection of stormwater was initially designed with tree growth in mind, early in the design process the design team recognized that the system had the potential to manage stormwater on a broader scale through interception, absorption, and evapo-transpiration. The design for the irrigation system (see Photo) was fully integrated into the storm water system for the street, with input from the City, to ensure that performance and maintenance requirements were met.
Prior to the reconstruction, the existing storm system on the street surcharged and was over-capacity during most rain events. The new integrated system showed important positive impacts on the overall stormwater calculations for the site. Surface runoff, flowing water from the Martin Goodman Trail, and boulevard surfaces, now enters the system via custom designed catch basins that capture and store the first flush of runoff, and allows stormwater to enter the soil cells through a network of perforated pipes that passively irrigate the trees. In total, 47% of surface runoff is being diverted into the soil cells and the entire system is designed to handle a 100-year rain event. The stormwater results achieved on these projects are directly related to the specific type of soil cell used. Not all soil cells have stormwater capabilities and will not necessarily provide the same results.
In addition to the low-impact features of the site, landscape materials were selected to be sustainable, robust, and durable. The granite cobbles that pave the street with a maple leaf mosaic hail from Quebec and the yellow cedar (Cupressus nootkatensis) for the custom wood street light poles are harvested sustainably in British Columbia. Wood benches line the promenade and add a splash of color with their bright red cast aluminum supports that also sport the abstracted maple leaf. The project as a whole comes together as a street that welcomes not only residents of the City, but visitors from around the country, and the world.
People look at this street as a long public square, according to Michael James of DeepRoot Canada Corp. who supplied the soil cells. The street now has all the amenities of a central, public square with transit stops, places to sit, and eat, and shop, and places where things slow down and become pedestrian in scale. And it is much easier to connect to and enjoy the waterfront.
New Trees at the Navy Pier Case Study
By Shane Carpani
The Navy Pier on Lake Michigan has been a part of Chicago's history since 1916. The time for the city's highly visited lake front playground to receive a much needed makeover had arrived. To revitalize 50 acres of downtown waterfront, a model of sustainability for the park was created which improved the health and vitality of the local community.
To minimize the time that the Navy Pier would be closed to the public, the renovation plans were produced quickly and construction crews worked around the clock in preparation for the Navy Pier’s one hundredth birthday. A magnificent centennial celebration took place in the summer of 2016. The Navy Pier is already a spectacular tourist destination enjoyed by millions of visitors every year.
The renovation and construction at the South Dock of Chicago's Navy Pier included adding 59 large precast concrete tree pits in eight sizes, the largest being 28 feet (8 meters) long. The tree root balls measured more than 8 feet (2.4 meters) in diameter. The city specified 12 cubic yards (9.2 cubic meters) of uncompacted, root-able soil for each tree pit, which is not ideal, given that mature tree roots frequently occupy 40 cubic yards (30 cubic meters) of soil. However, by using soil cells, the tree roots were able to share the soil in the soil cells and grow beyond in the uncompacted soil. The soil cells create a forest floor environment for the trees, and are always installed with adequate drainage and soil ventilation to allow the roots to breathe.
Designed by an award-winning landscape architectural firm, the plan incorporated the latest in ecological design principles and environmental best practices. This included the planting of mature trees with root balls up to eight feet (2.4 meters) in diameter, creating a tree grove promenade of healthy Marmo maples – Acer × freemanii 'Marmo' and American sycamores - Platanus occidentalis. The mature 'Marmo' maples, a resilient variety of the Freeman maples were originally developed at the nearby Morton Arboretum. The American sycamores, one of the largest hardwood trees of the Eastern U.S. forests, were locally-sourced from within 50 miles and are native to the Chicago region.
With the high volume of traffic endured by the area each year, it was critical to install an engineered surface that would withstand the extremely heavy pedestrian movement and the weight of occasional vehicular traffic. To accomplish this structural stability and still provide healthy soil and growing conditions for the trees that would be creating the focal point of the pier, soil cells were the only solution that made sense at this location. It’s important to note that not all soil cells are rated for use under roadways and other vehicular trafficked areas. In this case, high-strength soil cells that have been approved for use under highway traffic areas with only minimal sub-base were specified.
Another concern at the site was dealing with stormwater runoff. Ideally, the stormwater would be captured through the landscape plantings and the permeable pavements made of recycled content and locally-sourced aggregate. The stormwater was designed to go into bio-infiltration basins, then to underground storage facilities for reuse as irrigation. For a specification on bio-retention soils see item 11 in our planting spec.
The soil cells selected for this project, provided 95% of the underground space for uncompacted soil that would be used by the tree roots. The slab-on-slab pier made these tree pits completely man-made with no natural earth below. The landscape architect specified a soil blend that filled the soil cells and met the specific needs for the highly mature maples and sycamores. The soil mix created a forest-like subsurface environment with tree-friendly soil volumes for the already mature trees to flourish for many more years. And with the structural capabilities of the soil cell, able to withstand surface weights of up to 9 tons per 20” x 20” soil cell module, the landscape architects and engineers were assured that the underground growing medium was not affecting the structural stability of the surface.
The waterfront transformation has turned the Navy Pier’s outdoor landscape into an even more vibrant setting for recreation and social life. Through this sustainable design, the Navy Pier has made a very positive environmental impact on the local area. The planting of these large trees resulted in a green oasis that invited visitors to escape the concrete of the downtown and enjoy unfettered views of the Lake Michigan water in a more natural setting. With the help of stainless steel tree grates and built-in LED lighting, the Navy Pier is now used for many more hours beyond daylight.
Photo courtesy of GreenBlue Urban.
Author Shane Carpani is the Program Development Manager at GreenBlue Urban, a global manufacturer of urban tree planting systems.
Sources:
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LA CES will award 1.0 PDH (HSW) credit for a passing grade. North Carolina Board of LA and New Jersey Board of Architects will award 1.0 credits for a passing grade.
The cost for taking this test is $20 per credit. If you purchase an annual subscription for 12 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report your passing test score to LA CES. If you are also ISA* certified we will report your passing score to ISA for no additional cost. Please be sure to add your ISA Certification number when you sign in. Tests with passing scores may be submitted only once to each organization.
*ISA has approved this course for .5 CEUs per section for a total of 1.5 CEUs. Kensico Dam section is applied toward Certified Arborist, Municipal Specialist, or BCMA management credits. The Toronto Waterfront and Navy Pier sections are applied toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. If you are an ISA and/or CLARB member, please be sure to include your certification/member number(s) along with your LA license and ASLA numbers.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks after that.
LA CES maintains a record of earned PDH credits on their website http://laces.asla.org/
ISA maintains a record of earned CEU credits on their website http://www.isa-arbor.com/
By Shane Carpani
The Navy Pier on Lake Michigan has been a part of Chicago's history since 1916. The time for the city's highly visited lake front playground to receive a much needed makeover had arrived. To revitalize 50 acres of downtown waterfront, a model of sustainability for the park was created which improved the health and vitality of the local community.
To minimize the time that the Navy Pier would be closed to the public, the renovation plans were produced quickly and construction crews worked around the clock in preparation for the Navy Pier’s one hundredth birthday. A magnificent centennial celebration took place in the summer of 2016. The Navy Pier is already a spectacular tourist destination enjoyed by millions of visitors every year.
The renovation and construction at the South Dock of Chicago's Navy Pier included adding 59 large precast concrete tree pits in eight sizes, the largest being 28 feet (8 meters) long. The tree root balls measured more than 8 feet (2.4 meters) in diameter. The city specified 12 cubic yards (9.2 cubic meters) of uncompacted, root-able soil for each tree pit, which is not ideal, given that mature tree roots frequently occupy 40 cubic yards (30 cubic meters) of soil. However, by using soil cells, the tree roots were able to share the soil in the soil cells and grow beyond in the uncompacted soil. The soil cells create a forest floor environment for the trees, and are always installed with adequate drainage and soil ventilation to allow the roots to breathe.
Designed by an award-winning landscape architectural firm, the plan incorporated the latest in ecological design principles and environmental best practices. This included the planting of mature trees with root balls up to eight feet (2.4 meters) in diameter, creating a tree grove promenade of healthy Marmo maples – Acer × freemanii 'Marmo' and American sycamores - Platanus occidentalis. The mature 'Marmo' maples, a resilient variety of the Freeman maples were originally developed at the nearby Morton Arboretum. The American sycamores, one of the largest hardwood trees of the Eastern U.S. forests, were locally-sourced from within 50 miles and are native to the Chicago region.
With the high volume of traffic endured by the area each year, it was critical to install an engineered surface that would withstand the extremely heavy pedestrian movement and the weight of occasional vehicular traffic. To accomplish this structural stability and still provide healthy soil and growing conditions for the trees that would be creating the focal point of the pier, soil cells were the only solution that made sense at this location. It’s important to note that not all soil cells are rated for use under roadways and other vehicular trafficked areas. In this case, high-strength soil cells that have been approved for use under highway traffic areas with only minimal sub-base were specified.
Another concern at the site was dealing with stormwater runoff. Ideally, the stormwater would be captured through the landscape plantings and the permeable pavements made of recycled content and locally-sourced aggregate. The stormwater was designed to go into bio-infiltration basins, then to underground storage facilities for reuse as irrigation. For a specification on bio-retention soils see item 11 in our planting spec.
The soil cells selected for this project, provided 95% of the underground space for uncompacted soil that would be used by the tree roots. The slab-on-slab pier made these tree pits completely man-made with no natural earth below. The landscape architect specified a soil blend that filled the soil cells and met the specific needs for the highly mature maples and sycamores. The soil mix created a forest-like subsurface environment with tree-friendly soil volumes for the already mature trees to flourish for many more years. And with the structural capabilities of the soil cell, able to withstand surface weights of up to 9 tons per 20” x 20” soil cell module, the landscape architects and engineers were assured that the underground growing medium was not affecting the structural stability of the surface.
The waterfront transformation has turned the Navy Pier’s outdoor landscape into an even more vibrant setting for recreation and social life. Through this sustainable design, the Navy Pier has made a very positive environmental impact on the local area. The planting of these large trees resulted in a green oasis that invited visitors to escape the concrete of the downtown and enjoy unfettered views of the Lake Michigan water in a more natural setting. With the help of stainless steel tree grates and built-in LED lighting, the Navy Pier is now used for many more hours beyond daylight.
Photo courtesy of GreenBlue Urban.
Author Shane Carpani is the Program Development Manager at GreenBlue Urban, a global manufacturer of urban tree planting systems.
Sources:
- Amereq, Inc. manufacturers of CU-Structural Soil® installation instructions and photos
- Westchester County Parks - Robert P. Astorino, Westchester County Executive
- DeepRoot Canada, special thanks to Michael James, General Manager
- Silva Cell Case Studies, “Revitalizing Toronto’s Waterfront Along Queens Quay”, The Queensway Toronto, ON, 2016.
The test that follows contains 30 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
LA CES will award 1.0 PDH (HSW) credit for a passing grade. North Carolina Board of LA and New Jersey Board of Architects will award 1.0 credits for a passing grade.
The cost for taking this test is $20 per credit. If you purchase an annual subscription for 12 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report your passing test score to LA CES. If you are also ISA* certified we will report your passing score to ISA for no additional cost. Please be sure to add your ISA Certification number when you sign in. Tests with passing scores may be submitted only once to each organization.
*ISA has approved this course for .5 CEUs per section for a total of 1.5 CEUs. Kensico Dam section is applied toward Certified Arborist, Municipal Specialist, or BCMA management credits. The Toronto Waterfront and Navy Pier sections are applied toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. If you are an ISA and/or CLARB member, please be sure to include your certification/member number(s) along with your LA license and ASLA numbers.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks after that.
LA CES maintains a record of earned PDH credits on their website http://laces.asla.org/
ISA maintains a record of earned CEU credits on their website http://www.isa-arbor.com/