Implementation of a Roof Garden & Water Harvesting System on the MU’s West Plaza

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STRUCTURAL LIMITATIONSThe following structural limitations of the West Plaza were determined following an evaluation conducted by Charles Saul Engineering (CSE), Inc.:

General structural loading capacity of West Plaza is 100 psf Limited growing medium used to 10” depth (Typical 1’ green roof soil mix = 120 psf)

DESIGN IMPLICATIONSa

No shrubs or trees Loads focused on outside perimeter of structure (Ability to withstand 20 more psf than center)

“Soften” the space.

ABSTRACT

An original part of the iconic Memorial Union building, the west plaza area offers a scenic view of the nearyby Lake LaVerne and serves as a high-traffic area utilized by students, university em-ployees, and and other campus visitors. As evident in the aerial view to the right, however, this space is currently a barren, “con-crete wasteland,” with little-to-no amenities to support the area’s plethora of potential uses - eating, studying, hosting university or prrivate events, etc. This creative project explored how the incorpo-ration of semi-intensive green roof planters - in synchronization with a green fascade and water harvesting system - could better accommodate for these uses and exemplify Iowa State’s committ-ment to educating & implementing sustainable practices.

West Entrance & Plaza AreaISU Memorial UnionAmes, IA

Andrew FoyHorticulture - Landscape Design, Maintenance & Installation Option

GREENING THE MEMORIAL UNION

Offset the surrounding, concrete-dominated arh-citecture of the MU buildng with a diverse and colorful plant pallet. In aesthetically improving the current, dull west plaza space, plants will en-courage and invite students, staff, and other visi-tors to make better use of the space.

Provide ample amenities. Resurface the plaza. Educate plaza visitors.Utilize surrounding architecture.

Since the Memorial Union’s construction in 1922, the West Plaza’s membrane has only been re-surfaced once, and, as depicted in the images above, the cur-rent plaza membrane lacks integrity and aesthetic appeal. To address this issue, an American Hydrotech Waterproofing & Architectural Roof Paver System is proposed in the green roof design.

Located in such a high-traffic area of campus, the West Plaza green roof concept not only has the potential to transform the way in which the space is currently being used, but it also has the potential to act as an educate hundreds of its visitors of the university’s committment to sustainability. For this reason, signage and on-site pamphlets are planned to be available on-site.

Aside from giving the building its iconic, rustic appear-ance and scale, the architecture surrounding the west plaza area currently serves no other purpose and is some-what disconnected from the space. The proposed design accounts for this by transforming the static roofs and walls of the Memorial Union into aesthetic green fas-cades and functional water harvesting systems.

SITE CONSIDERATIONS

SUN WIND RAINTwo distinct areas:1.) Sun-Exposed Area

2). Shaded Area - East side of plaza - against building - 1-2 hours partial sunlight per day - 6-8 hours full shade per day

CURRENT SITE

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View when approaching northplaza entrance.

View of south plaza area withaccess to C-store & bookstore.

Overview of plaza area outsideFood Court & cafeteria.

The plaza’s convenient location enables it to have a number of poten-tial uses, including: outdoor studying space for students, additional space to enjoy a meal from the nearby cafeteria, a destination for socializing with friends & work colleagues, and even a space to host university-sponsored or private receptions. To accomodate for these activities, the proposed design features ample areas for seating and overhead shade structures that maintain a comfortable atmosphere and frame the view of nearby Lake LaVerne.

CIRCULATION PATTERNS

The diagram to the right highlights the primary means of access & egress to and from the west terrace area. On a daily basis, the area experiences heavy traffic due to its close proximity to a number of popular destinations inside the Memorial Union. Adhering to university standards, un-obtruded, 10’-wide walkways were maintained in the design to promote adequate space for circulation during periods of heavy use.

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Average Iowa rainfall for central Iowa is around 36” - normally an adequate amount of moisture to support typical landscape plants found in the region. However, due to the more re-occurent peri-ods drought and the unique, drought-prone char-acteristics of the plaza, supplemental irrigation will be required to ensure plant health & longevity.

- West side of plaza- 8-10 hours of full sunlight per day

West and southwest edges will be exposed to harsh, winter winds. Vegetation in these area may need winter protection from wind scorch or freezing damage.

HUNTER PDL SUB-SURFACE IRRIGATION SYSTEM

SOURCES “The Ultimate Assembly.” American Hydrotech. <http://www.hydrotechusa.com/assemblies/ultimate-assembly>.

“Modular, Wall Hung Trellis Panels.” Green Screen. < http://www.greenscreen.com/home.html>.

WEST PLAZA DESIGN

PLANTER & ROOF DECK CROSS-SECTION

RAINWATER HARVESTING SYSTEM

WEIGHING THE WATER

EXISTING ROOF DECK

PROTECTION COURSE

INSULATION

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CH HANOVER ARCHITECTURAL PAVERS

(Gray Finish)

WATERPROOFING MEMBRANE(Hot Rubberized Asphalt)

VEGETATION(SUCCULENTS, COLORFUL FLOWERS, GRASSES)

1’ ROOFLITE SEMI-INTENSIVE GROWING MEDIA

STYRAFOAM INSERTSTM

2’ X 4’ CUSTOMIZED ALUMINUM PLANTER

FILTER FABRIC

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“Rainwater Harvesting Products.” Jay R. Smith Manufacturing Company. <http://www.jrsmith.com/product-category.aspx?ProductCategoryID=124>.

Hershfield, David S. “Rainfall Frequency Atlas of United States.” U.S. Deptartment of Commerce. May, 1961.

“PDL Sub-Surface Irrigation.” Hunter Industries. <http://www.hunterindustries.- com/irrigation-product/micro-irrigation/eco-matr-and-pld-esd>.

DRAINAGE LAYER

(Empties to Nearby Roof Deck Drain) PVC DRAINAGE PIPE

Comparing the Runoff Rates of the Current Plaza vs. Anticipated Rates of the Proposed Green Roof Design

CALCULATION ASSUMPTIONS:

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Underground Water Starage Tank (3,500 Gallon Tank)

Connected Irrigation System (Use for both Green Roof & N. Turf area)

Multi-Functional Overflow Device

Storage Tank Floating Filter

Irrigation Pump

PVC Feed Pipe(Water Planters) Rainwater Harvesting Products

Initial Water Capture

Storage, Filtration & Utilization in the Landscape

Gravity Tranfer to Planters & Storage TankAfter the rainwater reaches the planters via the PVC piping, it is then emptied in specially-crafted water resevoirs at the bottom of the planters. Once in the reservoirs, the water continues to be grav-ity-fed down a sloped surface to an underground water storage tank buried within the NE retaining wall.

During the first stage of rainwater harvesting, water is collected from the roof above the West Plaza entrance. Water from the drain then moves to a connected PVC pipe, which transfers it to the planters below.

The final stage of rainwater collection involves the pumping of rainwater into a 3,500 gallon, underground storage tank through a PVC intake pipe. Once in the tank, the water is processed and either pumped back into the landscape to be used for irriga-tion or released into the stormwater sewage system in the event of a tank overflow.

CIRCULATION PROCESS

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Water ReservoirFoam Slope

IMPLICATIONS In this single rain event, the proposed green roof design reduces the amount of site runoff by 331 cubic feet of water (the equivalent of 2,478 gallons) in comparri-son to the current plaza. When taking into account the average yearly rainfall received by Ames, IA - 35.8”- the wider-scale, storm-water management benefits offered by the proposed green roof design can be realized.

Total Impervious Concrete Area 11,237 SFa

Total Permeable Surface Area 0 SFa

Yield of Precipitation in Rain Event 2.2” (0.1875’)a

Runoff Coefficient of Concrete 0.88

CALCULATIONSa

Runoff from Impervious Surface:a

11,237 SF x 0.1875’ x 0.88 = 1,854 cu. ft. +Runoff from Permeable Surface: N/A = 0 cu. ft.

aTOTAL RUNOFF FROM SITE: 1,854 cu. ft.

(SOURCE: Kuichling, 1989)

CURRENT PLAZAPROPOSED GREEN ROOF DESIGN

ROOF RUNOFF = AREA OF ROOF x PRECIPITATION YIELD x RUNOFF COEFFICIENT(of Specific Rain Event) (of Respective Roof Materials)

Total Impervious Concrete Area 8,848 SFa

Total Permeable Surface Area ~2,400 SFa

Yield of Precipitation in Rain Event 2.2” (0.1875’)a

Runoff Coefficient of Concrete 0.88

a

Runoff Coefficient of Planters 0.14

CALCULATIONSa

Runoff from Impervious Surface:a

8,848 SF x 0.1875’ x 0.88 = 1,460 cu. ft. Runoff from Permeable Surface: + 2,400 SF x 0.1875’ x 0.14 = 63 cu. ft.

aTOTAL RUNOFF FROM SITE: 1,523 cu. ft.

(SOURCE: Kuichling, 1989)

(SOURCE: Kuichling, 1989 - “Meadow” with Type A Soil)

(4’-wide Planters Lining ~2,400’ Perimeter of Plaza)

Assuming the occurrance of a 1 year, 12 hour rain event in Ames, Iowa - which yields 2.2” inches of rain. (Source: NOAA Technical Report on Rainfall Frequency in U.S.)

Runoff from a site can be determined by taking the area of the roof multiplied by the average precipitation yieldexpected in a specific precipitation event; multiplied by the specific runoff coefficient of the materials that composethe roof. The equation is given below:

Bergenia cordifolia Pigsqueak

Astilbe ‘Fanal Red’ Fanal Red Astilbe

Hosta ‘Blue Umbrella’ Blue Umbrella Hosta

Liriope spicata Lilyturf

Liatris spicata ‘Floristan White’ White Gayfeather

Echinacea purpurea Purple Coneflower

Asclepias tuberosa Butterfly Weed

Sporobolus heterolepis Prairie Dropseed

Salvia sylvestris ‘May Night’ Perennial Sage

Rudbeckia fulgida ‘Goldsturm’ Black-Eyed Susan

SUN-LOVINGSun-loving, drought tolerant flowers & grasses embody the colorful plant palette seen on plaza edge. Well-adapted to the harsh, dry condi-tions in this area, the majority of these plants are native to the Iowa prairie.

SHADE-TOLERANTA number of shade-tolerant flowers, grasses, and groundcovers are also featured in the design. These plants are well-adapted to the low-light and cooler conditions experienced by the planters closest to the building. SE

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Hosta ‘The Rocket’ Rocket Ligularia

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The West Plaza green roof design brings a very noticeable improvement to the area’s aesthetics and more ap-propriately accomodates for the areas potential uses. Lush greenery invigo-rates the space - sparking visitors’ in-terest and curiosity - while ample site amenities invite students and staff to stay, sit, and enjoy the outdoors.

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PROPOSED DESIGN

Main Seating Area1

Shaded Seating AreaPergola Leisure Area2 3