Stormwater Academy: Green Roofs

Green Roof Design andGreen Roof Design and OperationOperation

(Part III)(Part III)

2006 FSA Annual Conference2006 FSA Annual ConferenceJune 14June 14, 2006, 2006

By Marty Wanielista and Mike Hardin

FSA

DESIGN and CONSTRUCTION

• Type of Plants?• Maintenance?• Source of make-up water cistern water?• Infrastructure (location of cistern, electrical)?

Native Plants: Green Roofs

Plant Selection based on

1. Perennial with color, preferably woody (having secondary growth) creeping prostrate, or shrubby plants with full sun, high temperature, low soil nutrient, and severe drought tolerances.2. Shallow, fibrous rooting habit.3. Cold hardiness to just below freezing.

Plant Selection: Green Roofs

Continued: Plant Selection based on4. No severe pest problems or special horticultural requirements.5. Florida native species preferred when suitable and available.6. Evergreen foliage preferred, to maintain higher ET and cover and attractiveness all year.7. Bloom or fruit display desirable but not mandatory.8. Due to irrigation plant selection no longer dependent on drought tolerance

Florida Native Dune or Beach Sunflower Helianthus Deblis

Florida: Green Roofs

Lonicera sempervirens(Coral honeysuckle)

A perennial vine-like shrub with bright red flowers in a shape much loved by hummingbirds. Common to central and north Florida. Typically found in wooded areas.

Florida: Green Roofs

Gaillardia pulchella(Firewheel Daisy)

Large flowers, have a wide variation in form and yellow/red combinations. This is a hardy annual that easily grows from self-sown seeds. Often found growing in hot, dry, difficult areas throughout Florida. Grows up to 24 inches tall.

Florida: Green Roofs

Myrcianthes fragrans(Simpson’s stoppers)

This evergreen shrub has fragrant white flowers that produce a red fruit with edible seeds. The leaves, when crushed, smell of eucalyptus. They start out red, turning green later in the growing season. Found throughout south and central Florida, these shrubs provide shelter and food for a variety of birds and animals.

Florida: Green Roofs

Muhlenbergia capillaris(Muhly grass)

Various natural varieities found in pine flatwoods, sandhills, moist hammocks and beach dunes. Grown throughout the entire state, and very drought tolerant. This grass reaches up to 3 ft when in flower. The flowering part resemble pink or purple plumes. Blooms in the summer and early fall.

Florida: Green Roofs

Helianthus debilis(Beach or Dune daisy)

A low-lying, spreading daisy that tolerates harsh conditions: salt spray, drought, acid or alkaline soils. Often used to stabilize dunes that are subject to erosion.

Florida: Green Roofs

A HAVEN for POLLINATORS

AESTHETICS AND HABITAT CONSERVATION

Additional Plant Selections

See a Landscape Architect for local plants.

Some additional ones being considered are:Salvia coccinea (Tropical sage)Monarda punctata (Spotted Beebalm)Hamelia patens (Firebush)Erythrina herbacea (Coral bean)Mimosa strigillosa (Powderpuff)Solidago spp (Goldenrod)Hypericum hypericoides (St. Andrew’s Cross)Oenothera laciniata (Cutleaf primrose)Scoparia dulcis (Sweet broom)Phyla nodiflora (Carpet flower)Scutellaria integrifolia (Rough scullcap)

Cost Considerations

Construction: • Generally $7-$15 per square foot• For retrofits add about $3 per square foot• This price can vary significantly depending on the needs of the client• The most important part of the construction process is the water proof membrane

• Leak detection must be done before construction proceeds• The price for this will vary per project but is about $0.06-$0.10 per square foot

Cost Considerations

Construction (cont): • Added features can be incorporated into any green roof design (price will vary with feature)• These features are typically associated with an active roof

• Water feature• Putting green• Benches and tables• Pervious Concrete Basketball court• More…

• Care must be taken in the design and construction process to ensure safety and successful implementation

Cost Considerations

Maintenance: • Will vary with design• Most active roofs will be about the same as yard or garden maintenance• Most passive roofs require minimal maintenance (twice per yr)• Use of Herbicides and pesticides will be minimized• Leak Detection

• Electric Field Vector Mapping• Able to detect pin hole size leaks

Cost Considerations

Maintenance (cont.): • Irrigation system

• Clogging of drip system• Broken or misplaced pipes• Replacement of filters

• Cistern• Cleaning about once every 2 years• Check pressure gage regularly

• Plants• Replacement of dead or damaged plants• Pruning and trimming• Weed pulling• Fertilization

The cistern operation

FSA

The cistern is supplied with water from the green roof, however, during dry periods, the stored water in the cistern may not be sufficient to meet the demand. THUS

• Source of alternative water supply during the “dry season”?

• Filtration of the alternative source water?• Some alternative sources are stormwater from other

areas, reclaimed water (subject to constraints), potable water, groundwater, and others that meet plant growth conditions (Salinity, pH, SAR, Conductivity, and others)

Questions and Comments