THINK TANK DRINK TANK

   
     Aerial Photo 
Precipitation / Drainage

The McTavish Reservoir / Parc Rutherford site is a uniformly flat field at an elevation of about 236 feet above sea level. The site, including the sloped areas, are grassy, with some trees and other vegetation around the edges (see Landscape group research ).

Water drains onto the site from a cliff wall (and Mount Royal immediately behind it) on the northwest side and drains off it on the relatively steep south and east sides.

An impervious pathway with a culvert and a sewage line run the perimeter of the tanks below (see Pump house group research ). 

Sewage lines in the paved roads that surround the site carry all the rainwater runoff to the main collector along the southern shore of the island. 

RAINWATER HARVESTING

•    Very old technology found in civilizations over 4000 years ago.
•    Used in Ancient Rome, Negev Desert, the Island of Gibraltar has one of the largest rainwater collection systems. 
•    Disappeared not very long ago with the accessibility of well digging technology.  

Definition:
An above or below ground system that collects stores and distributes run-off of rain or snow from roofs and hard surfaces around the property.

Considerations:
•    What this water will be for (toilets, irrigation of landscape, laundry).
•    Type of purification
•    If the amount of water that can be collected will be sufficient.
•    Provide for emergencies (droughts, overflows, etc…).
•    Engineering of the system.
•    Repercussions on facades-exterior of building as well as landscape.

Benefits:
•    Reduces the use of treated municipal water.
•    Reduces the need for well drilling.
•    Regulates the water volume in soil.
•    Regulates the availability of water.

Limitations:
•    Can be costly.
•    Quality of rainwater in certain areas.
•    Needs maintenance and monitoring.

Rain Harvesting
GREY, BLACK WATER TREATMENT

Grey water
•    All water that comes from the household/institution that contains no organic waste.
•    Beware of the laundry water that can contain organic waste if, for example, diapers are washed, or food particles and greases are found in dishwashing water.
•    Because it needs less oxygen to decompose, it is less damaging then black water to the environment.
•    It takes about 5 days to decompose.
•    Plants can be nourished by its nutrients.

Black water
•    Water from the toilet which contains organic matter.
•    Very damageable for the environment because it is difficult to decompose.  It needs a great amount of oxygen and a far longer time (by the time grey water is decomposed; only 40% of black water has had time to be processed).
•    It is toxic for plants as well as humans.

Separating grey water and black water
Most municipalities now treat both waters as same in the sewer system. Grey water could be disposed of in a better way since it is easily digested by the environment if it is placed in the right setting.  The only real way to dispose of black water without damaging our water supply is through composts.

Grey water can be used for landscape irrigation or recycled for the toilet system.  It could also be treated to a point it is drinkable (although this requires a lot of monitoring and maintenance and can become very costly).

Benefits
•    Lower fresh water use.
•    Less strain on municipal treatment plant.
•    Highly effective purification.
•    Less energy and chemical use.
•    Ground water recharge.
•    Plant growth.
•    Reclamation of otherwise wasted nutrients.
•    Making the loop in environmental cycle.

Limitations
•    Monitoring and testing needed.
•    Need to be aware of the products washed down in the water, change a few habits.
•    Difficult to control contamination through sickness.
•    Can be costly.
Grey Water
TREATMENT

Aquatic / Dryland / Wetland / Terrestrial
These can serve both for grey water or rainwater treatment, but are unsuitable for black water.  Composting is the only safe way to dispose of it.

Aquatic
Filtration through one body or a succession of bodies of water containing plants and/or animal that “digests” pollutants.

Terrestrial
Filtration of water using gravity by slowly passing through a specific soil (composed of a layering of different types). It is often done in a septic tank which is not considered the most ecological solution since pollutants are absorbed through the soil at a deep level where vegetation and animal life is sparse.  However, it can be done in an independent artificial septic tank.  The process can be divided in different steps.

Dryland / wetland
Creation of both water and vegetation bodies as a filtration device such as ponds, swamps.  A dry land is not meant to be constantly visible to the eye: it does not store water and is dependent on the seasonal inflow of rain.  A wetland is visible all year round. They both attract wildlife and enhance the landscape.  One should be careful with the placement of wetland in hot weather: the heat reduces even more its content in oxygen and it develops a foul odor.

See it to believe it.
There is a tendency to believe part of the reason we are using damageable sewer systems for our environment is due to our detachment towards the process of purifying water.  In other words, people should live it and see it in order to understand it and naturally become careful.
When it is decided upon to use an ecologic treatment for the water, people have to be sensitized to it and showed how it functions in order to prevent the poisoning of the water.  This ancient method has become alien to us since the development of drilling technology.  
Treatment
BIBLIOGRAPHY

Gray water for Residential Irrigation, Landscape Architecture, vol.85 n.1, Jan1995, p82-85 & 87.

Environmental Planning for Wastewater Land Application: Lessons from Penn State’s “Living Filter”, Landscape Planning, vol.10 n.3, Oct.1983, p205-218.

The Poetics of Stormwater, Landscape Architecture, vol89, Jan1999, p58-63 & 86-88.

Topical reports Green Construction
http://www.pprc.org

Cistern/Rainwater Harvesting Systems
http://www.advancedbuilding.org

Rainwater Harvesting and Purification system
http://www.rdrop.com/users/krishna/rainwatr.htm

Rainwater harvesting: a new water source
http://twri.tamu.edu/twripubs/WtrSavrs/v3n2/article-1.html

Water Harvesting
http://www.rainwaterharvesting.org

Grey Water Systems
http://www.bioloo.conz/page5.html

Sustainable Building Sourcebook
http://www.greenbuilder.com

Grey Water
http://www.greywater.com

Grey Water Central
http://www.oasisdesign.net/greywater/greywater
 




. school of architecture . mcgill university .