We will start this site assessment by discussing the two big pieces of it—a base map and a sector analysis map.
Polly to discuss: this site assessment phase is all about two types of maps:A base map that gives us the big picture of existing vegetation, pathways, surfaces, structures, boundaries, and utilities. It inventories the existing space we live in. A sector analysis map that gives a sum total of the energies that flow across and through our property—obvious things like wind and light, and not so obvious like wildlife and water in the soil.
Note that before we go on into the details of the results of our work, there were many “Ah Ha!” moments during this process, but also some really obvious “DOH!”s that restated the obvious many of us already know well from experience.
This map shows a birds-eye view of our neighborhood. Notice that we are on a greenbelt which is also a wildlife corridor.Our greenbelt has at it’s heart a perennial stream, North Johnson Creek. The vegetation and the stream influence each other (riparian zone). This area is conserved under Oregon and County law.
Notice the pink zone is Roger Tilbury Park. There will be no more development in our immediate neighborhood. And improvements to the park are minimal impact with regards to the core ecological functions of the stream corridor.
Here is a close-up view of our property – 3.65 acres. The property boundary is in yellow. Note that 1.08 acres is hardscape (that’s almost 1/3). Notice the stream, the trees, N-S orientation of our front and back slopes.
Here is an image of the abundance of impervious—hard—surfaces on the property. These do make a big difference in how water and life are managed around here.
Because of all the hard surfaces on the property, Trillium Hollow must rely on stormwater systems represented by the green lines on this map.This map shows that and other infrastructure that moves waste water and stormwater from our property. Note the dark green line is a piped stream – a stream that formerly ran across what is now the plaza and drained into North Johnson Creek (blue line). Not all stormwater conveyance is shown on this map.
Here’s that stream—its headwaters in the wetland, the big grating that protects the entrance to it, and the pipe it exists just past the bioswale area.
This map shows elevations of the bare earth represented by colors. It was taken by a special, very accurate process that captures only the earth itself—not trees or structures. Bright green is the highest elevation and deep purple is the lowest. Notice the lowest parts of the property and the highest areas. If you look carefully, you can almost see the channel of the buried (piped) stream from before the driveway and Plaza were built. Note: we DO live in a hollow!Note the areas of terracing—we have two main terraces or flat zones on the property and three significant slopes: back, front, and creek-side areas.
This rather complicated looking map shows the path of the sun across our property at various points in the year including the solstices and equinoxes. What this means for us is that the winter sun tends to shine across the garden and plaza from the south, while in the summer it shines more overhead (or northerly) which means that trees and buildings to tend to cast deeper shadows. The orange polygon is the area where the maximum sunlight is received all year. It’s not always 100% in sunshine, but when the sun shines, it receives the bulk of the solar rays hitting the property.
The rest of the suns rays are captured by the tallest members of our community—the big trees we have here. Related to the sun path, this image shows the height of the tallest objects on our property—the trees—which limit our sun exposure on various parts of our land. Note the evergreens—which will cast year round shadows, and the deciduous trees which cast their shade in the summer when the sun is overhead. Here’s the area of maximum solar absorption again.
Here you can see the triangle of light that the Plaza and gardens receive, and see the depth of shadows too—at this time of year.
Here’s another way to look at that sunpath, from the ground and late in the afternoon. The sun is coming from the SW.
Notice the trees here and their ability to cast shadows across our gardens and cob bench.
Elevations on the property show that there is a high of over 500 feet at the top of the drive and a low of less than 450 at the plaza and even lower at the creek. This is significant because it influences how air travels across our property, especially cold air.
Warm air flows AGAINST the contours and heats our front slope, our berm area and the buildings.
Of course, we all know, we live in wildlife corridor and share our property—and our veggies—with many other creatures besides the human ones. The yellow areas are wetlands that will contain a high number of species potentially including amphibians. And of course, we all know that even the wildlife enjoy the same places as the humans do. Like cute little Bambi and Thumper coming to the garden to nosh on some of Rob and Jude’s beans and chard.
Deer on thebackslope.
Lots of other neighbors to consider the flow of wildlife and its occupancy of our property.
Here is a map of hydrographic soil types on our property. The colors represent the ability for the soil to absorb and shed water. The soils in greenish yellow are most typical of wetland areas and are the least able to hold excess water because they are full of clay. The brownish areas are soils that do not hold water well when they are saturated and are also high in clay. We have not upland soils here that absorb water easily. The cross hatching represents an officially designated wetland. Also note the areas of disturbed soil from the construction of our homes.
And going back to those areas in the previous map, here what we mean by disturbed soils. Often disturbed means that important soil layers such as organic matter and top soil were removed or mixed under, and soil was compacted by construction equipment and building materials. Some soil erosion practices were required but they do not make up for the loss of hundreds of years of soil evolution. Now we must help rebuild those soils.
Here’s one of those Homer Simpson moments—everyone say it with me “DOH!”
And again—all together now: “DOH!”
So next steps are that we need to take this data, put it together with the results of the community conversations and move through a final process that builds consensus about our property’s uses in various areas, then captures that for the now and future residents. For this, we anticipate that NOW is the time to ask for funds to hire a collaborator to do this skilled activity. We will be coming to the Budget Faire with a proposal on this. If funded, we hope to move forward this winter.
And lets just end by seeing the people in our landscape again.
All of this adds up to a whole—like a set of petals and sepals yields a lovely flower.
Land use site assessment presentation 10.23.12
Trillium Hollow Site Assessment Joanne Delmonico, Rob Emanuel, Polly Helm October 23, 2012
Agenda• Reintroduction to the process• Base maps• Sector analysis maps• Climate• Q&A• Discuss next steps
Phases of Activity Last SpringNow Assessing community wishes and appreciations Assessing what the land can sustain Synthesis Design charette Living document & implementation
Trillium Hollow Base Maps • Neighborhood • Zoning • Boundaries • Underground Infrastructure • Shape of the land (slopes and flats)“A base map captures everything that is already on your chosen site. It includes buildings,borders, vegetation, pathways, driveways and utilities.”
BM 2: Drop off fromlast terrace to creekand lowest point onproperty.
Trillium Hollow Sector Analysis • Sunlight & Shade • Topography & Microclimate • Soil & Soil Moisture • Wildlife & Human Corridors • Climate Patterns“A sector analysis is a summary of the energies that affect the site and whichoriginate from different directions outside of it.”
SECTOR ANALYSIS – Sun and Shade Trillium Hollow Sector Analysis 1: Annual Solar Exposure
SECTOR ANALYSIS – Elevations (vegetation heights and types) Trillium Hollow Sector Analysis 2: Elevation & Tree CanopyDeepest blue = highest elevation objects Lightest blue = lowest elevation surfaces
SA 1: Marcia and Polly’s Deck, October 6, 11:30 AM