See my comments throughout this report in
callouts or in the body of the text. My husband
told me there were too much good ideas in here
to just give away, so I’ve censored some
goodies by replacing them with comments that
look like this in the report. The rest of the text is
what I wrote for the original report.
Project Name
Sustainable Site Opportunities
Early Design Review
Date
Client:
Client Name
Address
Contact
I recommend that the final version of this report
be incorporated into the final design deliverables
to the contractor, so they have a clear
understanding of why we’re doing things a little
differently on this project.
This report could also easily be formatted in html
for posting to the project website.
7345 SW 29th Avenue Portland, OR 97219
p 503.334.8634
f 503.892.2321
greengirl@greengirlpdx.com
www.greengirlpdx.com
Green Girl Land Development Solutions
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Table of Contents
Introduction........................................................................................................................................................ 3
To Be or Not to Be (Pervious Pavements) ......................................................................................................... 3
Sustainable Stormwater – An Overview ............................................................................................................. 3
Graywater Recycling ...................................................................................................................................... 4
Rainwater Harvesting ..................................................................................................................................... 4
Overland Flow through Rocked & Lined Swales ............................................................................................. 4
Materials - Plastics ............................................................................................................................................ 4
Erosion Control .................................................................................................................................................. 4
Save a Tree ....................................................................................................................................................... 5
Reduce Disturbance .......................................................................................................................................... 5
Appendix A -- Summary of Best Management Practices to Apply ...................................................................... 6
Appendix B – The Reasons for Recommended Best Management Practices .................................................... 6
Sustainable Stormwater -- Rainwater Harvesting ........................................................................................... 6
Reduce Disturbance ...................................................................................................................................... 6
Save a Tree ................................................................................................................................................... 6
Table of Figures
Figure 1.
Minimum depth to bedrock ........................................................................................................... 3
Figure 2.
Downstream Flooding from Upstream Development..................................................................... 4
Figure 3.
Detail of a compost berm .............................................................................................................. 5
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Introduction
The school is already utilizing a number of good approaches to develop the site including saving many
significant trees and minimizing disturbance through careful grading. This report summarizes additional
possible development opportunities (aka best management practices) that can be applied to the site design to
minimize impacts to both on- and off-site resources. Clicking on the underlined text peppered throughout this
report will take you to various related websites for additional information. Graphics may also have links.
To Be or Not to Be (Pervious Pavements)
Pervious pavements are probably a waste of money at this site for a few reasons:
1. Pervious pavements would not be good collectors for a rainwater harvesting system.
2. Bedrock is rather shallow, which complicates the design. Care would need to be taken in the design of
any pervious pavement to ensure that there is a minimum of 3’ of native soils between the bottom of the
pavement section, which includes the pavement course or paver and the base rock below, and the top
of the bedrock.
Quick sketches to illuminate
confusing concepts may be
included.
This report is meant to be
delivered electronically so
that live links for additional
info can be accessed easily.
Figure 1.
Minimum depth to bedrock
However, if the rainwater harvesting system is value engineered from the system later, the prospect of
using pervious pavements might be revisited since structural soil could be imported to create the 3’ of
soil depth needed.
3. Due to the “sticky” nature of the native soils when water is concentrated over it, a special subgrade
grading plan would need to be generated to ensure that rainfall infiltrates uniformly.
4. The use of pervious pavements for the sidewalks at this site is probably not warranted. If this were a
small, infill site crammed for space, pervious sidewalks would be a good investment, but since there’s
copious open space for runoff from small areas to flow into and be treated both for water quantity and
water quality. The City of Portland’s Stormwater Management Manual has a detail of filter strip that
would be a cost effective solution for stormwater. An even less formal strip of grass would also do the
trick!
However, if the aesthetic of pavers is desired, then they might as well be designed to be pervious to
serve as an educational/demonstration component for the school.
Sustainable Stormwater – An Overview
Before development, some rainfall became runoff, some of it was evapotranspired by trees and other
vegetation, and some of it infiltrated into the ground to recharge the aquifer and to become base flow to feed
water to streams and rivers downhill. After development, land cover is usually changed dramatically –
impervious areas for buildings and vehicles are added and rainfall can no longer infiltrate to recharge the
aquifer. There are usually fewer trees to evapotranspire rainfall. The loss of these two important stormwater
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I give an overview of the concepts
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behind important but sometimes
complex issues as needed. I try to be
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succinct, but as my client, you can
always ask me to expand my
explanation!
management components means that much more rainfall becomes runoff. And, the runoff flows at a much
faster pace after we put it in a pipe. Conventional stormwater management sends all the additional
downstream volume for a much longer period of time to scour streambanks and associated habitats and create
flooding conditions at the bottom of the watershed.
Photos may be incorporated
to stress a point or clarify an
approach.
Photo courtesy of Walter Siegmund
Figure 2.
Downstream Flooding from Upstream Development
The amount of rainfall that becomes runoff, infiltration, or evaporation is called the “water balance”. The postdeveloped water balance should be modeled carefully to assure that the pre-developed water balance has
been mimicked. The following sustainable stormwater approaches, when used with the right mix, can provide
for the needs of the watershed and the immediate needs of the new building’s inhabitants.
Graywater Recycling
Discussion of how best to integrate Graywater Recycling here.
Rainwater Harvesting
Discussion of a few ideas for incorporating rainwater harvesting into the landscape and storage options
with links to resources on the internet and photos of examples. Also, I discuss how this approach might be
incorporated into the school’s curriculum.
Overland Flow through Rocked & Lined Swales
A discussion of the importance of overland flow and a hand drawn detail/sketch of how rocked and lined
swales could convey runoff.
Materials - Plastics
This was a discussion regarding the toxicity of various materials that are indicated to be used on the plans and
suggested alternatives.
Erosion Control
California is one of the strictest erosion control jurisdictions; however there are still some things we can do that
the state doesn’t necessarily require.
Trees that are being removed can be ground up on-site to be reused as mulch to stabilize bare soils or as a
compost berm or compost sock for erosion control. Compost berms and socks are used in a similar fashion to
sediment fences in that they reduce suspended solids carried in sheet flow; however, they are much more
effective at removing turbidity than sediment fences.
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Each report is tailored for the
project. This project was in
CA, so I found a good native
seed supplier there.
Figure 3.
Detail of a compost berm
When bare soil will be exposed for a few days, hydroseeding is required. This seeding should be done with a
native seed mix. This will reduce the introduction of troublesome invasive species that may be difficult to
maintain when the site becomes established.
Save a Tree
I talk about how to save a tree and how and why some trees on the plans may not survive.
Reduce Disturbance
This section discusses ideas for reducing disturbance during the planning, design, and construction phases of
the project.
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Appendix A -- Summary of Best Management Practices to Apply
This section distills all the recommended best management practices discussed in the report into a sentence or
two for easy reference. Examples:
1. Install impervious concrete pavements (or light-colored pavers)
2. Harvest rainwater from the roof for potable uses inside building, especially for flushing toilets during the
rainy season when the water storage tanks are full.
For people in a hurry (i.e. everybody in
3. etc.
land development!) 
Appendix B – The Reasons for Recommended Best Management Practices
This section summarizes why the recommended best management practices are important with links to studies
to support the claims.
Sustainable Stormwater -- Rainwater Harvesting
If rainwater is harvested for building uses as suggested above, harvesting rainwater can:

Reduce energy use and greenhouse gas emissions generated to convey potable water

Etc.
Reduce Disturbance
Disturbance of soil should be minimized to:

Reduce the potential for the emission of greenhouse gases

Etc.
Save a Tree
Save a tree because trees:

improve air quality

reduce the heat island effect and greenhouse gas emissions
o
EPA: Heat Island Effect
o
EPA: Trees reduce cooling loads

provide erosion control by holding soil

treat stormwater with microbes on the roots that eat pollutants
o

EPA: Bioretention pollution control study
increase property values
o
USA Today article, July 1994
o
Washington Post, September 2006
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
protect biodiversity

reduce runoff volumes

reduce stream temperatures
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