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Living More Lightly:

A Resident’s Guide to Low-impact Development

Produced by Washington State University Thurston County Extension

With Funding from Puget Sound Partnership

DRAFT—This document is currently being edited and produced by Puget Sound Partnership. This draft is for educational purposes only & not intended for distribution.

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Acknowledgements Funding This publication was produced with funding by the Puget Sound Action Team, and will be forthcoming from the Puget Sound Partnership. Author Erica Guttman, WSU Thurston County Extension, Native Plant Salvage Project Photos Erica Guttman Linda Andrews Gary Schuldt Concrete Council Interlocking Concrete Pavement Institute Pin Foundations Inc. Thurston County Stream Team Advisory Committee In preparing this booklet, we are grateful to our advisory committee for their guidance:

Toni Droscher, Puget Sound Partnership Curtis Hinman, WSU Pierce County Extension David McDonald, Seattle Public Utilities Rae Ann McNally, Puget Sound Partnership Joy Monjure, City of Bellingham Robert Simmons, WSU Mason County Extension Bruce Wulkan, Puget Sound Partnership

Other Technical Guidance Many thanks to these individuals for their assistance: Linda Andrews, Linda Andrews Landscape & Design

Patrick Carey, Hadj Design Rick Gagliano, PIN Foundations Andy Gersten, Gersten Company Dustin Glist, Invisible Structures Chris Jackson, City of Olympia Water Resources Jennifer Johnson, Thurston County Environmental Health Andrew E. Marks, Puget Sound Concrete Specifications Council Elliott Menashe, Greenbelt Consulting Andrew Potts, Cahill Associates David R. Smith, Interlocking Concrete Pavement Institute Brian Taylor, Magnusson Klemencic Associates

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Low-impact Development: Protecting our waters as we grow The Puget Sound lowlands are beautiful and life here has many rewards. So it’s not surprising that more people than ever want to call the Puget Sound region home. By 2025, an additional 1.4 million people are expected to move here. As we grow, we replace forests and prairies with rooftops and pavement—increasing the stormwater that runs off and harms local waterways and Puget Sound.

Tips for Using this Guide

Pressed for time? You don’t have to read this guidebook cover to cover. But you might find it useful to at least skim through all the sections to see what LID ideas might work for you. Some ideas may apply more to new construction or home additions.

How much will it cost? Wherever possible, this guide will

provide cost information. Costs can vary depending on factors such as your location, site access, time of year, and how much you do yourself vs. hiring professionals.

How hard is it? You can do many LID strategies yourself,

for very little cost and sometimes savings! Other ideas may require you to seek expert advice. Still others might require you to hire a professional. This guide provides tips in each section so you’ll know when to seek help and where to go for assistance.

New construction: If you’re building new, look out for the

blue text for extra suggestions.

Fortunately, low-impact development (LID) is catching on as a way to grow smarter and reduce the problem of stormwater runoff. This guidebook is filled with lots of useful ideas to help protect and conserve the water you depend on, while also beautifying your home and yard. What’s the problem with stormwater? Around your house, you might find stormwater a problem when heavy storms cause flooding around your foundation or in your basement, and you have puddles on your walkways and driveway. But even if you don’t see it, stormwater is a problem in your community. Stormwater—and the pollution it carries—is causing problems in our region. Here are some of the consequences:

Several species of Northwest salmon face the threat of extinction. Numerous beaches on Puget Sound are too polluted to harvest shellfish. Pollutants—such as motor oil, yard chemicals, and pet wastes—get picked up by the stormwater

and end up in our local waterways, threatening human health and wildlife. English sole are developing liver disease in association with contaminated runoff from roadways. Winter rains flood streams, threatening buildings and eroding farmland. During summer and fall, many streams lack sufficient water to support fish because rains have

rushed off the landscape instead of recharging groundwater aquifers. Looking for LID

If you’re in the market for a new house, consider a home designed with LID in mind. In addition to seeking features described in this guide, look for:

Sites with mature vegetation. Houses with a smaller footprint. Developments whose common spaces

contain lots of trees and shrubs. Location offers you more sustainable

transportation choices, such as: short walk to a bus stop; sidewalks and bike lanes to encourage less driving to work and errands; close to markets, workplace, and other places you go often. The less we all drive, the fewer roads will be built or widened—helping us preserve our communities and keeping waterways cleaner!

After development, stormwater is no longer managed naturally in the forest. Photo courtesy of Thurston County Stream Team.

Our typical ways of developing land aren’t working. When we clear and grade the land to make room for more houses or shopping centers, we replace natural systems that have processed our heavy rainstorms for eons with engineered systems that aren’t as effective

as Mother Nature. In an undeveloped system, native soils and many layers of plants slow down and absorb our heavy

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winter rainfall. The water slowly seeps into the ground to replenish our aquifers, evaporates back into the atmosphere, or is used by plants. Only a tiny fraction (less than one percent) runs off the land.

Sustainable Landscaping: Building soils with compost and planting water-wise plants that don’t need supplemental watering combine two key LID ideas.

After development, the rain hits roofs and pavement and is channeled into storm drains. The drains release fast-flowing stormwater into creeks, ponds, and sometimes directly into Puget Sound. We expect detention ponds to prevent flooding, remove pollutants, and recharge aquifers. What is “Low-impact development” and how can it help? LID techniques look to nature for managing stormwater, conserving water, and keeping pollution out of our waterways. Some LID strategies include:

Save native soils, forests, and prairies by grading and clearing as little as possible.

Build rain gardens that manage stormwater on site. Capture rainwater to re-use around your yard. Build pervious driveways, walkways, and patios that allow stormwater to absorb back into the

ground instead of running off. Minimize the use of yard chemicals to protect groundwater and surface waterways. Install a green roof that absorbs stormwater and slows down the run off.

Be a Good Water Neighbor!

Before you start putting LID to work around your house, consider talking to your neighbors about your plans. Help them understand what you’re doing. You might find they’re interested in joining forces with you! Remember:

Stormwater knows no boundaries. Often, what happens on your lot affects your neighbors’ property, and vice versa.

Water flows downhill. If you live at the bottom of a neighborhood slope, you should be concerned about drainage. You might have a neighbor with the same concern. Consider working together to share costs and labor. As a team, you might manage stormwater more effectively, too.

Pesticides can travel across property lines. Work with your neighbors to reduce or do away with pesticides and herbicides in your yards. You’ll all be healthier, and so will your community’s water!

Green spaces make good neighbors for wildlife. If you want to attract birds and butterflies, joining forces with a neighbor with similar goals can create a bigger swath of green space, which helps create better habitat.

Who can do LID? You can do LID if you:

Live in a city on a small lot. Live in a suburban development on a large

lot. Live in a rural setting on many acres. Are planning to build a new house or an

addition. Have a lawn or garden. Have hard—or impervious—surfaces, such

as a patio, walkway, or driveway. Need to deal with a drainage problem. Want to add value to your home. Want to create beautiful outdoor-living

areas. Want to create privacy in your yard. Want to attract birds and butterflies to your

yard. In short, everyone can do LID, for all kinds of reasons, no matter where you live or the size of your lot! Let’s get started planning your LID activities!

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Section 1: Getting Started with LID Step One: Evaluate Your Site

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Taking stock of different features of your site will help you understand how water moves around your property and which particular LID strategies might help you better manage stormwater runoff from your property. If you’re doing new construction, your evaluation will need to be much more complete. You’ll likely need help from professionals involved in planning your utilities and wastewater systems. Here are some features of your site that you’ll want to understand better. Make a simple map of your site so you can mark these features. Or, mark them on construction plans or on photos.

Topography: Understanding the three-dimensional lay of your land is a good starting point to consider your possibilities and look out for potential concerns. Your terrain will affect how water flows and drains across the property. Sudden changes in elevation might be places where natural springs occur—often seasonally. Sunken areas may have seasonal water and might have different soils than other parts of your property. If you have steep slopes on your site, you need to ensure that they remain stable with a healthy cover of trees and shrubs.

Steep Slopes If your site has steep slopes, including marine bluffs, you will need to be especially careful in developing or planning LID strategies. Avoid removing vegetation from the slope or the slope edge. Replant any cleared areas as soon as possible with trees and shrubs to prevent erosion and intercept stormwater. If your property includes steep slopes, learn how water flows and drains within the slope as well as across it before using LID strategies. For instance, rain gardens should almost never be placed near a home on a marine bluff, and must be sited at least 50 feet back from any slope greater than 15 percent. See the resources section for helpful guides to understanding and replanting slopes.

In evaluating your topography, be sure you note where your house is placed (or where you’re considering placing it) and how drainage and slopes might affect it.

Water: As you begin assessing your topography, you’ll start to get a sense of how water flows and drains on your site. Understanding your water flow will help you decide what kinds of LID projects will help you and where you can place different drainage systems. Make note of:

o How and where your roof, driveway and other hard surfaces drain during rainstorms. o Obvious standing water (wetlands, seasonal or year-round streams, ponds). o Natural springs, which can be identified by spongy ground or the presence of moisture-

loving vegetation, such as skunk cabbage, buttercups, willows, or salmonberries. o Other water coming onto your property, such as from drainage ditches, swales, or runoff

from developments up hill from you. o Saturated soils or seasonally wet spots, which will be spongy or mucky to walk through

during winter (at least), and are usually in depressions in the ground. In evaluating your site’s water, check with your local water utility to see if your property is in a wellhead protection area or near one. There are usually regulations that govern what you can do if you’re in proximity to a drinking-water source. Additionally, the staff from the drinking-water-protection office might be able to help you with your LID project or might have information about incentive programs.

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Soils: The soils on your property are critical for absorbing stormwater. Your soils hold the key to many LID options, including landscaping, pervious paving systems, and rain gardens. The more information you can gather about your soils, the more you will understand the range of LID choices available to you. If you’re doing new construction, you will likely be required to gather detailed information about your soils, including possibly a report from a specialist.

If you’ve done any gardening on your site, you might have a general sense of your soil, such as how rocky or sandy it is, or if it has a lot of clay. To do many LID strategies, you’ll need to have some detailed but simple information about your soil. Fortunately, there are easy tests that almost anyone can do:

o Shovel test: If you can’t get a shovel in the ground with moderate force, you either have terribly compacted soils or most of your topsoil has been removed during development.

o Hand-textural analysis or ribbon test: This simple test helps you determine about how much clay, sand, and silt your soil contains. This information tells you how quickly water drains through and how available nutrients are to your plants. This test can be done in minutes with a small soil sample using just your hand and a little water. See the resources section for a step-by-step guide to doing this test.

o Simple pit test: Dig a two-feet wide by two-feet deep by two-feet long hole and fill it at least halfway full of water. Track how fast water drains. At one-half inch per hour, your drainage is adequate to do a lot of LID practices, and one-inch per hour is great! If your soil drains less than one-half inch per hour, you can still do many LID practices, but you might want to seek help from a soil expert, such as from your conservation district or extension office, to give you more details about your soil. If you dig your test pit during the dry months, fill and drain the hole

three times to simulate wet-weather conditions. o Soil analysis: Check with the staff at your local

conservation district or extension office to see if they offer free or low-cost soil analyses. They’ll give you instructions for gathering samples, and their reports will tell you more precisely what kinds of soils you have, how much organic matter is present, and even some information about nutrients.

A simple pit test will tell you how well your soils drain.

o Soil surveys: Natural Resources Conservation Service produces soil surveys, which are available on the Internet, at your library, or directly from your local conservation district or NRCS office. However, soil survey information is usually general. Another problem with soil surveys is that soils often get disrupted or removed during development, so the surveys might tell you what kinds of soils used to be on your site, not necessarily what’s there now.

Other soil tips:

o Test for different soils: If you have changes in topography or vegetation, you should check to see if the soils under those spots are different than other areas on your site.

o Clay: You might find ribbons of clay here and there, which is different than wide expanses of clay. If you have soils that are mostly clay, you will have to add a lot of organic matter to your soils (see pages 11-12) to be able to absorb most of your stormwater on your property.

o Groundwater: Keep an eye out for signs of perched groundwater or a high water table. While digging your test pit described above, look out for rust-colored veins or steel-gray patches. If you see these signs, you might want to consult with a specialist, such as a soil

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scientist or hydrologist, to provide details about potential underlying drainage problems in your soil, or the limits to on-site infiltration of stormwater. If water starts pouring into your hole while you’re digging, it’s a sure sign you have perched groundwater or a high water table, but this might only happen during winter. Depending on the depth, perched groundwater might limit your site’s ability to absorb stormwater, especially through a rain garden (see page 19).

o Organic matter is an important part of healthy soils. It also holds on to a lot of water and releases it slowly after rainstorms. Most visual tests, such as pit tests or ribbon tests, won’t give you good information about how much organic matter your soil contains. An undisturbed forest, for example, will have a lot of organic matter in the soil from the years of leaves and other materials decomposing in the soil. Section 2 will offer details for how and when to increase organic matter in your soil.

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Vegetation: Documenting the existing plants

on your site is the next step in your site evaluation.

o Mature vegetation: Take note of big trees and shrubs, along with healthy layers of low-growing shrubs and groundcovers. Places with mature vegetation on your property will likely have soils rich in organic matter and will already be doing a lot to absorb stormwater on site. Mature vegetation might include native plants, but non-native plants are great as long as they aren’t weeds!

A large expanse of open lawn might be a good candidate for conversion to planting beds or a rain garden.

o Planting beds: These areas might include landscaped areas where the soils have been built up with new topsoil or compost. Planting beds absorb some stormwater, but not as much as mature vegetation. Sometimes you can modify existing planting beds to be LID features, such as rain gardens (see page 19) or more expansive, layered planting areas (see page 14).

o Lawn areas: Lawns don’t usually absorb stormwater effectively, especially where underlying soils were removed and compacted during construction or they have not been well amended with organic matter. Some lawn spaces are good candidates for creating LID areas, such as rain gardens, pervious patios (see page 19), or expanded, layered landscaping (see page 14).

o Invasive plants: Invasive plants are those that will try to take over an area so nothing else can grow. You will need to remove these before you can install appropriate, sustainable plantings. Some invasive plants of concern: English ivy, Scot’s broom, Himalayan blackberry, traveler’s joy (Clematis vitalba), Japanese (and other) knotweed, some varieties of butterfly bush, herb Robert, and field bindweed. The resources section includes guides to help you identify your invasive plants and get tips for removing them.

Hard surfaces: Your map should note paved or highly compacted areas where stormwater can’t

absorb, including: o Structures with roofs o Sidewalks or walkways o Driveways o Patios or other paved or mortared surfaces

Wildlife value/potential: If your site is completely cleared, it may be hard to imagine the potential to attract wildlife such as birds, butterflies, small mammals, and amphibians. But even a

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small lot can provide habitat in just a few years with the right plants in place. If you have connections to other greenways—a neighbor’s yard with mature vegetation, or a nearby park, for instance—the potential to attract wildlife is even greater.

If you already have mature vegetation, you’ll want to take note of some of the animals already using the space so that your development plans don’t disrupt important habitat and so your LID practices can enhance it.

Next steps: Now that you know what your site conditions are, let’s look at the specific LID options that might be good choices for you! Step Two: Identify Options & Benefits In evaluating your property, you might have identified many areas where you can put LID into practice. As you consider the LID options outlined in Section 2, keep in mind what will work best on your property based on your site evaluation. Many LID options can have multiple benefits. For example, in addition to absorbing stormwater on your property, you could see these additional benefits:

Privacy and noise screens (planting trees and shrubs, for instance, pages 14-15).

Multiple benefits: Planting in layers will not only help you manage stormwater on your property, but will also provide privacy, noise reduction, a home for birds and butterflies, and reduced yard maintenance.

Healthier, disease-resistant plants and improved health for your family (building soils with compost and avoiding pesticides, pages 11 & 16).

Birds and butterflies using your yard throughout the year (planting in layers, avoiding pesticides, pages 14-16).

Drainage kept away from your house foundation and basement (directing downspouts to rain garden, page 19).

No more messy puddles during winter storms (pervious paving techniques, pages 21-26). Step Three: Make an Action Plan Once you’ve made a list of LID techniques appropriate for your site, you’ll need to figure out how and when to do your projects. Your action plan should:

Prioritize projects.

Many LID projects can be done more quickly with the help of rented equipment. If you’re planning a big project, your action plan should prioritize your tasks so that disruptive projects are done first and you don’t get “boxed in.”

Define a realistic timeframe for each project. Establish a budget. Identify steps necessary to complete each project.

If you’re doing new construction or an addition on your home, your plan will be clearly defined by your construction schedule. Bear in mind that there may be more steps in making sure your LID goals are met, including bringing your contractor or planning officials up to speed on your LID plans. If you’re doing retrofits on your current home, your timeframe may be determined by natural replacement opportunities, such as when a roof or driveway needs to be repaired or replaced.

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Most opportunities for making modifications will depend on your own schedule and resources. Make lists of what you have and what you’ll need. For example:

Labor (your own, hours offered by family and friends, and hired help). Tools (your own and those you can borrow). Transportation of materials (such as stones or soil). Materials (such as compost, soil, plants, pavers, roofing systems). Expertise (which could be free from public and non-profit groups or bought from professional

designers, installers, and other experts). As you develop your plan, keep these tips in mind:

Don’t box yourself in: Make sure you maintain access for any part of your project that might require heavy equipment. That might mean prioritizing your “to-do” list so that you finish disruptive projects before activities such as planting.

Time: Many LID projects can be done quickly, especially with some help from friends and family. Other projects may take longer and require you to plan carefully, especially when working with contractors and permitting agencies. To avoid feeling crunched for time, build reasonable time lines into your action plan (and remember that almost all projects usually take longer than you imagine they will).

Budget: Even if you’re on a limited budget, you can still do many LID strategies. o Some public agencies offer grants and

other incentives for residential LID—check with your city or county.

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o Many LID techniques are low-cost or save you money. Eliminating pesticides and conserving water will save money. Improving your soils and planting in layers can be done for little cost (see resources for ideas).

o Some public agencies and non-profit environmental organizations help residents try LID techniques by offering advice and sometimes tools and materials.

o Some public agencies offer funding to residents willing to do LID projects that can be models for others.

o Some LID projects, such as green roofs, may cost more up front but will save money over time.

o You can enlist the help of friends and family members to tackle some do-it-yourself projects. Ask other friends to help prepare food to keep the workers fueled all day. You’ll be surprised by how much you can accomplish with good planning and a team of committed friends for a day!

Start Permitting Early: LID is catching on in communities throughout Puget Sound. However, some counties and cities aren’t familiar with many of the concepts of LID. If any of your projects will require a permit, it’s a good idea to get local officials involved early in your project.

Find out if your planning and permitting department staff members are knowledgeable about LID ideas, such as rain gardens instead of required dry wells. Setting up an early meeting to discuss your plans might save you extra time and disappointments later on.

Some local governments offer incentives through their stormwater departments that can support your LID plans. Incentives can include financial support or technical help.

Find out what codes or regulations might affect your plans, including design guidelines. If you’re doing something unconventional, you might need extra time to get approval.

In the resources section, you’ll find tools to take with you when you go to meet with planning staff.

New Construction: If you’re building a new house or an addition, you’re in a wonderful position to explore and pursue many LID strategies! Consider these options:

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Retain soils and native/mature vegetation: The physician’s oath, “First do no harm,” should be your mantra when planning new construction. Avoid grading and clearing wherever possible. To the greatest extent you can, save large intact sections of mature vegetation and accompanying native soils (see Working with contractors to save your trees, below).

Restore plants & soils: Where soil must be disturbed for grading and construction, restore soil functions by breaking up compaction, stockpiling and replacing topsoil, or tilling in compost before replanting (see page 11). If you clear areas with healthy native plants, you can dig some up and replant them in your landscape after construction (see resources for tips on this).

Careful siting: You have a golden opportunity to place your home, other structures, utilities, and driveway in the best location to lessen your impact. Some ideas include:

Place your house closer to the access road, to leave the back of your property undeveloped. Share partial driveway access with a neighbor. Place your home and utilities in areas that are already disturbed or have poor soils. Carefully routing your driveway through tree stands to minimize cutting. Consider setbacks in regulations as a minimum and place your structures even further away

from sensitive habitats, such as marine shorelines, wetlands, or streams. Early LID design: Plan early to include LID techniques such as:

Small footprint (see page 33). Foundations that require minimal excavation (see page 33). Pervious paving systems, based on soils analysis for best infiltration (see pages 21-26). Stockpiling and replacing topsoil or amending site soils with compost (see pages 11-12). Rain gardens or other on-site stormwater-management systems, based on site evaluation

information (see page 19). Grading impervious surfaces to flow to on-site stormwater-management systems. Erosion-control and sediment-control systems that protect pervious-pavement systems from

clogging.

Mature trees are irreplaceable for LID benefits, wildlife, privacy, and slope stability. Work with your contractor to save them.

Good engineering for green roofs (see pages 30-32).

Working with Contractors to Save Your Trees Your trees will need your help to survive new construction! Long before ground is broken on your project, you must provide root-protection zones around all mature vegetation within the construction zone. More than 90 percent of a tree’s fine feeder roots are in the top three feet of soil, and over half of them are in the top 12 inches! Depending on the type of soil and depth of the water table, larger diameter anchoring roots—critical to protecting the tree from windthrow—may extend to 15 feet deep. These anchoring roots may also be present as fairly shallow lateral roots in fine-grained or wet soils. Damage to both the feeder and anchoring roots can happen with a quick, accidental slip of a backhoe, or over a few days by compaction from construction vehicles driving over the roots, especially in wet weather. Even piling a few inches of extra soil on top of this sensitive zone can impair a tree’s ability to function. Here are some basics for saving your trees:

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Initial assessment: Hire a qualified tree specialist with International Society for Arboriculture Certification to evaluate your trees. Make sure the trees you want to save are all worth saving (some may be unhealthy already or be species that are known to be hazardous in developed landscapes).

Sizing root-protection zone: Forest specialists advise using the tree’s trunk diameter at breast height,

or DBH (4.5 feet from the ground), as a guide for protecting your trees. o For every inch of DBH, protect a minimum of one-foot radius (for instance, a 10-inch DBH

requires a minimum 10-foot radius of protection). o Shallow, compacted, or saturated soils might require up to twice as much room. o Deep, well-drained soils may only require two-thirds that distance. o Make the root-protection zone as big as you can.

Written plan: Overlay your root-protection zones on your construction plans and go over details with

the contractor and all subcontractors. Ensure that all contractors understand that they will be financially penalized for any damage to trees or their roots.

Fencing: Protect this zone (and the trunk and branches) from damage by installing secure fencing

around each zone. Make sure the fencing cannot be easily knocked down. Suggestions include temporary chain-link, securely anchored barbed-wire strands with bright flagging attached, or bright-orange plastic fencing attached to well-anchored fence posts. Check fences regularly during construction.

Contract penalties: A mature tree is irreplaceable! Make tree protection part of your contract, with

severe penalties for negligence. Prohibited practices within the root-protection zones should include: o Vehicular traffic or parking. o Storing materials. o Grading. o Dumping chemicals or other materials. o Piling extra soil, even for temporary storage. Never permit the soil level to change within the

root zone.

Prior to construction—especially if you can’t protect them at the levels recommended above—prepare your trees by watering them deeply. Then apply two to four inches of mulch (such as wood chips or “hog fuel”) around any unprotected impact zone. Ensure that utilities are bored rather than trenched through the root zone.

Repair any injuries to broken branches or torn roots by cutting them cleanly with pruning saws.

Monitor trees for signs of stress or damage and have them inspected by a qualified arborist to ensure they do not become hazards.

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Section 2: Specific LID Options I. SUSTAINABLE LANDSCAPING PRACTICES A well-designed yard can be a beautiful extension of your house, a place to relax and entertain, a place to play, a place to grow food, and a worthwhile investment. While you may not be able to see it, your yard can also help protect drinking-water supplies, streams, lakes, and Puget Sound, as well as the salmon, shellfish, birds, other wildlife, and people that depend on clean water. You will be able to enjoy visits from birds and butterflies—and a healthier yard for your family—as you create habitat right outside your windows. Keys to sustainable landscaping:

Building healthy soils Planting in layers—like a forest Smart plant choices Safe pesticide practices “Just enough” lawn & healthy lawn care Pervious decks, patios and walkways Managing drainage on site

Building Healthy Soils Healthy soil grows healthier plants, allows stormwater to infiltrate, stores water for plants in the summer, and reduces the need for chemicals—such as fertilizers and pesticides—that are bad for streams and our families’ health.

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Healthy topsoil has 50 percent pore space (half its volume is available for stormwater storage!). But construction-compacted and stripped soils may have only 5 percent. Because it covers your whole yard, improving your soil is the easiest way to slow and infiltrate stormwater, and healthier soil makes your yard beautiful, too! You’ll know if you have healthy soils if:

You can dig in a few feet without needing a pickaxe. Your soil is loose and open, and absorbs water easily. Plants are growing robustly, showing signs of having water

and nutrients readily available. The top 6 to 12 inches shows signs of organic matter, with

a rich brown color like decomposed leaves or compost. Your soil feels smooth and crumbly, and it smells sweet

and earthy. You have lots of earthworms (they live on decaying

organic matter, and keep the soil loose and fertile). Some rocks and bits of clay are a natural reflection of your soil, but if your soil is consistently as hard as a rock, or mostly clay, you’ll benefit by improving it with compost and mulch. If your soil has been removed or compacted by machinery during construction, you’ll need to

Healthy soils mimic our forest soils: Adding compost we make from yard trimmings is similar to the broken-down leaves and other organic matter on the forest floor.

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break up the compaction and mix in compost, or add a compost-amended topsoil, to get off to a good start. Benefits of Compost Compost is the earthy-smelling material that is produced from decaying matter. You can buy compost or make your own from yard trimmings and food scraps. Compost is an essential part of healthy soil, as it supports a complex web of hard-working soil organisms that regulate soil moisture, aerate the soil, and maintain soil fertility. Compost increases the soil’s ability to absorb rainwater, and it filters pollutants.

How to Recognize Good Compost When buying compost, always visit the supplier to see and feel the product first hand. Note these features:

Texture should be loose, fibrous (not clumpy or gooey).

Color should be dark brown or black. Smell should be sweet and “earthy.” Check for weeds, such as white runner-

grass roots. Check for poor screening, such as big

chunks of material. Check for signs of unfinished

decomposition, which can tie up nutrients in your soil until it finishes composting.

Buy compost produced at a permitted composting facility – they have to meet stringent quality standards.

The Washington State Department of Ecology lists permitted composting facilities; see the resources section for details.

There are billions of organisms in just a spoonful of healthy soil, including earthworms, insects, bacteria, fungi, and protozoa. Where natural organic matter is lacking in soil, compost reinvigorates soil with these hard-working organisms. What this means for you is a more beautiful yard and reduced water bills. For your whole community, it means cleaner groundwater, streams, and Puget Sound.

Soil organisms recycle and store nutrients, making them readily available to plants.

Soil organisms help keep disease-causing organisms in check, resulting in healthier plants.

Compost keeps soils more open so plants’ roots can penetrate farther into the soil.

Compost is the solution to help clay soils drain better and support more plants.

Compost soaks up rainfall and stores it for plants’ use over time.

Compost-amended soils slow down and soak up excess stormwater runoff, protecting streams by reducing flooding and allowing time for rainwater to recharge groundwater aquifers.

Compost-amended soils filter pollution, including oil, pesticides, and heavy metals. Some of the soil organisms in compost-amended soils bind up, break down, or convert harmful

pollutants to keep water resources cleaner. When & How to Add Compost

On new construction sites, till two to four inches of compost in to an eight- to twelve-inch depth to get a good start for lawns or landscapes, and to absorb stormwater.

In new garden beds, dig in or till in one to four inches of compost. Continue to amend garden beds over time by adding up to two inches each year—especially if you

have clay soils. To increase the health and drainage of your lawn, rake in one-quarter to one-half of an inch of

compost in the spring or fall after aerating. Add compost to an entire planting area, not just in the planting hole.

For more details on building good soils with compost and mulch, see “Growing Healthy Soil,” listed in the resources section.

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Mulch: Applying mulch is another way to build healthy soils and reduce your maintenance hassles. Mulch is a layer of coarse organic material (although there are non-organic mulches available for certain applications) that is spread on the surface of the soil.

Mulch is critical for conserving water, reducing maintenance, and adding organic material to soil over time. Photo courtesy of Linda Andrews.

Why use mulch? Mulch:

Conserves water by reducing evaporation. Regulates soil temperatures, so your plants are warmer in

winter and cooler in summer. Provides a barrier that prevents some new weed seeds

from getting established in bare soil, can suppress some weeds already in the soil, and makes it easier to pull many weeds.

Breaks down over time, further nourishing your soil with new organic matter.

Prevents compaction and surface erosion of bare soil, and allows for more rainfall to absorb into the soil.

When and how to mulch?

Mulch right away after planting. Mulch about two inches deep around new plants. Apply mulch more thickly between plants—up to three or four inches deep. Keep mulch about an inch away from the stems or trunks of your new plantings—it could cause rot. Re-apply mulch every year or so as it breaks down. Remove weeds before you apply mulch.

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What makes a good mulch? The best mulches are coarse organic material, such as wood chips. Here are some tips:

Request wood chips from local arborists, who will generally deliver them for free when working in your area. (Check to be sure their wood chips are well ground, with just a few larger, unchipped pieces that you can pull out.)

Allow wood chips to compost in a pile for a while before applying them.

Heavier mulches, such as wood chips, prevent more weed growth, and stay in place better than light materials, such as raked leaves.

Coarse wood chips should be chipped or shredded finely enough that they will decompose within a few years and will not be unsightly when applied.

Large sticks or unchipped branches provide too many openings for weeds while also inhibiting the growth of your desired plantings. Avoid mulching with these.

You can buy mulches, including dark bark (black) and beauty bark (red). Dark bark is coarser and therefore makes a better weed barrier than beauty bark. Take care if applying beauty bark, as it has tiny slivers that are difficult to remove from hands and arms.

Well-ground wood chips from arborists make a good mulch to prevent weeds and erosion.

Annual flowers and vegetables do best with a lighter mulch, such as compost, grass clippings and shredded leaves.

Mulch rings made from recycled tires are another option for mulching around trees in a lawn—the water and nutrients can penetrate through the open weave.

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Avoid using landscaping fabrics in planting beds. The fabric eventually becomes clogged with weed roots, binds up good soil, and must be painstakingly removed and disposed to address the weed problem.

Finely ground fresh sawdust (such as from alders), although widely available and inexpensive, can form a crust on top that resists water penetration—use coarser chips or bark instead.

Planting in Layers—Like the Forest Once you’ve enriched your soils, it’s time to think about your plantings. You should aim to plant layers—or different heights—of vegetation wherever possible. Layers mimic the structure of our native forests, with trees, mid-sized shrubs, low shrubs, and groundcovers, providing lots of benefits in your yard:

Planting in layers creates an aesthetically appealing structure for your landscape. Layered plantings offer more seasons of

interest, with varying flowers, fruit, foliage, and bark all in one scene.

Aim to plant trees, large shrubs, low shrubs, and groundcovers to process the most water and provide more wildlife habitat.

Layered plantings do more to slow down stormwater and allow it to evaporate, transpire, and slowly trickle back into the ground instead of running off to storm drains.

Layered plantings offer more habitat potential for animals you might want to attract to your yard, especially songbirds and butterflies.

Layered plantings will reduce your maintenance requirements over time, as the plants will grow more closely together to crowd out weeds.

Trees are especially important. They soak up more rainfall, stabilize slopes, buffer winter winds, and provide summer shade.

In open areas of your yard, you might have just a few layers, such as low shrubs with groundcovers and perennials. In another part of your yard, you can create a little “wildlife zone” with a tree or two and several plant layers below. If you’re on a small lot, choose trees that are well suited to small spaces (see resources section for tips). Good planning: You can make your own landscape plan or hire a professional.

Educate yourself about landscaping options and costs through publications and web sites (see resources section). Take free or low-cost classes offered by your local planning and conservation agencies, extension service, or conservation district.

Even if you hire a landscape designer to help you develop a plan, you can save a lot of time and money by educating yourself so you are clear about your goals and aesthetic preferences.

Becoming acquainted with some of the beautiful water-wise plants available will help you develop a list of plants best suited to your yard so you can shop wisely.

Smart Plant Choices to Protect Water Choosing the right plants for your yard will save you time and money, and will protect and conserve water. Water-wise plants: In our region, we’re lucky to have a wide range of beautiful plants that are adapted to our climate, soils, pests, and diseases. Water-wise plants help protect water because they are:

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Resistant to drought, so they can thrive in our wet winters and dry summers without supplemental water once they’re established.

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Resistant to diseases and pests, so they won’t require extra fussing or the use of chemical treatments that can harm groundwater and local waterways.

Tough and hardy, so they won’t require frequent replacement. Replacing plants uses more water as you repeat the process of getting them well established for the first two summers.

Watershed-friendly Lawn Reducing your lawn size and replacing part of it with water-wise plants will help protect local water resources and cut down on mowing chores. Fertilizers: Chemical fertilizers come into our houses on our feet and wash into local waterways when it rains. Fortunately, lawns can be beautiful and functional without adding fertilizers. Create a healthy lawn with natural lawn-care recommendations such as establishing lawn on compost-amended soils; “cutting it high and letting it lie” when mowing; and occasionally aerating and top-dressing with compost. This approach is healthier for local waterways and for your family. If you do need to fertilize your lawn, organic, slow-release fertilizers will do the most to make your lawn healthy and are less likely to leach or flow off to local waters. Follow natural lawn-care recommendations for when and how to fertilize. Nitrogen in fertilizers can run off your yard and cause algae blooms, particularly in marine waters. If you fertilize, make sure you use “just enough” nitrogen from a slow-release source. Too much can actually encourage unhealthy lawn growth. Phosphorus is an important nutrient for gardens. It primarily benefits flower and fruit production, so not every plant needs it. Phosphorus is found in fallen leaves and grass clippings, and is a common ingredient in fertilizers. Phosphorus is a troublesome pollutant in stormwater runoff. Excess phosphorus in lakes and streams causes algae blooms that block sunlight and prevent other plants from growing. Then the algae mass dies and decays, robbing the water of oxygen needed by fish and other aquatic animals. You can help prevent these problems.

Only apply as much nitrogen and phosphorus as your lawn actually needs. A soil test will tell you how much—if any—is necessary. (See resources section.)

Keep grass clippings and leaves off sidewalks and streets. Sweep them up and place in compost bins or use as mulch.

For sources with more details about making your lawn watershed friendly, refer to the resources section.

See the resources section for lists of beautiful water-wise plants for a variety of conditions.

In our region, there are many beautiful plants for every landscape layer that are water-wise and attractive to wildlife, such as this subshrub called Helianthemum, or sun rose.

Right plant, right place: Once you choose your favorite water-wise plants, make sure you understand their requirements. Some plants are versatile, and can thrive equally well in sun or shade, but many have specific requirements. A shade-loving plant will never be water-wise if it’s placed in the sun, and a sun-loving plant will never thrive in the shade. Group plants by water needs: Sometimes it’s hard to resist a few thirsty plants, even for a water-wise gardener. Plant water-loving plants in their own bed so you can manage their water needs, with either drip irrigation or soaker hoses, or with careful hand watering. Placing these high-need plants closer to your house helps you keep track of when they need a drink. See the resources section for more tips on conserving water.

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Safe Alternatives to Pesticides & Fertilizers Giving up or even reducing your use of chemical pesticides and fertilizers in favor of organic alternatives may be one of the easiest LID strategies to embrace! Benefits:

Improved health for your family and pets. Improved soil function and healthier plants. Improved health for your whole watershed!

We know that chemical pesticides, herbicides, and fertilizers are running off our yards and contaminating Puget Sound streams—researchers found 23 pesticides in a number of King County streams. The most frequently found pesticide is the chemical found in weed-and-feed products.

Instead of using a chemical pesticide that can harm children’s bodies, find ways to involve your children in pulling weeds and planting to prevent weeds and pests.

Toxic products also impact your family’s health. Children absorb chemicals when they play in the yard, and the chemicals come into your house on shoes and clothing. Once inside, chemicals attach to house dust and persist much longer than they do outside where sunlight and rain help them break down. Here are some tips to get started:

Prevent problems: Select disease-resistant plants. Keep your plants healthy with good soil and mulch to make them less vulnerable to pests or diseases. Pull weeds before they can spread. Plant closely to crowd out weeds. Use mulch and groundcovers.

Close plant spacing, groundcovers, and mulch help crowd out weeds. Photo courtesy of Gary Schuldt.

Investigate: Most bugs are good bugs!

Before resorting to a chemical spray, find out what the real problem is. Some plant damage suggests insects are the problem, but it could be from too much sun or other causes. Take part of your problem plant or insect of concern to your local Master Gardener clinic or conservation district office for help identifying the culprit.

Let nature work: Some insect infestations

need to get big enough to attract predatory insects, such as ladybugs or green lacewings. Once the predators arrive, they’ll wipe out the pests, and your plants should recover.

Here are guides for more help, listed in the resources section:

Common Sense Gardening Guides, Thurston County Environmental Health Natural Lawn & Garden Care, Seattle Public Utilities Natural Yard Care, King County

“Just Enough” Lawn

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Only you can decide what size lawn is just right for your family. Some families play sports regularly that require a big lawn; some families enjoy a tiny patch of lawn for summer lounging; and some families have given up all their lawn! Consider these questions when deciding how much lawn area you need:

How do you use your lawn space? Are there parts that are never used?

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Are there parts that are hard to mow (such as beneath trees or on slopes)?

Do you and your family regularly play sports that require lawn at home, or do you go to public playfields and parks?

How much time do you have to mow, water, and weed your lawn?

When you transform lawn space to another use, you eliminate the hassle and expense of regular mowing, watering, and weed care. For your watershed, that means saving water, cutting down on pollution from lawn-care

products, and less stormwater running off lawns. For your neighborhood, that means less noise pollution, less air pollution, and more green spaces to provide homes for songbirds, butterflies, and other small animals.

Sheet mulching: Laying down layers of cardboard or burlap sacks (for hillsides) and then covering with woodchips saves work, keeps soil intact, and adds organic matter to your soil as the grass and mulches decay. In a year or less, you can create a new landscape on a former lawn monoculture.

Former lawn space can become:

New garden beds, providing year-round beauty and wildlife habitat

Pervious patio or walkways (see pages 18-19)

Spaces to grow fresh vegetables and fruit Rain gardens to manage stormwater on

your property (see page 19). Shrinking Your Lawn There are several methods for reducing your lawn when you’re ready. Converting a little lawn at a time is one way to ease in to lawn removal. Sheet-mulching method: Sheet mulching is a smothering method. Lay down four to six layers of cardboard (or burlap sacks, if on a hillside). Next, apply a thick layer of wood chips over the top. Then wait nine months to a year before planting. If you sheet mulch in early spring, you avoid mowing all season and can often plant by late fall. The wood chips prevent erosion and give your yard an acceptable appearance while you wait for your grass to die. Sheet mulching helps retain soil and adds organic matter as the grass and cardboard decompose beneath the wood chips.

Work in small chunks: Try to plan so you don’t take on too much at once and end up with an unmanageable situation. You wouldn’t gut your kitchen without having new cabinets on order; neither should you rip up your yard without having a plan for re-covering bare soil with plants, mulch, and other materials.

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Spot-sheet mulching: This method can be used if you want to get a few plants—such as trees and large shrubs—planted right way, but are willing to wait until later to add more layers of plants, such as smaller shrubs, groundcovers, and perennials.

Making the Most of Your Sod Hauling sod away for disposal is expensive and a lot of work! If possible, recycle it back into your yard by making future planting beds. If you don’t have room, you might have friends who want to build soil in their yards. Pile the sod in areas where you want to build soil. Make the piles a little higher than you want your future beds to be—the sod will settle a little as it decomposes. Cover it with cardboard and wood chips (as in sheet mulching) and let it sit for 9 to 18 months. Decomposition times vary. You’ll find your old pile will make some of the richest soil in your yard, allowing you to reap the rewards of healthier plants that need less water.

In this method, fully clear large circles of grass with a shovel or pick-axe where you intend to plant trees. After planting, apply cardboard layers and wood chips all around the new plantings to kill the remaining grass over the next nine months to a year. Detailed instructions on sheet mulching can be found in links noted in the resources section. Sod-cutting method: Renting a sod-cutting machine is another option for shrinking your lawn. Advantages and disadvantages include:

Very fast results! No need to wait for the grass to die before replanting.

Sod-cutting decreases organic matter as you remove the top layer of soil. More compost will be required to restore soil.

You’ll make a lot of cut sod! Sod can be turned into rich planting soil if allowed to decompose (see box, “Making the Most of Your Sod”).

Sod cutters are heavy and require a strong hand to guide them.

It is very difficult to use a sod cutter on a slope. Sheet mulching with old burlap sacks is recommended instead.

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Outdoor-living Spaces A sustainable landscape will be beautiful and inviting. Once your plants are flourishing, and your yard is alive with birds, butterflies, and other beneficial insects, you’ll want to enjoy it whenever possible. Traditional concrete or mortared patios and walkways contribute to stormwater runoff. But you can create stunning outdoor-living spaces with these LID techniques:

Fig. 3. New plants thrive in decomposed sod pile, creating new garden feature.

Fig. 2. Sod has decomposed for a year, and new bench is created.

Fig. 1. Fresh sod pile.

A big sod pile can be covered

with cardboard and woodchips to decompose

over time. It will become rich garden soil, and can even be used to create an amenity, as shown in this example where

a new garden seat was created from the old sod pile.

Raised decks, including those built with long-lasting decking made from recycled plastics. Decks are a

great place to use a minimal-excavation foundation (page 33) to build a sturdy deck without disrupting your existing soils and landscaping.

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Pervious concrete and permeable pavers (see pages 24-27 for details).

Low groundcovers such as spreading thymes or brass buttons are drought tolerant and able to handle light foot traffic. Use them to fill spaces between stepping-stones to absorb stormwater and add more green space to your outdoor living areas.

Grading your yard so that mortared or tightly built stone patios drain into an on-site stormwater feature, such as a rain garden or dry streambed (see page 19).

Free-draining walkways and patios. Free-draining walkways and patios: You can create walkways and patio spaces in which the hard surfaces—such as stones or broken concrete—are separated by free-draining spaces in between.

Many groundcovers, such as spreading thymes, can handle foot traffic. These can fill the spaces between a woven pathway of stepping stones, flagstones, pavers, or other hard material that offers secure footing. Building such walkways is less exacting than building a mortared patio.

Loose materials, such as wood chips, nut hulls (from processors), or crushed rock, allow water to drain through and provide a uniform look for pathways or children’s toy areas. Loose materials have to be refreshed every few years to look their best, and crushed rock can become compacted, reducing its ability to absorb water over time.

Pervious systems, including stone pavers and interlocking plastic grids that contain crushed stone, can be a great alternative to an impervious patio or walkway (see page 25 for details). These systems are commonly used for parking lots and driveways, and they provide substantial water absorption (generally less than three percent runoff). These systems are also more effective than loose materials for people with physical disabilities who require the use of a wheelchair or other mechanical assistance.

Managing Drainage—Beautifully For many homeowners in our rainy region, keeping stormwater away from building foundations is a headache every winter. LID techniques can help you eliminate this hassle by creating a beautiful landscape feature! There are many ways to effectively manage drainage on your property—keeping it away from your house and out of the stormwater system. Rain Gardens: Building a rain garden or two to collect water from roof downspouts and other hard surfaces is a popular technique for managing drainage. Rain gardens mimic nature, with a mix of plants and soils working together to process and clean stormwater. The water going into a well-designed rain garden will soak back into the ground and recharge groundwater aquifers.

A rain garden mimics the forest with plant roots and rich soils absorbing and filtering stormwater, while also creating a landscape amenity and wildlife habitat.

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Rain gardens are attractive, and can be a stand-alone garden bed, or can be integrated into your larger landscape. They can be designed and shaped to look like a natural pond, or be narrow and meandering like a stream. Because they are so effective at treating pollution, placing a rain garden to receive runoff from your driveway can be especially beneficial to protecting your local water. Rain gardens are dug out 12 to 36 inches, depending on the type of soil. Removed soils are usually mixed with compost and then replaced, leaving at least six inches below the original grade for stormwater to pond for a day or so after a heavy rain. The extra soil can be used to make a berm or for other landscaping. Many wonderful drought-tolerant plants will enhance the beauty of a rain garden in all seasons.

A “dry” water feature can also manage stormwater on site, but is not as effective as a rain garden. Dry streambeds or swales can be used to convey water to a rain garden or to manage water flowing off a driveway.

To learn about how to design and build a rain garden, including a list of recommended plants, read Rain Garden Handbook for Western Washington Homeowners: Designing your landscape to protect our streams, lakes, bays, and wetlands, which is listed in the resources section. Dry “water” features: You can create a different aesthetic that still handles your stormwater by creating dry streams or dry ponds. These are rock-lined features that store and slowly infiltrate stormwater—they only have standing water after a heavy rainstorm.

Although rock-lined dry features don’t contain plants like rain gardens do, you can still create an attractive garden amenity by planting ornamental grasses and perennial flowers along their borders to mimic the aesthetic of a natural stream or pond. The plant list in the Rain Garden Handbook offers suggestions to guide you. You can use some of the same guidelines in the Rain Garden Handbook to design a dry feature. However, since dry features don’t depend on a specialized soil mix or plants to process water, they usually need to be dug much deeper than rain gardens. To handle heavy winter storms, typical dry features may be as deep as three feet or more and then be partially refilled with drain rock. Whether you’re building a rain garden or a dry feature, keep these tips in mind:

You’ll need to safely convey your stormwater away from your house and into your stormwater feature. This can be done underground with secure pipes, or above ground with a feature such as a dry stream, a modest trench, or vegetated berm.

Place your stormwater feature so that you can take advantage of gravity with as little digging as possible.

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During big storms that last many days, you may have more stormwater than your feature can handle. To prevent it drainage or erosion worries, design a controlled overflow system that will take excess rainwater to another site—either to the local stormwater system or another on-site stormwater feature—if the amount of rainwater becomes too great to be processed.

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If you have a perched ground water or a high water table, you may be limited in the depth of your stormwater feature (and you may not be able to build one at all). You must have at least one foot of separation between the bottom of your feature and the highest level of your groundwater.

Call 800-424-5555 for utilities to be located before you dig on your property, and make sure that all utilities have been marked before you dig.

Don’t place a stormwater feature: o within 10 feet of a building foundation. o within 50 feet of a steep slope (over 15

percent). o on a marine bluff without consulting a

specialist, such as a geotechnical engineer or geological consultant specializing in marine sites.

o over shallow utilities. o over a septic drain field or tank. o over major tree roots, or anywhere where digging will disrupt your trees’ roots.

Rain Gardens: Driveway Partners Depending on how your landscape is arranged, building a rain garden (discussed on page 19) near your driveway can be the perfect solution to managing stormwater runoff and treating the pollution. If your groundwater is too high for a rain garden, or you have a slope on one side of your driveway, you could also try a method called sloped bio-detention to slow down your water. In sloped bio-detention, you plant a wide line of dense vegetation along the length of the drainage area. The dense stems of the plants slow down the water and encourage it to absorb back into the ground. Plants such as bunching ornamental grasses and shrubby snowberries work well for this, and can be rejuvenated every year with an annual summer mowing or shearing.

Do place your stormwater feature where you can enjoy its beauty! II. DRIVEWAYS

A driveway designed for LID absorbs and filters water, eliminates puddles, and allows water to reach plants’ roots. Photo: Interlocking Concrete Paving Institute.

Driveways often account for a large amount of a home’s total impervious surface area, making them an important target for LID approaches. The stormwater that collects and flows off driveways contains a surprising amount of pollution—including oil and heavy metals, such as copper and zinc—that threatens fish and other wildlife in local waterways. This pollution comes from:

Cars leaking fluids Fuel spills Gradual wearing of metal parts Washing cars Repairing cars Repairing and cleaning other vehicles, such as

lawnmowers Animal and pet wastes.

Whether you plan to build a new driveway or need to replace one that is in disrepair, you’ll be able to choose from a number of LID solutions.

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Benefits of LID-designed driveways include: Deconstructing Your Driveway

There are many ways to demolish an old driveway, and the method you choose will depend on:

the driveway material; the thickness of the slab (which may vary—

many slabs are deeper around the perimeter and thinner in the interior); and

its condition. Before you begin any demolition project:

Research all available options. Make a plan for the rubble. Determine what safety gear you need—

gloves, safety goggles, and hearing protection are the minimum.

Be prepared for some hard work! Many projects, especially with thinner, deteriorating slabs, may be accomplished with some basic hand tools, such as chisels, sledgehammers, and pry bars. Others may require you to rent specialized drills or diamond-blade saws. If you have a mini-excavator on your site for other tasks, it can make quick work of demolishing a slab and loosening the underlying soil so you can prepare a sound base. Old concrete chunks can be reused for gardening projects or for making a unique broken-concrete mosaic driveway. If you don’t want the concrete, chances are you can find gardeners who will eagerly haul away your “urbanite.” Old asphalt chunks can often be recycled. Check with your local industrial recyclers.

Attractive Can require less maintenance, depending on the

system Durable and long lasting Manage drainage better to eliminate troublesome

puddles Cost effective Reduce impact of stormwater runoff Filter pollution to protect water resources Allow water to reach tree roots

Driveway options: Options fall into two categories: design options and style/material choice. Design options:

The best way to reduce stormwater runoff is to simply reduce impervious surfaces. If you’re building new, reduce the length and width of your driveway to the greatest extent possible, while remaining in compliance with local requirements. Regulations vary by community, but experts recommend eight-foot-maximum widths for straight driveways; nine-foot widths for curved driveways; and 18-foot widths for two-lane driveways.

Share driveway access with neighbors. Grade and pitch driveway so that runoff flows to

an on-site stormwater feature, such as a rain garden (see page 19 for details).

Style and materials choices:

Ribbon driveway Broken-concrete mosaic Permeable pavers Porous aggregate containment systems or reinforced turf systems Pervious concrete or porous asphalt

You can combine design options with a material choice to be more effective. For instance, you could choose a pervious pavement t, grade your driveway to treat runoff on site in a rain garden, and share access with a neighbor. You can also combine style and material choices. For instance, you could create a ribbon driveway with pervious concrete, and the driveway apron or parking area could be a different material, such as permeable pavers or porous aggregate. Ribbon Driveway Sometimes called a “California strip,” a ribbon driveway involves using the least amount of impervious surface possible, while still providing a safe driving surface. Ribbon driveways are built by laying down two strips of concrete, each two-feet wide, with an open middle space in which grass, spreading thymes, or other groundcovers are planted.

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With two-foot wide strips, there will be three feet of unpaved space in between. To be effective, the unpaved space must absorb stormwater well. The top 12 to 18 inches of soil should be loosened and amended well with compost prior to planting. Apply enough compost so that your base is about two-thirds soil and one-third compost (apply more if the soil is clay, or remove some of the poorly draining soils and add in a sandier mix with compost). Alternatively, if you are concerned about potentially driving in the middle section, replace the soil in the middle with a “structural soil mix” that has large rocks in the mix allowing it to bear weight but also be free draining. A soil supplier should be able to help you with this mix.

A ribbon driveway, or “California strip,” places the impervious surface just where it’s needed and allows drainage in the middle and on the sides.

Maintenance: Ribbon driveways require very little maintenance. The unpaved section should be weeded—especially during establishment—to prevent weeds from overtaking the groundcovers or grass. If grass is used, sustainable lawn-care practices should be used, including top dressing with compost each year, which will maintain permeability and keep the grass healthier. Cost: Ribbon driveways can be less expensive than traditional driveways because they use a smaller volume of concrete. However, preparation costs may be higher due to forming four sides instead of two. Depending on your access, there may be additional costs for delivering the concrete. Broken-Concrete Mosaic This style is usually a do-it-yourself project—maybe with the help of a few strong friends! A broken-concrete driveway is usually inspired by an old concrete driveway that has already started to crack. With the help of some chisels and sledgehammers, you can finish breaking up the concrete into manageable chunks. These chunks should be temporarily moved so you can create a more permeable base in the driveway. With the driveway clear, you will need to excavate and/or break up the old, compacted soils and be sure that the top 12 to 18 inches are adequately loosened so stormwater can drain. Then you can add clean gravel and/or sand to make a free-draining base. More excavation will be required in heavier soils than in those that are already free draining. Once you have achieved a suitable base layer of sandy, gravelly soil, you can begin laying your concrete chunks down in an attractive design. References on laying patios will help you achieve the correct grade. Make sure you have enough support for cars’ tires by placing two lines of concrete in two-foot wide blocks five feet on center. You can mimic a ribbon driveway by placing less concrete in the center, where cars won’t drive. Be sure you place concrete chunks far enough apart from each other that you can pull or flame-torch any weeds that settle in the cracks. When all the concrete is placed, you can fill the cracks with attractive crushed rock, sand, or fine pea gravel to hold the chunks securely in place—look for interesting colors to add interest to your design.

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Planning for Weeds The adage “nature abhors a vacuum” might have been coined to describe weeds! Weeds love to colonize cracks in driveways and sidewalks, and they’ll take advantage of open areas in a pervious driveway, too. Plan ahead to prevent problems:

Intentionally plant tough, drought-tolerant plants in gaps that receive foot traffic only.

Fill other gaps with pea gravel or other small stones that will allow weeding.

Check out non-toxic weeding methods appropriate for hard surfaces, such as flame weeders and horticultural-grade vinegar.

See resources section for details.

On the non-driving surfaces, you can add tough groundcovers such as spreading thymes, just like in a ribbon driveway. If planting in spaces between the concrete chunks, add compost to support the plants and add permeability to the soil. Maintenance: If built correctly, your broken-concrete driveway should be trouble free. You will need to occasionally replace the aggregate between the concrete chunks, or sweep it back into place if it is disturbed. Prevent weeds from taking hold in the cracks by removing them or flame-weeding them as soon as they appear. Cost: Since they rely on recycled materials, broken-concrete mosaics are one of the most affordable LID driveway strategies, and they offer you a chance to create a unique, personally appealing landscape feature. Your main expenses will be from soil amendments and any plants you choose to install. Permeable Pavers These pavers are made of pre-cast concrete and are assembled in an interlocking pattern that creates gaps between each stone. The gaps are filled with gravel, allowing stormwater to percolate through. Permeable pavers can withstand very heavy loads and regular, low-speed traffic. Permeable pavers are produced in a range of colors to suit various architectural styles.

Permeable pavers are made in a range of colors and can be replaced in sections if repairs are necessary, offering long-term benefits over traditional paving. Photo courtesy of Interlocking Concrete Pavement Institute.

The key to successful stormwater absorption is creating just the right grading, soil preparation, and base layer below the pavers. Permeable paver systems have specific, technical installation requirements, and are installed by experienced contractors with certifications in working with these materials. To find an installer in your area, use the service provided by the Interlocking Concrete Pavement Institute (see resources). Ask vendors about their specific experience with permeable pavers. (See the tips in the box “Free-draining pavements,” above, for more ideas in finding a qualified contractor.)

Maintenance: Each manufacturer will recommend a specified maintenance plan for its brand of pervious pavers. It’s important to inspect them at least annually and to keep them clean to prevent the voids from becoming clogged. Regular sweeping is usually recommended. If the small stones in the joints become clogged with soil, they should be removed and replaced with clean stones. Cost: Permeable-paver systems can range in cost from $7 to $12 per square foot, installed. (Smaller projects might have a higher cost per square foot.) Permeable pavers have the advantage of being very durable, and—if repairs become necessary—they can be replaced in small sections, making maintenance more affordable than with traditional paving systems.

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Porous Aggregate-Containment & Reinforced Turf Systems These systems are another form of pervious paving in which an interlocking grid keeps free-draining gravel in place or protects grass from compaction. The grid can be made of high-strength plastic, concrete, or non-corrosive metal.

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Reinforced turf systems are most suitable for driveways or parking areas that are relatively flat, as turf is slippery when wet. Grass must be well established before driving on it. As with other porous pavements, these systems require careful work to properly excavate, grade, and prepare the soils and aggregate base layer below the grids. Proper installation is critical for these systems to work; some manufacturers require hiring trained installers, others will provide instructions for those wanting to do their own installations. To find a distributor or installer of high-strength plastic-grid or concrete-grid systems, see the resources section. Maintenance: Aggregate-containment systems are generally trouble free. In high-traffic areas, you may need to refill the grids with new, clean stones, or brush dislodged stones back into place. This should not be necessary more than once or twice per year. Reinforced turf systems require the same maintenance as normal lawns: mow and irrigate as needed. It is not necessary to aerate—in fact aerating may damage structures.

Porous aggregate-containment systems are made in high-strength plastic, concrete, or metal, and are suitable for low-speed driveways and wheelchair friendly walkways.

Free-draining pavements—important tips:

Regardless of what kind of pervious system you choose, keep these tips in mind: Hire qualified, experienced contractors. All these systems are proven to work, but only if they are installed correctly. Ask potential contractors to document their training and experience specific to pervious pavement, and then follow up to check out their work. Traditional paving systems require different techniques, so make sure the projects you investigate are really pervious paving. Make sure suppliers provide materials exactly matching the manufacturer’s specifications. Technical specifications have been developed to ensure that the pervious pavement system functions as designed. Substituting a different material—especially in preparing the site—could render your pavement ineffective for stormwater and structurally unsound. Control sediment. Eroding sediment running off from nearby areas can cause the air spaces in pervious systems to get clogged. Always make sure that sediment is being properly controlled through mulching, planting, and other stabilizing techniques. During new construction, especially, you must be vigilant in preventing muddy construction vehicles from affecting new pervious pavement.

Costs: The systems vary in cost depending on the type chosen, size of project, and where you live. Generally, these systems are comparable in price to traditional concrete paving and about 10 to 15 percent more than traditional asphalt paving. Aggregate containment systems last 15 to 20 years and don’t require repaving maintenance expenses of traditional asphalt and concrete. Reinforced turf systems last up to 60 years.

Pervious Concrete & Porous Asphalt Pervious concrete and porous asphalt look similar to their traditional counterparts, but they don’t include fine aggregate and they are established over a base specifically designed to store stormwater. By not adding the fine aggregate, they have more pores, or air space. The pores allow stormwater to drain through the pavement and into the reservoir base before absorbing back into the ground. Both these pervious pavements have been used in states throughout the country and have performed well in a wide range of climates. Pervious concrete is a specially formulated mix of Portland cement, coarse aggregate, and water.

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Because of the way it is constructed, and the removal of the fine particles, it has void spaces of 15 to 20 percent of its volume. It has an open appearance, similar to exposed-aggregate concrete. Pervious concrete also provides filtering and biological removal of pollutants. The rock layer beneath the concrete pavement provides storage for stormwater so it has a longer time to absorb into the ground before there is any runoff.

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Pervious concrete pavement is as durable and lasts as long as conventional concrete pavement. Pervious concrete has been found to be resistant to damage from freeze-thaw cycles. In fact, because the water flows through the surface, rather than freezing on top of it, ice is less of a problem with pervious pavement than conventional pavement. Porous asphalt is made from coarse stone aggregate and an asphalt binder. It has very little fine aggregate, which allows for more voids to be left in the finished product. These voids allow stormwater to drain through the pavement. A clean gravel base layer allows water to absorb quickly back into the ground. Porous asphalt has a rougher appearance than traditional asphalt. When properly designed, constructed and maintained, porous asphalt pavements last as long as—and in some cases longer than—conventional asphalt. They have a more substantial base than conventional asphalt pavements and wear from freeze-thaw cycles is reduced. Installation: All permeable pavement systems require careful preparation to prepare the site and ensure a proper base layer that holds and drains water back to the soil. Each paving material has its own specifications and must be installed by well-qualified, experienced professionals. (See the box on page 25 for tips on selecting a qualified contractor.) Maintenance: The most important maintenance concern for pervious pavements is preventing sediments from filling the

void spaces. If there is any adjacent construction occurring, it is critical to adequately protect pervious pavement from fine sediment. Erosion-control systems are a must to ensure that no sediment runs off from other areas on your site to the pervious pavement. If the system should become clogged, some studies report that pressure washing pervious concrete will restore its porosity. Remove leaves and surface debris as needed to maintain permeability.

Pervious concrete and porous asphalt are specially created and then installed over a proper base layer to absorb and filter stormwater. Photo: Concrete Council.

A seal coat should never be applied to porous asphalt, as it will render it impermeable. It’s important that any future owners know about any pervious pavements on the property and how to maintain them. Costs: Materials costs for pervious concrete and porous asphalt are not necessarily higher than for traditional, but there may be secondary costs in creating batches or installing them at this point in their development. For concrete, where each load is always custom mixed, the contractor may have additional costs in working with an unfamiliar material correctly. For asphalt, which is produced at a plant in a continuous flow, there will likely be a charge from the asphalt plant for shutting down equipment and

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changing the formula to create a special batch of porous asphalt. Ordering in larger batches will likely be more cost effective, so porous asphalt is best applied to larger projects or when several small projects in close proximity can be done simultaneously. Costs are expected to drop as orders for pervious pavements rise. III. ROOFS

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The roof on your house is likely the largest impervious surface on your lot. In addition to the harm stormwater can cause to local waterways, the rainwater that runs off your roof can cause drainage problems around your foundation. LID techniques for managing roof water can help you prevent drainage problems and reap the benefits of roof water. LID options for roofs include:

Directing downspouts for maximum infiltration on site.

Rainwater harvest. Green roofs (also called vegetated

roofs or eco-roofs). Directing Downspouts An important LID principle is to direct rooftop water so that it is managed on your site as much as possible. Taking an active role in deciding where your downspouts drain can also prevent problems caused by stormwater collecting along the foundation of your house.

Comparing Apples & Oranges Some LID options may seem more costly at first glance, but initial cost is just a starting point when comparing conventional products with LID products. A higher-priced product, such as a green roof or metal roof compatible with rainwater harvesting, might be a better deal when looking at long-term costs and savings. Factors to consider include: Roof replacement costs—a more durable roof with reusable components will save money over the life of the roof. Compare a roof with a 40- to 50-year lifespan to one with a 15-year lifespan by dividing the installed price by the number of years of the warranty. Roof disposal costs—a roof that has minimal waste at the end of its life will save you this expense. A green roof only requires replacing its waterproof membrane after 40 to 50 years; all other parts are reinstalled. Energy efficiency—some roof systems will cut your utility bills, and those savings need to be figured into the price of the roof. Overall community benefits—it’s hard to put a price on the value of cleaner water, less air pollution, and a reduction in greenhouse gases that result from choosing a green roof.

Choosing to direct your downspouts for maximum absorption in your yard is one of the easiest LID strategies. Consider these basic principles:

Don’t allow your downspouts to discharge onto your driveway. This will increase the amount of pollution running off your property, and will affect the function of pervious paving systems.

Wherever possible, tie your downspouts into an on-site stormwater feature such as a rain garden or dry stream (see pages 19-21).

If your downspout discharges on a slope, consider installing a planting bed with lots of compost to intercept and absorb as much runoff as possible. You could also plant a sloped biodetention hedgerow (see page 21).

To disperse downspout flow into lawns or landscapes, use a splash block or perforated pipe to get the flow at least two feet away from the house foundation and spread it out into “sheet flow” that can infiltrate slowly. Be sure that the flow will disperse and absorb on your property, not rush off onto neighbors or streets and cause problems. If you have drainage problems around your foundation, make sure your downspouts discharge at least 10 feet away from your house, and that your landscape is graded so that water flows away from the house.

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If your downspout drains across your lawn, keep up good natural lawn-care practices by adding compost and aerating annually to make your lawn as pervious as possible (see pages 10-14).

Rainwater Harvest Options Rainwater harvesting combines two important LID goals: reduce peak stormwater flows from rooftops, and conserve water that comes from drinking-water supplies. Rainwater harvesting is nothing new—people have been collecting water from rooftops for centuries, especially in areas with limited water supply. In our region, rooftop water is harvested and used for private residences as well as large commercial buildings. You might be surprised by how much rainwater collects on your roof. A half-inch of rain falling on a 1,000 square-foot roof generates about 300 gallons of water. When you consider how many inches of rain you receive every rainy season, you quickly recognize that it would take a lot of storage capacity to capture all the rain that hits your roof.

How to Use Rain Barrel Water Even a few rain barrels can provide water for a lot of outside watering and clean-up jobs.

You can attach a hose to the barrel’s spigot—or just fill watering cans—to water patio containers, trees, and other landscaping plants.

Never use moss killers or other

chemicals on your roof that could contaminate your rain barrel water.

Rain barrel water is great for

cleaning paintbrushes, washing muddy boots, and other messy outdoor clean-up tasks. (Cleaning jobs should be done using a bucket so you can prevent pollution by controlling where the wastewater is disposed.)

Rain barrel water can be safely used

by children playing in sand boxes or wanting to “help” with watering tasks where they might spill and waste potable water.

Make sure your children know never

to drink rain barrel water.

Options for harvesting rainwater include:

Rain barrels (usually 40 to 80 gallons of capacity) to collect water for outdoor use.

Cisterns to collect water for outdoor use and non-drinking uses (e.g., flushing toilets).

Cisterns combined with treatment systems to collect water for all household uses, including drinking. These systems are becoming more widely used in areas that have limited drinking water available, such as on the San Juan Islands. This guide will not address filtration, but offers information for further investigation in the resources section.

Managing stormwater: Rain barrels and cisterns only help slow stormwater flow if they are empty at the start of a winter storm. You can accomplish this, and still save water in the summer, by attaching a garden hose in winter and opening the valve so that water rushing into the barrel from your gutters is slowly dispersed into your lawn or landscape. In late spring, close the valve to store water for summer. Once rain barrels and cisterns are full, the roof water needs to be redirected to prevent overflowing. The best option is to use a downspout diverter that returns the water to downspouts when the storage tank is full (see resources). Downspouts should then be directed into a stormwater feature (see pages 19-21) or fully dispersed in the landscape. Rain barrels: Rain barrels are available in a variety of sizes and are made from a variety of materials, including recycled oak whiskey barrels and recycled plastic storage drums. You can make your own or buy one ready made. Some water utilities sell them at a subsidized price to their customers. Use only barrels

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that you know were used for food or food-grade materials—never use drums that stored chemicals or petroleum products. Rain barrels should have a tight-fitting lid to protect children and prevent mosquitoes from breeding, as well as a built-in, easy-to-clean screen on top to filter large debris. Rain barrels are sold in a range of colors. You can paint yours to blend in to your home’s exterior.

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Rain barrels are heavy when full, so they need to sit on level, packed earth or gravel, or elevated on leveled concrete blocks. Don’t place them where they would block doorways if they fell over in an earthquake. Some municipalities require them to be strapped to the house for this reason. Capacity: Given their limited size, rain barrels do not offer the capacity of cisterns. However, you can increase the storage capacity to harvest enough water to meet many summer watering needs, especially if you also use drought-tolerant plants.

Place rain barrels at each downspout. Link two or more rain barrels together to

increase the storage at each downspout. You can buy ready-made linking kits or

make your own (see resources). For a house with four downspouts,

linking two 75-gallon barrels at each downspout could store 600 gallons of water for summer use.

Multiple rain barrels can be easily linked to provide more storage space and keep more rainwater on site. Rain barrels can be painted to match the color of your house and you can install a downspout diverter that automatically closes when your barrels are full.

Regulatory Considerations Technically, the Washington State Department of Ecology has authority over any water in the state—including the runoff from your roof. In April 2007, the Department of Ecology asserted that in would not require a water-rights permit for residential rainwater harvesting: “Ecology recognizes that rainwater collection has many benefits and that regulating the use of small amounts of rainwater was probably not the intention of existing laws. Therefore, Ecology is currently not requiring a permit for small (de minimus) uses of rainwater. ... Ecology is directed by law to protect existing water rights and water resources. Ecology could respond to any complaints of harmful effects from your rainwater use.”

The simplest and least expensive step up from a rain barrel to a larger (300-500-gallon) storage capacity may be to buy poly tanks sold by agricultural suppliers. For safety, choose one with a broad base. Provide a perfectly level foundation of cement or packed gravel.

Capturing the roof runoff:

Position your first rain barrel directly below your downspout, and any linking barrels immediately adjacent to the first.

Elevate the rain barrels by placing them on stable concrete blocks. This will help with water flow when you harvest your water in the summer.

Install a downspout diverter into your downspout. Some diverters automatically close when the rain barrel is full so that your roof runoff once again flows to the bottom of the downspout. Others require you to monitor fullness and close the diverter yourself.

Once the rain barrels are full, the water should flow to the bottom of your downspout and ideally be diverted to an on-site stormwater feature (see pages 19-21).

Keep your gutters and downspouts clean to prevent leaves from clogging your downspout diverter.

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Cost: Rain barrels range in price depending on whether they’ve been made from discarded barrels or fabricated for the retail market; whether you make your own or buy one already made; and whether your water utility offers barrels at a subsidized price. Expect to pay $20 to $200 (and even more) for a standard barrel with 40 to 80 gallons of capacity. Downspout diverters that automatically close when the rain barrel is full are sold through garden-supply companies for $20 to $30, or you can make a simpler device on your own. Linking systems are sold as kits for $10 to $15, or you can make your own for much less with a few simple supplies from your hardware store. Cisterns: An investment in a cistern system to collect and store rainwater will take your harvesting options to a whole new level over rain barrels. While the concepts and materials for cistern systems are simple, designing a system for your household’s use can be complex. When planning a cistern system, hire an experienced, well-qualified rainwater-harvest designer or engineer. Cisterns are made from a variety of materials, including plastic, fiberglass, concrete, metal and wood. Each tank can hold hundreds or even thousands of gallons of water. Most systems rely on several tanks to meet their water needs. Tanks can be above ground or buried. They can be artfully designed to add to your home’s aesthetics or hidden under a deck or by vegetation. Untreated cistern water can be used for a variety of household tasks, including laundry and toilet flushing, as well as landscape irrigation. Harvesting water for these needs requires installing pumps as part of the overall design. Cost: Cistern systems can be expensive, but can pay for themselves over time with water savings. Costs will vary tremendously depending on system components and design. In new construction, cistern systems can save money by decreasing some stormwater infrastructure costs. In one example, supplying a home with a 10,000-gallon storage capacity for laundry and toilets added about $8,000 to construction costs.

Green Roofs Green roofs are designed to absorb and slow down roof runoff. They have many benefits, including:

Stormwater reduction Aesthetic improvements & habitat value Indoor noise reduction “Green roofs are a way of

repaying the earth for taking up a parking space.” -- Patrick Carey, Hadj Design

Heating/cooling cost savings Longer-lasting roofs Reducing the “urban heat island effect.” (Conventional

roofs are much hotter than green roofs.) Importance of residential roofs: In cities, many businesses and government agencies are taking the lead on building or retrofitting with green roofs. But residential roof surface area is six to eight times greater than commercial roof surface in cities. Residential roofs account for even more roof surface area in suburban and rural areas. As more homes convert to green roofs, the benefits of this LID technique will really become evident in our region. In parts of Europe, green roofs have been common in residential construction for many decades. Green roofs are catching on in the U.S., with many more qualified designers and installers available to guide you. When planning new construction or roof replacement, think green!

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How green roofs work: There are two types of green roofs: extensive and intensive. Extensive systems are very shallow and much lighter than intensive systems. They are more practical for residential construction or roof replacement, so this guide will only consider extensive systems. Green roofs are a combination of biology and engineering. The plants and soil absorb and filter stormwater; all the other components manage the water to protect your house. Components: Green roofs are composed of several layers. Starting from the inside working out, they include:

New Research Shows Green Roof Promise

While Germany and other European countries have detailed specifications for green roof designs, in the U.S. researchers are still testing different approaches to find the best mix of components for different climates. For Puget Sound, research led by Magnusson Klemencic Associates during 2005-2007 shows green roofs might be able to manage stormwater flows even better than expected. In their tests, runoff volume was reduced by 65 to 94 percent, and runoff rates were reduced up to 76 percent, even during extreme rainfall. Their team’s research also found better overall success using:

Engineered soil mix of 4 to 6 inches maximum depth;

Succulent groundcover plants, such as stonecrops (Sedum species) and hens & chicks (Sempervivum species); and

Granular drainage layer, which significantly slowed the water runoff.

More research is planned. Keep track of new findings by checking websites for Magnusson Klemencic and Portland’s Bureau of Environmental Services, listed in the resources section.

Roof deck (often plywood) Sub-membrane layer to cushion and protect the

membrane Waterproof membrane Drainage layer to store and manage water Soil filter fabric to retain soil Special engineered soil mix Plant layer

Each of these components must be carefully designed for your individual project. For each component, there may be many choices that an experienced, qualified green-roof designer and installer can discuss with you. (See page 32 for tips on hiring a consultant.) Weight: Extensive green roofs are similar in weight to a tile or slate roof. Your home, garage or shed must be able to support a load of 20 to 75 pounds per square foot (in addition to snow load), depending on your choices for the depth of engineered soil mix and plant species. Shallower engineered soil depths will be lighter in weight but support fewer plant species. Many structures may already be adequately engineered to handle the weight of an extensive green roof. If not, retrofitting remedies such as roof trusses, deeper roof joists, and columns through existing walls might be required. Whether doing new construction or a retrofit, plan early with your contractor if you want to integrate a green roof into your project. Roof pitch: Green roofs can be installed on houses with pitches up to 40 degrees, but pitches ranging from 5 to 20 degrees are more suitable. Steeper roofs will require an additional grid to hold some of the components in place. Results from some studies suggest that flatter roofs retain more stormwater than steeper roofs. Longer life: Green roofs aren’t subjected to UV degradation or the usual level of thermal expansion and contraction of the membrane, so they last much longer than conventional roofs—at least 50 years for most designs. When it’s time to replace the waterproof membrane, all other components—including plants—can be stockpiled and reapplied, thereby saving substantially on replacement costs. 32

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Maintenance: Green roofs require monitoring to inspect system components about twice per year. For instance, drain inlets must be cleared of any debris. The plants will require regular maintenance early on until they are established with at least 90 percent coverage. Weeds must be removed by hand before they go to seed, and weeding must be done with care to prevent soil disruption or loss. Lightweight mineral mulches may be used to discourage weeds initially, but successful plant establishment is the key to maintaining a functioning roof system. Depending on the plant mix and soil depth, occasional summer irrigation may be required, especially during the first few years of establishment. Choose hardy, drought-tolerant species able to survive in difficult conditions such as harsh winds, drought, full sun and limited soil to help you avoid more fussy plant care. The toughest choices are specific species of stonecrop (Sedum) and hens & chicks (Sempervivum). Costs: Depending on the system, all components of extensive green roofs usually range in cost from $17.50 to $22 per square foot installed (2007 figures). In new construction, green roof systems often aren’t substantially more expensive than high-quality conventional roofing, including metal roofs. When considering long-term costs and benefits, green roofs may be less expensive because of their durability. They will also save substantially on energy bills, and add other value to your home, as well.

Green roofs use tough plants to absorb and process stormwater. Green roofs are cost effective over time as they are very durable and all parts can be reused when the underlying waterproof membrane is replaced, approximately every 50 years.

Choosing a consultant: Before working with a green-roof designer, you will need to hire a licensed structural engineer and/or an architect to make sure your building is designed to support a green roof. Once you get the green light to proceed, search for an experienced, qualified green-roof design and installation firm. Depending on the availability of consultants in your area, you may want to first hire an experienced designer who can then help you find a qualified installer.

Ask how many green roofs the firm has designed and installed. Find out the specific role your contact served in designing or installing a green roof.

Ask which components and services are included in the price.

Ask for references and documentation of past projects—and follow up to check on their success.

Ask what professional credentials team members have, especially their experience with residential roofs. You’ll want your team members have qualifications in the full range of specialties, including waterproof membranes, all green-roof components, engineered soil mix, appropriate plant species, and irrigation. Currently, Green Roofs for Healthy Cities is working to certify green-roof installers and designers (see www.greenroofs.org “find a member” to see which courses your consultant has taken).

Get Smart About Roofs Educate yourself so you can make the best decisions for your green roof. Begin by exploring websites: •Hwww.greenroofs.com •Hwww.greenroofs.org

Be sure that your installer is licensed by the manufacturer to apply the chosen waterproof membrane on a residential roof, and that the manufacturer will provide a written warranty for your roof once installed.

•Hwww.ecobuilding.org •www.greenroofs.ca •Hwww.ecoroofseverywhere.org

t•Hwww.hadj.ne To boost your knowledge, consider taking a workshop listed on one of these sites or offered in your region by a consultant or local agency.

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The more knowledge you have when you interview potential contractors, the better you’ll be able to find the best firm for your project. IV. FOUNDATIONS One key LID strategy is to disturb soils as little as possible. When natural soil layers are disturbed and compacted, their ability to absorb stormwater and support healthy plants is threatened. Heavy machinery can render soil as impervious as concrete and wipe out soil’s beneficial organisms. Fortunately, not all construction projects have to take a heavy toll on your site’s soils. When planning new construction or an addition to your home, you can make choices that will affect how your home’s site functions for years to come. With just two LID techniques, you can also limit your contribution to degrading your local waterways:

Design for smallest possible footprint. Install a minimum-excavation foundation.

Small Footprint The “footprint” simply refers to the amount of space on the ground for your home, other buildings, driveway, and other hard surfaces. For instance, you can build a sprawling single-story home or a two-story house that provides the same amount of living space with only half the footprint. Or you can expand your home’s living space by bumping out on the ground floor, or you can work with an architect and builder to add a second story to a single-story house. Smaller footprints offer these benefits:

Less impervious surface, so better for your local waterways. Better views from a two-story building. More green space and outdoor-living space—especially beneficial on a small lot.

Minimal-excavation Foundation A minimal-excavation foundation dramatically limits soil disturbance over traditional grading and foundation installation. It has many benefits, including:

This minimal excavation foundation, designed by Pin Foundations, requires minimal disturbance to soils and vegetation as well as limited tools to install. Photo courtesy of Pin Foundations Inc.

Undisturbed soils allow for more natural drainage patterns.

Allows absorption of stormwater adjacent and sometimes below foundation.

Reduces potential for erosion and need for erosion-control systems.

Saves expense and disruptions of major excavation and re-grading.

Protects tree and shrub roots from damage. Saves landscaping repair and soil-amendment

costs. How they work: Minimal-excavation foundations allow an entirely different approach to installation than conventional foundations. On flat sites, or

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sloping sites less than 2:1, there is very little grading work—just enough to provide a smooth work surface. The woody vegetation is removed and the topsoil is left where it lies. The foundation materials are light enough to be hand-carried to the site, and the system is installed with hand-held tools. With no on-site pouring of concrete, the big machinery typically used in building a foundation isn’t necessary. Minimal-excavation foundations can be installed in clay, silt, sand, and rounded gravel soils, including those with a high water table. They are not appropriate for highly rocky soils or loose fill.

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Installing the minimal-excavation system involves digging a few inches into the soil to place pre-cast concrete piers in line with the new foundation layout. Galvanized-steel pins are then driven diagonally through the pier providing both bearing and anchoring resistance deep in the ground. The pins are pre-cut to the correct length (typically ranging from three to seven feet) based on the soils and load needs of each individual project. Once installed, framing can begin immediately, without the usual delay of waiting for concrete to cure. Design and installation: Minimal-excavation foundations are compatible with almost any building project, and more architects and builders are becoming familiar with their use. Each foundation is custom designed and pre-engineered for your site and soil conditions. Your architect and foundation supplier should collaborate on the design, framing layout and site orientation.

A minimal-excavation foundation engineered by Pin Foundations allowed this house to be built without disturbing native soils or vegetation. Photo courtesy of Pin Foundations Inc.

Costs: Depending on your site features and building design, a minimal-excavation foundation can be comparable or less expensive than conventional foundations. They avoid the traditional expenses of extensive grading and excavation with heavy machinery, as well as concrete delivery. These systems may have additional cost savings from a reduction in stormwater infrastructure and avoided landscaping repair and soil-amendment expenses. When used on an addition to an existing structure, they have the added benefit of not requiring potentially disruptive access to the site for heavy machinery (such as removing fences). Resources: For more information about minimal-excavation foundations, see the resources section.

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Resources

These resources are provided to help you: Do further research on specific LID strategies. Find local-government support for your project. Find supplies and services.

Listings of particular companies do not constitute an endorsement or guarantee of the quality of the product offered, nor do they necessarily represent the only available suppliers. GENERAL LID PRACTICES

Low Impact Development Technical Guidance Manual for Puget Sound at: http://www.psat.wa.gov/Publications/LID_tech_manual05/lid_index.htm

City of Seattle Green Building Program: http://www.seattle.gov/dpd/GreenBuilding/OurProgram/Overview/

Seattle Public Utilities/UW Botanic Gardens Design Seminars: http://depts.washington.edu/urbhort/html/education/stormwater.htm

“A Sustainable Approach to Stormwater Management,” City of Portland Bureau of Environmental Services. http://www.portlandonline.com/bes/index.cfm?c=34598

Smart Growth Online, featuring ideas for livable communities: http://smartgrowth.org/default.asp

NEW CONSTRUCTION ON AN UNCLEARED LOT Technical Guidance Document for Clearing and Grading in Western Washington, Washington Department

of Community, Trade and Economic Development, May 2005 http://cted.wa.gov/_CTED/documents/ID_2062_Publications.pdf

“Making a Home in the Woods,” for those planning to build on a wooded lot. http://www.greenbeltconsulting.com/articles/homeinthewoods.html

“Value, Benefits and Limitations of Vegetation in Reducing Erosion” http://www.greenbeltconsulting.com/articles/valuesbenefits.html

Slopes & replanting

“Living on the Shore: A Resident’s Guide to Creating & Managing a Sound Landscape,” available at: www.nativeplantsalvage.org Washington Department of Ecology Publications:

Slope Stabilization and Erosion Control Using Vegetation Vegetation Management: A Guide for Puget Sound Bluff Property Owners Surface Water and Groundwater on Coastal Bluffs: A Guide for Puget Sound Property Owners

All available at: http://www.ecy.wa.gov/programs/sea/pubs/93-30/using01.html

Salvaging Plants Before Clearing Washington State University Extension Gardening in Western Washington: http://gardening.wsu.edu/text/nvsalvag.htm Grow Your Own Native Landscape: A Guide to Identifying, Propagating, and Landscaping with Western Washington Native Plants, Edited by Michael Leigh, WSU Thurston County Native Plant Salvage Project, 1999. Available from local libraries, WSU Publications (800-723-1763) or http://cru84.cahe.wsu.edu/cgi-bin/pubs/MISC0273.html?id=UMIDkvKf, and www.nativeplantsalvage.org

SOILS Seattle Public Utilities’ “Growing Healthy Soils” & “Get to Know Your Soils”:

http://www.seattle.gov/util/Services/Yard/Natural_Lawn_&_Garden_Care/Growing_Healthy_Soil/index.asp Washington Organic Recycling Council, “Soils for Salmon”: http://www.soilsforsalmon.org/

Presents best practices for new construction and redevelopment—includes specifications, compost sources, soil labs, and calculators for builders and designers.

Natural Resources Conservation Service: http://soils.usda.gov/ For illustrated Soil Biology Primer, see: http://soils.usda.gov/sqi/concepts/soil_biology/biology.html

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Hand-textural analysis http://soils.usda.gov/education/resources/k_12/lessons/texture/ or www.nativeplantsalvage.org

Soil textural triangle: http://www.pedosphere.com/resources/bulkdensity/triangle_us.cfm

Nutrient testing Contact your local conservation district, extension service, or organic nursery for low-cost and no-cost soil testing services.

Composting Seattle Public Utilities’ Guide: http://www.seattle.gov/util/Services/Yard/Composting/index.asp Workshops & Bin Sales: Check with your local WSU Master Gardeners and Master Composters as well as

city or county environmental offices. Washington Department of Ecology permitted composting facilities:

http://www.ecy.wa.gov/programs/swfa/compost/

Structural Soils These engineered soils use stone aggregate coated with compost and other materials to create a compact base that can support roads and sidewalks, but still have the large pores for water and airflow, and nutrients, that street trees need to thrive. One good reference is Cornell University’s http://www.hort.cornell.edu/UHI/outreach/index.html Building and Maintaining Urban Soils Seattle Green Factor workshop series at http://www.seattle.gov/dpd/Permits/GreenFactor/

IDENTIFYING & ERADICATING WEEDS/INVASIVE PLANTS Washington State Noxious Weed Board: http://www.nwcb.wa.gov/ King County Noxious Weed Board: http://dnr.metrokc.gov/wlr/lands/weeds/ The Nature Conservancy Global Invasive Species Initiative: http://tncweeds.ucdavis.edu/

Invasive Species in the Pacific Northwest, Edited by P.D. Boersma, S.E. Reichard and A.N. Van Buren, University of Washington Press, 2007.

Grow Smart, Grow Safe: A Consumer Guide to Lawn and Garden Products. Philip Dickey, Washington Toxics Coalition. Includes product reviews and sources for least-toxic products. Available at: http://savingwater.org/docs/Grow_Smart_Grow_Safe.pdf

Horticultural Vinegar for use in treating weeds in unplanted walkways and driveways (ask your local nursery to stock it): http://www.savvygardener.com/Reviews/Products/bradfield_vinegar.html

Flame Weeders, useful for killing weeds between pavers or in gravel in unplanted walkways or driveways, are available through local garden-supply and hardware stores or via the Internet.

SUSTAINABLE LANDSCAPING IDEAS

Thurston County Common-Sense Gardening Program: http://www.co.thurston.wa.us/health/ehcsg/index.html

City of Seattle Natural Yard Care: http://www.seattle.gov/util/Services/Yard/Natural_Lawn_&_Garden_Care/index.asp

The Common Sense Gardening Guide to Natural Lawn Care, Thurston County: http://www.co.thurston.wa.us/health/ehcsg/pdf/lawn_care.pdf

King County Yard & Garden Topics: http://dnr.metrokc.gov/topics/yard-and-garden/ Ecologically Sound Lawn Care for the Pacific Northwest, Seattle Public Utilities, David McDonald, 1999.

http://www.seattle.gov/util/stellent/groups/public/@spu/@csb/documents/webcontent/ecological_200312021255394.pdf

Landscape Planning

http://dnr.metrokc.gov/wlr/pi/go-native/PlanList.aspx http://dnr.metrokc.gov/wlr/pi/go-native/ArticleList.aspx Recommended books on “naturescaping”: http://www.oly-wa.us/NPS/UsefulBooks.php City of Portland Naturescaping program: http://www.portlandonline.com/bes/index.cfm?c=dcbec

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Water-wise/Drought-tolerant/Native Plants See lists of recommended plants at:

Thurston County Common Sense Gardening: http://www.co.thurston.wa.us/health/ehcsg/pdf/Plant_Lists/CSG_plants.pdf

Native Plant Salvage Foundation: http://www.oly-wa.us/NPS/Resources.php Saving Water. org : http://www.savingwater.org/outside_garden.htm See “Choosing the Right Plants” and

“The Plant List.” WSU Extension Native Plants database: http://gardening.wsu.edu/nwnative/ King County’s Native Plant Guide: http://dnr.metrokc.gov/wlr/pi/go-native/index.aspx

Water Conservation

Saving Water Partnership: http://savingwater.org/outside.htm Obtaining Plants Lists of Native Plant Nurseries & Other Sources: http://dnr.metrokc.gov/wlr/pi/npnursry.htm http://www.oly-wa.us/NPS/GoodSources.php Check with your local conservation district and master gardener program to find out about annual sales. Street Trees Check with your local urban forestry program for lists of recommended trees for a variety of spaces. Many supply lists for use in streetscapes that can also be applied to the rest of your yard. For instance: http://www.seattle.gov/transportation/treeplanting.htm#recommend http://www.ci.olympia.wa.us/cityservices/urbanforest/neighborwoods/

Sheet Mulching http://www.oly-wa.us/NPS/SheetMulching.pdf NATURAL DRAINAGE, RAIN GARDENS, BIORETENTION

Rain Garden Handbook for Western Washington Homeowners: Designing your landscape to protect our streams, lakes, bays, and wetlands, http://www.pierce.wsu.edu or www.nativeplantsalvage.org.

Overview of City of Seattle’s Natural Drainage Projects: http://www.seattle.gov/util/About_SPU/Drainage_&_Sewer_System/Natural_Drainage_Systems/index.asp

Recommended Maintenance Guide for City of Seattle, “Practically Easy Landscape Maintenance: A Care Manual for Natural Drainage Systems,” Fall 2006. http://www.seattle.gov/util/stellent/groups/public/@spu/@esb/documents/webcontent/spu01_002605.pdf

RAINWATER HARVESTING General There are many companies that sell rain barrels and larger storage systems. Check your local hardware stores or search the Internet for “rain barrels,” or “cisterns,” depending on your interest.

See this King County site for information on cisterns and options for building your own or buying rain barrels: “Rain Barrel Information and Sources—Saving for a Sunny Day: Rain Barrels in the Garden” http://dnr.metrokc.gov/wlr/PI/rainbarrels.htm

Seattle Rain Barrels offers general installation instructions and directions for determining how much rainwater your roof will generate at each downspout. http://www.seattlerainbarrels.com/index.html

Garden Watersaver site provides instructions for building your own rain barrel and linking systems. http://www.gardenwatersaver.com/1.html or 604-274-6630.

This Puget Sound Action Team newsletter provides case studies on collecting rainwater for gray-water and drinking-water systems: http://www.psat.wa.gov/Publications/LID_studies/rooftop_rainwater.htm

Downspout diverters

A few companies offer downspout diverters, with options for manual or automatic shut off when your rain barrel is full. Check local hardware stores or these companies:

Downspout Diverter, closes when barrel is full; $24.95 from Gardener’s Supply Company, 888-833-1412, http://www.gardeners.com/Downspout-Diverter/default/33-991.prd

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“Garden Watersaver,” closes when barrel is full; $29.99 from Clean Air Gardening, 214-363-5170, http://www.cleanairgardening.com/gawadoat.html

“Save the Rain Diverter,” must be manually closed when barrel is full; $22 from Real Goods, 877-989-6321, http://www.gaiam.com/retail/product/46209

“Drought Buster,” downspout rainwater redistributor, for use with or without rain barrels to direct roof runoff into a stormwater feature. From Clean Air Gardening, 214-363-5170, http://www.cleanairgardening.com/gawadoat.html

Installation instructions for manual diverter: www.nativeplantsalvage.org

Rain barrel linking systems Check local hardware stores for supplies for making your own. Directions for your own available at: http://www.gardenwatersaver.com/30.html and

www.nativeplantsalvage.org Rain Barrel Linking Kit, from Gardener’s Supply Company, 888-833-1412,

http://www.gardeners.com/Downspout-Diverter/default/33-991.prd PERVIOUS PAVEMENTS

Low Impact Development Technical Guidance Manual for Puget Sound at: http://www.psat.wa.gov/Publications/LID_tech_manual05/lid_index.htm

See Case Studies: http://www.psat.wa.gov/Publications/LID_studies/permeable_pavement.htm ToolBase Resources, overview of several systems and manufacturers: http://www.toolbase.org/Technology-

Inventory/Sitework/permeable-pavement

Permeable Pavers: Interlocking Concrete Pavement Institute: http://www.icpi.org/homeowners/find_installer.cfm Ecostone Pavers: http://www.mutualmaterials.com/Professional_product.asp?pt_id=123&p_id=304

Porous aggregate-containment or reinforced turf systems:

Invisible structures: http://www.invisiblestructures.com/GV2/gravelpave.htm TerraFirm EcoGrid: http://www.terrafirmenterprises.com/ecogrid.html Ecostone Pavers: http://www.mutualmaterials.com/Professional_product.asp?pt_id=123&p_id=304 Interlocking Concrete Pavement Institute: http://www.icpi.org/homeowners/find_installer.cfm

Pervious Concrete

Concrete Council: http://www.perviouspavement.org/

Porous Asphalt Asphalt Pavement Alliance: http://www.pavegreen.com/water_quality.asp GREEN ROOFS •www.greenroofs.com •www.greenroofs.org •www.ecobuilding.org •www.greenroofs.ca •www.ecoroofseverywhere.org •www.hadj.net Research on Green Roofs:

Magnusson Klemencic Associates: http://www.mka.com/home/home_frame.html City of Portland Bureau of Environmental Services: http://www.portlandonline.com/bes/index.cfm?c=36055&

MINIMAL-EXCAVATION FOUNDATIONS Pin Foundations, 253-858-8809: www.pinfoundations.com.

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