Site Assessment

Draw the general layout of your site (graph paper helps). Include hard surfaces such as buildings and pavement as well as important features such as powerlines, underground utilities, and easements.
Add impervious areas like the driveway, sidewalks, or parking areas.
Measure the length and width, then multiply the two together to get the area. Estimate hard, or impervious areas where water runs off and note the measurements on the map.
Locate the downspouts that drain water from your roof and mark them on your map. Note the rooflines and area draining to the downspout.
Look at other impervious surfaces on your site. Try to figure out where runoff from these areas goes. If it isn’t raining, use a hose. Use arrows to note on your map the direction the water flows.
Look at other surfaces of your property and mark any noticeable hills and dips. Note areas that stay wet and muddy. Note areas where water soaks in or are soft (lawns, planting beds, trees).
Soil type has a lot to do with how well rainwater soaks into the ground. Sandy, loamy soil soaks up water very quickly. Heavier soils with clay don’t soak up water as well.
Be aware of municipal permitting and requirements and the effect your project may cause your neighbors.

Before digging into the dirt, dig into the details!

When properly designed and constructed, a drainage plan protects the environment, property owners, and neighboring properties from adverse impacts related to residential development.

Seeking on site areas that infiltrate well will lead to the most cost-effective designs. Effective siting identifies soil variability and includes doing some initial infiltration rate testing for planning phases.

Evaluate Your Site Assessment Map

The goal is to direct stormwater towards water storage areas or those surfaces which soak up rain

such as vegetated surfaces like rain gardens or other garden areas. If the space is too small, a rain harvesting practice, such as a rain barrel can be used. You may need to reroute drainage systems to get water to where there is enough space to install a particular practice. What is possible depends onsite conditions, set back requirements, sizing, and soil constraints.

Sketch Some Ideas and Take Action

In this Example of Plan, they have decided to install rain barrels at 3 downspouts and a rain garden at the fourth. Along with directing rain water across driveway into second rain garden, they plan to install gutters and downspouts on garage. One drains to rain barrel, one drains to a rain garden. The more area where excess lawn is replaced with flowers, shrubs, and trees, the more water will be absorbed into the ground in a useful way.

NOTE:

All development within the special flood hazard areas (SFHA) must incorporate low impact development techniques where feasible to minimize or avoid stormwater effects. With various elements of low impact development (LID), most projects on parcels ½ acre in size or larger in rural areas can often meet these requirements by using dispersion as follows:

LID Dispersion worksheet

Maintain Natural Areas

Conserve natural areas wherever possible (Don't remove native trees and shrubs unnecessarily.)
Minimize the development impact on hydrology (Do not disturb or compact soil unnecessarily.
Maintain runoff rate and duration from the site (don’t let the water leave the site).
Distributed stormwater Best Management Practices (BMPs) (Use BMPs effectively throughout the site.)
Implement pollution prevention and proper maintenance.

Native, mature landscaping is a desired component of LID:

Trees and other vegetation have a 3-5 year establishment period during which they may require additional watering. Maintaining native vegetation reduces the time, effort, and expense of tending to newly planted vegetation.

Help your landscape to work for you.

Retain trees and other vegetation which intercept precipitation with the tree canopy, leaves, and roots.

Grade only as much of the land as needed so soil, terrain, and plants can slow runoff and hold water until it is absorbed into the soil.

Disperse water by directing runoff from roofs, pavements, and similar impervious surfaces to rain catchments or planted areas that can benefit from the water.

Create beautiful and useful outdoor spaces that limit lawn and other compacted areas while maintaining soil that can absorb water.

Place driveways and parking areas thoughtfully to limit compacted soil and direct runoff to planted areas.

Use natural mulch to improve soil's ability to absorb and filter water.

Site Planning Tips
to minimize the impact the construction project will have on the patterns of water flow and vegetated areas of the site and help facilitate stormwater infiltration on the property:

Place structures as close to the public access point as possible to minimize road/driveway length. Minimize paved parking areas and utilize porous paving options wherever possible.

Slope paved areas to facilitate drainage to stormwater management areas.

Reduce building footprints whenever possible. Utilize basements or taller structures with lofts or second stories to achieve square footage goals.

Orient buildings on slopes with long-axis along topographic contours to reduce grading requirements.

Set clearing limits that give maximum protection to soils and vegetation while allowing reasonable areas for equipment to maneuver on the site. Delineate the areas both on the construction plans and on the ground with temporary fencing or taping.

Depending on the soil type that you have, your water movement will be affected in certain ways. If your soil is predominantly sand, you are not likely to have flood issues, but may struggle to retain water, because sand’s large particles let water through easily. If you have predominantly clay soil, your soil’s tiny particles hold water very easily, become waterlogged quickly, and then tend to let water run off the surface thereafter.

Landscaping Tips

Use the shape of the land and the availability of light and water to shape your design.

When you're designing a landscape, keep planting zones in mind.

Group plants together that all have the same moisture and light requirements.

Make sure plants that require a lot of water are near a water source. (Sometimes that means a hose or rain catchment)

Make sure that plants that require more of your attention are easily accessible.

Consider the mature size of a plant. Make sure they have room to grow and make sure that plants that require more sun are not planted next to a plant that will grow up and shade them out.

A diagram showing ground level and overhead view of a rain garden. Text boxes describe the 3 planting Zones.

A colorful winter scene of red osier dogwood branches in the middle of green and purple heathers and dry ornamental grasses.

Choose a variety of plants, including shrubs, flowers and grasses, to create variety in color, height and texture.
Consider the year-round look of your rain garden – clumping grasses will hold their shape throughout the winter, and many types of shrubs develop striking red branches in the colder months.
Consider your home’s existing landscape, and the landscaping of the surrounding neighborhood.

Tip:

The more bare ground in your garden, the more you will be fighting invasions of weeds.

Keep the soil covered by plants or adding mulch. It will greatly reduce the amount of water transpiration, soil erosion, and weeds that will germinate in your garden,

A wheelbarrow filled with pruned branches on a woodchip covered path between ornamental grasses and shrubs .