How to Minimize Damage to Your Property and to Your Neighbors' Properties

• Do not set automatic sprinklers which are near the edge of the ravine or bluff to go off at regular intervals. Turn them on manually only when the soil is dry. If the soil is saturated from a heavy rain, sprinkling automatically not only wastes water but contributes to erosion caused by water flowing down the sides of the slope.

• Slope patios and pavement so that they drain toward the street and not toward the ravine or bluff. By sloping these structures away from the slope, less water will drain directly over the surface of the ravine or bluff. Water run-off, especially sheeting, weakens and erodes soil from the surface.

• Drain runoff from the roof of buildings into storm sewers, or direct it by hose to the bottom of the ravine or bluff. If the runoff from the roof gutters is allowed to drain over the edge of the ravine or bluff, it will tend to create gullies which will further erode during storms when runoff volume and velocity are great. If drainage into storm sewers is not possible, the runoff should be directed toward the street. Alternatively, the runoff can be collected in a large hose (elephant hose) which lies on the surface of the bluff or ravine and leads all the way to the bottom. At the bottom, the outflow should be directed to a layer of large stones so that the energy of the flow is dissipated and the flow does not wash away soil.

• Do not build swimming pools within 20 feet from the edge of the ravine or 50 feet from the edge of the bluff. Because swimming pools have a tendency to leak as they age they should be installed further away from the slope edge than other structures.

• Use terracing on the slopes only for stabilization, not for gardens or sitting areas. Don't let inexperienced workmen attempt terracing for slope stabilization. Permits are usually required for any construction on slopes. Terracing requires experts. Small terraces, with walls up to 4 feet can be done economically with unit paver wall systems which do not rot. Wood on grade is not recommended. Larger terraces require engineering studies. Terraces should be promptly vegetated.

• Revegetate bare spots on the slope using plants that are best suited to the conditions of your ravine. Ravines are generally quite shaded and require plants that grow well with little direct sunlight. The list below presents some plants that are recommended for ravine restoration. For a more complete list, refer to the City of Highland Park brochure, Planting in Ravines, or consult a landscape architect who is familiar with ravine vegetation.

• Inspect bluffs and ravines periodically and plan for routine maintenance. Regularly clean out debris from the ravine channel. If they don't obstruct the flow of water through the channel, dead trees can be left. If trees are cut, the stump should be left in the ground since the root structure will continue to contribute to slope stability. Gullies should be filled with soil and replanted. Don't fill gullies with debris--it will simply wash away. Correct the condition that led to the gullying. Large devegetated areas can be covered with a special fabric which can stabilize the slope until vegetation can be established.

• Don't allow heavy machinery into the ravine, or even light machines with treads. If motorized equipment must be used, use rubber-tired vehicles only.

• Use the greatest care when draining pools. City Ordinances require that swimming pools shall be drained/discharged (spring and fall maintenance) into the sanitary sewer system via a discharge hose directly into the nearest sanitary sewer manhole in the public right-of-way. Overland or ravine drainage is not permitted. Piping carrying backwash or other washwater from a swimming pool filter shall be installed as an indirect waste to the building drain or building sanitary sewer system. Piping utilized for carrying wastewater from deck drains around a pool shall be installed as an indirect waste to the storm or sanitary sewer. Leaking pools can create severe damage to the underlying soil, so repair leaks promptly.

• Inspect hose or pipe leading to the bottom of ravines at least twice a year. Old clay pipe is brittle and slight movements of the earth can disrupt it. If breaks or leaks do occur, clay pipe is very difficult to repair. It is best to replace clay pipe with elephant hose. The hose should lie on the ground's surface and not be buried. Leakage from existing pipe is a major contributor to erosion of slopes. Never drain water onto the surface of the ravine or bluff.

• Consult a professional experienced with ravine vegetation prior to removing or planting trees in a ravine. Due to their root structures, trees contribute to slope stability. City regulations require that a permit be obtained to remove any tree with a diameter of 8" or more. However, even the roots of much smaller tree make an important contribution to slope stability in a ravine and lake bluff community. Therefore, it is important to get expert advice prior to removing even these small trees. In addition, non-native trees which have been introduced into the ravine environment tend to develop dense canopies which block the sun and kill underlying vegetation. Therefore, it is also important to select native species when planting new trees. Consult a professional experienced with ravine vegetation, then call the City Forester at the number listed on the back of this brochure prior to removing or planting trees in a ravine.

• Protect the shoreline. Protection of the shoreline is a complex and expensive enterprise. If it is not done properly, it can cause further damage to one's own property and to neighbors' property. The least expensive protection is offered by installing large boulders at the toe of the bluff. If several neighbors cooperate to protect their shoreline, the cost is less and the results better. The boulders absorb the energy of the waves so that water reaching the soil does not have the destructive force it would otherwise have. When the level of Lake Michigan is high--and it can vary by 6 feet over several years--the beaches are narrower or non-existent, and the potential for damage by wave action very great. It takes but one major storm to do extensive damage to the bluff. There are other protective devices, such as steel walls, that can be effective, but costs can be prohibitive. Coastal engineers must be consulted before making any decision, and permits are required.

• Do not build structures close to the edge of the slope, nor cantilever them over the slope. The ground near the top edge of the slope is the most unstable and vulnerable part, and in general, buildings should be set back 20 feet or more. Buildings should not be erected out onto the slope because cantilevered structures prevent light from reaching the soil. Without this light, vegetation is destroyed and the soil is much more likely to erode.

• Do not permit heavy machinery to be used within 10 feet from the slope edge. The process of construction and use of heavy machinery may cause failure of the vulnerable ground at the edge of the slope, and heavy structures will hasten the failure of this vulnerable area.

• Have good, solid vegetation at the top edge of the ravine or bluff. If there is a flower bed there, plant it thickly. Do not turn over the soil so that bare soil is exposed. Thick vegetation helps hold the surface soil in place. It also purifies the water that runs over it, minimizing harmful bacteria entering Lake Michigan. Turning over the soil and leaving it bare promotes erosion.

• Never dump lawn clippings, leaves, debris, or waste into the ravine or onto bluffs. Lawn clippings and leaves form a mat which covers the natural vegetation and smothers it. In some communities it is illegal to dump anything into ravines.

In summary, the three main areas for homeowners' concerns are:

• Best water management;
• Good vegetation;
• and proper set-backs from the edge of the bluff.