Figure 8A-12D: Inlet Protection (Type 4)

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Figure 8A-12E: Inlet Protection (Type 5) Masonry AggregateA. Applications1. At inlets ready for use before completion of final stabilization and which receive runofffrom drainage areas less than one acre in size.2. At storm drain inlets downslope and within 500 feet of a disturbed area or constructionentrance.3. As a secondary measure downstream from erosion prevention and sediment trappingmeasures.B. Advantages1. Prevents sediment from entering the storm drain system.2. Reduces amount of sediment leaving the site.C. Disadvantages1. Useful only for LOW flows having LOW sediment loading,2. May result in ponding of water above the catch basin.3. Sediment removal may be difficult under high-flow conditions.4. May result in a traffic hazard.5. Short-circuiting of flow may occur if not properly installed.6. Improper installation, maintenance, or removal may introduce sediment and aggregateinto the storm drain system.D. Design Criteria1. Place inlet protection in areas where water can pond and where ponding will not haveadverse impacts.2. Inlet protection must allow for overflow in a severe storm event.3. Inlet protection types include:a. Sediment fence.b. Geotextile with aggregate filter.c. Catch basin insert.d. Biofilter bags.e. Masonry aggregate.f. Sod.Section I - DESIGN STANDARDS 8A - 45 EDSP 2002
Table 8A-8: Inlet Protection Selection Based on Site ConditionsSite ConditionsInlet Protection Type1 2 3 4 5 6Area Drain, Soil Y Y Y Y Y YArea Drain, Pavement N Y Y Y N NDitch Inlet, Soil Y N Y Y N YDitch Inlet, Pavement N N Y Y N NGrate Inlet Along Curb, Soil N Y Y Y Y NGrate Inlet Along Curb, N Y Y Y N NCurb Opening Inlet, Soil N N N Y Y YCurb Opening Inlet, Pavement N N N Y N NE. Maintenance1. Inspect and clean inlet protection during and after each significant storm and removesediment from behind structure after every storm.2. If the aggregate becomes clogged with sediment, it must be carefully removed from theinlet and either cleaned or replaced.3. Assess the impacts of allowing water to pond at the inlet and provide an overflow weiror some other type of relief as needed. Consider the effect of placing obstructions atinlets on grade may have on their efficiency.4. When possible, include a sediment sump 12 to 24 inches deep with 4H:1V side slopes.5. Do not use water to remove sediment.6. Remove sediment accumulated on or around the protection as needed to maintainintended functions.7. Repair or replace materials as needed to ensure proper functioning.F. Common FailuresThe most common problems with this BMP include torn geotextile material, improperlysealed gaps in the inlet structure, and aggregate that becomes filled with sediment.Section I - DESIGN STANDARDS 8A - 46 EDSP 2002
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Figure 8A-12D: Inlet Protection (Type 4)

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