7102 LOWER RIDGE RD 2018-07-25 - Laserfiche WebLink

A � a. The organic content for-pre-approved" amendment rates can be met only using compost that meets the definition of composted materials" in WAC I73-350-220. This code is available online at: http://www.ecy.wa.gov/programs/swfa/facilities/350.html. Compost used in bioretention areas should be stable,mature and derived from yard debris,wood waste,or other organic materials that meet the intent of the organic soil amendment specification. Biosolids and manure composts can be higher in bio-available phosphorus than compost derived from yard or plant waste and therefore are not allowed in bioretention areas due to the possibility of exporting bio-available phosphorus in effluent. The compost must also have an organic matter content of 35%to 65%,and a carbon to nitrogen ratio below 25:I. The carbon to nitrogen ratio may be as high as 35:I for plantings composed entirely of plants native to the Puget Sound Lowlands region. b. Calculated amendment rates may be met through use of composted materials as defined above; or other organic materials amended to meet the carbon to nitrogen ratio requirements, and meeting the contaminant standards of Grade A Compost. The resulting soil should be conducive to the type of vegetation to be established. • Implementation Options:The soil quality design guidelines listed above can be met by using one of the methods listed below. • I. Leave undisturbed native vegetation and soil, and protect from compaction during construction. 2.Amend disturbed soil according to the following procedures: b. Scarify subsoil to a depth of one foot c. In planting beds,place three inches of compost and till in to an eight-inch depth. d. In turf areas,place two inches of compost and till in to an eight-inch depth. e. Apply two to four inches of arborist wood chip, coarse bark mulch, or compost mulch to planting beds after final planting. Alternatively,disturbed soil can be amended on a site-customized manner so that it meets the soil quality criteria set forth above, as determined by a licensed engineer, geologist, landscape architect, or other person as approved by the City of Everett. 3. Stockpile existing topsoil during grading, and replace it prior to planting. Stockpiled topsoil must be amended if needed to meet the organic matter and depth requirements by following the procedures in method(2)above). 4. Import topsoil mix of sufficient organic content and depth to meet the organic matter and depth requirements. 5. More than one method may be used on different portions of the same site. Soil that already meets the depth and organic matter quality standards, and is not compacted, does not need to be amended. Maintenance • Soil quality and depth should be established toward the end of construction and once established, should be protected from compaction, such as from large machinery use, and from erosion. • Soil should be planted and mulched after installation. • Plant debris or its equivalent should be left on the soil surface to replenish organic matter. 7102 Lower Ridge RD Full Drainage Report Revised:November 3,2017 Page 13