10105 1ST DR SE 2021-12-14 - Laserfiche WebLink

Developing a Soil Management Plan — SECTION FIVE Step 3: Select Amendment Options. The most convenient and economic method for achieving the Soil Quality and Depth guidelines depends on: site soil conditions, grading, and resulting subgrade compaction; the practicality of stockpiling topsoil during grading; and site access issues. "Pre -Approved" or custom calculated rates? Use of "Pre -Approved" amendment rates may simplify planning, however custom calculated rates can save substantial effort and expense —easily repaying the expense of testing and calculations. (See testing required for custom rates at right and on next page, and calculation method in Section 7 "Resources".) Often pasture or woodland soils have adequate organic matter if existing organic layers are preserved. Also, compost products will frequently provide the desired soil organic matter content at lower applications than the Pre - Approved rates (which are based on "average" conditions). Identifying Options on the Site Plan and SNIP form • Identify the areas where each amendment option will be applied by outlining each area on the site plan with a dark, thick -line pen. • Assign each area an identifying number or letter (A, B, C... ) on the plan, and on the Soil Management Plan form. Step 4: Identify Compost, Topsoils and Other Organic Materials for Amendment and Mulch. Amendments for Pre -Approved rates must be compost meeting the defmition for "Composted Materials" in WAC 173-350, section 220, (available online at www.ecy.wa.gov/programs/swfa/oManies/soil.html ) or topsoil manufactured from these composts plus clean sand or sandy loam soil. Products must be identified on the Soil Management Plan form, and recent product test results must be provided showing that they meet the additional requirements in this Guide for organic matter content and carbon to nitrogen ratio (see specification in Section 3). For Custom Calculated amendment rates (see right, next page, and formula in Section 7 "Resources"), organic matter may be provided by: • Compost (as defined above), or • Other by organic materials with a carbon to nitrogen ratio under 25:1 (35:1 for native plantings), meeting the same contaminant standards as "Composted Materials" in WAC 173-350, section 220. These products must be identified on the Soil Management Plan form, and recent test results provided showing that they meet these requirements. Step 5: Calculate Amendment, Topsoil and Mulch Volumes on SMP form • For Pre -Approved amendment rates, figure the square footage of each area and complete the simple calculation to convert inches of amendment into cubic yards. • To compute custom calculated amendment rates, use soil and amendment test results and the Model Amendment Rate Calculator Spreadsheet and/or the Equation for Calculating Compost Application Rates (both are in Section 7 "Resources") to achieve the target Soil Organic Matter content (10% SOM for landscape beds, or 5% SOM for turf areas). Site Assessment Supplies • Copy of site grading plan • Sturdy shovel • Tape measure If using custom calculated amendment rates requiring soil tests: • Clean bucket or stainless steel bowl for mixing soil samples • Sealable bags for soil samples, and indelible ink pen to label Sampling and Testing for Custom Calculated Amendment Rates Soil and amendments submitted for testing should be a composite of samples taken from several spots on a site or in a pile of amendment. Soil: Gather samples from soil that will be the subgrade after all grading operations are completed, before placement of imported topsoil or amendments. • Take samples from 10-12 spots in each area. Imagine a line dividing the area in half lengthwise, then divide each half into five near equal sized widths. Take samples near the middle of each subsection. • At each sampling spot dig a spades -width hole at least 8 inches deep, then shave a 1 inch slice from the side of the hole to use in the composite sample. • Thoroughly mix the 10-12 samples from each turf or planting area together in a clean plastic bucket or bowl. Place 2 cups of the mix into a sealable plastic bag for testing (some tests may require more soil, ask laboratories). • Label the bag with the site information, area of sample; plus your name, address and phone number. Amendment: Producers of composts and manufactured topsoils can usually provide test results for their products. If tests are 11