05-28-2002 Council Packet - Laserfiche WebLink

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Gr««n Construction Continued STEP1 STEP 2 STEPS STEP 4 STEPS STEPS The Subgrade. It is most important to match the contours of the subgrade to the contours of the proposed finished grade. Deviances greater than one inch between the subgrade and finished grade can cause wet spots in low areas or dry spots in higher areas. The subgrade will be established approximately 16 to 18 inches below the proposed finish grade. The subgrade requires thorough compaction in order to prevent any future settling. The layers of material above the subgrade wiU consist of four inches of gravel, two to four irKhes of course sand, arxl a top layer of 12 inches of root zone mix. The total depth is approximately 18 inches. Settling of approximately 16 inches can be anticipated after installation. Drainage. Tile lines of corrugated plastic should be four inches in diameter. Spacing should be such that water will not have to travel more that ten feet to reach a tile drain. The settled and compacted subgrade should be trenched so that tile lines slope uniformly. Tile will be installed on a firm bed of gravel and then backfilled with gravel taking care to maintain proper downslope through the entire system. Proper design consideration should be given to surface drainage as well. The finished green surface should drain at least two to three directions. Gravel and Course Sand Layers. Grade stakes should be placed at frequent spacing throughout the green site. Each stake should be marked to correspond with the planned depth of the gravel, course sand, and top mix layers. Each layer is then installed and spread to the prescribed depth. The course sand layer must be spread by hand labor, not by machine. Root Zone Mixture. The putting green root zone mixture must be comprised of the proper mix of sand, soil, and fibrous organic amendments. Native soils rarely contain the physical properties necessary for this mix. Because of extreme local variations in these materials, a competent soil laboratory analysis may be necessary to identify factors such as infiltration and percolation capacity, porosity, bulk density, water retention capacity, arxl particle size. Once the proper proportions of root zone components are identified, it is important that they be mixed accurately at an off-site location. It is also prudent to prepare and stockpile enough root zone mix to meet topdressing requirements for the first two years. Top Mix Covering. Placement, Smoothing, and Firming. An absolute minimum of 12 inches of uncompacted top mix is spread, smoothed, and compacted uniformly. The firming process must not be rushed and may require more than one attempt to achieve complete success. Sterilization of Top Mix and Establishment of Turf. After the top mix has been installed and un'ifomrily firmed, sterilization is required to eliminate any undesirable weed seed or disease that could have been introduced during the root zone mixing operation. Once sterilization is complete and adequate ventilation time has elapsed, final seedbed preparation occurs. At this time fertilization should occur prior to the placement of a climate suitable bentgrass seed. A geotextile cover is recommended to limit erosion and promote growth. At this point irrigation, light fertilization, and mowing complete the turfgrass maturation process. ^