2600 FEDERAL AVE 2021 PORT OF EVERETT 2025-09-29

Substantive Requirements Review Landau Associates 3.3.1 Preload LAI recommends using a preload to help limit settlement in areas of the site with significant wood waste deposits and no buried structures within 4 ft of finished grade. Preload height should match the anticipated load that will be exerted by proposed improvements, including fill placed during construction. A faster settlement rate could be achieved by increasing the preload height. Following completion of the preload, up to 5 inches of recompression settlement should be anticipated. This does not include long-term settlement caused by decomposition of wood waste. Areas in the southern half of the site, where buried wood waste is not present, may experience up to 5.5 inches of static settlement. Common Borrow that conforms to the requirements in Section 9-03.14(3) of the 2020 WSDOT Standard Specifications should be placed to the desired preload thickness. Preload thickness should be determined based on anticipated loading, inclusive of fill and other materials used to bring the site to finished grade. Preload material should extend beyond the footprint of the proposed improvements a distance equal to the height of the preload. Preload side slopes should be no steeper than 1% horizontal to 1 vertical (1%H:1V). If steeper side slopes are necessary, the preload soil may be retained by a temporary structure, such as a mechanically stabilized earth or modular block wall. Preloading may cause total or differential settlement of adjacent structures not supported on deep foundations. If adjacent structures are supported on deep foundations, preloading adjacent to these structures could increase downdrag loads on deep foundation elements. Nearby structures should be evaluated before preload fill is placed. Settlement magnitude should be monitored with settlement plates. At least one settlement plate should be placed near the center of the preload fill and two on opposite edges of the preload fill. LAI can provide specific recommendations for settlement plate installation, if needed. Preload fill settlement should be measured every 7 to 10 days, with two baseline readings before fill placement. The Geotechnical Engineer should be provided with records of preload fill displacements as the data is being collected. 3.3.2 Multi-Layer Geogrid Reinforcement A representative concentration of buried historical foundation elements is shown in the bottom left quadrant of Figure 6. Constructing pavement sections on top of the buried foundation elements could result in reflective cracking at the pavement surface. A multi-layer geogrid-reinforced base course could be used to construct pavements in areas with a high concentration of buried structures, especially where structures are located within approximately 4 ft of finished grades. The geogrid- reinforced base course pavement section should consist of a layer of Tensar TX7 geogrid (or similar), placed over a subgrade that has been compacted to a firm, unyielding condition. Six inches of well-compacted crushed surfacing base course (CSBC) should be placed over the geogrid, followed by another layer of TX7 geogrid, followed by another 6 inches of well-compacted CSBC. The reinforced Geotechnical Engineering Report 0121049.040.041 Norton Terminal Development&MTCA 3rd Interim Action 3-5 May 7,2021