3301 SEAWAY BLVD WHOLE SITE 2025-10-30

tt CITY OF EVERETT STt)RMWATER MANAGEMENT MANUAi. Table 2.4 Clay Liner Specifications. Property Test Method Unit Specification Permeability ASTM D-2434 cm/sec 1 x 104m"` Plasticity Index of ASTM D-423 and D-424 percent Not less than 15 Clay Liquid Limit of Clay ASTM D-2216 percent Not less than 30 Clay Particles ASTM D-422 percent Not less than 30 Passing Clay Compaction ASTM D-2216 percent 95 percent of Standard Proctor Density Source: City of Austin,1988 Geomembrane'Lin s . Geo uenibrane liners shall be ultraviolet(UV)light resistant and have a minimum thickness of 30 mils. A thickness of 40 ills shall be used in areas of maintenance access or where h vy .. ttiacitinec3r�nttst be'opet'ated oet'#heeinbratte, t;bit Kw! C por,d� g 2. The geomembrane fabric shall be protected from puncture,tearing,and:abrasion by installing geotextile fabric,determined.to have a high survivability Per the WSDOT standard specifications as amended,specifically Section 9-33 Construction Geotextile(2006 or thelatest IterSiOrt as amended),on the top and bottom of the geomembrane. Equivalent methods for protection of the geotnembrane liner will be considered. Equivalency will be judged on the basis of ability to protect the geomembrane from puncture,tearing,and abrasion. 3. Geomembranes shall be bedded according to the manufacturer's recommendations. 4. Liners must be covered with 12 inches of top dressing forming the bottom and sides of the water quality facility,except for linear sand filters. Top dressing shall consist of 6 inches of crushed rock coveted with 6 inches of native soil. The rock layer is to mark the location of the liner for future maintenance operations. As an alternative to crushed rock,12 inches of native soil may be used if orange plastic"safety fencing"or another highly visible,continuous marker is embedded 6 inches abovethe membrane. 5. If possible,liners should be of a contrasting color so that maintenance workers are aware of any areas where a liner may have become exposed when maintaining the facility. 6. Geomembrane liners shall not be used on slopes steeper than 5H:1 V to prevent the top dressing maternal from slipping. Textured liners may be used on slopes tip to 3H:1 V upon recommendation by a geotechnical engineer that the top dressing will be stable for all site conditions,including maintenance. Table 2.6 Geotextile Properties for Impermeable Liner Protection Geotextile Property Test Method Geotextile Property Requirements j Grab Tensile Strength,min.In ASTM D4632 250 lbs min. machine and x-machine direction Grab Failure Strain,in ASTM 04632 >50 percent machine and x-machine direction Volume Ill—Flow Control and Treatment 2-91 1 •