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Cadman,Inc. August 31,2018 Page 5 <br /> INFILTRATION RECOMMENDATIONS <br /> Based on in-situ field infiltration testing within the footprint of the Hardeson Pond,the design infiltration rates <br /> calculated for PIT-1 through PIT-3 range from 0.4 to 14.2 in/hr.The calculated geometric mean of the three <br /> infiltration rates is 2.1 in/hr. However, on the basis of the verification PITs and the degree of variability <br /> indicated,we recommend using the previously reported design infiltration rate of 1.6 in/hr,assuming that all <br /> existing fill is removed from below the bottom of the planned pond. <br /> The Hardeson Pond Infiltration Facility Detail is shown on Figure 2.We understand that all existing fill material <br /> (approximately 1 to 5 feet)will be overexcavated and removed from below the base of the infiltration facility <br /> and will be replaced with 5 feet of approved sandy material,such as the washed waste sand product produced <br /> by Cadman, Inc. bringing the final base of the Hardeson Pond to Elevation 427.0. We recommend <br /> GeoEngineers be on site during overexcavation of the pond bottom to observe the removal of fill material and <br /> evaluate the nature of soils exposed over the full pond bottom area before placing the 5-foot sand layer.It may <br /> be necessary to overexcavate local zones of unsuitable soils that may be exposed along the pond bottom and <br /> replaced these zones with the sand. <br /> We appreciate the opportunity to provide additional services on this project. Please call if you have any <br /> questions or comments. <br /> Sincerely, <br /> GeoEngineers,Inc. <br /> 0.A,* r ,/, / <br /> • eiste, 401frelir/ <br /> Bridget A.August, LG, LHG C.Metcalf- G <br /> Hydrogeologist / Princip. l <br /> :::: <br /> W3shf <br /> ecs <br /> : $ • A '1!i�� <br /> Figure 1,Site Plan ' /r 1 :�tid <br /> �,r r �r_041- ' <br /> Figure 2.Hardeson Pond Infiltration Facility Detail Figure 3.PIT-2 Hydrograph 4",' jf ref;` f '"' � <br /> . �r' ,. ! ��.; t'��Hydrogedoyist i y ; , <br /> Figure 4.PIT-2 Infiltration Rates "' "� �� \`O� <br /> c <br /> Figure 5.PIT-3 Hydrograph / w,��`, ' a . i )y\ Ted GS° <br /> 4/1 Figure 6.PIT-3 Infiltration Rates p'� <br /> Attachment A.Exploration Logs and Laboratory Testing <br /> Michael Kenrick <br /> Disclaimer Any electronic form,facsimile or hard copy of the original document(email,text,table,and/or figure),if provided,and any attachments are only a copy of <br /> the original document.The original document is stored by GeoEngineers,Inc.and will serve as the official document of record. <br /> GEOENGINEERSji <br /> File No.7087-026-02 <br />