616 PECKS DR 2018-01-01 MF Import

W My � R np r s� Cb i0 A R1 C M � � x [verett School District W-6884 K � 15 June 1990 Page 4 � � N 79 o��GYx�,,l�rers. - � � � two feet of grass, topsoil or root-laden surfici soils in the proposed building area H � � southeast of the existing school. The uncontr ed fiil material disclosed at the proposed � H building location in the courtyard should b overdecorate reveal the underlying dense � y y to very dense silty sands (Weathered Tili). Due�to the expected variations in thickness � � and extent of root-laden or uncontrolled fill materiai, we recommend that RZA be allowed � y to monitor this over-excavation during grading in order to confirm appropriate excavation depths based on actual conditions encountered in the field. Any existing utilities or buried fuel or septic tanks within proposed buiiding areas should be removed or relocated outside the proposed building perimeter. The resulting excavations shouid then be backfilled up to subgrade elevation with structural fili as described in the subsequent section of this report. Buried tanks in areas to be paved should be abandoned according to State and local guidelines. The suitability of exposed native soils for the support of foundations, floors, walkways, �� pavements, or structural fill should be evaluated during construction. We generelly recommend that all subgrade areas be proofrolled and compacted with a rolier or other � suitable heavy equipment as necessary to achieve a firm and non-yielding condition. 1 1�� However, it should be noted that due to the high silt content of tfie native site soils, such proofrolling and compaction shouid be done only when the soils are at or very near the '�� optimum moisture content. The optimum moisture content allows the greatest ! ��.� compacted soil density under a given compactive effort. Furthermore, proofrolling and compaction of the dense glacial till may be unnecessary and may even lead to �-1+' degradation of the soils. Consequently, we recommend that an RZA representative evaluate the need for such subgrade preparation in the fieid at the time of construction. � !�� , Because the silty site soils are highly moisture sensitive and susceptible to disturbance � r when wet, the contractor shouid minimize trarfic over any prepared subgrades areas. I ! '��1 Surface water sources around the work areas should be intercepted and diverted prior ��r to construction. Once the native, silty soils are wet, it may be vary diHicult or impossible to recompact them. If wet conditions occur during earthwork, a working surface of quarry spalls or sand and gravel should be placed to protect the native subgrade, especially from vehicular traffic. Similarly, if groundwater or surface water collects on surfaces to receive structural (ill, a drainage I��er of quarry spalis or washed rock may be needed on the wet surface to allow further `iil placement. 8ased on our borings and