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.... <br /> .. , �. .,, ., , „ ,_ , <br /> .. . wr.A<;, <br /> :_�./nL�.-n. :. . r .��>YV fi ._. . . d, �p�.: k�*'�`.. hr. : . � <br /> . .. ' ' w'i f+n .. <br /> i � � <br /> 1 ��� � ' <br /> �� � � -.„ � r . ���.. <br /> � ,,s� ��� �=_' � ' <br /> r` <br /> � �� z���� <br /> h� : . . .,. _ <br /> _. _ ._:•,: . _.: <br /> ,Ya;, <br /> [ � N .... .. . . . .. . . . . <br /> � <br /> ro y <br /> „ .+� � � ,-. <br /> ,�. y y � <br /> N � M <br /> r, y SA <br /> y y H � LOJIS Corpontion WG-1049-01-067 <br /> s z ]uly 18, 1991 Page 6 ., <br /> �n � � � <br /> z � y� 8.2. Long-Term Drainage Measures ' - . <br /> n • �S <br /> � y , Long-term drainage measures shouid include (1) grading, (2) perimeter footing drains, and (3) <br /> y � retaining wall drains. Each oF these is discussed below. <br /> r7 O N <br /> ° � � 8.2.1. Grading <br /> � � `� Final site grades sho�ld allow for drainage away from the building foundations.We recommend - - <br /> that the ground be sloped at a minimum gradient of three percent for a distance of at least ten .�� ,n <br /> feet away from the structures. �� <br /> 8.2.2. Perimeter Footing Drains <br /> We recommend you install footing drains azound the buiiding perimeter. These drains should <br /> consist of a four-inch minimum diameter, perforated or slotted, rigid drain pipe laid with the <br /> perforations or slou facing down at, or just below, the invect of the footing with a gradient � ; <br /> su(ficient to initiate ilow. The drain line should be bedded on, surrounded by, and covered with <br /> a free-draining material that :neets the requirements of WDOT Stand:.�d Specifications, Section '} <br /> � ' 9-03.12(2). ; <br /> I [� 4�> <br /> TAI3LE 1 <br /> 1 ���' WDOT Standazd Specifications, Se�:tion 9-03.12(2) 'I <br /> a..,,., <br /> • U.S. Sieve Size Percent Passing' <br /> �� A" square 100 <br /> � !�►� 25 - 70 <br /> , I/4" square <br /> No. 200 5.0 max <br /> ��� <br /> '� All percentages arc by weight <br /> � �� , - A typical footing drain detail is provided on Figure 4. <br /> i Once the drains are installed, with the exception of the upper six (6)inches, the excavation can -�_��i::'::•'._ ' ��p( <br /> y �,d,ti!-"�� <br /> �-1�' ' � be backfilled with a granular fill material. The surficial six (6) inches of fill should consist of ' � <br /> compacted and relatively impermeable soil. It can be separated from the underlying more �, � <br /> granular drainage material uy a layer of geofabric or visqueen. The surface should be sloped , <br /> �"�a <br /> ro drain away from the building wall. Altematively, the surface can be sealed wilh asphalt or ;� <br /> �� �. <br /> wncrete paving, _ _ <br /> ' :� <br /> � � . ��d <br /> � <br /> , Ka�d��ecr Assotlales • <br />