284 PARKS 



(d) Drainage for wall foundations. It is very essential that founda- 

 tions of all walls other than dry walls should be thoroughly drained (see 

 Plates 115 and 116). Special drainage is not necessary in sandy or other 

 naturally well-drained soils. In other soils a four-inch agricultural tile laid 

 in accordance with the principles outlined under Drainage (page 288) is 

 sufficient to answer all requirements. After the forms for reinforced walls 

 are removed and after any necessary waterproofing is completed there 

 should be a layer of gravel or cinders backfilled against the back of the 

 wall (Plate 116, figures I and 2; Plate 115, figures i, 5 and 6). If the founda- 

 tion for the dry stone wall is of concrete or brick masonry construction 

 (Plate 115, figure 3) it is desirable that this should be drained. If the 

 foundation is of dry stone construction it is not essential that it should be 

 drained (Plate 115, figure 2). 



(e) Waterproofing of walls. When a brick masonry wall (Plate 115, 

 figure i) is constructed it is very desirable that the back of the wall should 

 be thoroughly waterproofed with some tar preparation. This will protect 

 the brick wall from absorbing an excessive amount of moisture. It is some- 

 times advisable, especially when a concrete retaining wall is veneered 

 (Plate 1 1 6, figure 3, and Plate 115, figure 6), that the back of the wall 

 should be thoroughly waterproofed with a standard preparation of tar or 

 other material. Whenever a retaining wall serves the two purposes of being 

 a retaining wall and a free-standing wall or parapet wall, it is very neces- 

 sary to provide adequate drainage on the upper level to prevent excessive 

 amounts of water coming in contact with the wall. It is sometimes desir- 

 able to provide at intervals of 15 or 20 feet a series of weep-holes which 

 will permit an outlet for free soil water that may accumulate at the back 

 of the wall. 



(/) Planting pockets. It may be a part of the design, especially in the 

 construction of stone or brick masonry walls, brick or stone veneered walls 

 and dry walls, to install planting pockets. Under all such conditions a 

 hole of suitable size and shape should be made or left in the face of the 

 wall, extending through the entire thickness of the wall, and becoming 

 larger at the back. Where planting pockets are required for wall planting 

 extreme care should be exercised to prevent excess drainage of soil water 

 from the soil at the back of the wall. Dry stone walls (Plate 115, figures 2 

 and 4) are ideal types in which to place planting pockets. The planting 

 pockets should be filled with a rich topsoil well fertilized. Planting pockets 

 should be given serious consideration when the forms for concrete, gravity 

 and reinforced (plain or veneered) walls are being constructed in order to 

 provide openings which will give a direct contact between the soil in the 

 wall pocket and the natural soil at the back of the wall. Excellent illustra- 



