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HUD LAND DEVELOPMENT WITH CONTROlLED EARTHWORK Special procedures ore needed for buildIngs ..hlch ore to be constructed In accordance ..Ith the requirements set forth by the United States Deportment of Housing and Urban Development (HUD). The specIal procedures relate to requirements for earthwork, foundations, floor slobs, and soil testing. The requirements, os described In the MPS (Minimum Property Standards) and Data Sheet 79G (Land Development with Controlled Earthwork), are outlined below. Controlled earthwork using highly compacted fill In accordance wIth Data Sheet 79G Is used on HUD projects where excavating and fIllIng Is done below proposed buildings. Controlled earthwork Involves excavating organIc or unstable soils (down to firm, Inorganic, naturlll solts) from below proposed building areas. All vegetable (organic) matter must be removed from the surfllce upon whIch fill Is to be placed. Adequate oversize of the excavlltlon must be Ilttlllned. The base of the excllvatlon must be observed by a soIls engineer prior to plllcement of fl II. FIlling may commence after a soils engIneer hilS observed the bllse of the excavlltlon and competent solis are exposed and adequllte overs I ze hilS been attlll ned. The fill shou I d be p I aced so thllt I tis thoroughly and uniformly compacted to the project specIfications. Field density tests should be taken as the fill Is placed to ascertain whether adequate compaction Is beIng achieved. CooperatIon between all partIes Involved In control led earthwork operatIons Is necessary. In general, fill which has not been placed under the technical supervisIon of a soils engineer will not be acceptable. A possible exception to this requires an extensive and time consuming Investigative and administrative process. The requirements of Data Sheet 79G are specifically applicable to land development for buildings In which: 1) foundations do not extend at least 6" Into natural undisturbed soil which 1'1" provide adequate bearing capacity; and 2) the depth of fill below floor slabs will exceed that permiTted by the WS usIng normal compaction methods. (Floor slabs Include the lowest floor levels of houses and garages.) The Data Sheet 79G alternative to having footings or foundation walls extend at least 6" Into natural undisturbed soil whiCh will provIde adequate bearIng Is to construct them on a (highly compacted) controlled fIll. The maximum depth of fill allowed below slabs using normal compaction methods Is as follows: Clean Sand or Grovel (5011 Types: GW, cp. SW, & SP) - 24 Inches Other Sands or Gravels (5011 Types: GM, Ge, SM, & SC) - 12 Inches Inert Slits or Clays (5011 Types: Ml & CL) - 8 Inches Organic or active clays and silts of the OL, MH, CH, OH. & PT groups shall not be used for support of slabs on grade. Alternatives to constructIng slabs using Data Sheet 79G controlled earthwork are: I) use normal compaction methods (I.e. have fill depths less than those shown above), or 2) use structural slabs supported at edges and through the center by piers or Intermediate foundation walls (construction of slabs on moderately compacted fill). Concrete slabs and pIers' shall be designed In accordance with ACI-318, "Building Code RequIrements for Reinforced Concrete." The design should be reviewed and accepted by HUD prior to adopting such a support system. If the structurol slab approach Is adopted, the soils exposed at the base of the pIers or Intermediate foundatIon walls must be observed and approved by a solis engineer or HUD representatIve. HUD requires a 4' separation between lowest floor slabs and the groundwater toble. HUD does not allow the use of deep foundatIon systems (pIling or caissons) for support of bearing walls and columns In single fomlly housing. For sIngle family housing, HUO requIres that the soIls engIneer prep~re a t~bul~tlon Indlc~tJng lots which will be subject to HUD Data Sheet 79G and MPS guidelines. 4-87 GEOTECHNICAL ENGINEERING CORPORATION