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AlternativeȱStormwaterȱManagementȱ DeepȬRippingȱandȱDecompactionȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ ȱ Recommended Application of Practice Description Theȱobjective of Deep Ripping and The two-phase practice of 1) “Deep Ripping;” and 2) “Decompaction” (deep subsoiling), of the Decompaction is to effectively fracture soil material as a step in the cleanup and restoration/landscaping of a construction site, helps (vertically and laterallly) through the thickness mitigate the physically induced impacts of soil compression; i.e.: soil compaction or the of the physically compressed subsoil material substantial increase in the bulk density of the soil material. (see Figure 3), restoring soil porosity and permeability and aiding infiltration to help Deep Ripping and Decompaction are key factors which help in restoring soil pore space and reduce runoff. Together with topsoil stripping, permeability for water infiltration. Conversely, the physical actions of cut-and-fill work, land the “two-phase” practice of Deep Ripping and grading, the ongoing movement of construction equipment and the transport of building Decompaction first became established as a “best materials throughout a site alter the architecture and structure of the soil, resulting in: the mixing management practice” through ongoing success of layers (horizons) of soil materials, compression of those materials and diminished soil on commercial farmlands affected by heavy Fig. 3. Construction site with significant porosity which, if left unchecked, severely impairs the soil’s water holding capacity and vertical utility construction right-of-way projects compaction of the deep basal till subsoil drainage (rainfall infiltration), from the surface downward. (transmission pipelines and large power lines). extends 24 inches below this exposed cut- and-fill work surface. In a humid climate region, compaction damage on a site is virtually guaranteed over the duration Soil permeability, soil drainage and cropland of a project. Soil in very moist to wet condition when compacted, will have severely reduced productivity were restored. For broader permeability. Figure 1 displays the early stage of the deep-ripping phase (Note that all topsoil construction application, the two-phase practice of Deep Ripping and Decompaction is best was stripped prior to construction access, and it remains stockpiled until the next phase – adapted to areas impacted with significant soil compaction, on contiguous open portions of large decompaction – is complete). A heavy-duty tractor is pulling a three-shank ripper on the first of construction sites and inside long, open construction corridors used as temporary access over the several series of incrementally deepening passes through the construction access corridor's duration of construction. Each mitigation area should have minimal above-and-below-ground densely compressed subsoil material. Figure 2 illustrates the approximate volumetric obstructions for the easy avoidance and maneuvering of a large tractor and ripping/decompacting composition of a loam surface soil when conditions are good for plant growth, with adequate implements. Conversely, the complete two-phase practice is not recommended in congested or natural pore space for fluctuating moisture conditions. obstructed areas due to the limitations on tractor and implement movement. Benefits Aggressive “deep ripping” through the compressed thickness of exposed subsoil before the replacement/respreading of the topsoil layer, followed by “decompaction,” i.e.: “sub-soiling,” through the restored topsoil layer down into the subsoil, offers the following benefits: x Increases the project (larger size) area’s direct surface infiltration of rainfall by providing the open site’s mitigated soil condition and lowers the demand on concentrated runoff control structures Fig. 1. A typical deep ripping phase of this practice, during the first in a series of Fig. 2. About 50% of the volume of undisturbed x Enhances direct groundwater recharge through greater dispersion across and through a progressively deeper “rips” through severely loam surface soil is pore space, when soil is in broader surface than afforded by some runoff-control structural measures compressed subsoil. good condition for plant growth. Brady, 2002. x Decreases runoff volume generated and provides hydrologic source control ȱ x May be planned for application in feasible open locations either alone or in 1 2 Page 304 of 1493