Llonard Yap's List: Earthworks Best Practices

• erosion and sediment control
• earthworks construction and subdividing land
• Without appropriate erosion and sediment control, these activities can result in accelerated on-site erosion and greatly increased sedimentation of waterways, lakes, estuaries and harbours.
• Various studies show earthworks sites may produce 10 to 100 times more sediment yield compared with pastoral land, and 1000 times more compared with permanent forest cover.
• Sediment can damage our waterways’ ecology by:
• water quality and habitat)
• Recovery from the impacts of sediment deposition is slow - years rather than months.
• instream communities
• spoil an area’s appearance
• Use these Guidelines when planning your earthworks project to develop an erosion and sediment control plan
• Erosion and sediment control guidelines
• Erosion and sediment control plan preparation guideline
• Pre-construction meeting checklist
• Pre-construction meeting checklist
• Sediment retention pond (SRP)
• Decanting earth bund (DEB)
• Silt fence/Super silt fence (SF/SSF)
• Diversion channel/Diversion bund (DC/DB)
• Earthworks guidelines
• River management guidelines
• Clean streams
• Land and soil
• Landslides and coastal erosion
• Stormwater pollution
• What lives in our coastal ecosystems

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• These areas allow for the main channel to link with backwater areas, tributaries, and groundwater systems; provide for increased channel diversity
• and contribute sources of needed nutrients and woody debris to the river
• recovery of aquatic and riparian habitat
• the areas immediately adjacent to the river channel can help protect surrounding development from potential flood damage and can be used to filter runoff water draining into the river.
• buffer area for natural flood flows, channel formation, riparian vegetation, and wildlife habitat and would protect riverbanks from human-caused impacts and associated erosion
• Regardless of the location of the water’s edge on any given day throughout the year, the River Protection Overlay is measured from the ordinary high water mark
• The width of the River Protection Overlay is determined by site topography and vegetation and includes the area needed to encompass riparian and adjacent upland vegetation and habitat.
• a wider band is required along the river in the flatter, open valleys, while a narrower buffer provides adequate protection in the steeper, V-shaped river gorges of the lower elevations
• should not be located in the River Protection Overlay
• New facilities and development may be constructed in the River Protection Overlay only when meeting these criteria and when located where they do not materially impair the natural function of the river, impede linkages to tributary inflow and backwater areas, or disrupt contribution of woody debris to the river, and where they do not have a direct and adverse impact on the Outstandingly Remarkable Values.

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• Determination of Site Conditions
• Bridging Over Soft Soils
• Excavation and Replacement of Soft Soils
• Air-Drying of Wet Soils
• Soil Stabilization of Residential Streets
• Treated San Francisco Bay Mud For Building Foundations
• has been used for centuries throughout the world
• Modification is commonly performed on subgrade and subbases in order to expedite compaction and subsequent paving.
• The common denominator for soil modification is the improvement of soil behavior, which permits other work to proceed without delay.
• The depth of modification needed to bridge a soft subgrade is generally equivalent to the depth required to stabilize the subgrade by excavation, placement of a geofabric, and backfilling with an aggregate material.
• If the flow of water is continuous, then dewatering will be required prior to any treatment. Dewatering should to be at least 1 inch below the bottom of treatment to allow for "wicking". If it is determined that the water is only perched, then areas containing any standing water should be pumped prior to treatment.
• Soil stabilization is the construction of a load-bearing subgrade or subbase for a structural purpose.
• For pavement design purposes, tests should be conducted to determine improvements in the R-Value or Unconfined Compressive Strength with different percentages of reagent.
• Treatment will increase the load-bearing capabilities of marginal subgrade materials, therefore decreasing the amount of aggregate base required for the pavement. The stabilization process has proved to be the structural and economic solution for correcting unexpected, poor pavement support conditions.
• The following factors should be considered in determining the type of treatment product, the size of area requiring treatment, the depth, and the amount of product required.
• amount of area requiring treatment
• A rule of thumb in making this determination is that area requiring more than $6,000 of remediation or over two days of repair should be considered good candidates for treatment using additives.
• depth of treatment required
• A general rule is that the more clayey soils should be treated with quicklime products and the more granular materials should use products containing cement
• what type of product is appropriate for the soil types and conditions
• If the purpose of the treatment is to dry out the site, then the consultant can be flexible in his recommendations for percentage of product required. If the purpose of treatment is to enhance the strength or for other design considerations, then the engineer should qualify the mix design percentage with the appropriate laboratory testing.
• percentage of product necessary to meet project requirements
• One of the crucial elements of the bridging process is the curing time of the treated section. It is critical to determine when the section has been fully cured in order for the bridge to hold the loading of construction equipment.
• Excavation and Replacement of Soft Soils
• This method also would be the most expensive repair based on a square foot price.
• Continual discing is required to break up material into smaller sizing. An alternative would be to use pulverization equipment that operates more like a rototiller, immediately breaking down the particle size of soil and allowing for quicker drying times.
• Treatment eliminates the need to off-haul unsuitable material and enables the treated material to become impervious to additional saturation due to rain.
• The amount of lime or cement required to stabilize marginal aggregate bases is typically between 0.5 and 4.0 percent by weight of the total aggregate. This generally results in a fairly high lime or cement content by weight of the fines (- No. 40 sieve) fraction.
• Ultimate cure strength of lime or cement treated soils is a time-dependent function. Unconfined compression strengths improve with age. Early strengths of 450 psi are common with older sections of over 1000 psi being found in some lime or cement soil mixtures.
• f the subgrade is dry, the stabilization contractor will often flood these areas with water to avoid the possibility of this dryness pulling excess water from the treated material, retarding proper hydration of the lime and cement, and causing early failure of the section, such as longitudinal cracking or differential expansion along contact areas.
• phenolphalein

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