Changes

==Clearing and grubbing==

==Clearing and grubbing==

Clearing and grubbing is the stripping of vegetation and topsoil prior to excavation and rough grading within designated areas.

Clearing and grubbing is the stripping of vegetation and [[topsoil]] prior to excavation and rough grading within designated areas.

[[File:Scarification.jpg|400px|thumb|right|Scarifying native soils helps to increase infiltration rates. (Photo source: CVC, 2022)]]

[[File:Scarification.jpg|400px|thumb|right|Scarifying native soils helps to increase [[infiltration]] rates. (Photo source: CVC, 2022)]]

'''Construction steps'''  

'''Construction steps'''  

#Clear trees, large shrubs, stumps, etc. (grubbing).

#Clear [[trees]], large [[shrubs]], stumps, etc. (grubbing).

#Use appropriately sized machinery (e.g. a mini-excavator) to strip sod and ground-level vegetation (clearing).

#Use appropriately sized machinery (e.g. a mini-excavator) to strip sod and ground-level [[vegetation]] (clearing).

#Stockpile materials within designated areas if necessary. If the materials are being hauled offsite, stripped materials ideally would go straight into the back of a dump truck.

#Stockpile materials within designated areas if necessary. If the materials are being hauled offsite, stripped materials ideally would go straight into the back of a dump truck.

#Secure stockpiles with appropriate erosion and sediment control (ESC) measures if the material must be stored before hauling offsite or will be reused.

#Secure stockpiles with appropriate erosion and sediment control (ESC) measures if the material must be stored before hauling offsite or will be reused.

==Excavation and rough grade==

==Excavation and rough grade==

Excavation to the specified depths in the drawings is critical to the LID feature’s future performance. It also requires heavy machinery which, if used incorrectly, can compact soils and lower their native infiltration rates. <br/>

Excavation to the specified depths in the drawings is critical to the LID feature’s future performance. It also requires heavy machinery which, if used incorrectly, can compact soils and lower their native infiltration rates. Over compaction of native soil underlying LID practices that infiltrate stormwater has been shown to negatively affect their drainage function.  To limit soil compaction the location of infiltration practices should be well-marked and surrounded by perimeter controls to protect the area from heavy equipment and vehicle traffic during site construction.  Excavation should be performed by a low ground pressure tracked excavator that is kept outside the footprint of the infiltration facility and should not be performed when soils are saturated.  If over-compaction does occur, it can be alleviated by soil fracturing (i.e., scooping and re-depositing native soils at the base of the practice), tilling with a subsoiler or rototiller, or raking using a toothed excavator bucket.

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[[File:Excavation outside in 2.jpg|400px|thumb|right|Excavating from impervious surfaces adjacent to the LID practice minimizes compaction. (Photo Source: CVC, 2018)]]

[[File:Excavation outside in 2.jpg|400px|thumb|right|Excavating from impervious surfaces adjacent to the LID practice minimizes compaction. (Photo Source: CVC, 2018)]]

'''Construction steps'''

'''Construction steps'''

*Use of excavation equipment specified in the contract, in the required manner (from the outside in, with a mini excavator, etc.).

*Use of excavation equipment specified in the contract, in the required manner (from the outside in, with a mini excavator, etc.).

*Confirm excavated rough grade and final grade prior to backfilling using survey equipment.

*Confirm excavated rough grade and final grade prior to backfilling using survey equipment.

*Use of toothed bucket and scouring the bottom of practice if applicable.

*Use of a toothed excavator bucket to rake the bottom of infiltration practices to reduce soil compaction and smearing where applicable (e.g., does not apply to load bearing practices like infiltration trenches, permeable pavements or stormwater tree trenches).

*If appropriate, measure compaction using a cone penetration test or a cone penetrometer .

*If appropriate, measure compaction using a soil cone penetrometer.

*If appropriate, field verify infiltration rates at excavated bottom of practice using Guelph permeameter or double ring infiltrometer.

*If appropriate, field verify infiltration rates at excavated bottom of practice using [[Permeameters|Guelph permeameter]] or [[double ring infiltrometer]].

 

'''Mistakes to avoid:'''

'''Mistakes to avoid:'''

*Making too many passes with heavy machinery within the LID footprint.

*Making too many passes with heavy machinery within the LID footprint.