Changes

*Confirm the limit of excavation.

*Confirm the limit of excavation.

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

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

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

*leaving heavy machinery within the LID’s footprint (for breaks, lunch, overnight, etc.)

*Leaving heavy machinery within the LID’s footprint (for breaks, lunch, overnight, etc.).

*using the wrong equipment

*Using the wrong equipment.

*over excavating

*Over excavating.

*smearing the bottom of the practice with the bucket, which can compact native soils

*Smearing the bottom of the practice with the bucket, which can compact native soils.

==Final excavated grade and verification==

==Final excavated grade and verification==

LID designs typically have specific grading requirements. Verifying depths and slopes is critical for the optimal performance of the facility. For example, if the design calls for a channel with a 1% slope, the channel may not function as designed if it has a 2% slope instead.  

LID designs typically have specific grading requirements. Verifying depths and slopes is critical for the optimal performance of the facility. For example, if the design calls for a channel with a 1% slope, the channel may not function as designed if it has a 2% slope instead.  

[[File:trimble unit.JPG|400px|thumb|right|Always confirm elevations throughout construction. (Photo source: CVC)]]

[[File:trimble unit.JPG|400px|thumb|right|Always confirm elevations throughout construction. (Photo source: CVC, 2022)]]

Excavation to the sub-grade will differ depending on whether the design is for a [[Bioretention: Variations|full infiltration, partial infiltration, or no infiltration LID system]]. If it’s a full infiltration or partial infiltration practice, the sub-grade should be as level as possible to promote even infiltration across the facility’s footprint.  For no infiltration designs,  excavate sub-grade slopes to the design grade in the direction of the underdrain, typically 1 to 2%.  

Excavation to the sub-grade will differ depending on whether the design is for a [[Bioretention: Variations|full infiltration, partial infiltration, or no infiltration LID system]]. If it’s a full infiltration or partial infiltration practice, the sub-grade should be as level as possible to promote even infiltration across the facility’s footprint.  For no infiltration designs,  excavate sub-grade slopes to the design grade in the direction of the underdrain, typically 1 to 2%.  

*Confirm final excavated depths and slopes.

*Confirm final excavated depths and slopes.

'''Mistakes to avoid'''

'''Mistakes to avoid'''

*“eye-balling” depths and slopes

*“Eye-balling” depths and slopes