Construction Inspections Of BMPs

Question 1

When should inspectors evaluate the success of a Sheet Flow to Filter Strip BMP?

What should inspectors look for during this inspection?

Answer 1

Inspectors should evaluate the performance of the Filter Strip after the first big storm and look for evidence of gullies, outflanking, under cutting, or sparse vegetative cover.

VA DEQ Spec. 2 Page 17/20

Question 2

Why is construction inspection critical to the success of Sheet Flow to a Filter Strip?

Answer 2

• To obtain adequate spot elevations
• To ensure the gravel diaphragm or ELS is completely level, on the same contour, and constructed to design elevation.

VA DEQ Spec. 2 Page 17/20

Question 3

When is the “real test” for a Grass Channel BMP?

Answer 3

After the first big storm.

VA DEQ Spec. 3 Page 19/20

Question 4

What 3 things should be inspected during a post-storm inspection of a Grass Channel BMP?

Answer 4

1). Make sure the desired coverage of turf of erosion control fabric has been achieved; 2). Inspect check dams and pre-treatment structures to make sure they have correct elevations, proper installation and are working effectively; 3). Make sure outfall protection/energy dissipation at concentrated inflows are stable.
VA DEQ Spec. 3 Page 18 and 19/20

Question 5

What might a construction inspection of Soil Compost Amendments involve?

Answer 5

Digging a test pit to verify the depth of mulch, amended soil, and scarification.

A rod penetrometer should be used to establish the depth of uncompacted soil at one location per 10,000 square feet.

VA DEQ Spec. 4 Page 7/10

Question 6

Given the importance to ensure a Vegetative Roof BMP is built in accordance with these specifications, what measure should be taken during construction to confirm this?

Answer 6

Detailed inspection checklists should be used that include sign-offs by qualified individuals at critical stages of construction and confirm that the contractor’s interpretation of the plan is consistent with the intent of the designer and manufacturer.

VA DEQ Spec. 5 Page 14/17

Question 7

Name two things the operator can do to help ensure a Vegetative Roof BMP is built correctly?

Answer 7

1). Hire an experienced installer to construct the vegetative roof system; and 2). Construct the roof in sections for easier inspection and maintenance access to the membrane and roof drains.

VA DEQ Spec. 5 Page 15/17

Question 8

What 6 steps during Vegetative Roof BMP installation require careful supervision?

Answer 8

1). During placement of the waterproofing layer; 2). During placement of the drainage layer and system; 3). During placement of the growing media(correct depth); 4). Upon installation of the plants; 5). Before issuing use and occupancy approvals, 6). At the end of the 1st or 2nd growing system(desired surface cover)
VA DEQ Spec. 5 Page 15/17

Question 9

What 8 things should be inspected during a post-storm inspection of a Rainwater Harvesting BMP?

Answer 9

1). Rooftop area matches plans; 2). Diversion system properly designed and installed; 3). Pretreatment system is installed; 4). Mosquito screens are installed on all openings; 5). Overflow device matches plans; 6). Rainwater harvesting system foundation matches plans. 7).catchment area and overflow area are stabilized; and 8). Secondary runoff reduction practice matches plans.

Question 10

What are common pitfalls, during construction of Permeable Pavement BMPs that should be avoided related to materials?

Answer 10

• Storage of materials should occur in a protected area away from dirt, mud, and other foreign materials.
• make sure aggregate material is clean and washed and meets specifications.

VA DEQ Spec. 7 Page 21/25

Question 11

What are common pitfalls, during construction of Permeable Pavement BMPs that should be avoided that are directly related to the construction of the driveway?

Answer 11

• Correct depth of aggregate material.
• Correct elevation for underdrain, inflow and outflow points, and correct surface slope.
• Make sure caps are placed on the upstream (but not the downstream) ends of the underdrains.

VA DEQ Spec. 7 Page 21/25

Question 12

What are common pitfalls, during construction of Permeable Pavement BMPs that should be avoided that are related to the area surrounding the driveway?

Answer 12

• The contributing drainage area should be stabilized prior to directing water to the permeable pavement area.
• Make sure pretreatment structures are properly installed and working effectively.

VA DEQ Spec. 7 Page 21/25

Question 13

What are erosion and sediment control concerns for Permeable Pavememt BMPs?

Answer 13

1). Permeable pavement areas should be protected by silt fence; 2). Permeable pavement areas should remain outside the limits of disturbance to prevent soil compaction; 3). Avoid tracking sediments onto permeable pavements; 4). Do not use a permeable pavement area as the site of a sediment basin.

Question 14

What are bad times to install a Permeable Pavement BMP system?

Answer 14

• During rain
• During snow
• During cold temperatures when bedding material is frozen

VA DEQ Spec. 7 Page 18/25

Question 15

What should be done if construction material for a Permeable Pavement BMP are contaminated by sediments?

Answer 15

They must be removed and replaced with clean materials.

VA DEQ Spec. 7 Page 18/25

Question 16

During construction of a Permeable Pavement BMP what is the ideal location for excavators or backhoes during excavation of the reservoir layer? What is an ideal location for excavated material?

Answer 16

Excavators or backhoes should work from the sides to excavate the reservoir layer.

Excavated material should be placed away from open excavation as to not jeopardize the stability of the side walls.

VA DEQ Spec. 7 Page 18/25

Question 17

What are two reasons that infiltration practices are particularly vulnerable to failure?

Answer 17

1). If the construction sequence is not followed correctly, construction sediment can clog the practice; 2). Heavy construction can result in compaction of the soil, which can reduce the soils infiltration rate.

VA DEQ Spec. 8 Page 16/24

Question 18

During the construction of an Infiltration BMP what 4 steps are absolutely critical?

Answer 18

1). Avoid excessive compaction; 2). Keep infiltration practices “off-line” until construction is complete; 3). Make sure the infiltration practice site is not used as the site for temporary sediment control devices; 4). Upland drainage areas need to be completely stabilized prior to commencing excavation.

VA DEQ Spec. 8 Page 17/24

Question 19

How can you prevent sediment from entering the site of an infiltration BMP during construction?

Answer 19

By using super silt fence, diversion berms or other means.

VA DEQ Spec. 8 Page 16/24

Question 20

What location should filter fabric be installed for a typical infiltration practice? What action should be taken to prevent puncturing or tearing of the filter fabric?

Answer 20

Filter fabric should be installed on the trench sides.

Large tree roots should be trimmed flush with the sides of infiltration trenches to prevent puncturing or tearing of filter fabric.

VA DEQ Spec. 8 Page 17/24

Question 21

During construction what procedures must an operator follow if they would like to use a bio-retention pond as a small sediment trap or basin?

Answer 21

1). The maximum excavation depth at the construction stage must be at least 1 foot above the post construction installation; 2). The facility must contain an under-drain.

VA DEQ Spec. 9 Page 33/54

Question 22

During construction of Bio-retention BMPs, what practices are ideal to protect the BMP site and prevent soil compaction?

Answer 22

The Bio-Retention area should be fully protected by silt fence or construction fencing and the Bio-retention area should remain outside the limits of disturbance.

VA DEQ Spec. 9 Page 33/54

Question 23

When can construction of the Bio-retention area begin?

Answer 23

After the entire contributing drainage area has been stabilized with vegetation.

VA DEQ Spec. 9 Page 34/54

Question 24

What action(s) should be taken during construction of a Dry Swale BMP to “promote greater infiltration”?

Answer 24

The bottom of the dry swale should be ripped, roto-tilled, or otherwise scarified.

VA DEQ Spec. 10 Page 19/21

Question 25

What 4 type of minor adjustments are common during post-storm inspections of Dry Swale BMPs?

Answer 25

1) . Spot Reseeding
2) . Gully Repair
3) . Added armoring at inlets or outfalls
4) . Check dam realignment

VA DEQ Spec. 10 Page 20/21