BMP Installation Guide for Construction Sites: Types, Specs, and When to Use Each
A practical installation guide for the most common erosion control and sediment control BMPs on construction sites -- covering silt fence, compost sock, sediment basins, inlet protection, and more, with spec requirements and common installation failures.
Terms used in these guides(19 terms, plain-language definitions)
- SWPPP — Stormwater Pollution Prevention Plan
- The written plan describing how a site keeps dirt, concrete washout, fuel and other pollutants out of storm drains and streams.
- BMP — Best Management Practice
- A physical control or work practice that reduces pollution in runoff, such as silt fence, a gravel construction entrance or covered stockpiles.
- NOI — Notice of Intent
- The form an operator files to request coverage under a general stormwater permit before ground is disturbed.
- NOT — Notice of Termination
- The form filed when a site is finished and stabilized, ending permit coverage.
- CGP — Construction General Permit
- The stormwater permit that covers construction sites, issued by EPA or a state program.
- MSGP — Multi-Sector General Permit
- The stormwater permit that covers operating industrial facilities, as opposed to construction sites.
- NPDES — National Pollutant Discharge Elimination System
- The federal Clean Water Act program under which stormwater permits are issued.
- NMPDES — New Mexico Pollutant Discharge Elimination System
- New Mexico's state-run version of the NPDES program.
- AZPDES — Arizona Pollutant Discharge Elimination System
- Arizona's state-run version of the NPDES program, administered by ADEQ.
- TPDES — Texas Pollutant Discharge Elimination System
- Texas's state-run version of the NPDES program.
- EPA — United States Environmental Protection Agency
- The federal agency that writes the NPDES rules and issues permits where a state has not taken over the program.
- NMED — New Mexico Environment Department
- The state agency responsible for water quality in New Mexico.
- ADEQ — Arizona Department of Environmental Quality
- The state agency that runs the AZPDES program.
- WQCC — Water Quality Control Commission
- The New Mexico body that adopts the state's water quality rules.
- PE — Professional Engineer
- A licensed engineer; some plans or certifications must be prepared or stamped by one.
- E&O — Errors and Omissions insurance
- Professional liability insurance a consultant carries against mistakes in their work.
- Discharge
- Water leaving a site, typically stormwater runoff that reaches a storm drain, ditch or stream.
- Outfall
- The point where runoff leaves a site or enters a water body.
- Stabilization — Final stabilization
- Covering exposed soil with vegetation, pavement or other permanent cover so it no longer erodes; usually the condition for ending permit coverage.
BMP Installation: The Difference Between a SWPPP on Paper and a SWPPP That Works
A Stormwater Pollution Prevention Plan identifies the Best Management Practices (BMPs) that will be installed on your construction site. But a SWPPP is only as effective as the quality of BMP installation and maintenance -- and substandard installation is the most common reason sites fail SWPPP inspections and generate regulatory violations.
This guide covers installation specifications, placement logic, and failure modes for the BMPs most commonly used on construction sites in the Southwest -- with specific attention to the performance requirements under NMPDES, AZPDES, and the federal CGP.
Erosion Control BMPs: Preventing Soil from Becoming a Pollutant
Erosion control BMPs target the source: they prevent soil from detaching in the first place by protecting disturbed surfaces from raindrop impact and overland flow.
Temporary Seeding and Mulching
Purpose: Establish rapid vegetative cover on disturbed areas to prevent erosion between grading phases or during construction delays.
Installation standards:
- Seeding rates vary by species and region. For New Mexico and Arizona, native seed mixes (blue grama, sideoats grama, alkali sacaton) are preferred and often required for NMPDES compliance. Introduced species like ryegrass establish faster but do not meet NM's final stabilization standard.
- Seed-to-soil contact is critical. Disk or rake seed in rather than surface-broadcasting on compacted soils.
- Mulch at minimum 2 inches depth (straw) or 3 inches (wood fiber) to protect seed from wind and rainfall.
- In high-wind areas (common in NM and AZ), straw mulch must be crimped or tackified. Loose straw scattered on a site is not a BMP -- it is a fire hazard and a compliance failure.
When to use: Any disturbed area that will not be graded again for 14+ days. NMPDES requires temporary stabilization within 14 days of grading completion in any area.
Common failure: Seeding on overly compacted, caliche-heavy soils without scarification. Seed germinates poorly and the area shows up as "no vegetative establishment" on inspection -- triggering corrective action.
Erosion Control Blankets and Matting
Purpose: Protect disturbed slopes and channels from raindrop impact and overland flow, while providing microclimate support for seed establishment.
Installation standards:
- Match product type to slope and channel velocity:
- Slopes up to 3:1 (H:V): Straw/coconut fiber blankets (100-150 lbs/sq yd tensile strength)
- Slopes 2:1 to 3:1: Coconut fiber or synthetic mat with higher tensile strength
- Channels with flow velocity up to 5 fps: Coconut fiber or synthetic mat
- High-velocity channels (5+ fps): Turf reinforcement mat (TRM) or articulated concrete block
- Install blanket from top of slope downward; unroll with the net on top.
- Use a minimum 6-inch overlap at seams, with seam stapled every 12 inches.
- Staple pattern on slopes: check pattern at 2.5 ft x 3 ft minimum; increase to 1.5 ft x 2 ft on steeper slopes.
- Bury leading edge in a 6-inch trench at the top of slope; compact trench. An unanchored leading edge is the single most common blanket failure mode.
When to use: Slopes steeper than 3:1, drainage channels, areas with concentrated flow potential.
Common failure: Blanket installed over uncompacted seed bed; blanket lifts in wind before seeds germinate; staples pull out in sandy soils (use longer staples in sandy conditions).
Construction Entrance Pads
Purpose: Remove mud and sediment from vehicle tires before they exit the site onto public roads, preventing off-site sediment tracking.
Installation standards:
- Minimum dimensions: 50 feet long x 20 feet wide (or full width of entrance).
- Aggregate size: 3/4-inch to 3-inch clean crushed stone. Do not use fine aggregate -- it packs down and loses effectiveness.
- Depth: Minimum 6 inches over geotextile fabric.
- Install geotextile beneath aggregate to prevent aggregate from sinking into subgrade.
- Include a wash rack (water trough or wheel wash station) for sites with heavy clay soils or prolonged wet conditions.
When to use: Every vehicle entrance and exit point from a construction site. Multiple entrances require multiple pads.
Common failure: Pad degrades over time as aggregate is pushed into subgrade; operator does not replace aggregate until a formal inspection identifies sediment tracking on public road. By then, a reportable discharge may have already occurred.
Sediment Control BMPs: Capturing What Erosion Produces
Sediment control BMPs are the last line of defense -- they capture sediment that has already detached from the soil and prevent it from leaving the site boundary or entering stormwater conveyances.
Silt Fence
Purpose: Intercept overland sheet flow and filter out suspended sediment before runoff leaves the site.
When to use: Downslope site perimeters, around stockpiles, adjacent to drainage channels.
When NOT to use: In areas of concentrated flow (swales, ditches, channels). Silt fence is designed for sheet flow only -- concentrated flow will undercut or blow out silt fence, resulting in a BMP failure and a reportable discharge.
Installation standards:
- Use woven geotextile with minimum permeability of 0.02 cm/sec; avoid non-woven fabrics (they clog faster).
- Posts: hardwood, 5 feet minimum height, driven 18-24 inches into soil.
- Post spacing: Maximum 6 feet on flat ground; reduce to 4 feet on steeper slopes or in high-flow areas.
- Fabric attachment: Secure to posts at least every 6 inches on the top wire; attach to bottom wire as well.
- Trenching: Bury 6-8 inches of fabric in a trench at the base of the fence, backfilled and compacted. This is the most commonly skipped installation step and the most common failure mode -- runoff undercuts the fence.
- Slope limitation: Do not install silt fence on slopes steeper than 2:1 (H:V). On steeper slopes, use fiber rolls or compost sock instead.
Maintenance: Inspect after every storm event. Remove sediment when it accumulates to one-third of the fence height. Failure to maintain silt fence voids its effectiveness and creates an inspection documentation problem.
Common failure: Installation without trenching; concentrated flow channeling under or around fence; sediment accumulation not removed after storm events.
Compost Sock and Fiber Log Berms
Purpose: Provide sediment filtering while also promoting water infiltration and reducing peak runoff velocity. More versatile than silt fence in concentrated flow areas and on steeper slopes.
Installation standards:
- Select diameter based on drainage area and slope:
- 9-inch diameter: suitable for slopes up to 6% and drainage areas up to 0.25 acres
- 12-inch diameter: slopes up to 10%, drainage areas up to 0.5 acres
- 18-inch or 24-inch: steeper slopes and larger drainage areas; requires engineering review
- Staking: Drive steel or wood stakes through the sock at 4-foot intervals; stakes must penetrate minimum 8 inches into soil.
- Spacing of check dams in swales: H = D/(slope in percent) x 3; this maintains a continuous pool from the toe of one berm to the top of the next, eliminating gaps in coverage.
- Overlap at joints by minimum 12 inches; do not gap between sock segments.
When to use: Drainage swales and channels (where silt fence cannot be used), perimeter controls on slopes steeper than 2:1, check dams in construction drainage channels, around storm drain inlets.
Common failure: Understaking (sock floats off grade during storm); gaps between segments allowing flow to bypass; material degradation in UV-intense environments (NM/AZ) -- check manufacturer UV rating.
Storm Drain Inlet Protection
Purpose: Prevent sediment-laden runoff from entering storm drain systems, which discharge directly to receiving waters.
Installation standards:
- Select device type based on inlet configuration and runoff volume:
- Silt sacks (fabric inserts): effective for low-flow inlets; must be inspected and cleaned after each storm event
- Block and rock filters: more robust; require verification that flow bypass does not cause flooding
- Earth berms around inlets: only where ponding will not cause off-site flooding or create safety hazards
- Maximum ponding depth allowed by most state CGPs: 1 foot; check local floodplain requirements
- For curb inlets: install fabric from the back of curb to 18 inches past the face; fold and stake fabric into curb expansion joints
Common failure: Inlet protection overloaded and bypassed during significant storm event; silt sacks not cleaned between events and becoming ineffective.
Sediment Basins
Purpose: Provide temporary water storage to allow suspended sediment to settle out before discharge. Required for sites with drainage areas exceeding 10 acres under most state CGPs.
Design requirements (NMPDES):
- Minimum storage volume: 1,800 cubic feet per acre of disturbed area draining to the basin
- Emergency spillway sized for the 10-year, 24-hour storm event
- Design and specifications must be prepared and sealed by a PE in most state programs
- Outlet structure must include a sediment-cleaning cleanout port
Installation: Excavate below existing grade and use excavated material for berms. Compact berm material in 6-inch lifts to minimum 95% standard Proctor density. Install anti-seep collar on outlet pipe.
Common failure: Insufficient basin sizing; failure to clean accumulated sediment from basin (renders basin ineffective for subsequent storm events); emergency spillway erosion during large events.
BMP Selection Decision Matrix
| Site Condition | Recommended Primary BMP | Notes |
|---|---|---|
| Flat site perimeter, sheet flow | Silt fence | Must trench; avoid concentrated flow areas |
| Steep slope (steeper than 2:1) | Compost sock or TRM | Silt fence not appropriate on steep slopes |
| Drainage swale / channel | Compost sock check dams | Spacing critical; see formula above |
| Active storm drain inlets | Silt sack or block filter | Clean after every storm event |
| Disturbed slope, temporary | Erosion control blanket + seed | Anchor leading edge; match product to slope |
| Large drainage area (10+ acres) | Sediment basin | PE design required in most states |
| Vehicle exit points | Construction entrance pad | 50 ft minimum; maintain aggregate depth |
| Stockpile | Silt fence + tarp cover | Tarp required if stockpile contains chemically active material |
Documentation Requirements for BMPs
Every BMP on your site must be documented in the SWPPP, including:
- BMP type, location, dimensions, and design specifications
- Installation date
- Maintenance schedule and responsible party
- Inspection observations and corrective actions taken
For multi-site operators: a photographic BMP log -- with GPS coordinates, installation date stamps, and sequential "before / after storm" photos -- provides the most defensible compliance documentation.
Professional BMP Installation Services
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Related Resources
Authoritative sources
This guide is education, not advice. The permit text and the agency that administers it are the final word.
- U.S. EPA:Construction General Permit (CGP)
- U.S. EPA:Multi-Sector General Permit (MSGP) for industrial stormwater
- New Mexico Environment Department:Surface Water Quality Bureau
- Arizona Department of Environmental Quality:AZPDES stormwater program
What next, and who is responsible
The permit holds the operator responsible: whoever controls the construction plans or the day-to-day work on the ground, which is usually the general contractor and often the owner as well. A landowner who has hired others to build is still named on the permit whenever they control the plans, so confirm who is filing before ground is disturbed.