This document provides an overview of current issues in stormwater management. It discusses how increased stormwater runoff from development can negatively impact water quality and the environment by altering hydrology, increasing erosion, degrading habitats, and reducing water quality. It also reviews regulations around stormwater management, including the National Pollutant Discharge Elimination System (NPDES) permitting process, state and local regulations, and water quality standards. Finally, it discusses best management practices (BMPs) for erosion and sediment control during construction as well as post-construction stormwater management, including low impact development techniques and engineered structural practices.

1. Current Issues in Stormwater
Management
Stormwater Management and Water
Resources
Presentation for Lorman Educational Services
Washington, DC
March 20, 2014
Andrew T. Der & Associates, LLC
Environmental Consulting
1000 Fell Street | Baltimore, MD 21231
1.410.491.2808 | AndrewTDer@comcast.net

2. STORMWATER EFFECTS ON
WATER QUALITY AND THE
ENVIRONMENT

3. Why Are We Here?

4. What Happens

5. Four Categories of Effects
• Hydrology
• Geomorphology
• Habitat
• Water Quality

6. Hydrology
• Increase in flow and
velocities
• Increase in flooding
• Increase in frequency
• Increase in bankfull flows

7. Geomorphology
• Stream Widening
• Channel Instability
• Erosion

8. Habitat
• Fish Barriers
• Loss of Substrate
• Loss of Riparian
Zone
• Loss of
Micro-topography

9. Water Quality
• Sediments
Channel erosion can be the
primary sediment source!
• Nutrients
Maintained vegetated areas
& ag
• Temperature
Warm pavements and
pond pools
• Other
Oils, Greases, heavy metals,
toxics

10. Water Quality

11. Instability

12. Instability

13. Regulations and
Permitting Overview

14. What is a Stream?
• Waters of the U. S.
• Definition includes tidal navigable water, nontidal
navigable water and adjacent headwaters and
wetlands adjacent to such waters – but how far
up does it go?
• Determines extent of Sec 401 (Water Quality
Certification), 402 (NPDES) and 404 (Dredge
and Fill) components of the Clean Water Act.

15. What is an impact?
• Impacts are discharges or grading
• Discharges can be out of a pipe or placement
of material (CWA Sec 402 & 404)
• Discharges can be permitted
• Individual Permits or General Permits

16. Types of Stormwater Permitting
• NPDES Phase I and II – U. S. EPA delegated to States by GP – regulates
new construction AND existing older stormwater sources – passes
through localities – only permit means to retrofit
• DoD and federal facility SWM mandates
• State/local Stormwater Management Regulations – new construction
• State/local Erosion and Sediment Control Regulations – new construction
• Other (Wetlands, Flood Plain, etc.)
• Both Individual & General NPDES permitting - Most new construction
under GP

17. NPDES Phase I &II Permitting
• 1972 amendments to the Federal Water Pollution
Control Act (Clean Water Act) prohibit the discharge
of any pollutant to waters of the United States from a
point source unless the discharge is authorized by a
National Pollutant Discharge Elimination System
(NPDES) permit.
• Past efforts to address stormwater discharges under
the NPDES program have generally been limited to
certain industrial categories

18. Background
• Stormwater out of a pipe was not necessarily a
point source discharge
• National Urban Runoff Program (NURP) – first
meaningful stormwater study showed stormwater
impacts
• In response to water quality concerns, in 1987,
the EPA was required to issue regulations
addressing stormwater discharges under the
NPDES program

19. Phase I
• NPDES established first regulations in 1990 permit
requirements for existing stormwater:
1) existing “medium” and “large” municipal separate storm
sewer systems (MS4) – individual permits by State to locality
with conditions
2) new construction activity disturbing 5 (changed to 1) acres of
land or greater – general permits
3) certain industrial activities
• Many continue to operate under Phase I

20. MDE Phase I Permit
Conditions
• Effectively prohibit pollutants in stormwater discharges
as necessary to comply with water quality standards
• Attain wasteload allocations (WLAs) for approved
TMDL
• Assess existing programs and ID licit and illicit
Sources
• Implement SWM and E/S
• Hot spots
• Trash and litter
• Watershed Management and Restoration (often
needs its own water and state wetland permit!)
• Utilize current collected best management practice
(BMP) data to modify and improve programs
• Monitoring and mapping
• Reduction in impervious surfaces
• Fiscal Analysis and Annual Reports

21. Phase II
• In 1999, new rule automatically covers on a nationwide
basis all existing small MS4s located in urbanized areas
and new construction activities of 1 acre or more
• Most localities already complying
• Can authorize industries or facilities
• Have more flexible permitting options
GP including the NOI process
Utilizing existing programs in place
Combine with other Phase II
Combine with a Phase I

22. Six Requirements of
Phase II
• Personnel education/outreach
• Public involvement/participation
• Illicit discharge detection elimination
• Construction site stormwater runoff control
(E/S)
• Post construction stormwater management
• Pollution prevention/good housekeeping

23. Phase II Can be Subjective
• Monitoring, public outreach and BMPs can be flexible as long as:
– Reduces pollutants to the maximum extent practical
– Protects water quality
– Satisfies CWA
– Many existing SWM programs are satisfactory
– Newer MS4 permits will be templates

24. How Does NPDES Affect New
Construction?
• Compliance with NPDES Stormwater permits is
primarily through BMP implementation
• E/S and SWM plans are not the same as NPDES
compliance – but can usually serve as compliance
with NPDES requirements
• However, a good E/S and SWM plan alone does not
necessarily assure compliance with all NPDES criteria

25. How Does NPDES Affect
New Construction?
To comply with NPDES General Permit (GP) requirements, submit Notice of
Intent NOI if 1 acre or more of disturbance. In addition to customary (“sediment-
centric”) E/S plans, compliance can include:
• Water quality and sensitive construction techniques for waters with an established
Total Maximum Daily Load (TMDL)
• If significant sediment discharge, then additional inspection, evaluation and
installation of site controls
• Control measures that minimize pollutants as necessary to meet applicable water
quality standard
• Conduct weekly inspections and the next day (changed from next business day)
after a rainfall event resulting in runoff
• If there is “an excursion” above any applicable water quality standard, modify
controls to indicate receiving water is attaining water quality standards
• Hot topic - Potential for flocculent or turbidity controls?

26. How Does NPDES Affect
New Construction?
• NPDES Compliance is by NOI and a Stormwater Pollution
Prevention Plan (SWPPP) – what is it and when is one
required?
- Includes E/S and SWM plans (structural) but also
includes ESD and nonstructural: other pollutant
management considerations (spillage, storage, litter),
monitoring records
- In MD, not typically required under general permit
• Potential vs. Actual Discharges – treated the same?!

27. State & Local SWM
Concurrently along with new NPDES compliance, need to comply with
following regulations
• State Erosion and Sediment Control Law
• State Stormwater Management Law
Incorporates SWM Manual by reference - Revised by 2007
Maryland Stormwater Management Act – Effective May 2009
Formalizes “LID-like” or Environmental Site Design to “Maximum
Extent Practicable” - MEP is met if channel stability and
predevelopment groundwater recharge rates are maintained and
nonpoint source pollution is minimized…. structural stormwater
practices may be used only if determined to be absolutely
necessary

28. State & Local SWM
Applies via approved local ordinance
• In MD, primary MEP standard is to use ESD to reduce
post development runoff to levels found in natural,
forested conditions – need to treat 1 to 2.6 in rainfall
depending on site and design conditions
• In Virginia starting July 2014 will require TP oriented
management of 1 inch runoff of entire site utilizing their
Srormwater BMP Clearinghouse also emphasizing
nonstructural disconnections

29. Other Permitting Criteria
• CWA Section 404 dredge and fill permit
U. S. Army Corps of Engineers Waters of the U. S. including wetlands
• State Wetland and Waterway Permit
Can have special NTW E/S BMP Conditions
• State Tidal Wetlands and Waters permits
• Coastal Zone Management Act
• MD Tier II Waters Criteria
• MD Chesapeake Bay Critical Area Law
Administered through local zoning and subdivision ordinances for overlay 1,000 feet from
shoreline - 10% SWM rule in Intensely Developed Areas
• MD State Forest Conservation Law
Delegated to localities Requires NRI or FSD which could be first SWM concept under new
regulations - silt fences frequently double as tree save fence
• VA Chesapeake Bay Preservation Act
Through localities Resource protection Areas, Better Site Design

30. Water Quality Standards for
Permitting Criteria
• Wetland permitting processes can incorporate CWA Section 401 Water
Quality Certification Requirements required when 404 Corps permit
required
• Numeric and Narrative Water Quality Standards are basis for sensitive
waters requirements
• Numeric - DO, Temp, pH, Turbidity, fecal coliform, toxics
• Narrative – basis of more stringent controls
Protection of aquatic life...fishable…swimmable…includes EPA
Anti-degradation policy:
“…To accomplish the objective of maintaining existing
water quality…Nonpoint sources shall achieve all cost
effective and reasonable best management practices for
nonpoint source control…”

31. Even More Water Quality
Initiatives in Progress!
• Chesapeake Bay
TMDL for N & P –
what does this mean
for SWM?
• Largest most
complex TMDL in the
country, covering the
64,000 s. m.
watershed in six
states & DC =
Watershed
Implementation Plans
(WIP) in progress
now

32. Issues under Deliberation Now
• What should be most sound
priorities of focus? Sediments,
P, O, Flow?
• ESD (and LID) versus Smart
Growth versus impervious
surface criteria?
• TMDL model assumptions
challenged
• Financing TMDL WIPs (rain
tax)
• TMDL AFG Offset credits vs.
existing SWM criteria
• Nutrient trading

33. Construction Compliance
• Usually oriented to E/S compliance
• Locality primary inspector
• State (and occasionally EPA) inspect also for
NPDES, E/S and Wetland and Waterways Permit
• Corps inspects for Wetland and Waterways Permit

34. Newer Compliance
Requirements
• Usually oriented to post-construction assessment
• Third party quality control construction monitoring
• Specific SWM device maintenance conditions
• Post-construction BMP performance can be required

35. • Used also for MS4
Compliance
• Can be state requirement
• Preconstruction,
construction and post-
construction
• Macroinvertebrate Studies
(from WWTP & mining)
• Chemistry
• Geomorphology
• Groundwater
Post-Construction BMP and Water
Quality Monitoring

36. For Construction Activities -
Remember!
• Have most current approved plans on site during construction
• Diligence over perfection – develop a good relationship with regulatory
agencies
• Any E/S modifications made after permitting may potentially have other
regulated impacts.
• Any temporary material storage, staging or heavy equipment in or near
flood plain, streams, wetlands, buffers, forest, specimen tree may
potentially be a regulated impact
• Document all E/S plan changes, rectification measures and spill control
measures in log book

37. Types of Designs for
Storm Water Control

38. What is a Best Management
Practice (BMP)?
Best Management Practices (BMPs) are policies, practices, procedures, or
structures implemented to mitigate the adverse environmental effects on
surface water quality resulting from development. BMPs are categorized
as structural or non-structural.
• Early Planning
• Low Impact Development
– “LID-like” or Better Site Design or Environmental Site Design
• Local stream buffers and setbacks
• Minimize or disconnect impervious surfaces sheet flow, open section
pavement
• Devices
Most significant factor affecting performance is construction
and maintenance

39. Erosion and Sediment Control
vs. Stormwater Management
E/S
• Construction Phase
• Sediments are primary criteria
• Can be temporary or “permanent”
SWM
• Post-construction
• Manages various pollutants
• Permanent

40. Common E/S Practices
• Silt Fence
• Vegetative Stabilization
• Stone lined conveyance
• Temporary Sediment Basin/Trap
• Temporary Use of Permanent Pond or other facility

41. Common E/S Practices

42. Common E/S Practices

43. Surface Stabilization

44. Sensitive Resources

45. Newer Technologies

46. Common Compliance Issues

47. Common Compliance Issues
Similar for E/S & SWM
Construction
Maintenance

48. Common SWM Practices
• Better/Environmental Site Design
• Sheet flow management – prior to and after
conveyance
• Open section surfaces
• Engineered practices

49. Common “ESD” Practices
• Preserving and protecting natural
resources
• Conserving natural drainage
patterns
• Minimizing impervious area
• Reducing runoff volume
• Using ESD practices to maintain
100 percent of the
• Annual predevelopment
groundwater recharge volume
• Using green roofs, permeable
pavement, reinforced turf,
• And other alternative surfaces
• Limiting soil disturbance, mass
grading, and compaction
• Clustering development
• Any practices approved by the
Administration.

50. The Best BMP - Work with Forest
and Wetland Conservation

51. Work with Site Character Before
Devices

52. When Using Engineered Practices
Smaller Volumes
Most compatible with ESD and BSD
At Source & Pretreatment
Quality Control Only
• Infiltration
– trench/basin
• Filtering
– sand filter/bioretention
• Hydrodynamic Devices
• “New” Technology
– pervious surfaces/green roofs
Larger Volumes
When preferred is
Insufficient
Central Locations
For Quantity and Quality
Control
• Stormwater Ponds
– wet pond
– wet ED pond
– dry ED pond (for cold water w/
pre-treatment)
– multiple pond system
• Stormwater Wetlands
– shallow marsh
– ED shallow wetland
– pond/wetland systems

53. Bioretention & Infiltration

54. Bioretention & Infiltration

55. Landscaped Bioretention Facility

56. Hydrodynamic Devices

57. Get Creative

58. Pond and Wetlands

59. Pond and Wetlands

60. Transition Habitat

61. Transition Habitat

62. SWM & Amenity Not Incompatible

63. Detention or Dry Pond

64. Enhance & Plant Dry Ponds Also

65. Stream Stabilization as a BMP
• Can be effective
watershed
sediment control
practice
• Can be local
approval
requirement
• Can be a traded
credit
• Can be out-of-kind
wetland mitigation

66. “Newer” Technologies