The document outlines the agenda for a two-day environmental technical training program. Day 1 covers an introduction to stormwater concepts like the hydrologic cycle, soils, and pre/post-construction conditions. It also covers terminology, rational method calculations, and a field visit. Day 2 covers best management practices, infiltration, and another field visit. Key concepts discussed in more depth include the hydrologic cycle, soils classification, rational method calculations, and how development impacts stormwater runoff rates and volumes.

1. Day 1
Environmental Technical Training Program 2014

2. Course Overview – First Day
 Introduction to Stormwater (90 min)
 Hydrologic Cycle
 Terminology
 Soils
 Pre and Post Construction
 Rational Method
 Group Problem (30 min)
 Water Quality
 Field Visit

3. Course Overview – Second Day
 Best Management Practices(90 min)
 Hyrdologic Cycle
 Soils
 Design Concepts
 Pre vs. Post Conditions
 Group Problem (30 min)
 Best Management Practices (90 min)
 Infiltration
 Group Problem (30 min)
 Field Visit

6. Hydrologic Cycle
The Hydrologic Cycle is the continuous process of water
moving within the earth’s atmosphere, on the earth’s
surface, and within the earth’s subsurface.
 Atmosphere –Water Vapor.
 Reaches earth’s surface thru precipitation (rain, snow,
hail, and fog).
 Enters the earth’s subsurface thru infiltration.

7. Hydrologic Cycle
Ref: MA DEP Hydrologic Handbook for Conservation Commissioners, 2002

8. Stormwater and the
Hydrologic Cycle
Concerns
 Surface Runoff –Water from precipitation that flows
over the ground surface.
 Groundwater Recharge – The water that infiltrates into
the ground.

9. Stormwater and
the Hydrologic Cycle
Runoff
 Increased volume changes wetland ecosystems.
 Increase flooding.
 Increased erosion.
Recharge
 Decreased groundwater available for surface water.
 Decreased water available for drinking water.

10. Terminology (The language of
stormwater)
 Stormwater – Stormwater is the water that runs off surfaces
such as rooftops, paved streets, highways, and parking lots.
It can also come from hard grassy surfaces like lawns, play
fields, and from graveled roads and parking lots.
 Non-Point Source Pollution: Pollutants from many diffuse
sources. Nonpoint-source pollution is caused by rainfall or
snowmelt moving over and through the ground. As the
runoff moves, it picks up and carries away natural and
human-made pollutants, finally depositing them into
lakes, rivers, wetlands, coastal waters, and even
underground sources of drinking water.

11. Terminology (The language of
stormwater)
 Runoff -Water from precipitation that flows over the
ground surface.
 Recharge -The water that infiltrates into the ground.
 Stormwater –
 Best Management Practices (BMPs) - Activities or
structural improvements that help reduce the quantity and
improve the quality of stormwater runoff.
 Impervious Surface or Cover: The characteristic of a
material which prevents the infiltration of liquid through
it. This may apply to roads, streets, parking lots, rooftops
and sidewalks.

12. Terminology (The language of
stormwater)
 Watershed: Geographical area that drains to a specified
point on a water course, usually a confluence of streams
or rivers, can also be known as drainage area,
catchments, or a river basin.
 Detention - Release of surface and storm water runoff
from the site at a slower rate than it is collected by the
drainage facility system, the difference being held in
temporary storage.
 Drainage - The collection, conveyance, containment,
and/or discharge of surface and storm water runoff.

13. SOILS

14. SOILS

15. SOILS
Four hydrologic groups are used. In the definitions to follow, the infiltration rate
is the rate at which water enters the soil at the surface and which is controlled by
surface conditions. The hydrologic soil groups, as defined by NRCS are:
 A. (Low runoff potential) Soils having high infiltration rates even when
thoroughly wetted and consisting chiefly of deep, well to excessively drained
sands or gravels.
 B. Soils having moderate infiltration rates when thoroughly wetted and
consisting chiefly of moderately deep to deep, moderately well-to-well drained
soils with moderately fine to moderately coarse textures.
 C. Soils having slow infiltration rates when thoroughly wetted and consisting
chiefly of soils with a layer that impedes downward movement of water, or
soils with moderately fine to fine texture.
 D. (High runoff potential) Soils having very slow infiltration rates when
thoroughly wetted and consisting chiefly of clay soils with a high swelling
potential, soils with a permanent high water table, soils with a clay pan or clay
layer at or near the surface, and shallow soils over nearly impervious material.

16. SOILS
Hydrologic Soil Group Infiltration (Inches/Hour)
A Exceeds 5.7
B 5.7 to 1.4
C 1.4 to 0.14
D Less than 0.14

17. Infiltration Rates – Rule of thumb
 Class A Soils – 5 to 8 in/hour: Sand, Loamy Sand,
Sandy Loam (well to excessively drained)
 Class B Soils – 1 to 2 in/hour: silt loam, loam
(moderately to well drained)
 Class C Soils – 0.1 to 0.5 in/hour: Sandy clay loams
(slow infiltration)
 Class D Soils – no infiltration.

18. SOILS
Ref: MA DEP Hydrologic Handbook for Conservation Commissioners, 2002

19. Soil Survey
NRCS Soils Map
http://websoilsurvey.nrcs.usda.gov/app/

20. Cohasset, MA

21. Cohasset MA

23. Pre and Post Development

24. Pre and Post Development

25. What is a 100-year storm?
A 100-year storm refers to rainfall totals that have a one
percent probability of occurring at that location in that year.
Encountering a "100-year storm" on one day does not
decrease the chance of a second 100-year storm occurring in
that same year or any year to follow. In other words, there is
a 1 in 100 or 1% chance that a storm will reach this intensity
in any given year. Likewise, a 50-year rainfall event has a 1 in
50 or 2% chance of occurring in a year. In addition, each
locality has its own criteria for how much rain must fall
within 24 hours to classify as a particular rain event. See
chart below for other rainfall events.

26. What is a 100-year storm?
Storm Intervals and Probabilities
Occurrence
Interval (years)
Probability in
Any Year
Percent Chance
in Any Year
100 1 in 100 1%
50 1 in 50 2%
25 1 in 25 4%
10 1 in 10 10%
5 1 in 5 20%
2 1 in 2 50%

27. ESTIMATING RUNOFF QUANTITIES
Runoff = Rainfall – Interception – Infiltration – Depression Storage
or simplified
Runoff = Rainfall - Infiltration

28. ESTIMATING RUNOFF QUANTITIES
Volume
A parking lot has an area equal to a football field. It is 360 feet long by 160
Feet wide. An inch of rain falls on the parking lot of a course of an hour.
a.) What is the volume in cubic feet?
b.) What is the volume in acre-feet?
c.) What is the volume in gallons?
a.) Volume = (360-feet)(160-feet)(1-inch) (1-foot/12-inches)
Volume = 4,800 cubic feet = a cube with 17 foot sides
b.) Volume = (4,800 cubic feet)(1 acre/43,560 square feet) = 0.11 acre-feet
c.) Volume = (4,800 cubic feet)(7.48 gallons/cubic foot) = 36,000 gallons
Three to Four large tankers.

29. RUNOFF RATE
The runoff rate is the volume of runoff from a watershed
over a period if time. Usually measured as cubic feet per
second.
Depends on:
 Ground surface roughness
 Slope
 Distance of travel
Higher rates increase flooding and erosion.

30. Finding Runoff Rates
One way is the Rational Method. Watersheds less than
20 acres. Used to size pipes. Other methods are
available.
We will review the Rational Method to for the purposes
of determining what information is important.

31. Rational Method
Rational formula is:
q = C ∙ i ∙ A
q = Peak rate of runoff – cubic feet per second
C = Runoff coefficient
i = Rainfall intensity
A = Watershed area in acres

32. Rational Method
Determine Runoff coefficient.
Parking Lot – Use asphalt
streets 0.7 to 0.95. Use 0.85.
Sandy soils - .05 to 0.10
Use 0.10.

33. Rational Method
Intensity – Duration – Frequency
Curve
Pick a duration, and a frequency,
then determine amount of rain in
that time period.

34. Rational Method
Intensity – Duration – Frequency
Curve
Pick a duration, and a frequency,
then determine amount of rain in
that time period.
Duration– 1 hour.

35. Rational Method
Intensity – Duration – Frequency
Curve
Pick a duration, and a frequency,
then determine amount of rain in
that time period.
Duration– 1 hour.
Frequency – 2 years

36. Rational Method
Intensity – Duration – Frequency
Curve
Pick a duration, and a frequency,
then determine amount of rain in
that time period.
Duration– 1 hour.
Frequency – 2 years
Intensity – 1.2 Inches per hour
i = 1.2 in/hr

37. Runoff Curve Numbers
Runoff curve numbers for the
NRCS Methods.

39. Problem
Site is 2 acres. The difference in elevation across site is 5
feet. The length of the site is 400 feet. The soil is sand.
It is currently a grassed area. It will all be paved as a
parking lot.
Determine slope = difference in slope/length

40. Problem
Site is 2 acres. The difference in elevation across site is 5
feet. The length of the site is 400 feet. The soil is sand.
It is currently a grassed area. It will all be paved as a
parking lot.
Determine slope = difference in slope/length
= 5 feet/400 feet

41. Problem
Site is 2 acres. The difference in elevation across site is 5
feet. The length of the site is 400 feet. The soil is sand.
It is currently a grassed area. It will all be paved as a
parking lot.
Determine slope = difference in slope/length
= 5 feet/400 feet
= 0.012 feet/foot or 1.2 %

42. Problem
Site is 2 acres. The difference in elevation across site is 5
feet. The length of the site is 400 feet. The soil is sand.
It is currently a grassed area. It will all be paved as a
parking lot.
Slope = 1.2%

43. Rational Method
Determine Runoff coefficient.
Parking Lot – Use asphalt
streets 0.7 to 0.95. Use 0.85.
Sandy soils, flat - .05 to 0.10
Use 0.10.

44. Problem
Site is 2 acres. The difference in elevation across site is 5
feet. The length of the site is 400 feet. The soil is sand.
It is currently a grassed area. It will all be paved as a
parking lot.
Slope = 1.2%
CExisting = 0.1 CProposed = 0.85
Area = 2 acres

45. Problem
Using the rainfall intensity previously provided.
qgrass = C∙i∙A

46. Problem
Using the rainfall intensity previously provided.
qgrass = C∙i∙A = 0.10

47. Problem
Using the rainfall intensity previously provided. Two
year, one hour storm.
qgrass = C∙i∙A = 0.10 ∙ 1.2 in/hour ∙

48. Problem
Using the rainfall intensity previously provided. Two
year, one hour storm.
qgrass = C∙i∙A = 0.10 ∙ 1.2 in/hour ∙ 2 Acres

49. Problem
Using the rainfall intensity previously provided. Two
year, one hour storm.
qgrass = C∙i∙A = 0.10 ∙ 1.2 in/hour ∙ 2 Acres
= 0.24 cfs

50. Problem
Using the rainfall intensity previously provided. Two
year, one hour storm.
qgrass = C∙i∙A = 0.10 ∙ 1.2 in/hour ∙ 2 Acres
= 0.24 cfs
qparking lot = C∙i∙A = 0.85 ∙ 1.2 in/hour ∙ 2 Acres
= 2.04 cfs
8.5 times more runoff

51. WATER QUALITY
Water is essential to human life and to the health of the
environment. As a valuable natural resource, it
comprises marine, estuarine, freshwater (river and lakes)
and groundwater environments, across coastal and
inland areas. Water has two dimensions that are closely
linked - quantity and quality. Water quality is commonly
defined by its physical, chemical, biological and
aesthetic (appearance and smell) characteristics. A
healthy environment is one in which the water quality
supports a rich and varied community of organisms and
protects public health. Water quality in a body of water
influences the way in which communities use the water.

52. WATER QUALITY
More specifically, the water may be used by the community
for:
1. supplying drinking water
2. recreation (swimming, boating)
3. irrigating crops and watering stock
4. industrial processes
5. navigation and shipping
6. production of edible fish, shellfish and crustaceans
7. protection of aquatic ecosystems
8. wildlife habitats
9. scientific study and education

54. Degraded Stream

55. Stormwater Pollutants
 Oils and Greases
 Metals
 Sediments
 Oxygen-Demanding Substances
 Nutrients
 Toxic Organic Compounds
 Fecal Coliform Bacteria
 pH
 High Tempature

56. Oil and Grease
Oils and greases are a common component of stormwater runoff
pollutants, primarily because there are so many common sources:
streets and highways, parking lots, food waste storage areas, heavy
equipment and machinery storage areas, and areas where
pesticides have been applied. The familiar sight of a rainbow-colored
puddle or trickling stream in parking lots, driveways, and
street gutters is a reminder of the presence of oils and greases in
stormwater runoff. Oils and greases can be petroleum-based or
food-related (such as cooking oils). No type of oil or grease belongs
in surface water. Oil and grease are known to be toxic to aquatic
organisms at relatively low concentrations; they can coat fish gills,
prevent oxygen from entering the water, and clog drainage facilities
(leading to increased maintenance costs and potential flooding
problems)

57. Oil and Grease

58. Metals
Many heavy metals, including lead, copper, zinc and
cadmium, are commonly found in urban runoff. Metals
can contaminate surface and ground waters and
concentrate in bottom sediments, presenting health
problems for fish and animals that eat from the bottom.
Reproductive cycles of bottom-dwelling species can be
severely reduced, and fish inhabiting such metal-contaminated
locations often exhibit lesions and
tumors. Metals can also contaminate drinking water
supplies. Industrial areas, scrap yards, paints, pesticides,
and fallout from automobile emissions are typical
sources of heavy metals in runoff.

59. Metals
Copper and other common heavy metal
dust are produced during normal
automobile use. These fine particulates
settled onto paved surfaces and add to
the vehicular impact.

60. Sediments
Sediment - often originating as topsoil, sand, and clay - is the most common
pollutant in stormwater runoff by volume and weight. Sediments readily wash off
paved surfaces and exposed earth during storms. Sediment may seem harmless
enough, but it poses serious problems in the water. Excess sediment
concentrations turn stream and lake water cloudy, making it less suitable for
recreation, fish life, and plant growth. Sediment is of particular concern in fish
bearing streams where it can smother trout and salmon eggs, destroy habitat for
insects (a food source for fish), and cover prime spawning areas. Uncontrolled
sediment can also clog storm drains, leading to increased private and public
maintenance costs and flooding problems. Sediment is also of concern because
many other pollutants including oils, metals, bacteria, and nutrients tend to
attach to soil particles. Therefore when sediments enter water they usually carry
other pollutants with them. Cleared construction sites and exposed earth are
generally the greatest contributors of soil particles in surface waters. Other
sources include erosion from agricultural lands, application of sand and salts to
icy roads, fallout from pressure washing and sandblasting operations, dirt from
equipment and vehicles, and dirt and grit from parking lots, driveways, and
sidewalks

61. Sediments

62. Nutrients
Nutrients such as phosphorus and nitrogen are needed by plants to grow, but high levels can
be harmful to water quality. Excess nutrient levels can over-stimulate the growth of algae
and other aquatic plants, resulting in unpleasant odors, unsightly surface scums, and
lowered dissolved oxygen levels from plant decay. Nutrients are most likely to pose a
problem in slow moving water such as lakes or sluggish streams. Some forms of algae are
toxic to fish and other aquatic organisms and may even cause death in animals that drink
affected water. Algae can also cause taste and odors problems in drinking waters, foul-smelling
odor in ponds and lakes, and problems with clogged water intakes, drains, and
pipes. Heavy loading of nutrients into slow-moving waters can adversely affect many
beneficial uses of the water. Forms of nitrogen (ammonium), in combination with pH and
temperature variations, can cause water quality problems and be toxic to fish. This process
consumes large amounts of oxygen in the water and subsequently stresses or kills fish and
other aquatic organisms when oxygen levels are reduced. Ammonia toxicity, due to nitrogen
in its ammonium form, can harm fish and other aquatic organisms.
Fertilizers, animal wastes, failing septic systems, detergents, road deicing salts, automobile
emissions, and organic matter such as lawn clippings and leaves are all contributors to
excessive nutrient levels in urban and agricultural stormwater runoff.

63. Nutrients

64. Toxic Organic Compounds
Pesticides and PCBs are toxic organic compounds that are particularly dangerous
in the aquatic environment. Excessive application of insecticides, herbicides,
fungicides, and rodenticides, or application of any of these shortly before a storm,
can result in toxic pesticide chemicals being carried from agricultural lands,
construction sites, parks, golf courses, and residential lawns to receiving waters.
Many pesticide compounds are extremely toxic to aquatic organisms and can
cause fish kills. PCBs are a similar class of toxic organic compounds. They can
contaminate stormwater through leaking electrical transformers. PCBs can settle
in sediments of receiving waters and, like pesticide compounds, present a serious
toxic threat to aquatic organisms that come in contact with them. Many other
toxic organic compounds can also affect receiving waters. These toxic compounds
include phenols, glycol ethers, esters, nitrosamines, and other nitrogen
compounds. Common sources of these compounds include wood preservatives,
antifreeze, dry cleaning chemicals, cleansers, and a variety of other chemical
products. Like pesticides and PCBs these other toxic organic compounds can be
lethal to aquatic organisms.

65. Toxic Organic Compounds

66. Fecal Coliform Bacteria
Fecal coliform bacteria in water may indicate the
presence of pathogenic (disease-causing) bacteria and
viruses. Pet and other animal wastes, failing septic
systems, livestock waste in agricultural areas and on
hobby farms, and fertilizers can all contribute fecal
coliform bacteria. This can be a problem for treatment of
drinking water and can limit recreational use of a water
body. Bacterial contamination has led to closures of
numerous shellfish harvesting areas and public
swimming beaches in Puget Sound.

67. Fecal Coliform Bacteria

68. High Temperature
Rainfall falling on roofs and pavements
Which have been heated by the sun will
be heated by these surfaces. The high
temperatures of this runoff can be
lethal to fish and other creatures/.

69. The Problem
The
Solution
Conventional Development Smart Development
Reduce land clearing and grading costs
Reduced infrastructure costs
Protect regional water quality
Reduce stormwater runoff
Impacts on open space