Coalition for the Delaware River Watershed Presents: 2nd Annual Delaware River Watershed Forum

1. Coalition for the Delaware
River presents:
2nd Annual Delaware River
Watershed Forum
Geoff Reese, PE
Travis Bartholomew, PE
October 22, 2014
Hotel Bethlehem

2. Act 167 Overview
• Pennsylvania Stormwater Management Act of 1978
• Major Components
• Places responsibility on counties to prepare watershed plans.
• Outlines 13 plan requirements.
• Authorizes DEP to prepare guidelines to assist counties.
• Authorizes DEP to designate watersheds.
• Authorizes grant program to reimburse counties.
• Places responsibilities on land developers.
• Purposes
• Encourage the sound planning and management of storm runoff.
• Coordinate the storm runoff management efforts within each
watershed.
• Encourage the local administration and management of storm
runoff.

3. 1. Survey of existing runoff
characteristics
2. Survey of obstructions
3. Assessment of projected
land development
4. Analysis of Flood Hazard
Area development
5. Survey of existing
drainage problems
6. Survey of existing and
proposed storm sewers
7. Assessment of
alternative runoff
controls
13 Plan Requirements

4. 13 Plan Requirements
8. Identification of future
flood control projects
9. Designation of future
storm sewer areas
10.Identification of
floodplains
11.Development of runoff
control criteria
12.Development of
implementation
priorities
13.Development of plan
review/revision process

5. Prior Land Developments
• Act 167 does not
attempt to regulate
past development
• Plan requirements only
apply to land
developments proposed
since the adoption date
of the plan
• Focused on preserving
“status quo” - the state
of the watershed at
time of plan
development

6. Act 167 Responsibilities
• County Responsibilities
• Develop an Act 167 Plan for
each watershed within its
boundaries.
• Consult with municipalities
through the Watershed Plan
Advisory Committee.
• Adopt the plan by resolution
after holding a public
hearing and making the
appropriate changes.
• Submit adopted plan to
DEP.
• Lehigh and Northampton
counties have delegated
plan preparation to the
LVPC

7. Act 167 Responsibilities
• Municipal Responsibilities
• Participate in the plan
development through the
Watershed Plan Advisory
Committee.
• Review the draft plan and
provide comments.
• Adopt the necessary
ordinances to control storm
runoff after the plan is
approved by DEP.
• Implement the plan through
the enforcement of the new
stormwater ordinance.

8. Act 167 Modeling
• The LVPC creates hydrologic models to test proposed control
strategies against existing stream flows
• Model input data and sources include:
• Geology and soils data – Existing mapping
• Existing land use data – GIS and field data
• Future land use data – Current zoning
• Stream channel geometry – Aerial photography and field data
• LVPC also collects data on existing drainage problems
• Obstruction documentation – Field data
• Existing problem area documentation – Municipal questionnaire

9. Geology for Lehigh and Northampton Counties

11. Saucon Creek Watershed
Existing Land Use

12. Saucon Creek Watershed
Future Land Use

13. Release Rate Development
• Release Rates control runoff
based on its impact on the
flood peak
• Expressed as a percentage of
the existing runoff that can be
discharged after development
• Ranges from 30% to 100%
• Goal to allow development,
but not increase peak flow at
any point in the watershed

14. Saucon Creek Release Rates

15. Water Quality
• In general:
• Quantity control =
manage large events
• Quality control = manage
small events
• Pre-2004 Act 167 Plans
controls only addressed
water quantity
• Peak rate control
• Severe flooding
• New plans must also
address water quality
• Channel erosion
• Nutrient loading
• Temperature control

16. Return Periods
•Return periods
describe the
rarity/magnitude of
large rainfall events
•2-year event is
approximately a
“bankfull” event
•100-year is usually the
largest controlled
Return
Period
Annual %
Exceedance
2-year 50%
10-year 10%
25-year 4%
100-year 1%

17. Water Quality
• Since 2004, new plans have
incorporated elements of NPDES
and MS4 programs
• Requiring runoff treatment with Best
Management Practices (BMPs)
• Promoting runoff volume reduction
(infiltration and capture/reuse)
• Indirectly promoting Low Impact
Development (LID) practices
• Most recent Act 167 ordinances
attempt to maintain the natural
“water balance”
• Post-development runoff, infiltration,
and evapotranspiration should
match pre-development
• DEP standard is no increase in 2
year volume pre- to post-
development

18. LVPC Review Function
• LVPC review provides
evaluation of watershed-
level impacts
• Provides consistent review
process independent of
municipal boundaries
• LVPC interaction in the
review process provides
first-hand feedback for
strengths and weaknesses
of the ordinance
• Feeds into development of
new plans and plan updates

19. Ordinance Cycle
Create and
adopt
ordinance for
new plan
Implement ordinance through
engineering reviews
Special Studies
- CN & Rational “c”
- Erosion issues
- Minimum orifice
- Water quality

20. Questions?
gar@lvpc.org
tib@lvpc.org