Forge Pond TMDL & Diagnostic/Feasibility
Study
The first design project for CEE 577
is a TMDL and Diagnostic/Feasibility Study for Forge Pond in
Problem Statement
The quality of the water in Forge
Pond has been deteriorating for many years.
In the past few decades it has reached the point where the use of the
pond is severely restricted.
1. Can
no longer be used for contact recreation
heavy
weed growth
duckweed
covers parts like "green paint"
anoxic
bottom
surface
scums
massive
seasonal algal blooms
2. Not
likely to be used for recreational fishing
Only
4% gamefish (chain pickerel and largemouth bass)
most
fish are white suckers and large golden shiners (rough fish)
high
abundance of lesions and parasites
unbalanced
size distribution.
3. Elevated
organic concentrations and off-odors make it an undesirable water supply
You have been asked by the state and
town to conduct a "TMDL and Diagnostic/Feasibility Study". This has as an objective to assess the total
maximum daily loading, determine the source of the problems, to suggest
possible remedial actions, and to comment on the feasibility of those actions.
Your assignment
will include the following major tasks:
I.
Hydrologic
Investigation: Find
drainage areas, and Estimate major inflows
II.
Water
Quality Investigation & Model Development: Determine WQ Parameters of importance, Identify &
Evaluate Major Sources, and Estimate Loadings, present a calibrated model or
some rational method to evaluate impacts of changes and management alternatives
III.
Propose
Engineering/Management Solutions: Discussion
of options, impacts of various management strategies.
I. Hydrologic
Investigation: Drainage areas, Major inflows, and Residence Time.
A. Determine Drainage Areas
1. Trace out the relevant
drainage areas[1]
Each
group must buy one "Belchertown Quadrangle" U.S. Geological Survey
topographic map (1:25,000 scale). These
can be found in many camping stores (e.g., EMS, Adventure Outfitters) some
office supply stores (e.g., Hastings, Staples) or maybe from Dennis Swartwout
in the Earth Science Information Office (trailer next to the Environmental
Institute, Blaisdell House; http://www.umass.edu/tei/esio/ )
Trace
out the drainage areas for the following tributaries: Bachelor Brook, and
Weston Brook. These are called
sub-basins. Also trace out the left-over
drainage area that sits to the north of the dam, and to the east side of the
pond, but doesn't fall into the Bachelor Brook sub-basin.
Bring
your map with the traced sub-basin boundaries into class on Friday, February 12th. I will check each for accuracy.
2. Measure the traced areas
Determine
each sub-basin area and estimate your uncertainty.
Also
determine the area of the Pond itself
To
save you from buying more topographic maps, I've given you the drainage areas
for the other two sub-basins (Forge Pond Brook or Turkey Hill Brook, and the
Unnamed Tributary)
B. Determine Major Inflows
1. Obtain rainfall data (1.11 m/yr based on 1988)
2. Calculate Inflows
Use
the "rational formula"
Assume
a runoff coefficient of 0.40
C. Calculate Mean Residence Time for
the Pond
Calculate
pond volume; use the hypsographic profile of Forge Pond
Determine
mean water residence time
D. Prepare and Submit Draft Report on
Hydrological Investigations
Useful
information for Part I.
Breakdown of Drainage
Basins
|
Sub-basin |
Drainage Area (square miles) |
|
Forge Pond
Brook |
3.54 |
|
Unnamed
Tributary |
1.02 |
|
Bachelor
Brook |
???? |
|
Weston Brook |
???? |
Hypsographic
Profile of Forge Pond (original scale not preserved)
II. Water Quality Investigation & Model
Development:
Determine WQ Parameters of importance,
Identify & Evaluate Major Sources, and Estimate Loadings, present a model
or some rational method to evaluate impacts of changes and management
alternatives
Here you will want to formulate some
sort of phosphorus model. This includes
a model for the lake as well as a model for the watershed. The first choice is whether to use
“mechanistic” and spatially resolved models or “empirical” and zero-dimensional
models. The former may not be
appropriate, as you really have no internal flow data on Forge Pond, nor do you
have any system –specific data on phosphorus transformation and cycling. A classical mechanistic lake/river model
formulation would incorporate explicit settling rates, release rates,
hydrolysis rates, algal uptake rates, etc.,
none of which you have. While you
do have spatially-resolved land use information on the watershed, your budget
probably doesn’t permit development of a fully mechanistic, distributed
watershed model.
The level of information you have on
the system (i.e., some water quality, but really no internal transformations),
and the fact that this is a small lake with no internal flow information
(forcing you to use a zero-dimensional model or CSTR) probably makes the
empirical lake modeling approach the best choice. The size (budget) of the project and level of
effort on the lake model probably makes an export coefficient watershed model
most appropriate.
The objectives for your modeling
work include two that focus on the lake itself (1&2) and two that are more concerned
with the watershed (3&4):
1. To test the response of Forge Pond to
its known phosphorus loadings, verifying that it does behave like most lakes of
its size, and thereby giving confidence that all major loads have been accounted
for, and that there are no other important processes that have been ignored.
2. To refine the lake model, better
adapting it to Forge Pond, so that impacts of future scenarios can be better
predicted.
3. To test the expected watershed export of
phosphorus against the known export, so that you can verify that you’ve
considered the major sources of phosphorus in the watershed.
4. To refine the export model, better
adapting it to the Forge Pond watershed, so that the impacts of future
scenarios can be better predicted.
Recommended
sequence of tasks
A. Calculate loadings to FP based on
estimated flows and measured concentrations
B. Use Vollenweider’s 1975 model[2],
as summarized by Reckhow & Chapra (1983), and presented in the class handout,
“Empirical Lake Model for Phosphorus with Uncertainty” along with loadings from
part “a” to calculate in-lake phosphorus concentration (no need at this point to use the
export-coefficient areal loading method).
You may also want to consult the material presented in class on this (Lecture #6 and Lecture #7).
C. Compare the predicted phosphorus value
with the actual measured one. Comment, especially
as regards to comparison with other lakes.
Make adjustments to Vollenweider’s model if needed. When considering this, you might also want to
look at the outflow phosphorus level make appropriate comparisons with the
total loading.
D. Next consider the watershed model. I would use an export coefficient
approach. As a first approximation, you
have export coefficients in the Lake Higgins example. For more depth, you should consult the
Reckhow et al., 1980 compilation[3]. Compare predictions based on these
coefficients with the loadings you calculated from actual concentrations.
E. Adjust or re-select your export
coefficients to better match observations.
F. Present your final system model
including calibrated models for the watershed and pond
Important
Data for Part II
Land Use in the Forge
Pond Watershed (estimate from 1989)
|
Land
Use |
%
of Total |
|
|
75.4 |
|
Agriculture |
8.9 |
|
Urban/Residential |
7.2 |
|
Marsh/Wetland |
2.4 |
|
Institutional |
2.1 |
|
Open |
1.8 |
|
Abandoned
Fields |
0.8 |
|
Lakes (w/o
Forge Pond) |
0.8 |
|
Commercial |
0.6 |
Notes:
Institutional:
St. Hyacinth's Seminary,
Open: power
transmission lines, road corridors, sand and gravel pits, town landfills, and
automobile junkyards
Abandoned Fields:
mostly agricultural lands undergoing secondary succession
Commercial:
primarily Belchertown center
Major Database (Regular Sites) on Water
Quality in Forge Pond and Major Inputs/Outputs (Jan-Dec, 1986)
|
|
Bachelor Br. |
Weston Br. |
Forge Pond Br |
Unnamed Trib |
Forge Pond |
Outlet |
|
||||||||
|
Parameter |
@ entry to FP |
@
entry to FP |
@
entry to FP |
@
entry to FP |
Surface |
Bottom |
@
outlet from FP |
Units |
|||||||
|
|
Mean |
Min |
Mean |
Min |
Mean |
Min |
Mean |
Min |
Mean |
Min |
Mean |
Min |
Mean |
Min |
|
|
Total-P |
15 |
10 50 |
210 |
92 400 |
31 |
10 56 |
23 |
10 50 |
77 |
23 180 |
98 |
29 250 |
79 |
30 160 |
µg/L |
|
Ortho-P |
11 |
10 44 |
188 |
17 400 |
12 |
10 38 |
15 |
10 40 |
35 |
10 70 |
45 |
10 130 |
34 |
10 90 |
µg/L |
|
NH4-N |
0.066 |
0.01 1.3 |
0.109 |
0.01 0.41 |
0.099 |
0.01 0.64 |
0.063 |
0.1 0.12 |
0.04 |
0.01 0.16 |
0.05 |
0.01 015 |
0.059 |
0.01 0.17 |
mg/L |
|
NO3-N |
0.297 |
0.06 0.89 |
0.351 |
0.01 1.2 |
0.063 |
0.02 0.18 |
0.137 |
0.02 0.31 |
0.09 |
0.01 0.39 |
0.09 |
0.02 0.39 |
0.157 |
0.01 0.76 |
mg/L |
|
TKN |
0.448 |
0.18 3.5 |
0.672 |
0.37 0.84 |
0.407 |
0.10 0.80 |
0.265 |
0.11 0.61 |
0.77 |
0.14 2.31 |
0.82 |
0.13 2.2 |
0.557 |
0.21 2.3 |
mg/L |
|
Diss O2 |
10.7 |
6.6 13.6 |
10.7 |
6.8 13.6 |
7.2 |
0.2 12.4 |
8.3 |
5.9 11.6 |
11.0 |
6.3 16.1 |
4.9 |
0.2 11.8 |
10.3 |
5.5 14.0 |
mg/L |
|
Conduct. |
130 |
84 320 |
193 |
139 335 |
99 |
58 235 |
81 |
54 97 |
131 |
89 230 |
131 |
94 240 |
132 |
87 240 |
µmho/cm |
|
Chloride |
11 |
6 24 |
26 |
5 40 |
6 |
2 13 |
7 |
2 10 |
13 |
7 18 |
14 |
8 26 |
14 |
7 25 |
mg/L |
|
Chloro- phyll a |
|
|
|
|
|
|
|
|
49.8 |
1.8 231.8 |
|
|
|
|
µg/L |
Nutrient
Budget
Location of Supplemental Sampling sites
Supplemental sampling Data for Total
Phosphate (µg/L): Single samples: May-Aug 1987.
|
Site |
5/19/87 |
6/18/87 |
8/27/87 |
Description |
|
8 |
50 |
|
|
Lampson
Brook, north branch, 1500 ft downstream of #7 |
|
9 |
80 |
140 |
30 |
Lampson Brook
above Belchertown WWTP outfall |
|
10 |
2,440 |
2,250 |
4,060 |
Lampson
Brook, at Belchertown WWTP outfall |
|
11 |
1,340 |
|
2,110 |
Lampson Brook
below Belchertown WWTP outfall |
|
12 |
|
100 |
|
Lampson
Brook, south branch upstream of Belchertown WWTP |
|
17 |
100 |
|
|
Lampson
Brook, upper northern branch @ Hannum Road |
|
18 |
650 |
1,340 |
1,210 |
Lampson
Brook, 100 ft above confluence with Weston Brook |
|
19 |
460 |
1,220 |
1,040 |
Weston Brook,
50 ft downstream of confluence with Lamson Br. |
|
20 |
400 |
910 |
790 |
Weston Brook,
at Rural Street (same as regular site) |
|
23 |
150 |
|
|
Forge Pond
Brook below Chicopee St. |
|
24 |
190 |
|
|
Tributary to
Forge Pond Brook |
|
25 |
50 |
|
|
Forge Pond
Brook at route 202 |
|
26 |
60 |
|
|
Bachelor Brook
at Stebbins Road |
|
27 |
10 |
|
|
Bachelor
Brook 500 ft downstream of #1 |
Tributary
Inflow results in
nutrient loading that can be easily calculated from flow and concentration.
W=QC
Atmospheric
Deposition occurs when
phosphorus falls directly on the surface of the lake. This phosphorus may be come from the settling
of dust particles or from rain or other forms of moisture. The amount that falls in a year is directly
proportional to the surface area of the lake.
Atmospheric
deposition factor for phosphorus may be estimated using:
0.45 kg-P/ha/yr
Abutting
Septic Systems
contribute nutrients, because they typically only remove 75% of phosphorus that
is generated in the home. The remaining
25% will reach an abutting surface water (e.g., a lake) or groundwater, if
there is no nearby surface water. This
loading can be obtained by a "per capita generation rate" multiplied
by the number of abutting dwellings, the occupancy rate (number of persons per
dwelling), the average occupancy span (fraction of the year each person is
living there), and the fraction remaining after passing through the septic
system.
Per capita waste generation rate for
phosphorus:
1.8 kg/person/yr
Note:
ha = hectares = 10,000 square meters
kg = kilogram
Abutters are of greatest importance,
others are probably inconsequential
at
Forge Pond, there are
24
homes located on the shore.
an
average of 2.3 persons per home
each
person lives his/her home an average of 93% of the year.
In assessing the current impact of
the WWTP discharge to Lampson Brook, you will need to consider the population
in Belchertown and the fact that only a portion of the total population is
sewered (~20%), the rest being on individual septic systems. The Donahue Institute provides some good
population data and projections on their website at: http://www.massbenchmarks.org/statedata/data.htm
In 1989, the plant had a comminutor,
aerated grit chamber, a series of aeration tanks, trickling filter and
secondary clarifier. All water was then passed
through a series of lagoons, totaling 80,000 cubic feet in volume. Sludge from these lagoons has been removed
periodically and placed in a landfill. Effluent
was seasonally chlorinated and discharged to Lampson Brook. The Belchertown WWTP was not designed for
nutrient removal. Average flow in 1985
was about 0.35 MGD, whereas it had risen to about 0.50 MGD by 2007.
Front End of the Belchertown WWTP (ca.
1989)
III. Propose
Engineering/Management Solutions
For estimating impacts of management
alternatives, you should consider using the model developed in part II as much
as you can. There will be some options
that may lend themselves to this type of analysis (e.g., reduction of point
sources, changes in land use) and some that will not (e.g., biomanipulation). You may also want to consider impacts of
population growth (i.e., since 1989 when water quality data were collected, and
into the future), as well as anticipated climate change.
Important
information for assessment of Management Alternatives:
Watershed Management vs
In-Lake Management
|
Watershed/Lake
Area Ratio |
Management
Approach |
|
<10 |
In-lake
measures may work by themselves. |
|
10-50 |
In-lake
measures are difficult, but may still work.
Watershed management may be needed. |
|
>50 |
In-lake measures
are infeasible, watershed management is needed. |
In-Lake Management
Techniques
|
|
Technique |
Notes |
|
1 |
Dredging |
removal of
sediments |
|
2 |
Macrophyte
Harvesting |
mechanical
removal of plants |
|
3 |
Biocidal
Chemical Treatment |
chemicals
added to inhibit growth of undesirable plants |
|
4 |
Water Level
Control |
flooding or
drying of troublesome areas to control growths |
|
5 |
Hypolimnetic
Aeration or Destratification |
addition of
oxygen, and mixing |
|
6 |
Hypolimnetic
Withdrawal |
removal of
bottom waters low in oxygen and high in nutrients |
|
7 |
Bottom
Sealing/Sediment Treatment |
obstruction
of the bottom by physical or chemical means |
|
8 |
Nutrient
Inactivation |
chemical
precipitation or complexation of dissolved phosphorus, nitrogen, etc. |
|
9 |
Dilution and |
increase flow
to help "flush out" pollutants |
|
10 |
Biomanipulation
or Habitat Management |
encouragement
of biological interactions to alter ecosystem processes |
Watershed Management
Techniques
|
|
Technique |
Notes |
|
1 |
Zoning/Land
Use Planning |
Management of
land use |
|
2 |
Stormwater/Wastewater
Diversion |
re-routing of
wastewater flows |
|
3 |
|
increase time
of travel for polluted waters so that natural purification processes act |
|
4 |
Sanitary
Sewers |
installation
of community-level collection systems |
|
5 |
Maintenance
and Upgrade of On-site Treatment Systems |
better
operation & performance of home septic systems, etc. |
|
6 |
Agricultural
Best Management Practices |
use of
improved techniques in forestry, animal and crop science |
|
7 |
Bank and
slope stabilization |
erosion
control to reduce sediment and associated loadings |
|
8 |
Increased
street sweeping |
frequent
washing and removal of urban runoff contaminants |
|
9 |
Behavioral
Modifications |
|
|
|
a. use
of Non-phosphate detergents |
eliminates
source of P |
|
|
b. eliminate
garbage grinders |
reduces
general organic loading |
|
|
c. minimize
lawn fertilization |
reduces
nutrient loading |
|
|
d. restrict
motorboat activity |
reduce
turbulence and sediment resuspension |
|
|
e. eliminate
illegal dumping |
reduce a wide
range of conventional and toxic inputs |
Guidelines for the
Preparation of your Report entitled:
Diagnostic/Feasibility
Study of Forge Pond
You should
prepare your report in the style of a classic engineering technical
report. This should include:
1. Title Page
title
name
of authors
authors'
affiliation
2. Abstract
about
200 words in length
summary
of recommendations
brief
mention of critical results, logic behind recommendations, how results were
obtained
3. Main Body
highly
variable in length
full
recommendations
full
discussion of supporting arguments
summary
presentation of data used
discussion
on how data were collected and analyzed
4. Appendices
broken
down into sections (hydrologic, water quality modeling, management, etc.) and
perhaps subsections
listing
of important data
full
description of how data were analyzed including uncertainty
detailed
descriptions of field methods or laboratory methods used
justification
for selection of model parameters
As a first step I ask you to submit
for inspection a draft report on the Hydrological Investigations. The information you gathered during this
phase of the project would go into one or more Appendices (e.g., Appendix A:
Determination of Sub-basin Drainage Areas.).
Your analysis of the Forge Pond water budget or mass balance, which is
based on this information, would make up one section of the Main Body. Please remember to prepare only one report
per group.
Later you need to incorporate your
Water Quality Investigation (including phosphorus budget/loading) data and
discussion in the appropriate sections of the report. And as a final step, recommendations or
proposed engineering solutions must be presented. The Main Body should begin with these, as
this is your "bottom line". A
reasonable length for the Main Body is 4-10 pages. The Appendices may be substantially longer.
For individual reports on land use in the towns of
Belchertown and
Portions of this document that pertain to Belchertown and
You may find
some additional resources that have been published more recently than
1979. Please feel free to cite and use
these.
[1] What I have described here is an old methodology not using modern computer methods (e.g., GIS). If you are familiar with programs such as Arc-GIS, you are certainly free to use this approach instead.
[2] Vollenweider, R.A., 1975, “Input-Output Models with Special Reference to the Phosphorus Loading Concept in Limnology,” Schweiz. Z. Hydrol. 37: 53-84.
[3] Reckhow, KH, MN Beaulac, JT Simpson, 1980, Modeling Phosphorus Loading and Lake Response under Uncertainty: A Manual and Compilation of Export Coefficients. USEPA 440/5-80-011.