HomeMy WebLinkAboutVer _Complete File_19890106WW-- -40
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MEMORANDUM
TO:
THROUGH:
FROM:
SUBJECT:
DIVISION OF ENVIRONMENTAL MANAGEMENT
January 3, 1989
Bill Mills, Environmental Engineer
Operations Branch
Roger K. Thorpe, Water Quality Regional Supervisor
Washington Regional Office '
Deborah Sawyer, Environmental
Water Quality Section, WaRO
Tec
,,?,frL cian n
a S.
Pursey Harrel Canal
Chowan County
On December 20, 1988, Mr. Bill Moore and I investigated the
unpermitted canal connecting with a tributary to the Chowan River.
The property is owned by Mr. Pursey Harrel of Rt. 3, Box 158A, Edenton
NC 27932. At the request of the CAMA office in Elizabeth City, Mr.
Moore and I investigated the site to determine if water quality may be
contravened by the presence of the canal. The canal is perpendicular
in construction and appears to be approximately 1500 feet in length
and approximately 20-25 feet in width. The owner of the site's
representative, Steve Harrel, stated that the depth is approximately 4
to 5 feet. Mr. Harrel stated to Mr. Moore and me that-the purpose of
the canal is for agricultural drainage and possibly an aquaculture
operation in the future. It is the opinion of this office that this
canal is wider and deeper than agricultural drainage canals which are
exempt from the permitting process and that this canal would cause
water quality to be adversely affected. Historically this Division is
aware of long, dead-end canals having water quality problems in the
warmer summer months due to lower dissolved oxygen levels,
stratification, poor flushing, and increased potential for
eutrophication. If Mr. Harrel had submitted an application for this
project, this office would have recommended denial due to known
effects to water quality of this type of canal system. Documentation
supporting this recommendation is enclosed. If you have any questions
or comments, please notify Mr. Moore or me.
DAS/cm
cc: CAMA - Elizabeth City
4?
DIVISION OF ENVIRONMENTAL MANAGEMENT
December 20, 1988
M E M O R A N D U M
TO: Deborah Sawyer, WaRO
FROM: Jimmie Overton
SUBJECT: Algal Bloom Occurrences in Poorly Circulating Waters
WASH MTO OFFICE
OE--c 2 21988
11 &_I&
Please find enclosed information relating to algal bloom occurrence in
poorly circulating waters. Any water with significant concentrations of major
nutrients and adequate residence time is likely to have problems. These
problems are more pronounced in waters having very poor mixing characteristics
and lack of flushing ability as is generally the case with dead-end canals.
I believe the Washington Regional Office has a file on Whichards Beach
canals. The attached information was pulled from our files on other water
bodies with documented problems related to enrichment and poor circulation.
During late summer, canals are much more likely to promote algal growth,
stratify (even in shallow water), and suffer from anoxia than are waters with
better mixing characteristics.
If I can provide more information on this topic or review specific
information on the project in question, please feel free to contact me at
733-6946.
JO:ps
DIVISION OF ENVIRONMENTAL MANAGEMENT
September 6,1984
M E M O R A N D U M
T0: Lynn Henry
FROM: Jim Overton
SUBJECT: Lake Phelps Bloom
0- LW
As I informed you by telephone, the alga responsible for
extensive growth in Lake Phelps during April, 1984 was
Mougeotia sp. Results of phytoplankton analysis at Station
LP-3 were as follows:
Total phytoplankton density 1900 units/ml (Mougeotia sp. 1132)
Total phytoplankton biomass 23.9 mg/l (Mougeotia sp. 21.7
The attached printout lists the species and relative abundance
of other phytoplankton at that station. Mougeotia sp. was also
strongly dominant in other samples collected. The biomass and
chlorophyll-a measurements were extremely high as would be ex-
pected from your visual observations.
The occurrence of this alga in short lived massive popu-
lations during the spring (March, 1980 and April, 1984) indi-
cates optimum ultization of nutrients which have most likely
built up in the lake during the wiriter.
The excellent light penetration in Lake Phelps promotes
growth throughout the water column when other conditions are
favorable. While algal growth is difficult to predict, I would
expect similar growths in future years as water temperatures
approach 200C in the spring.
JO:ps
cc: Steve Tedder
Bob Holman
Jim Mulligan
wk${-? NGTO. -OFFICE-
i.s?_Z 2 21988
LAKE PHELPS CANALS, TYRELL CO.
Sampled by L. Henry 840416 1000-1205
Canals draining Lake Phelps contained extensive growths of Mougeotia
species, a filamentous green algae. This sudden spurt of algal growth is most
likely a response to winter-buildup of nutrients. In addition, the clear water
in Lake Phelps allows for a high degree of light penetration, promoting algal
growth.
Very high chlorophyll-a levels of 260 µg/l were found at the mouth of
the canal and at the water control structure. Near the boat ramp, an
elevated chlorophyll-a level of 170 }fig/l was present correlating with the
high phytoplankton biovolume of 23,900 mm3/m3.
FAIRFIEM HAPMUR, UT TO NORTMMST CREEK
x DOMINANT SPECIES BY BIOVOLUME
SPECIES CLASS BIOV % BY
BIOV.
?YCLOTFLT.A SPECIES 2 BAC 1053 21.27
OSCILLATORIA GEMINATA CYA 1040 21.01
KATODTNIUM ASYMETRTCt?!?! DIN 997 20.14
OCHROMONAS SPECIES 3 CHR 594 12.01
CRYPTOMONAS EROSA REFLEXA CRY 433 8.74
TOTAL BIOVOLUNE = 4950
1#
DOMINANT SPECIES BY DENSITY
SPECIES CLASS DENS % BY
DENS.
C'YC'T C)TF.T.T,A SPECIES 2 RAC 47165 48.91
OQ,HROMQhW SPECIES 3 CHR 22011 22.83
OS .T I ATQ TA , .MTNATA CYA 19216 19.93
TOTAL DENSITY = 96427
Fairfield Harbour, Craven Co. -
Sampled by Barry Adams 870923 1530
Fairfield Harbour was sampled in conjunction with a fish kill
involving many different species of fish. In these dead-end canals
with little inflow or outflow, stratified layers of water are mixed
seasonally during overturn, causing low dissolved oxygen throughout
the water column resulting in a fish kill. A similar fish kill was
documented in fall of 1986 and according to Washington Regional
Office staff, fish kills of this nature have historically been known
to occur.
The sample contained bloom levels of Cyclotella species 2, a
small brackishwater diatom, Oscillatoria aem?, a filamentous
blue-green, and other chrysophytes and dinoflagellates.
-47-
D 3
CRYSTAL LAS
DOMINANT SPECIES BY BIOVOLUME
SPECIES CLASS BIOV % BY
BIOV.
OgMLLATORIA GEMTNATA CYA 6220 59.61
CYCLOTETd A SPECIES BAC 3271 31.35
TOTAL BIOVOLUME = 10435
DOMINANT SPECIES BY DENSITY
SPECIES CLASS DENS % BY
DENS.
QSCTLLATO TA GEMTKATA CYA 96427 85.19
Y T.LL SPECIES BAC 10831 9.57
TOTAL DENSITY = 113197
Crystal Lake, trib. to Slocum Creek, Craven Co.
Sampled by Dick Denton 870710 1700
Phytoplankton samples were collected from Crystal Lake, a
marina, after reports of extensive algal mats. The- water sample
contained a large biovolume, mostly dominated by Oscillatoria
min , a small filamentous blue-green, and Cyclotella, a diatom.
The visible algal mats were not contained in the phytoplankton
sample, and therefore were not identified.
-46-
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Lover Canal, tri buterq to Pungo Creek (Sample *3)
Reported by Steve Warlick, WA Moore 860424 1745
Phusical/Chemical Data
Chlorophyll -a (corrected) 48 u911 D.O. 4.6/0.3 mg 11
NH3+NH4 .39 mg/1 pH 7.4
N02+NO3 .16 mg/l Temp. (°C) 19/17
Total P .11 mg/l Conductivity 5000/8000 umhos
Salinity 3/6 ppt
Total Biovolume 6587 (mm3/m3)
Total Density 54,852 (units/ml)
Dominant Species By B=
z_
r
4 •
S ift Biovolume Percent
Cyclotelle species 2 (BAC) 5559 84
Ochromonea species (CHR) 676 10
Dominant Species By nsit
Species Densitu Percent
CWlotella species 2 (BAC) 46,117 84
Upper Canal, tributary to. Pungo Creek (Sample *4) 860424 1800
Phusieel/Chemical Data
Chlorophyll-a (corrected) 160 ug/1 D.O. 18.0/0.3 mg/l
pH 8.5
no nutrients taken Temp. (°C) 17/18
Conductivity 5000/800 umhos
Total Biovolume 14,589 (mm3/m3)
Total Dc.Osity 99,222 (unita/mi)
Dominant Species By Biovol ume
SpNies Biovolume Percent
Cyclotella species 2 (BAC) 9229 63
Ochromones species (CHR) 2329 16
Trachelomonas crebe obese (EUG) 1395 10
t
SW
Slmig,
Cyclotella species 2
Chlam moms species 3
Ochromones species
Dominant Species By Density
(BAC} X72,6 0 7?3
(CHO 11,879 12
(CHR) 1 0,831 11
Pungo Creek (lower site *5)
Reported by Steve Warlick, W.J. Moore 860424 1645
Phusical/Chemic al Data (top/botto m data)
Chlorophyll-a (corrected) 28 ug/1 D.O. 4.5/4.5 mg/1
NH3+NH4 .54 mg/1 pH __ 7.0
N02+NO3 .16 mg/l Temp. (°C) 19/19
Total P .11 mg/l Conductivity 5000/6000 umhos
Sali MAY 3.5/6.0 ppt
Total Biovolume 4289 Imm3/m3)
Total Density 52,755 (units/ml)
Dominant Species By Biovolume
Species Biovol ume Percent
ryyb&Ilgspecies 2 (BAC) 1865 43
Chlamydomonas species 3 (CHL) 1239 29
Chroomonas minute (CRY) 362 8
jrach^loM9m species (ELIG) 356 8
Dominant Species By Densitu
Donsit Percent
C,yGlotella species 2 (BAC) 16,537 31
Chlamydmanas species 3 (CHL) 15,489 29
Chroomona minute (CRY) 9783 19
Ochromones species 3 (CHR) 9550 18
Pungo Creek (upper site *2)
Physical /Chemical
Chlorophyll-a (corrected) 7 ugA
NH3+NH4 1.3 n-qA
N02+NQ3 .33 mg/1
Total P .61 mg /1
Total Biovolume 1654 (mm3/m3) '
860424 1730
Date
D.Q. 5.0/4.4 mg/1
pH 6.9
Temp (°C) 17/17
Conductivity 900/1900 umhos
Salinity 0/1 ppt
Total Density 6009 (units/ml)
Dominant Species By Biovolume
S ies Biovol ume Percent
Ochoomones species (CHR) 496 30
Dominant Species By nsit
species Density Percent
Ochromones species (CHR) 2306 38
Nitmhie pale (BAC) 699 12
Cyclotella species 2 (BAC) 629 10
-37-
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Pungo Creek ! US 264 Bridge
Reported by Steve Warlick, WA Moore 860424 1830
Php, ical /Chemical Dote (top/bottom data)
Chlorophyll-a (corrected) 22 lag/1 D.O. 7.8/0.0 mgA
NH3+NH4 .40 mg/1 pH 7.3
N02+NO3 .11 *A Temp. (°C) 18/17
Total P .09 mg/1 Conductivity 6000/10,000 umhos
Sali pity 4/7 ppt
Total Biovolume 2896 (mm3/m3)
Total Density 10,481 (writs/ml)
ftecin
E_gu leer species C
•lotella species 2
Chlam ° moues pecies
Gymnodinium species
Dominant Species Bu Biovolume
Biovolume
(EUG) 641
(BAC) 432
(CHL) 346
(DIN) 337
Percent
22
15
12
12
Dominant Species By Density
S ?a Density Percent
C lotella species 2 (BAC) 3882 37
Chlam mores species (CHL) 2174 21
Samples from Pungo Creek and adjacent canals were collected in association with a fish
kill. The bloom was mainly restricted to Pungo Canal (Samples 3 &4) as evidenced by high pH,
chlorophyll-a and phytoplankton biovolume and density estimates. A de-oxygenized salt wedge
was present, causing a fish kill.
-38-
• ' u (1) PUNGO SWAMP @ MOUTH 0
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(3) PUNGO SWAMP (LOWER SI
(4) PUNGO CANAL (UPPER SIT
„
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Fairfield Harbor Canal
Reported by Borry Adoms 861010 1500
h -cal/Chemical Data
Chlorophyll -a (corrected) 31 ugA
no other physical /chemical date taken
Total Biovol ume 110,694 (mm3/m3)
Total Density 83,850 (units/ml)
Dominant Species By Biovolume
ante-* Biovolume Percent
Melosire monoliformis (BAC) 30,855 28
jumft fie (BAC) 19,998 18
ft species 2 (CHL) 14,928 13
Dominant Species By nsit
Skies Densltu Percent
SJt nedra ul no (BAC) 10481 13
Nitzschia plea (BAC) 8036 10
A fish kill resulting in approximately 1000 dead freshwater fish occurred in Fairfield
Harbor, on an unnamed tributary to Northwest Creek, which is a tributary to the Noun River.
According to local residents, the fish kill occurs twice a year in early spring and fall. it is
dilricult to assess axactiy what caused the fish kill without chemical/physical data, but fall
overturn may hive been responsible. Mixing of stratified layers may have resulted in near
anoxic conditions throughout the water column.
-81-
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RIVER BEND PLANTATION, CRAVEN CO.
Sampled by D. Denton 880616 1230
A dead end canal off of River Bend Plantation was sampled due to a
citizen's complaint. An obvious bloom was in progress as the water column
appeared bright green. Large floating algal mats (6-8 feet in diameter) were
also present. A high surface dissolved oxygen level of 19.5 mg/l further
signaled algal bloom conditions.
Nutrient analysis revealed elevated levels of total nitrogen (1.8 mg/1)
and total phosphorus (.60 mg/1) indicating an available nutrient source.
Green algae (Chlorophyta) comprized 97% of the bloom sample by
biovolume, with C.eria species boing the dominant alga. A very high
chlorophyll-a level of 510 was recorded, corresponding with the large
phytoplankton standing crop. The visible algal mats were not contained in
the quantitative phytoplankton sample, therefore not identified.
DOMINANT SPECIES BY BIOVOLUME
SPECIES
CARTERIA SPECIES
TOTAL BIOVOLUME =108,802 mm3/m3
DOMINANT SPECIES BY DENSITY
SPECIES
CARTERIA SPECIES
CHLAMYDOMONAS SPECIES 3
BIOVOLUME % BIOV.
101563 93
DENSITY % DENSITY
44545 49
27426 30
TOTAL DENSITY = 90,837 units/ml
BOGUE SOUND, CARTERET CO.
Sampled by J. Gregson, S. Long 880609 1500
A phytoplankton sample was collected from a canal near Salter Path in
conjunction with a massive fish kill, involving several thousand menhaden. At
the time of sampling, the high surface dissolved oxygen (18.7 mg/1) and pH
(8.5) readings indicated elevated algal activity in this brackish water canal.
Phytoplankton analysis revealed high numbers of Gomphos hp aeria
aponi?, a colonial blue-green. G. agofiia can be found in fresh, brackish or
marine waters in protected areas. A high chlorophyll-a level (820µg/1) was
also present, indicating an algal bloom. Elevated concentrations of total
nitrogen (3.94 mg/1), total phosphorus (.63 mg/1) and ammonia (.35 mg/1)
were found in the canal.
Although the dissolved oxygen in the epilimnion was high, mixing of
stratified layers may have resulted in nearly anoxic conditions, causing a fish
kill. Without stratified or bottom data, it is difficult to ascertain the exact
cause of the fish kill.
DOMINANT SPECIES BY BIOVOLUME
SPECIES CLASS BIOV. % BIOV,
CYA 29164 70
CRY 3587 9
TOTAL BIOVOLUME = 41,427 mm3/m3
DOMINANT SPECIES BY DENSITY
SPECIES
CHRO OMONA S MIN UTA
GOM PHOSPH AERIA APO NIA
CHRO OMON AS CAU DATA
CLASS DENS. % DENSITY
CRY %951 66
CYA 34064 23
CRY 11791 8
TOTAL DENSITY=147,610 units/ml.
Uiv;-i Lli S`1"A"fES ENVII-? ONMErl`A1_ PR0_f'E_C'I_i01'J AGENCY
C
REGION IV
ENVIRONMLNTAL SERVICES DIVlt 110"
ATHENS, GEORGIA 306 t 3
REF: 4ES-ES
?.;
Mr. Thomas Hilliard, III
Office of Legal Counsel
North Carolina Department of Natural 0?
Resources and Community Development
P. 0. Box 27687 i
Raleigh, North Carolina
Dear Mr. Hilliard:
Accompanying this letter are the findings of the water quality survey con-
ducted on the Warren Whichard canal system by EPA, Environmental Services
Division personnel during September 1985. As you are aware from reviewing
the history of the Whichard project which commenced in the early 1970's,
-EPA has severe reservations regarding the use of septic tank systems adja-
cent to the canal and previously indicated the potential for substandard
water quality conditions if the project was completed as originally pro-
posed. Review of project files indicates that soil percolation rates are
unacceptable for septic tank systems. On the basis of the above, as well
as wetland destruction, EPA, in a letter dated April 3, 1975, to the Wil-
mington District, Corps of Engineers recommended denial of the federal
permit for the project. Nevertheless, under:.the pretense of constructing
a plugged system, the Whichard Canal was completed and development ensued
to its present level with the use of septic tank systems as the method of
sewage disposal.
As you know from your visit to the site during the EPA study, six stations
were sampled within the Whichard Canal, two in the Pamlico River, and three
in an open, older canal just upstream of the Whichard project. As indicated
in the attached Findings of Fact, the anticipated water quality problems
which served as the basis for earlier opposition to the project were mani-
fested in the Whichard Canal during the EPA study. The Whichard Canal is
a strongly oxygen stratified system which experiences broad dissolved oxygen
(DO) fluctuations over a diurnal (24-hour) period and acute DO suppression
in the bottom waters. Violations of the DO standard (5.0 mg/L - Class SB
waters) are prevalent throughout the system both day and night. High nutri-
ent concentrations are manifested in high chlorophyll a concentrations
which exceed state standards. The canal bottoms are low or void in dissolved
oxygen, have hydrogen sulfide present indicating anaerobic (without free
oxygen) conditions, and are dominated by a loosely consolidated fine silt
matrix. These factors, either alone or in combination, inhibit development
of a viable benthic macroinvertebrate community in the canal bottom. Such
a community is an essential link in food web dynamics. The beneficial ef-
fects of adequate DO concentrations and a suitable bottom substrate on the
development of a diverse macroinvertebrate community is illustrated by the
submerged canal sides and littoral area which are in sharp contrast to
canal bottoms relative to the number of macroinvertebrate taxa.
t
{
II 1 -2-
The open canal system was similar to the Whichard system, experiencing the
same diel dissolved oxygen excursions and standards violation relative to
DO and chlorophyll a, with increased concentrations of hydrogen sulfide.
Accordingly, based on comparison of the opened canal with the Whichard
system, substantial improvements to the Whichard Canal could not be expected
if the plug were removed. In this regard, it should be pointed out that
the earthen plug at the mouth of the Whichard Canal was being replaced as
the survey team arrived. It was further indicated to us that the canal had
been opened to the Pamlico River, at some level, for a considerable time
prior to the study so, in essence,,we were not studying a steady state
closed system.
Pamlico River dissolved oxygen concentrations were generally above the 5.0
mg/L standard during the study period except for a few observations. The
level and duration of the observations below standard were not nearly as
pronounced as in the canal systems. However, at the stations sampled, the
river bottom exhibited similar substrate and biological communities as the
center canal stations in the Whichard Canal.
Investigation of three septic tank systems alongside the Whichard Canal re-
vealed a strong potential for interaction of septic tank system water with
surface (canal) waters. The study was conducted in, and preceded by, a dry
period. Dye fortified septic tank effluent within the leach field were found
perched well above ground waters and very near the ground surface. At one
location the dye actually moved upward on to the ground surface. In the
event of heavy storm related rainfall or an extended wet period, the proba-
bility for the perched septic tank waters to reach the ground surface and --
canal waters via runoff is quite likely as evidenced by previous EPA studies
in coastal North Carolina.
We are pleased to have been of assistance in this matter. If you wish to
discuss any of the findings, please do not hesitate to call.
Sincerely,
Philip J. Murphy
Marine & Wetlands Unit
Attachments
FINDING OF FACTS
WARREN WHICHARD CANAL STUDY
1. Dissolved Oxygen. Dissolved oxygen (DO) is probably the single most
parameter of attention respective to water quality standards. The Pamlico
River in the vicinity of the Whichard Canal is designated as Class SB waters
with a dissolved oxygen standard of 5.0 mg/L. Measurement of dissolved
oxygen concentrations were conducted at the 3-hour intervals (or continuously
at some stations) over a 24-hour period in the Whichard Canal system, two
stations in the Pamlico River, and three stations in a nearby open (unplugged)
canal (Figure 21). The water quality standard of 5.0 mg/L dissolved oxygen
was violated at all Whichard Canal stations. Dissolved oxygen concentrations
well below 5.0 mg/L and sometimes near zero (0) were particularly evident in
the bottom water (lower 2 feet) at all Whichard Canal stations (Figures 1-6).
Durations of the violations (i.e. total time below 5.0 mg/L within the 24-hour
study period) ranged from 14 to 24 hours, depending on the station, for the
bottom water strata.
The upper part of the water column (3 feet to surface) at the Whichard
Canal stations was usually at, or above, the 5.0 mg/L DO standard except at
Station W-1 and W-6 where the standard was violated at all depths at some
time during the diurnal period.
Dissolved oxygen concentrations in the Pamlico River (Station 7) (Figure
7) were generally above standards for the sampling period except for two
observations at the 5-foot depth. Station 8, Pamlico River, experienced DO
concentrations below the water quality standard in the lower strata (5- and 6-
foot depths) of the water column (Figure 8).
-2-
The open canal system (Stations 9, 10 and 11) located immediately upstream
from the Whichard Canal on the Pamlico River exhibited a dissolved oxygen
regime similar to the Whichard Canal with bottom DO concentrations being
severely depressed at Station 11 (near 0.0 mg/L for most of the 24-hour period).
DO concentrations at Station,10 decreased to substandard levels from early to late
morning (5:00 - 11:00am) (Figure•10). Station 9, at the mouth of the canal,
responded similarly to the Pamlico River with DO concentrations predominately
above 5.0 mg/L at all depths for all but four observations (Figure 9).
2. Water Chemistry. I-later chemistry parameters in Table 1 show similar
concentrations of TOC, TKN, and NH3 in the Whichard Canal and the Pamlico
River. In comparison to water chemistry data from other deadend canal systems
in North Carolina, total phosphorus (TP) concentrations are elevated at all
stations, including the Pamlico River.
3. Chlorophyll a. Chlorophyll a concentrations were well above the state
standard of 40 mg/m3 (Table 1). Chlorophyll a concentrations in the Whichard
Canal were comparable or greater than the Pamlico River ranging from 100.86
to 66.65. The chlorophyll a concentration at Pamlico River Station 7 during
the study was 67.52.
4. Sediment Chemistry. Sediment chemistry analyses included Total Kjeldahl
nitrogen (TKN), ammonia nitrogen (NH3-N), total phosphorus (TP), and percent
volatile organics (Table 2). Total phosphorus concentrations were higher
in the canal sediments than in the Pamlico River sediments. Conversely, the river
and open canal exhibited a higher percentage of organic material than the
Whichard Canal with the exception of Station W-5. Station W-5, located in
the Whichard Canal, exhibited the highest percentage of volatile organics of
all stations. If the Whichard Canal was opened on a continuous basis, it is
r
It.
t
i ?
-3-
expected that the percentage of volatile organics would increase to levels
similar to the river and older open canal systems sampled during the study.
5. Sediment Particle Size. The opened canal system and Pamlico River sedi-
ments were dominated by finer components (silts and clays) of the sediment
matrix. Over 50% of the sediment,matrix was composed of silts and clays at
Stations 7 through 11 (Table 3 and Figure 12). Stations W-1 and W-2 in the
Whichard Canal system were dominated by sand (70%). With progression toward
the end of the Whichard Canal (Stations 4 and 5), the sand component decreased
and was replaced by increasely larger percentage of silt and clay (60 to 70%)
(Figure 13). The high percentage of sands at Station W-1 reflects its prox-
imity to the sandy beach area, as well as erosion of the sand plug, at the
mouth of the canal while the sandy nature of W-2 is consistent with the fact
that the W-2 basin originated as a sand borrow pit.
6. Benthic Macroinvertebrates. The interaction of the physical and chemical
components to yield suitable conditions and habitat for a balanced biological
community is best reflected in the benthic macroinvertebrate data (Table 4).
Most notable is the disparity in the number of taxa between benthic communities
on the side slope of the canal in comparison to the center, or trough, of the
canal. The side slope at all canal stations exhibiteda diverse benthic
macroinvertebrate community ranging from 10 to 17 different taxa, with the
exception of Station 9 which was bulkheaded and atypical to canal side slopes.
The center trough at all stations, including the Pamlico River, exhibited a
rather depauperate macroinvertebrate community ranging from zero (0) to
four (4) taxa. The exception was Station W-1, near the mouth of the Whichard
Canal which had seven (7) different taxa. Review of the sediment size data
reveals a marked difference between Station W-1 and all other benthic
-4-
macroinvertebrate stations. Station W-1 was dominated by sand (70%) while
all other stations sampled for benthic macroinvertebrates were dominated by
fine silt and clays.
Review of the dissolved oxygen profiles, diurnal DO curves, water
chemistry, and sediment size data in conjunction with the benthic macroin-
vertebrate data provide a good explanation'for differences in the macro-
invertebrate community of sides versus canal trough. Macroinvertebrate samples
collected at canal side locations were in shallow (less than three feet deep)
water near the bank and influenced by sand substrate and sparce littoral
vegetation (diver observations). Dissolved oxygen concentrations in the
shallow depths (one to two feet) were generally above DO standards for most
of the diurnal period. Under such conditions, DO concentrations are sufficient
to sustain a diverse macroinvertebrate community. These conditions are in
direct contrast to physical and chemical conditions in the center trough of
the Whichard canal. All canal stations, as well as the river, experienced
some period of suppressed DO concentrations, and were dominated by soft mud
(silts/clays 60 to 70%) except for the previously stated exception, Station
W-1. The consistency of such a finely divided substrate is not conducive to
development of a diverse benthic macroinvertebrate community which would be
further inhibited by the suppressed DO.
7. Septic Tank Leachate. Of the three septic tank systems investigated which
are associated with the Whichard Canal system (Figure 14) none were function-
ing properly. As designed, the systems depend on a downward percolation of
effluent through the bed of the disposal area. A dye tracer added to each of
the three tested disposal systems revealed that rather than a downward
percolation, the water within the system is being ponded or perched within
4 .4
-5-
the disposal field at least two feet above the surrounding ground water.
Rather than percolating downward, the dye fortified leachate was found at
the ground surface or within 1.7 feet of the ground surface at all three
locations (Table 5, Figure 15).
Past EPA studies in coastal North Carolina have shown that high water
tables within a disposal field can result in leachate degradation of surface
water during moderate to heavy rainfall events (USEPA, 1975). The Whichard
Canal study was conducted in a relatively dry period and not during a rain-
fall event. With the septic tank effluent already at or within close proximity
to the ground surface, a strong potential exists for interaction of septic tank
leachate with surface and canal waters during storm events or seasonally
wet periods. -
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00 000 008 coo 000 0000 00 000 00 00 o8c
N N N N N N N N N N N N N N N
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Table 2. Sediment chemistry as mg/kg dry weight, with percent.volatile
organics, Whichard Project, Chocowinity, North Carolina, September 1985._
Station Date TKN NH3-N TP % Volatile Organics
11-1 9/13 1300 40 126 1.1
W-2 9/13 1300 36 388 7.76
W-4 9/13 2800 120 700 7.0
W-5 9/13 880 28 116 23.3
7 9/13 2200 44 178 17.07
9 9/13 2700 79 725 18.09
10 9/13 3900 126 548 17.7
11 9/13 2600 170 790 16.07
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TABLE 5
HYDROGEOLOGIC DATA
WHICHARD PROJECT
CHOCOWINITY, NORTH CAROLINA
SEPTEMBER 1985
Station
Wyatt Wood
ww-1
Top of septic tank
WW-2
WW-4
W W-5
WW-6
Ground surface @
canal bank
Canal
Bobby Weathington
Canal
BW-1
Canal
BW°7
BW-8
B W-5
BW-4
L Leachfield
BW-9
BW-6
Canal
Barbara Laughinghouse
Canal
Canal bank
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Distribution box
A
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Ground Surface Water Surface
Elevation (Ft.) Elevation Date Time
4.29 -0.05 9/11/85
4.42 -- 9/11/85
4.08 -0.68 9/11/85
-- 3.13 9/11/85
4.165 0.03 9/11/85
4.07 3.02 9/11/85
3.28 -- 9/11/85
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2.73
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9/11/85 1925
9/11/85
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9/12/85
9/12/85
9/12/85
9/12/85
9/12/85
9/12/85
9/12/85
9/12/85 1747
2.49
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9/13/85
9/13/85
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-. ?.?? I`•% 1 STATION LOCATIONS, WHICHARD CANAL STUDY. • 1
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\ 7
OPEN CANAL WHICHARD PROJECT \ , ?? •\
(Sta. 9,10,11) (Sta. 1 thru b)^.
.EPA 904/9.76-017
FINGER- FILL CANAL STUDIES
FLORIDA AND NORTH CAROLINA
MAY 1975
??.?EO srq?
s UNITED STATES
'W ENVIRONMENTAL PROTECTION AGENCY
o SURVEILLANCE AND ANALYSIS DIVISION
COL{.EOS STATION ROAD
ZN4';
4 PR;( ATHENS, GEORGIA 30601
7
• 2
H. SUMMARY
Poor f ushingr__coupl-ed aith_seasonal inflow of fresh water, produced
extensive salinity stratification in canal systems_surveye_d in_._southwestern
Florida. A bottom layering of!high salinity water resulted in stagnation,
putrification, and excessive nutrient enrichment of the water column. De-
stratification was realized with seasonally diminished inputs of fresh water.
State established water quality standards and associated criteria
provide the basis of assessing water quality violations. Violations ?£
dissolved oxygen criteria were documented for all canal systems _surveyed
in both Florida and North Carolina. These violations were demonstrated to
occur in those canals whose depths exceeded four to five feet.
Total nitrogen and organic carbon were the most salient chemical
constituents characterizing water quality differences between developed
and undeveloped canal systems. In nearly every case, concentrations of
these constituents were greater in the developed waterways. Equally evi-
dent was that their concentrations varied inversely with averaged dissolved
oxygen concentrations.
B - SEDIMENTS
Canal sediments examined during the study featured an accumulation
of organic carbon and nitrogen that were maximized with increasing dis-
tances from the mouths of the canals. The reported carbon:nitro,gen ratios
of canal sediments were low and indicated that most canal sediments were
fairly well stabilized with respect to microbial decomposition. Relative
stages of development (dwelling unit density) along canal banks were posi-
tively correlated to general sediment composition. The greater the dwelling
unit density, the greater the nutrient concentration in the sediment.
C - MICROBIOLOGY
Total coliform bacteria densities exceeded allowable water quality
criteria associated with applicable standards at all canal study areas,
with the exception of the Big Pine Key site. No standard violations were
noted at any of the background stations nor at undeveloped canal sites.
As a rule, total coliform densities increased from the mouth to the dead
end of all the developed canals. Dead-end stations had fecal coliform
densities which exceeded their respective background stations by: 43
percent at Punta Gorda; 1,200 percent at Big Pine Key; 33,000 percent at
Panama City (Woodlawn Canal); 50 percent at Panama City (Rentz Canal);
37,000 percent at Atlantic Beach; and 3,500 percent at Spooners Creek.
D - CANAL FLUSHING AND MODELING
In general, the dispersive properties of natural bay-estuarine
systems were two orders of magnitude greater than those canal systems
investigated. A measure of dispersive properties of estuaries and canals
A - WATER QUALITY
V
3
included in these investigations indicated the following dispersion
coefficients:
Miles2/Day
Waccasassa Estuary - Cedar Key, Florida 1/ 2.0-2.7
Hillsboro Bay - Tampa, Florida 1/ 0.7-6.0
Canal I - Punta Gorda, Florida 0.006
Canal II - Punta Gorda, Florida 0.003
Canal III - Big Pine Key, Florida 0.002
Canal IV - Big Pine Key, Florida 0.001
Canal V - Big Pine Key, Florida 0.003
Canal VI - Atlantic Beach, North Carolina 0.007
Canal VII - Atlantic Beach, North Carolina 0.011
1/ Measured by others.
Flushing of canals to the 90-percent level required from 70 to 250
hours in the systems investigated.
Based upon mathematical model simulations, the canal systems studied
did not have the assimilative capacity to receive wastewater effluent.
Flushing times were found to be responsive to both canal depth and
length. Computer simulations demonstrated that depth is the dominant
factor affecting flushing. Conseguently, if flushing times and assimila-
tive-capacity are to be maximized, lcanal de -ths_an$ ,to_a,lesser extent,
lengths must Fd-minrlm3zed.
E - SEPTIC TANKS
Considerable documentation exists in the literature of chemical,
bacterial, and viral contaminants from septic tank leachates traveling
significant distances in ground water systems. Confirmed illnesses re-
sulting from the consumption of ground water contaminated by septic tank
leachates emphasize the public health implications where lateral movement
of ground water occurs. Similarly, documentation exists demonstrating
movement of septic tank leachates through ground waters to estuarine
waters.
With the exception of the Big Pine Key studies, tracer dyes intro-
duced into septic tank systems located approximately 50 feet from finger
canals demonstrated that septic tank leachates were rapidly transmitted
to the adjacent canal waters. At Punta Gorda, dye was detected in the
canal system 25 hours after injection into a septic tank system. At
Atlantic Beach, dye was confirmed in two canal systems four and sixty
hours after injection into septic tank systems.
F - BIOLOGICAL
Except for shallow shoreline habitat, physical and chemical conditions
of the bottom in the Punta Gorda canal system severely limited the kinds
and numbers of bottom-dwelling organisms. During the wet season, the canal
systems featured salinity stratification with an anoxic benthic environment.
a , -x
4
Bottom sediments were unconsolidated, rich in organic matter, and often
laden with sulfides.
Excessive turbidity, unconsolidated substrate, and lack of dissolved
oxygen precluded the survival of attached benthic macrophytes. Phyto-
planktonic chlorophyll values for the Punta Gorda canals were comparable
to levels found in most inshore regions of the Gulf of Mexico. The growth
of algae on artificial substrates was more luxurious in the developed
canal. Inorganic nutrients did not appear to be a factor limiting peri-
phytic growth.
At Big Pine Key, both the developed and undeveloped canals supported
a benthic environment suitable for numerous kinds of macroinvertebrates.
Diversity and numerical abundance were keyed to the abundance of benthic
attached plants. Bottom sediments appeared to have a low level of organic
matter and were comprised mainly of clay and silt. Seagrasses and attached
algae were common to all canals in the study. Their abundance was suffi-
cient to effect a marked day-night variation in dissolved oxygen. Seasonal
-- - - ------- __
variations in standing crop biomass were maximized in the developed canal
with seasonal lows appearing premature for benthic plant communities. The
undeveloped canal supported a plant community yielding only slight sea-
sonal changes in standing crop biomass. Phytoplanktonic chlorophyll values
were significantly greater in the developed canal with chlorophyll values
being maximized when benthic macrophytes were reduced in standing crop
biomass.
The Sea-Air Estate canal system at Marathon, Florida, featured sedi-
ments comprised mainly of silt and clay with organic content similar to
the Big Pine Key canals. Macrophytes and macroalgae were virtually excluded
from the bottom community. Low dissolved oxygen concentrations were common
to the bottom environment.
.A community comprised of few benthic macroinvertebrates was found in
the Atlantic Beach canals. Dead-end and mid-canal regions were void of
a benthic macroinvertebrate community. Sediments in these regions were
excessively enriched with organic matter and unconsolidated. Low dissolved
oxygen concentrations were common to the benthic habitat.
5
III. RECOIO ENDATIONS
1. Coastal canal developments should be restricted to non-wetland areas.
Access canals should be routed from housing developments to the parent
body of water by the shortest and least environmentally damaging course.
2. During the planning phase of a coastal canal development, a hydrologic
investigation should be made to `determine the presence of, and project
effect on, shallow aquifers. In addition, with consideration of
surrounding hydrologic features, circulation patterns of the proposed
canal system should be described.
3. As part of the permitting process, the party responsible for mainte-
nance of water quality standards and/or correction of water quality
violations in coastal canal developments should be designated.
4. Canal depths should not be governed by fill requirements. An appro-
priate canal depth for shallow draft pleasure craft should be no more
than four_to six feet below mean low water.
5. Centralized.waste-.collection and treatment systems are necessary in
• coastal canal housing developments.
6. No sewage treatment plant effluent or other point-source discharges
should be discharged directly into finger-fill canal waters. Dis-
charges into surface waters should be sufficiently distant from the
canals to ensure that the effluent is not carried into the canal
systems by tidal currents.
7. Surface drainage patterns should be designed with swales to minimize
direct runoff into canal waterways.
?1 ( I ?
6
8. The grade of canal bottoms should be such that no sills are created
at any point in the system, especially at the confluence with the
parent water body.
9. Orientation of canals should take into account prevailing wind
direction so that flushing/mixing would be enhanced and wind drift
of floating debris minimized.
10. To the extent possible, dead-end features should be eliminated from
canal system design.
Since the studies discussed in this report were completed, EPA Region
IV has initiated additional studies to evaluate the physical, chemical,
and biological aspects associated with dead-end canals featuring maximum
depths of 4-6 feet MLW. Preliminary analysis of these study results indi-
cate the above recommendations remain appropriate.
e
IV. RATIONALE FOR RESTRICTING CANAL DEPTHS
AND THE USE OF SEPTIC TANKS
A. CANAL DEPTHS
What is an optimum canal depth? As shallow as possible, yet deep
enough to meet navigation requirements. In the context of finger-fill
canals, navigational needs are those of small pleasure craft. The
State of Florida reports 297,894 boats registered as of June 10, 1974.
Of the total, 94 percent of the vessels measured 26 feet or less in
length. Similarly, North CaroliAa reports 112,530 vessels registered
as of January 1, 1975, of which 98.3 percent measure less than 28 feet
in length. Obviously, shallow-draft boats are to be the principal
vessels of consideration in establishing navigational depths. The
majority of boats are amenable to navigational depths of four to six
feet.
Based on the above consideration and the results of these environ-
mental studies, it is recommended that canal depths not exceed four to
six feet at mean low tide. The environmental considerations leading to
this recommendation are presented in the following discussion.
Flushing or residence time(s) is a relative measure of the ability
of a system to purge itself of a given constituent. The coupling of
dispersive and advective forces establishes the flushing characteristics
of a waterway. _In_the cases_of-.the Florida and North Carolina canals,
elapsed times ranging from 70 to 250 hours were required to effect a
90-percent removal of a dye tracer. Considering the water quality con-
stituent five-day biochemical oxygen demand (BOD5), approximately 70 to 80
percent of the total BOD is exerted in 120 hours. Thus, increasing
residence time requires the canal to assimilate an increasingly greater
share of the oxygen-demanding matter. Furthermore, the restricted circu-
lation of the canal systems limits their reaeration capability.
Flushing dynamics result from a complex set of physical conditions.
Many of these factors are not presently understood, others can not be
controlled, and some are effected for conveniences. The dimensions of a
canal system are a matter of economic convenience. Flushing times under
variations in canal depth and length were simulated. Flushing times are
maximized with increases in depth. For example, Canal V at Big Pine
Key, a doubling of depth increased flushing time from 230 to 660 hours.
A doubling of length effected an increase to 400 hours, while a halving
of the depth decreased the flushing time to 90 hours. Consequently,
if flushing times and assimilative capacities are to be optimized, then
canal depths and lengths (to a lesser extent) must be minimized.
If the "coast line" is identified as the most seaward point of above-
ground vegetation, a point 1/4 of a mile inland to a point 1/4 mile
seaward from this coastline is generally the extremes of the mixing zone
for inland drainage and saline waters. Ground surface/bay bottoms eleva-
tion tapers from approximately +2 to -4 feet mean sea level. Yearly tidal
A
r
•
8
ranges are on the order of -1 to +2 feet mean sea level with a mean ele-
vation of 1.0 foot. This tidal prism (tide range) then constitutes
70-100 percent of the total water column, thus optimizing mixing and flush-
ing. If depths of -20 feet mean sea level are introduced, only 14 percent.
(3/22) of the water column is moved in the tidal excursion. In addition,
the shallow estuaries are mixed by wind-induced circulation; whereas, canals
(deep and narrow) have little potential for appreciable mixing by wind.
The canal systems surveyed varied in depth from eight to twenty-five feet
at mean stage. Obviously, the design depth was predicated upon fill require-
manets and not optimization of tidal flushing. The consequences of poor
flushing were readily demonstrated by the results section of this report.
Salinity stratification in the canals at Punta Gorda, Florida had a
paramount affect on water quality. An example of severe stratification is
given in Figure 1. The data accompanying the figure show the water quality
consequences--i.e., anoxic conditions and nutrient enrichment of the
entrapped and dense saline stratum. In addition, bottom life was eliminated.
Nutrients (nitrogen and-phosphorus) diffusing to the upper layer were ex-
ported from the canal via tidal exchange at a loading rate equivalent to
that produced from a 25,000 to 30,000 gallon per day activated sludge
treatment plant.
Violations of state dissolved oxygen standards were common occurrences
in all canals surveyed in August - September 1974. In Figures two t9 three,
a summation of dissolved oxygen (DO) observations with respect to depth is
presented -for_the canal studies involving interior canal stations--background
stations were excluded from figures. In both states, water quality standards
were violated in the canal systems at depths usually exceeding four to five
feet. Datum is. mean stage--approximately one foot above mean low water.
Aside from the developmental loads to the canals (septic tank leachate
and runoff), poor flushing characteristics can be identified as the princi-
pal factors affecting the dissolved oxygen budget of the canal systems.
In turn, flushing is functionally related to depth of the canal. Thus.
needed is a determination of an optimum depth that will maximize
canal flushing and meet navigational needs and minimize the potential for
violations of state DO standards. It is recommended that depths be no
more than four to six feet at mean low water.
B. SEPTIC TANKS
The Environmental Protection Agency is endeavoring to enforce "best
practical treatment" in the 1970's with efforts to obtain "best available
treatment" in the early 1980's. Septic tank/sorption fields may be
viewed as acceptable treatment in the context of rural development where
the purity of the ground and surface waters can be protected. This pro-
tection is safeguarded by adequate sorption field design, long distances
to surface water bodies and relatively low housing unit densities. In
contrast, coastal canal developments maximize housing unit density, and
proximity to surface water bodies and thus eliminates the safeguards
inherent in the rural environments.
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9
A simple mass balance reveals that constituents (chemical, bacterial
and viral) introduced into the sorption field are subject to either retain-
ment in the field, die off (in the case of bacteria and viruses) or.
transmitted to ground and surface waters. The prime concern is the
quality of the leachates entering the ground and surface waters.
Results of these studies show in several cases that leachates are
transmitted rapidly to the canal waters. Time of travel measured was four
to sixty hours. The effects of these rapid transmissions were evident
in: (1) high nutrient levels in ground and canal waters, and (2) viola-
tions of bacteriological standards in canal waters. Based on litera-
ture review these relatively short travel times indicate that both viable
bacteria and viruses can enter the canal waters and create a potential
public health problem. Our studies show the potential to be a reality
in many cases, i.e., 2,400,000 fecal colonies per 100 milliliter were
recorded in canal waters near septic tank leach fields during July 1975
at Surf City, NC, Also, the transmission of nutrients to the canals
via contaminated groundwaters must be viewed as being at least partially
responsible for observed ecological imbalances in canal systems.