workshop – water quality review july 1, 2013. purpose regulations ostds evaluation – east...
TRANSCRIPT
East / West Spring Lake Wastewater Expansion Pilot
Program
Workshop – Water Quality ReviewJuly 1, 2013
Purpose Regulations OSTDS Evaluation – East & West Spring
lake Sampling & Test Results Other Contributors Soils Data Relevant Studies Summary
PRESENTATION OUTLINE
Provide a summary of Water Quality Data collected within the East & West Spring Lake Area
Provide a summary of similar studies Provide a summary of
Regulations Provide a correlation with
Onsite Sewage Treatment and Disposal Systems (OSTDS)
Purpose
62E-06, Florida Administrative Code◦ OSTDS Regulations
62-302, Florida Administrative Code◦ Numeric Nutrient Criteria
Manchester Lock Permit
Regulations
Provides requirements for OSTDS construction & repair
1983 standards changed◦ Separation from seasonal high water table Increased from
12-inches to 24-inches◦ Setback from water body Increased from 50-feet to 75-
feet*◦ Septic tank and drainfield sizes increased
Sizes dependent on structure size
* Charlotte Code of Ordinances (3-7-56) restricts setback to 150-feet for tidally influenced water bodies
62E-6 OSTDS REGULATIONS
1983 standards changed◦ Separation from seasonal high water table Increased
from 12-inches to 24-inches◦ Setback from water body Increased from 50-feet to
75-feet*◦ Septic tank and drainfield sizes increased
Sizes dependent on structure size
* Charlotte Code of Ordinances (3-7-56) restricts setback to 150-feet for tidally influenced water bodies
62E-06 REGULATIONS CONT’D
7
62E-06 REPAIR REQUIREMENTS
WSWT
Septic Tank
Current Drainfield
6" (pre-1983)
Conventional Septic System
8
WSWT
Septic Tank
Drainfield
Pre 1983 homes that fail or have less than 6 inches to WSWT line will have to meet a 12-inch separation
Mound
6"
Tank & Pump
12"
62E-06 REPAIR REQUIREMENTS CONT’D
9
WSWT
Septic Tank
Drainfield
Post 1983 homes that fail or have less than 12 inches to WSWT line will have to meet a 24-inch separation
Mound
12"
Tank & Pump
24"
62E-06 REPAIR REQUIREMENTS CONT’D
Set nutrient loading limitations for estuaries◦ Arithmetic mean shall not to be exceeded more than
once in a 3-year period
62-302 NUMERIC NUTRIENTS
Region Total
Phosphorous
Total Nitrogen Chlorophyll a
4. Charlotte
Harbor Proper
0.19 mg/L 0.67 mg/L 6.1 µg/L
FDEP Permit 08-0210682-001◦ “A Phased Sewer Expansion – include in the
Charlotte County Sewer Expansion Plan those portions of the Alligator Bay Drainage Basin that have been shown to contribute to declining water quality (pre-1983 septic tanks)”
Manchester Lock Permit
1,708 recorded OSTDS’s in East/West Spring Lake
452 vacant lots Buildout percentage = 80% 1,286 OSTDS (75.3%) installed prior to 1983
OSTDS EVALUATIONS
OSTDS EVALUATIONS CONT’D
-
200
400
600
800
1,000
50's 60's 70's 80's 90's 00's
40
260
930
346
92 40
Systems Installed by Decade
No. Systems
-
500
1,000
51 yrs old& older
41-50 yrsold
31-40 yrsold
21-30 yrsold
11-20 yrsold
10 yrs old& newer
54 309
923
312 74 36
System Age
No. Systems
Water level data was collected in East/West Spring Lake to determine water table relative to ground surface
To meet 24-inches of separation for current regulations, the seasonal high water table should not be within 3.5 feet of ground surface or below land surface (BLS)
OSTDS EVALUATIONS CONT’D
Parameter June September November January
Mean Water Level (BLS)* 2.1 ft 2.1 ft 3.1 ft 3.9 ft
Number of samples < 3.5 ft BLS 39 35 29 16
Percentage < 3.5ft BLS 80% 80% 64% 42%
OSTDS EVALUATIONS CONT’D
Groundwater Elevations in East & West Spring Lake
* Based on mean water levels, it is estimated that the majority of the systems do not meet current or past separation requirements and some drainfields may be within the water table a portion of the year.
Ordinance 2007-061: Management of OSTDS Since adoption (2007 to Present), 250
repairs have been made in East & West Spring Lake
Prior to adoption (1950s to 2007), 132 repairs had been made
When a failure occurs, regulations require OSTDS to meet current standards. If separation from seasonal high water table cannot be met, the replacement system must be elevated (mounded)
OSTDS EVALUATIONS CONT’D
More expensive More maintenance / pump failure Affects aesthetics Difficult to maintain grounds Limits use of property Drainage problems Special construction needs:
◦ Dosing chamber◦ Pump◦ Retention/landscape wall
Mound System Impacts
23
Mound System Aerial View
24
50+ wells installed throughout East & West Spring Lake
21 canal sample points within & upstream of East & West Spring Lake
Wells sampled and tested every 2 months◦ Nitrogen◦ Phosphorous◦ Fecal Coliform◦ Water levels
SAMPLING & TEST RESULTS
Jun/Jul 2012 Sep/Oct 2012 Jan/Feb 2013 Mar/Apr
2013
Low 0.004 mg/L 0.004 mg/L 0.004 mg/L 0.004 mg/L
High 19.439 mg/L 4.692 mg/L 17.33 mg/L 39.17 mg/L
Water Table 2.1 ft BLS 2.1 ft BLS 3.1 ft BLS 3.9 ft BLS
Average .605 mg/L 0.184 mg/L 0.743 mg/L 1.02 mg/L
NITROGEN RESULTSNitrogen Concentrations in East & West Spring Lake
Jun/Jul 2012 Sep/Oct 2012 Jan/Feb 2013 Mar/Apr 2013
Low .004 mg/L 0.004 mg/L 0.004 mg/L 0.004 mg/L
High 0.033 mg/L 0.062 mg/L 0.033 mg/L 0.038 mg/L
Average 0.021 mg/L 0.03 mg/L 0.013 mg/L 0.012 mg/L
Nitrogen Concentrations in Canal System
Jun/Jul 2012 Sep/Oct 2012 Jan/Feb 2013 Mar/Apr 2013
Low .02 mg/L 0.02 mg/L 0.11 mg/L 0.15 mg/L
High 4.05 mg/L 13.53 mg/L 5.62 mg/L 31.69 mg/L
Water Table 2.1 ft BLS 2.1 ft BLS 3.1 ft BLS 3.9 ft BLS
Average 1.05 mg/L 1.36 mg/L 1.12 mg/L 2.39 mg/L
PHOSPHOROUS RESULTSPhosphorous Concentrations in East & West Spring Lake
Phosphorous Concentrations in Canal System Jun/Jul 2012 Sep/Oct 2012 Jan/Feb 2013 Mar/Apr 2013
Low 0.22 mg/L 0.29 mg/L 0.02 mg/L 0.04 mg/L
High 0.66 mg/L 0.52 mg/L 0.32 mg/L 0.42 mg/L
Average 0.42 mg/L 0.41 mg/L 0.18 mg/L 0.23 mg/L
Jun/Jul 2012 Sep/Oct 2012 Jan/Feb 2013 Mar/Apr 2013
Low 10 col/100 ml 10 col/100 ml 10 col/100 ml 10 col/100 ml
High 2940 col/100 ml 1720 col/100 ml 10 col/100 ml 10 col/100 ml
Water Table 2.1 ft BLS 2.1 ft BLS 3.1 ft BLS 3.9 ft BLS
Average 123.5 col/100 ml 44.9 col/100 ml 10 col/100 ml 10 col/100 ml
FECAL COLIFORM RESULTSFecal Coliform Concentrations in East & West Spring Lake
Fecal Coliform Concentrations in Canal System Jun/Jul 2012 Sep/Oct 2012 Jan/Feb 2013 Mar/Apr 2013
Low 10 col/100 ml 10 col/100 ml 10 col/100 ml 10 col/100 ml
High 90 col/100 ml 80 col/100 ml 200 col/100 ml 70 col/100 ml
Average 41.3 col/100 ml 29.1 col/100 ml 31.9 col/100 ml 18.1 col/100 ml
Nitrogen◦ Range: 0.004 mg/L to 39.17 mg/L◦ Drinking water limit: 10 mg/L◦ NNC limit: 0.67 mg/L◦ Wells closest to OSTDS had highest recordings◦ Groundwater levels > canal levels◦ Levels highest winter season when winter residents
are present
SUMMARY OF RESULTS
Phosphorous◦ Range: 0.02 mg/L to 31.69 mg/L◦ NNC limit: 0.19 mg/L◦ In wells, 150 of 171 samples tested higher than the NNC limit
(88%)◦ In canals, 55 of 69 samples tested higher than NNC limit
(80%)◦ The average for all samples was 0.895 mg/L, 5 x the NNC
limit◦ Wells closest to OSTDS had highest average recordings◦ Groundwater levels > canal levels◦ Levels highest in winter season when winter residents are
present
SUMMARY OF RESULTS CONT’D
Fecal Coliform◦ Range: 10 col/100 ml to 2940 col/100 ml◦ Multiple samples tested above 400 col/100, two (2)
from the same well◦ Canal levels > groundwater Levels◦ Levels highest during wet Season when soils are
saturated & filtration & adsorption is reduced due to high water table
SUMMARY OF RESULTS CONT’D
Atmospheric◦ Deposition of nutrients from atmosphere
Fertilizer◦ Can result in application of nitrogen & phosphorous◦ Restricted use (Ordinance 2011-017)
No phosphorous application June 1 to September 30 < 4 lbs of nitrogen can be applied / yr / 1,000 sf < 0.5 lbs of phosphorous can be applied / yr / 1,000 sf
Other (Animals, etc.)
OTHER CONTRIBUTORS
Difference between OSTDS and other contributors◦ Nutrients from other contributors are applied in the
atmosphere and are largely taken in by plant life◦ Nutrients from OSTDS are released below the
ground and depend on soils for removal prior to entering groundwater
OTHER CONTRIBUTORS CONT’D
Matlacha Sands Kesson Fine Sand Pineda Fine Sand Oldsmar Fine Sand Common traits of soils in E/W Spring Lake
◦ Gravelly fine sand◦ Poorly drained◦ Unsuitable for drainfields◦ Seasonal high water table within 10-inches BLS◦ Kesson, noted as being located in tidal swamps subject to
tidal flooding
SOIL CLASSIFICATIONS
Charlotte Harbor & Estero Bay Aquatic Preserves Water Quality Status & Trends for 1998-2005◦ Study reviewed water quality data within regions of
Charlotte Harbor & Estero Bay◦ Upper Charlotte Harbor results
Highest phosphorous levels of region Highest single nitrogen recording 70th Percentile of Florida estuaries for Phosphorous 80th Percentile of Florida estuaries for Nitrogen 80th Percentile of Florida estuaries for Fecal Coliform
RELEVANT STUDIES
Effects of Seasonal Variability on Microbial Fecal Pollution and Enteric Pathogens in a Subtropical Estuary◦ 12 sample stations were set within Charlotte Harbor and
sampled monthly for indicator bacteria◦ 4 of the stations were located in the vicinity of East & West
Spring Lake (East Spring Lake, West Spring Lake, Sunrise Waterway & Countryman Waterway)
◦ Of the samples tested, East & West Spring Lakes recorded the highest & 2nd highest fecal levels
◦ Concentrations were highest during wet season
RELEVANT STUDIES CONT’D
Groundwater System Water Quality Data Port Charlotte Area◦ Study performed for the purpose of characterizing surface &
groundwater quality in Port Charlotte◦ 8 study sites selected within a 400 home area◦ Monitoring wells installed to determine direction of
groundwater flow and plume potential for nutrients from OSTDS to edge of lot lines
◦ Average nitrogen levels of 21.62 mg/L at drainfield and 7.92mg/L at lot line
◦ Average phosphorous levels of 26.43 mg/L at drainfield and 14.80 at Lot Line
RELEVANT STUDIES CONT’D
Several factors reviewed link OSTDS’s to decreased water quality in East/West Spring Lake:◦ Soils unsuitable for OSTDS installation◦ A seasonal high water table unsupportive of treatment◦ A population density unfavorable for OSTDS◦ Close proximity to canals◦ Limited treatment capability of OSTDS◦ Test results indicating positive correlation with nutrients &
bacteria◦ Studies indicating high nutrient & fecal levels in upper
Charlotte Harbor, amongst the highest in the State
SUMMARY & CONCLUSIONS
Based on findings and factors and given the age, number of past repairs and projection of future replacement, it is recommended that Charlotte County consider installation of a centralized sewer system
A Centralized Sewer System would:◦ Eliminate dependence on OSTDS◦ Eliminate future OSTDS failure and pollution◦ Be a positive step towards cleaning the groundwater &
surface water and in helping diminish the impairment of Charlotte Harbor
SUMMARY & CONCLUSION CONT’D