Featherston Sludge Survey Report 29-11-12 - GW
Transcript of Featherston Sludge Survey Report 29-11-12 - GW
CONHUR LTDPO BOX 204021
Highbrook Mail CentreEast Tamaki
34 Oakleigh AvenueTakanini, Auckland
Ph 09 278 7109Fax 09 278 7108
www.Conhur.com
www.conhur.com
SOUTH WAIRARAPADISTRICT COUNCIL
Featherston OxidationPonds
Sludge Survey Report
November 2012
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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Table of Contents
1. INTRODUCTION 3
2. METHODOLOGY 3
3. SITE PHOTOGRAPHS 5
4. RESULTS 9
5. CONCLUSION 12
6. FEATHERSTON OXIDATION PONDS SLUDGE SURVEY DRAWINGS 13
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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1. INTRODUCTION
Conhur provides sludge surveys for both sludge lagoons and oxidation ponds. We utilize the latest
technology to provide as accurate a result as possible. Our sludge surveys provide estimates of:
x The volume of sludge contained within the ponds
x The average solids content of the sludge contained in the ponds
x The total tonnes dry solids (tDS) contained within the ponds
Conhur was contracted by South Wairarapa District Council to survey the sludge contained in the
primary and secondary oxidation ponds at the Featherston WWTP. The survey was undertaken on
22 November 2012 in fine, settled weather conditions.
2. METHODOLOGY
Pond Base survey
The bases of the Ponds were surveyed utilizing high accuracy GPS equipment and integrated
topographic software. This survey was carried out from a survey boat on the ponds. The ponds
were surveyed on grid system with survey points at 15m centres.
For this sludge survey, the GPS coordinate system used was NZGD2000, NZ Transverse Mercator.
The reduced levels provided are relative only and have not been calibrated against known survey
reference heights.
Sludge water interfaceThe level of the sludge water interface was measured utilizing a Royce 711 suspended solids
interface meter. This tool provides an accurate indication of the level of the top of the sludge.
Conhur recorded this information with high accuracy GPS equipment and integrated topographic
software. This survey was carried out from a survey boat on the ponds and provides a reasonably
accurate profile of the top of the sludge layer.
Sludge VolumeThe sludge volume within the ponds was calculated by comparing the base surveys and the
surveys of the top level of the sludge. This calculation is carried out by the topographic survey
software and enables the production of both cross sections through the ponds and plan profiles of
the sludge within the ponds.
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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Sludge SamplesConhur utilized a purpose built grab sample tube to recover sludge samples from within each of the
ponds. The sample tube has proven to provide the best method of sludge sample retrieval.
Up to five samples were retrieved at specific sludge survey locations on each pond. The retrieval of
intact, undisturbed insitu sludge samples from oxidation ponds is a difficult process and does not
provide 100% accurate results. This is especially true when the sludge layer is less than 500mm
deep. Conhur Ltd has made every attempt and used best industry practice to retrieve
representative samples, however we cannot guarantee accuracy of the solids analysis results.
Sludge Sample Analysis
The individual sludge samples retrieved were analysed for total solids by Conhur utilising an AND
MX-50 Moisture Analyser in accordance with best industry practice. The results are provided in
Section 4 of this report.
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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3 SITE PHOTOGRAPHS
Primary Oxidation Pond 1 from SW corner
Retaining wall at SE corner of Pond 1
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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Bund between Ponds 1 and 2, including Pond 1 outlet chamber
NE corner of Secondary Pond 2, showing HDPE bund liner
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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Pond 2 (left) and north end of Pond 1 (right)
Pond 2 Outlet Chamber
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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Operations Building
Site Access Road
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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4. SLUDGE SURVEY RESULTS
Primary Oxidation Pond (Pond 1)The RL of the pond water surface when surveyed was 17.700m in Pond 1. This level relates to the
top of concrete of the outlet structure on the eastern side of Pond 1, which was measured as RL
18.413m.
The average depth to the pond base from the water surface is 1.40m.
The total volume of the pond is estimated to be 33,320m3.
The average depth to the sludge surface from the water surface is 1.15m.
The average depth of sludge in the pond is 0.26m.
The maximum depth of sludge in the pond is 0.95m.
The total volume of sludge in the pond is estimated to be 5,950m3.
The weighted average solids contents of the 5 samples retrieved was 6.9%
Based on the above we estimate that Pond 1 contains approximately 411 dry tonnes (tDS) of
sludge.
The individual solids contents of the 5 samples retrieved from Pond 1 were as follows:
Sample F1-1 8.09%Sample F1-2 4.51%Sample F1-3 6.71%Sample F1-4 9.24%Sample F1-5 4.86%
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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Secondary Oxidation Pond (Pond 2)The RL of the pond water surface when surveyed was 17.690m in Pond 2. This level relates to the
top of concrete of the outlet structure on the eastern side of Pond 2, which was measured as RL
18.493m.
The average depth to the pond base from the water surface is 1.46m.
The total volume of the pond is estimated to be 17,430m3.
The average depth to the sludge surface from the water surface is 1.31m.
The average depth of sludge in the pond is 0.15m.
The maximum depth of sludge in the pond is 0.85m.
The total volume of sludge in the pond is estimated to be 1,990m3.
The weighted average solids contents of the 3 samples retrieved was 9.3%
Based on the above we estimate that Pond 2 contains approximately 185 dry tonnes (tDS) of
sludge.
The individual solids contents of the 3 samples retrieved from Pond 2 were as follows:
Sample F2-1 7.73%Sample F2-2 6.68%Sample F2-3 12.91%
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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Sludge Survey Summary Table
PondID
WaterLevel(m)
Avg.PondDepth(m)
Avg.Depthto
Sludge(m)
Avg.SludgeDepth(m)
Max.SludgeDepth(m)
Est.TotalPondVolume(m3)
Est.SludgeVolume(m3)
WeightedAverageSludgeSolidsContent
Est.TonnesDrySolids(tDS)
Pond 1 17.70 1.40 1.15 0.26 0.95 33,320 5,950 6.9% 411
Pond 2 17.69 1.46 1.31 0.15 0.85 17,430 1,990 9.3% 185
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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5. CONCLUSION
Primary Oxidation Pond (Pond 1):The survey confirms the volume of sludge in Pond 1 is approximately 5,950m3. There is almost no
sludge at the eastern side of the pond, building up to an average sludge depth of 260mm along the
western side, to a maximum 950mm sludge depth in the SW corner of the pond.
The sludge samples retrieved from the pond indicate that the average solids content is 6.9%.
Based on Conhurs experience with previous pond surveys, this is at the high end of the normal
expected range for sewage sludge which Conhur has found typically falls within 3%-7% depending
on sludge depth.
Based on the above, we estimate that the Primary Oxidation Pond contains approximately 411 drytonnes (tDS) of sludge, which equates to Pond 1 being approximately 18% full of sludge.
Secondary Oxidation Pond (Pond 2):The survey confirms the volume of sludge in Pond 2 is approximately 1,990m3. There is almost no
sludge in the southern end of the pond, building up to an average sludge depth of 150mm at the
northern end, to a maximum 850mm sludge depth in the NW corner of the pond.
The sludge samples retrieved from the pond indicate that the average solids content is 9.3%.
Based on Conhurs experience with previous pond surveys, this is at the high end of the normal
expected range for sewage sludge which Conhur has found typically falls within 3%-7% depending
on sludge depth.
Based on the above, we estimate that the Secondary Oxidation Pond contains approximately 185dry tonnes (tDS) of sludge, which equates to Pond 2 being approximately 11% full of sludge.
FEATHERSTON OXIDATION PONDS SLUDGE SURVEY
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6. FEATHERSTON OXIDATION PONDS SLUDGE SURVEY DRAWINGS
x Topographical Plan
x Sludge Depth Plan
x Profile Layout
x Cross Sections (Sheets 1 & 2)
ORIGINAL SIZE
A3
TITLE
OPER.APPR.CHKD.BY
SCALE
PROJECT No.
LOCATION DRAWN
CHECKED
DES. ENG.
PROJ. ENG.
APPROVED
OPERATIONS
REVISIONS
DESCRIPTIONDATENO
REVISIONDRAWING No
REF:
GENERAL NOTES1. Coordinates in terms of :2. Elevations in terms of : 3. Contour interval is :
34 Oakleigh AvenueCONHUR
PO Box 204021Takanini
East TamakiAUCKLAND 2161
Highbrook Mail CentreTOPOGRAPHICAL PLANSurveyed 22/11/12
FEATHERSTON-01 0
FEATHERSTON
125731:1250
L Vasey 29-11-12
M McLaughlin 30-11-12
. . . . . . .
Mean Sea Level (Approx.)0.5m
12573-01
Retaining wall
Outlet ChamberOutlet Manhole
Building
Inlet ChamberValve Box Lid
60m10
SCALE 1 : 1250
0 5040302010
Profile 1
Prof
ile 3
Profile 2
Prof
ile 4
11kVa Transformer Pole
BM01 (NE Corner of Chamber)1795055.64 mE5443483.46 mNEl 18.49m
Inlet Manhole
POND 1
POND 2
Outlet Chamber
ORIGINAL SIZE
A3
TITLE
OPER.APPR.CHKD.BY
SCALE
PROJECT No.
LOCATION DRAWN
CHECKED
DES. ENG.
PROJ. ENG.
APPROVED
OPERATIONS
REVISIONS
DESCRIPTIONDATENO
REVISIONDRAWING No
REF:
GENERAL NOTES1. Coordinates in terms of :2. Elevations in terms of : 3. Contour interval is :
34 Oakleigh AvenueCONHUR
PO Box 204021Takanini
East TamakiAUCKLAND 2161
Highbrook Mail CentreSLUDGE DEPTHSurveyed 22/11/12
FEATHERSTON-02 0
FEATHERSTON
125731:1250
L Vasey 29-11-12
M McLaughlin 30-11-12
. . . . . . .
Mean Sea Level (Approx.)0.1m
12573-01
60m10
SCALE 1 : 1250
0 5040302010
POND 1 TOTAL VOLUME 33,320 m³POND 1 SLUDGE VOLUME 5,950 m³
POND VOLUMES as at 22nd Nov 2012
POND 2 TOTAL VOLUME 17,430 m³POND 2 SLUDGE VOLUME 1,990 m³
POND 1POND 2
ORIGINAL SIZE
A3
TITLE
OPER.APPR.CHKD.BY
SCALE
PROJECT No.
LOCATION DRAWN
CHECKED
DES. ENG.
PROJ. ENG.
APPROVED
OPERATIONS
REVISIONS
DESCRIPTIONDATENO
REVISIONDRAWING No
REF:
GENERAL NOTES1. Coordinates in terms of :2. Elevations in terms of : 3. Contour interval is :
34 Oakleigh AvenueCONHUR
PO Box 204021Takanini
East TamakiAUCKLAND 2161
Highbrook Mail CentreCROSS SECTIONS - Sheet 1Surveyed 22/11/12
FEATHERSTON-03 0
FEATHERSTON
12573Hz 1:750 Vert 1:75
L Vasey 29-11-12
M McLaughlin 30-11-12
. . . . . . .
Mean Sea Level (Approx.)N/A
12573-01
Water Level Pond 1 17.70m Water Level Pond 2 17.69m
Water Level Pond 1 17.70m Water Level Pond 2 17.69m
Bottom of Pond
Top of Sludge
Bottom of Pond
Top of Sludge
Bottom of Pond
Top of Sludge
Bottom of PondTop of Sludge
ORIGINAL SIZE
A3
TITLE
OPER.APPR.CHKD.BY
SCALE
PROJECT No.
LOCATION DRAWN
CHECKED
DES. ENG.
PROJ. ENG.
APPROVED
OPERATIONS
REVISIONS
DESCRIPTIONDATENO
REVISIONDRAWING No
REF:
GENERAL NOTES1. Coordinates in terms of :2. Elevations in terms of : 3. Contour interval is :
34 Oakleigh AvenueCONHUR
PO Box 204021Takanini
East TamakiAUCKLAND 2161
Highbrook Mail CentreCROSS SECTIONS - Sheet 2Surveyed 22/11/12
FEATHERSTON-04 0
FEATHERSTON
12573Hz 1:750 Vert 1:75
L Vasey 29-11-12
M McLaughlin 30-11-12
. . . . . . .
Mean Sea Level (Approx.)N/A
12573-01
Water Level Pond 1 17.70m
Water Level Pond 2 17.69m
Bottom of Pond
Top of Sludge
Bottom of Pond
Top of Sludge