concept engineering - virginia deq · this concept engineering report (cer) has been prepared fothe...

CONCEPT ENGINEERING REPORT: WEST TREATMENT POND Bremo Power Station

Submitted To: Virginia Electric and Power Company 1038 Bremo Road Bremo Bluff, VA 23022 Submitted By: Golder Associates Inc. 2108 W. Laburnum Avenue Suite 200 Richmond, VA 23227

June 2016 1520-347.300

Conc

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CER: West Treatment Pond i Project No. 1520-347.300 Bremo Power Station June 2016

Table of Contents 1.0 INTRODUCTION ............................................................................................................................... 1

1.1 Site Description ............................................................................................................................. 1 2.0 WASTEWATER SOURCES .............................................................................................................. 1

2.1 During Closure .............................................................................................................................. 2 2.1.1 Metals Pond Pumped Decant Water ..................................................................................... 2 2.1.2 Metals Pond Contact Stormwater ......................................................................................... 2 2.1.3 Metals Pond Material Dewatering Water .............................................................................. 2 2.1.4 Ash Pond Decant Water ........................................................................................................ 2 2.1.5 Ash Pond Contact Stormwater .............................................................................................. 3 2.1.6 Ash Pond Ash Dewatering Water .......................................................................................... 3 2.1.7 Stormwater Treatment Pond Discharge ................................................................................ 3

2.2 Final Conditions ............................................................................................................................ 3 3.0 WEST TREATMENT POND CONSTRUCTION ............................................................................... 3

3.1 West Treatment Pond Capacity .................................................................................................... 4 3.2 Dam Safety .................................................................................................................................... 4

Drawings Drawing 1 – Site Location Map Drawing 2 – Site Plan Drawing 3 – Process Flow Diagram – During Closure Drawing 4 – Process Flow Diagram – Final Conditions Drawing 5 – West Treatment Pond Modification Plan Drawing 6 – West Treatment Pond Modification Details

CER: West Treatment Pond 1 Project No. 1520-347.300 Bremo Power Station June 2016

1.0 INTRODUCTION This Concept Engineering Report (CER) has been prepared for the proposed West Treatment Pond at

Dominion’s Bremo Power Station (Station), located in Fluvanna County, Virginia. The Station converted

from a coal-fired power plant to a natural gas-fired power plant in 2014. Coal Combustion Residuals (CCR)

from historical coal-fired operations are stored in three impoundments on-site (North Ash Pond, West Ash

Pond, and East Ash Pond). Process water from these ponds and other Station activities has historically

been discharged with contact stormwater to the James River pursuant to the authorization, limits, and

conditions of a Virginia Department of Environmental Quality (DEQ) Virginia Pollutant Discharge Elimination

System (VPDES) Permit (Permit No. VA0004138).

Dominion is preparing to close these three CCR surface impoundments in response to the U.S.

Environmental Protection Agency’s (EPA’s) publication of the Federal Hazardous and Solid Waste

Management System; Disposal of Coal Combustion Residuals from Electric Utilities; Final Rule

(40 CFR 257). During closure activities of these three CCR impoundments, Dominion will also close the

Metals Pond by dewatering and removing accumulated solids. Dominion has prepared this CER to provide

a description of the proposed West Treatment Pond, which is expected to be brought on-line following DEQ

approval of this CER.

1.1 Site Description The Bremo Power Station is owned and operated by Virginia Electric and Power Company (Dominion) in

Fluvanna County, Virginia, at 1038 Bremo Road, just east of Route 15 (James Madison Highway) and north

of the James River. The location of the Station is illustrated on the inset United States Geological Survey

(USGS) topographic map on Drawing 1. A Site Plan is presented on an aerial photograph as Drawing 2.

The Station property consists of wooded, open, and developed land just north of the James River. The

Station’s northern, eastern, and western boundaries are bordered by primarily undeveloped parcels, and

the Station is bordered to the south by a CSX rail line and the James River. Land use surrounding the

Station is classified as “A-1 Agricultural,” and consists of undeveloped wooded and agricultural properties

within a rural residential setting.

2.0 WASTEWATER SOURCES The Process Flow Diagram on Drawing 3 depicts the wastewater sources to the proposed West Treatment

Pond during the closure activities for the West (western portion), North, and East Ash Ponds, and the Metals

Pond. Drawing 4 is a Process Flow Diagram showing the final wastewater sources after the closure

activities are complete. These wastewater sources are described below.

CER: West Treatment Pond 2 Project No. 1520-347.300 Bremo Power Station June 2016 2.1 During Closure The following wastewater sources are expected to be routed to the West Treatment Pond during the closure

activities for the CCR impoundments and Metals Pond, as shown on Drawing 3.

2.1.1 Metals Pond Pumped Decant Water Metals Pond Pumped Decant Water is surface water that has accumulated in the Metals Pond and needs

to be removed as an initial step to facilitate closure. In the past, this water was periodically pumped to the

West Ash Pond via internal outfall 202 for ultimate discharge to the James River via outfall 002.

Decanting shall be accomplished by pumping the decant water to the centralized source water treatment

system (CSWTS) for treatment prior to discharge via internal outfall 504 or external outfall 002 via the West

Treatment Pond. Alternatively, the Metals Pond Pumped Decant Water may be transported off-site for

treatment and/or disposal at a permitted facility.

2.1.2 Metals Pond Contact Stormwater Metals Pond Contact Stormwater is stormwater that, following removal of the decant water, has contacted

the accumulated material in the Metals Pond during closure of the Metals Pond. Metals Pond Contact

Stormwater will need to be removed from the Metals Pond to facilitate closure. The Metals Pond Contact

Stormwater will be routed to the CSWTS for treatment prior to discharge via internal outfall 504 or external

outfall 002 via the West Treatment Pond. Alternatively, the Metals Pond Contact Stormwater may be

transported off-site for treatment and/or disposal at a permitted facility.

2.1.3 Metals Pond Material Dewatering Water Metals Pond Material Dewatering Water is the water that will be produced from dewatering the accumulated

material in the Metals Pond to allow for its removal and off-site disposal. This waste stream will be directed

to the CSWTS for treatment prior to discharge through internal outfall 504 or external outfall 002 via the

West Treatment Pond, or may be transported off-site for disposal at a permitted facility.

2.1.4 Ash Pond Decant Water Ash Pond Decant Water includes surface waters that result from the commingling of a number of

wastewater types, historically including but not necessarily limited to the following: ash pond contact

stormwater, low-volume Station wastewater, sewage treatment plant discharges, ash dewatering water,

and waters that are used to convey CCR to an impoundment through sluicing or dredging. As an initial

step in the process leading to closure of the ash impoundments, it will be necessary to remove the Ash

Pond Decant Water to dewater the CCR sufficiently to allow for preparation of a stable surface on which to

construct the closure cap, or to initiate CCR removal). Ash Pond Decant Water will be routed to the CSWTS

for treatment and discharge through internal outfall 504 or external outfall 002 via the West Treatment Pond,

or transported off-site for disposal at a permitted facility.

CER: West Treatment Pond 3 Project No. 1520-347.300 Bremo Power Station June 2016 2.1.5 Ash Pond Contact Stormwater Ash Pond Contact Stormwater is stormwater that has contacted the CCR in the North, East, and West Ash

Ponds, and is considered process wastewater. This waste stream will be directed to the CSWTS for

treatment prior to discharge through internal outfall 504 or external outfall 002 via the West Treatment Pond,

or transported off-site for disposal at a permitted facility.

2.1.6 Ash Pond Ash Dewatering Water Ash Pond Ash Dewatering Water is considered to be the pore water within the CCR mass in the West,

North, and East Ash Ponds. This wastewater refers to the water that is produced from dewatering the CCR

to stabilize the CCR and allow for its removal by mechanical dredging or excavation, or to support a closure

cap system. Ash Pond Ash Dewatering Water is generated from the CCR dewatering process through

mechanical means (e.g., vacuum wells, sump pumps, or other in situ withdrawal methods) and from cutting

drainage ditches and/or rim ditches into the CCR mass. Ash Pond Ash Dewatering Water will be directed

to the CSWTS for treatment prior to discharge through internal outfall 504 or external outfall 002 via the

West Treatment Pond, or transported off-site for disposal at a permitted facility.

2.1.7 Stormwater Treatment Pond Discharge Discharge from the Stormwater Treatment Pond is a potential wastewater source for the West Treatment

Pond during the closure activities for the North, East, and West Ash Ponds and the Metals Pond. Flow

from the Stormwater Treatment Pond is currently being discharged directly to Outfall 002 following filtration.

Once the West Treatment Pond is constructed, the Stormwater Treatment Pond will be directed to the West

Treatment Pond for solids removal via settling prior to discharge through Outfall 002.

2.2 Final Conditions The post-closure wastewater sources to the West Treatment Pond are shown on Drawing 4. After closure

of the CCR impoundments and Metals Pond, the discharge from the Stormwater Treatment Pond will

continue to be directed to the West Treatment Pond for treatment via settling. Some Station process waters,

low-volume waste and auxiliary process water may also be intermittently directed to the West Treatment

Pond.

3.0 WEST TREATMENT POND CONSTRUCTION Following removal of the CCR, the re-purposed eastern portion of the former West Ash Pond will be lined

with a 40-mil Ethylene Interpolymer Alloy (EIA) geomembrane liner system (XR-5) and placed back in

service as the West Treatment Pond with a discharge via outfall 002 (see Drawings 5 and 6 - West

Treatment Pond Modification Plan and Details). Construction of the West Treatment Pond will involve

removing the CCR and certifying the remaining soil subgrade as “clean closed.” CCR removal will be

considered complete based on a visual inspection determining the absence of CCR, followed by excavating

an additional 6 inches from the former West Ash Pond’s footprint.

CER: West Treatment Pond 4 Project No. 1520-347.300 Bremo Power Station June 2016 A new earthen fill embankment will be constructed across the pond to form the new western embankment

of the West Treatment Pond to a crest elevation of 234.0 feet above mean sea level (ft amsl). Additional

soil fill will be placed on the interior slopes of the existing embankments to flatten the slopes from 2H:1V to

3H:1V and to add an 8-foot-wide safety bench at elevation 228.0 ft amsl. Once the West Treatment Pond

embankments are complete, the remainder of the former West Ash Pond and Metals Pond embankments

will be removed, and the remainder of the former pond area to the west of the new West Treatment Pond

will be graded to drain and seeded.

The existing concrete intake tower will be modified slightly to eliminate the removable stop logs and install

a permanent discharge weir crest at elevation 230.0 ft amsl. The outlet weir will have a crest length of

5.5 feet. The existing 42-inch diameter corrugated metal pipe outlet at the base of the tower will remain

and continue to the James River through a series of junction boxes, manholes, and pipes via outfall 002.

As part of the pond closure project, it is planned to slip-line this pipe to increase its longevity.

The XR-5 liner will be underlain by an 8-ounce non-woven cushion geotextile installed over a prepared and

inspected subgrade in accordance with the project specifications. Penetrations into the pond liner for the

10-inch diameter stormwater discharge pipe and the 8-inch diameter process water pipe from the station

will be secured and booted to provide a watertight seal. The liner will also be connected to the concrete

outlet tower near the base of the tower using a batten strip connection for water tightness. Construction

Quality Assurance (CQA) oversight during construction will be carried out by third-party inspectors in

accordance with the approved CQA Plan. Documentation of the installation, including liner and geotextile

deployment, nondestructive and destructive seam testing, repairs, and surveyed record drawings, will be

prepared and certified by a licensed professional engineer.

3.1 West Treatment Pond Capacity Once constructed, the normal pool volume of the West Treatment Pond will be approximately

19,875,000 gallons as measured at the spillway crest (elevation 230.0 ft amsl). At normal pool, the pond

has a freeboard of 4 feet. The pond does not have a contributing drainage area other than the pond area

itself, approximately 5.9 acres, so stormwater inflows from large storm events are limited to what falls within

the pond. The modeled high water level for the 24-hour, 100-year storm event is elevation 231.0 ft amsl.

3.2 Dam Safety Due to the capacity of the West Treatment Pond being greater than 50 acre-feet (16,300,000 gallons), the

West Treatment Pond is regulated under the Virginia Department of Conservation and Recreation (DCR)

Dam Safety Program. The West Treatment Pond is anticipated to receive a Hazard Potential Classification

of “Low” once construction is complete. Requirements under the DCR certificate include annual

inspections, inspection by a licensed professional engineer every 6 years, maintenance of an emergency

preparedness plan, and development of breach inundation maps.

DRAWINGS

SITE LOCATION MAP

DRAWING 1DOMINION - BREMO POWER STATION

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EAST ASHPOND

NORTH ASHPOND

BASE MAP CONSISTS OF 7.5-MINUTE USGS TOPOGRAPHICQUADRANGLE NAMED ARVONIA, VIRGINIA, DATED 2013.

REFERENCE

JRD

DPM

METALSPOND

WEST ASH PONDWEST ASH POND

EAST ASH PONDEAST ASH POND

NORTH ASH PONDNORTH ASH PONDMHMH

MHMH

RISERRISER

OUTFALL 002OUTFALL 002

OUTFALL 202OUTFALL 202METALSMETALS

PONDPOND


BREMOBREMOPOWER STATIONPOWER STATION



~JAMES RIVER~

~JAMES RIVER~

BREMO ROAD

BREMO ROAD

BREMO ROADBREMO ROAD

BRICK ARCHBRICK ARCHCULVERTCULVERT

~HO

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~~H

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CULVERTCULVERT



RISERRISER

RISERRISER


CSXCSX

CSXCSXLEGENDLEGEND

- OUTFALL CONVEYANCE SYSTEM- OUTFALL CONVEYANCE SYSTEM

- APPROXIMATE PROPERTY BOUNDARY- APPROXIMATE PROPERTY BOUNDARY

- APPROXIMATE LIMITS OF ASH POND- APPROXIMATE LIMITS OF ASH POND

STORMWATER PONDOVERFLOW DISCHARGE(KNIFE GATE VALVE)

STORMWATER PONDOVERFLOW DISCHARGE(KNIFE GATE VALVE)

BRICK ARCHBRICK ARCH

COAL YARD(CLOSED)COAL YARD(CLOSED)


EXISTINGNORTH PONDTOE DRAINS

EXISTINGNORTH PONDTOE DRAINS

DISCHARGE FROMSTORMWATER PONDTO WEST POND(OUTFALL 204)

DISCHARGE FROMSTORMWATER PONDTO WEST POND(OUTFALL 204)

STORMWATERSTORMWATERPONDPOND

0250 250 500

SCALE FEET

1 09/23/15 PER DEQ COMMENTS JRD ABM ATN JRD

DRAWING 2

DOMINIONBREMO POWER STATION

CCR IMPOUNDMENT CLOSUREVPDES PERMIT APPLICATION AMENDMENT

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PROCESS FLOW DIAGRAM(STAGE II CONSTRUCTION)

2016-2018 TIME FRAME

DRAWING 3

CONTACT STORMWATERAND ASH DEWATERING WATER

4.0 MGD AVG(6.0 MGD MAX)3

DOMINIONBREMO POWER STATION

CCR IMPOUNDMENT CLOSUREVPDES PERMIT APPLICATION AMENDMENT

OUTFALL FLOW SUMMARY TABLE

SOURCE WATER AVG. FLOW MAX. FLOW

OUTFALL 001 91.8 MGD 172.8 MGD2

OUTFALL 002 1.53 MGD/5.53 MGD 4.2912 MGD2/10.2912 MGD

OUTFALL 204 >1.26 MGD/5.26 MGD >1.26 MGD1/7.26 MGD


OUTFALL 004 0.204/4.0 MGD 0.4090/6.0 MGD3


NON-CONTACTSTORMWATERDISCHARGE

(PRECIPITATIONDEPENDENT)

4.0 MGD AVG6.0 MGD MAX3

(IF FROMTREATMENT

SYSTEM)

UNDER FLOWSOLIDS









CONSTRUCTIONNON-CONTACTSTORMWATER


OUTFALL 204


(+4.0 MGD AVG/+6.0 MGD3 MAX IF

FROM TREATMENTSYSTEM)


(+4.0 MGD AVG/+6.0 MGD MAX3

IF FROM TREATMENTSYSTEM)

>1.26 MGD AVG(>1.26 MGD MAX)1

(+4.0 MGD AVG/+6.0 MGD MAX3

IF FROMTREATMENT

SYSTEM)



NOTES:1. WHERE FLOWS ARE LIMITED BY SYSTEM DESIGN, MAXIMUM FLOWS EQUAL THE AVERAGE

FLOWS.2. IF THE MAXIMUM FLOWS ARE LISTED IN THE PERMIT, THOSE FLOWS WERE USED.3. WHERE FLOWS ARE NOT LIMITED BY SYSTEM DESIGN AND MAXIMUM FLOWS WERE NOT LISTED

IN THE PERMIT, MAXIMUM FLOWS WERE CALCULATED BY MULTIPLYING THE AVERAGE FLOWS BYA FACTOR OF 1.5.

4. FLOWS FROM OUTFALL 101 ARE INCLUDED IN THE FLOWS IDENTIFIED FOR OUTFALL 001.5. FLOWS FROM THE STORMWATER MANAGEMENT POND ARE INCLUDED IN THE FLOWS FROM THE

WEST TREATMENT POND.6. FLOWS FROM THE METALS POND ARE INCLUDED IN THE FLOWS FROM THE WEST TREATMENT

POND.7. FLOWS FROM OUTFALL 002, 003, 004, AND 006 WILL INCREASE AS SHOWN IF FLOWS FROM THE

NORTH AND EAST ASH POND TREATMENT SYSTEM ARE INCLUDED.


(IF FROMTREATMENT

SYSTEM)




(4.0 MGD AVG6.0 MGD MAX3

IF FROMTREATMENT

SYSTEM)STAGE I & II CONTACT

STORMWATER AND ASHDEWATERING WATER





(+4.0 MGD AVG/+6.0 MGD3 MAX IF

FROM TREATMENTSYSTEM)

STAGE II CONTACTSTORMWATER AND

MATERIAL DEWATERINGWATER

1.0146 MGD AVG(1.6138 MGD MAX)2


OUTFALL 202

1.0146 MGD AVG(1.6138 MGD MAX)3

STAGE II PUMPEDDECANT WATER1.0146 MGD AVG

(1.6138 MGD MAX)2

CONSTRUCTION NON-CONTACTSTORMWATER (POST CCR AND

METALS POND MATERIALREMOVAL)

1.0146 MGD AVG(1.6138 MGD MAX)3

UNDER FLOWSOLIDS

VIRGINIA STORMWATER MANAGEMENT PROGRAM

ENHANCED TREATMENT (AS NEEDED)

SOURCE WATER AND OUTFALLS

SOLIDS REMOVAL

TABLE 4 REFERENCE

SAMPLING LOCATION

INTERMITTENT FLOW

LEGEND

1D

SS

S

S2G

S S

S

S

2B

2A

S

S2F

2D

2E

2C

S

UNDER FLOWSOLIDS


S

JAMES RIVER

RIVER INTAKE SCREEN

TRAVELING SCREENS

OUTFALL 1011.613 MGD

OUTFALL 001 INTO THE JAMES

RIVER 91.8 MGD*

OUTFALL 2030.008 MGD*

OUTFALL 002INTO THE JAMES RIVER

1.53 MGD*

OUTFALL 006 NON CONTACT STORMWATER

TO THE JAMES RIVER

OUTFALL 008NON CONTACT STORMWATER

TO THE JAMES RIVER

TURBINE GENERATOR

MAIN CONDENSERS

TURBINE GENERATOR HYDROGEN COOLERS

TURBINE GENERATOR OIL

COOLERS

BOILER FEED PUMP NON CONTACT COOLING WATER

CIRCULATING WATER SYSTEM

POLISHING FILTERSGRAVITY

FILTERS

REJECT WATER 0.0432 MGD

DEICING WATER SYSTEM

DOMESTIC WATER WELL

SEWAGE TREATMENT

PLANT

STORMWATER

DEMINERALIZATION DEIONIZATION

SYSTEM 125 gpm

BOILER UNITS 3&4COMBINED

BLOWDOWN 0.0418 MGD

EMERGENCY FIRE PUMP

BOILER UNITS 3&4

SCREENWASH 1.613 MGD

BOILER CLEANING

OFF-SITE DISPOSAL

LOW VOLUME WASTE

AUXILLARY PROCESS

WATER 2.592 MGD

CLOSED & CAPPED

NORTH ASH POND

WEST TREATMENT POND

STORMWATER TREATMENT PONDOUTFALL 204

SCREEN WELL

LEAKAGE

ADMIN BLDGMAINT SHOP

COAL YARD BLDGSTOREROOM

BEARING COOLING WATER

& AUXILLARY

SYSTEM 1.1434 MGD

SEENOTE 1

BACKWASH

0.0254 MGDBACKWASH

SPRAY WATER

179.3 MGD (MAX)

BREMO POWER STATION STATION WATER FLOW

POST CONSTRUCTION (FINAL)ONE LINE DIAGRAM

REVISED 9/2015

0.2232MGD

0.18MGD

SEE NOTE 3

TOE DRAINS

CLOSED & CAPPED

EAST ASH POND

OUTFALL 007NON CONTACT STORMWATER

TO THE JAMES RIVER

TOE DRAINS

BEARING COOLING WATER

SEENOTE 2

FIRE WATER TANK

NOTES:- DASHED LINES REPRESENT INTERMITTENT DISCHARGE.- DURING ALTERNATE RAW WATER SYSTEM OPERATION, BOILER FEED PUMP NON-CONTACT COOLING WATER MAY BE USED AS SYSTEM MAKE-UP WATER.- FLOW IS BASED ON DESIGN CAPACITY UNLESS DENOTED BY (*) WHICH INDICATES AVERAGE FLOW DERIVED FROM THE 8/2010-8/2014 DMRS.1. ALTERNATE WATER SUPPLY WILL RECIRCULATE 2.8 MGD AND NORMALLY WILL NOT INTERFACEWITH RIVER.2. DEICING WATER IS USED ONLY DURING SEVERE COLD WEATHER.3. COUNTY WATER IS USED WHEN RIVER WATER IS TOO TURBID FOR USE AS MAKE-UP WATER.

DRAWING 4

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EXISTING OUTLET

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TO BE MODIFIED

(BATTEN STRIP LINER

TO EX. STRUCTURE)

EXISTING INFLOW

FROM STATION

EXISTING VPDES

OUTFALL 002

H

O

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PROPOSED

10' GRAVEL

ACCESS ROAD

WEST

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POND

EXPOSED

XR-5

GEOMEMBRANE

VOL = 61.0 AC-FT

AT NORMAL POOL

(EL 230)

LIMITS OF

EXPOSED LINER /

ANCHOR TRENCH

+ 211.5

+ 211.5

PROPOSED 12"

DISCHARGE PIPE

(FROM STATION) TO

WEST TREATMENT

POND

PROPOSED RISER AND

DISCHARGE PIPE

EXISTING CHAIN LINK

FENCE TO REMAIN

3

DCR-12

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

PROPOSED GATE

PROPOSED CHAIN

LINK FENCE

(TIE INTO EXISTING)

212

220

228

230

232

234

222

224

212

220

228

230

232

2

1

8

2

1

8

216

216

216

2

1

4

228.08

8' SAFETY

BENCH

8' SAFETY

BENCH

REMOVE TREES WITHIN 25

FT. OF TOE OF DAM (TYP.)

REMOVE TREES WITHIN 25

FT. OF TOE OF DAM (TYP.)

2

.

0

:

1

3

.

0

:

1

3.0:1

3

.

0

:

1

3.0:1

3.0:1

3.0:1

PROPOSED

GATE

2

1

9

2

1

9

WEST STORMWATER

DETENTION POND

A

A'

B

B

'

CLASS 1 RIPRAP

OUTLET PROTECTION

L=10', W=10', D=2'

1

DCR-3

PROPOSED 12"

DISCHARGE PIPE (FROM

STATION)

2

DCR-3

3

DCR-3

EXISTING DISCHARGE PIPE

(FROM STORMWATER

MANAGEMENT POND) TO REMAIN

3

DCR-3

LIMITS OF

EXPOSED LINER /

ANCHOR TRENCH

EXISTING

MANHOLE

EL

EV

AT

IO

N (F

T)

200

210

220

230

240

250

260

270

0+00 0+40 0+80 1+20 1+60 2+00 2+40 2+80 3+20 3+60 4+00 4+40 4+80 5+20 5+60

NORMAL WATER EL. = 230.00

100 YR. WATER EL. = 230.98

BOTTOM EL. = 211.50

(EXPOSED LINER)

PROPOSED GRADE

(EXPOSED LINER)

EXISTING GRADE

(POST-CCR

REMOVAL)

EMBANKMENT MATERIAL

(SEE NOTE BELOW)

8 FT. SAFETY BENCH

EL. = 228.00

EXPOSED GEOMEMBRANE

ANCHOR TRENCH

1

3

3

DCR-3

EL

EV

AT

IO

N (F

T)

200

210

220

230

240

250

260

270

5+60 6+00 6+40 6+80 7+20 7+60 8+00 8+40 8+80 9+20 9+60 10+00 10+40 10+80

EMBANKMENT MATERIAL

(SEE NOTE BELOW)

WEST

STORMWATER

DETENTION POND


100 YR. WATER EL. = 230.98

BOTTOM EL. = 211.50

(EXPOSED LINER)

EXISTING GRADE

(POST-CCR

REMOVAL)

EXPOSED GEOMEMBRANE

ANCHOR TRENCH

8 FT. SAFETY BENCH

EL. = 228.00

PROPOSED GRADE

(EXPOSED LINER)

1

3

1

3

3

DCR-3

EL

EV

AT

IO

N (F

T)

EL

EV

AT

IO

N (F

T)

200

210

220

230

240

250

260

270

200

210

220

230

240

250

260

270

0+00 0+40 0+80 1+20 1+60 2+00 2+40 2+80 3+20 3+60 4+00 4+40 4+80 5+20

10 ft

4 ft

15 ft


100 YR. WATER EL. = 230.98

TOP OF DAM

EL. = 234.00

8 FT. SAFETY BENCH

EL. = 228.00

EXISTING OUTLET

STRUCTURE TO BE

MODIFIED

EXISTING EMBANKMENT

EXISTING 42" CMP

OUTLET PIPE TO BE SLIP

LINED WITH CURE-IN-

PLACE LINING TUBE

BOTTOM EL. = 211.50

(EXPOSED LINER)

EMBANKMENT

MATERIAL

(SEE NOTE

BELOW)

PROPOSED

GRADE

EXISTING GRADE

(POST-CCR

REMOVAL)

8 FT. SAFETY BENCH EL. = 228.00

EXISTING

MANHOLE

EXPOSED GEOMEMBRANE

ANCHOR TRENCH

EMBANKMENT MATERIAL

(SEE NOTE BELOW)

1

1

1

3

1

3

1

3

1

3

(TYP.)

3

DCR-3

1

DCR-3

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SCALE FEET

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DRAWING 5

DESIGN

PROJECT No.

CADD

CHECK

REVIEW

FILE No.

SCALEREV.

RE

VIS

IO

N D

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15-20347

1520347N02

0 AS SHOWN

JRD 02/05/15

ATN 02/05/15

WEST TREATMENT POND PLAN

WEST TREATMENT POND SECTION B-B'

WEST TREATMENT POND SECTION B-B'

WEST TREATMENT POND SECTION A-A'

MA

TC

HL

IN

E (S

EE

B

EL

OW

)

MA

TC

HL

IN

E (S

EE

A

BO

VE

)

(STA 0+00 - 5+60)

(STA 5+60 - 10+86)

THE EMBANKMENT SOILS ARE SPECIFIED TO BE LOW TO MODERATE

PLASTICITY SOIL (PI LESS THAN 30), GENERALLY FREE OF ORGANIC

MATTER AND OTHER DELETERIOUS MATERIALS AND ROCK FRAGMENTS

LARGER THAN 2 INCHES IN ANY DIMENSION. EMBANKMENT SOILS WILL

BE COMPACTED IN LIFTS TO AT LEAST 95% OF STANDARD PROCTOR

DRY DENSITY. SEE TECHNICAL SPECIFICATIONS FOR COMPLETE

MATERIAL DESCRIPTION, INSTALLATION, AND TESTING REQUIREMENTS.

EMBANKMENT MATERIAL NOTE

040 40

SCALE FEET

0

20

20

SC

AL

EF

EE

T

EL. 214.00

5

.

5

f

t

E

L

.

2

3

0

.

0

0

E

L

.

2

1

4

.

0

0

E

L

.

2

3

3

.

6

5

E

L

.

2

0

7

.

1

5

EL. 207.15

EL. 230.00

EL. 233.65

SECTION A-A'

A

'

DCR-3

1

NOT TO SCALE

FORMED CONCRETE

FROM ELEV. 214.00 TO

ELEV. 230.00

EXISTING 42" CMP OUTLET

PIPE TO BE SLIP LINED WITH

CURED-IN-PLACE LINING TUBE

EXISTING OUTLET STRUCTURE

MODIFICATION DETAIL

ISOMETRIC VIEW

A

EXISTING 42" CMP

OUTLET PIPE

EXISTING WEIR WITH

SLOTTED SIDES FOR

WOODEN BAFFLES TO BE

FILLED WITH FORMED

CONCRETE UP TO EL. 230.00

(SEE NOTES BELOW)

TEMPORARY

WOODEN

FORMS

BATTEN STRIP FOR

EXPOSED LINER (ALL

SIDES OF OUTLET

STRUCTURE)

PROPOSED GRADE

(EXPOSED LINER)

3

1

2

DCR-12

EXISTING HANDRAIL AND

WALKWAY TO BE REMOVED AND

REPLACED

CONCRETE BONDING AND FINISHING NOTES

1. 1. ALL CONCRETE CONSTRUCTION SHALL BE IN ACCORDANCE WITH ACI 318, "BUILDING

REQUIREMENTS FOR STRUCTURAL CONCRETE".

2. ALL CONCRETE SHALL OBTAIN A 28-DAY COMPRESSIVE STRENGTH OF 3,000 PSI (MINIMUM) AND

SHALL CONTAIN AN AIR ENTRAINING MIXTURE TO OBTAIN AN AIR CONTENT OF 6% ± 2%.

3. ALL REINFORCING STEEL SHALL BE ASTM A-615 GRADE 60.

4. EXISTING SURFACES TO RECEIVE ADDITIONAL CONCRETE APPLICATIONS SHALL BE BROOM

CLEANED AND CONCRETE CLEANER APPLIED TO REMOVE FOREIGN MATERIAL THAT WOULD

PREVENT ADHESION. DUE TO THE PROXIMITY OF THIS STRUCTURE TO THE POND AND STREAM

OUTFALL, CAREFUL APPLICATION AND CLEANUP OF CLEANER IS VERY IMPORTANT.

5. DRILL THE EXISTING CONCRETE AND INSTALL 6-INCH LONG, #4 REBAR DOWEL PINS. PINS SHALL

BE EMBEDDED THREE INCHES INTO THE EXISTING CONCRETE AND SECURED WITH A

WATERPROOF EPOXY SUITABLE FOR THIS APPLICATION. DOWELS SHALL BE INSTALLED ALONG

THE CENTERLINE OF THE EXISTING WALL THICKNESS.

6. CONCRETE SHALL BE PROTECTED FROM DRYING AND/OR FREEZING FOR 72 HOURS FOLLOWING

PLACEMENT.

7. REINFORCE CONCRETE WITH 4X4-W2.0XW2.0 WELDED WIRE FABRIC.

PERIMETER

ACCESS ROAD

2'x2' ANCHOR

TRENCH

3 ft

EXPOSED

XR-5 GEOMEMBRANE

6" (MIN.)

3

1

8 ft

SAFETY BENCH

1% MIN.

10 ft

3

1

3 ft

EXTRUSION WELD

(ALL SIDES)

EL. 230.00

(NORMAL POOL)

DCR-3

2

NOT TO SCALE

DISCHARGE PIPE FROM STATION

LINER PENETRATION DETAIL

EL. 233.00

EL. 228.00

PROPOSED 12"

DISCHARGE PIPE

(FROM STATION)

PROPOSED

SAFETY FENCE

15 ft

PIPE

CLAMPS

(M

IN

.)

3

DCR-12

PERIMETER

ACCESS ROAD

2'x2' ANCHOR

TRENCH

COMPACT PER

TECHNICAL

SPECIFICATIONS

3 ft

EXPOSED

XR-5 GEOMEMBRANE

6" min.

3

1

8 ft

SAFETY BENCH

1% MIN.

EL. 230

(NORMAL POOL)

10 ft

15 ft

8OZ NON-WOVEN

GEOTEXTILE

PROPOSED

SAFETY FENCE

FLAP VENT

@100' ON CENTER

3

1

DCR-3

3

NOT TO SCALE

WEST TREATMENT POND SAFETY

BENCH AND ANCHOR TRENCH DETAIL

4

DCR-3

3

DCR-12

EL. 228.00

TOP OF BERM

12"

1'x1' XR-5 FLAP

EXTRUSION WELD

(3 SIDES ONLY)

4"Ø HOLE IN LINER

AT CENTER OF

FLAP

DOWN SIDE OF

FLAP IS OPEN

XR-5

GEOMEMBRANE

DCR-3

4

NOT TO SCALE

FLAP VENT DETAIL

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DRAWING 6

DESIGN

PROJECT No.

CADD

CHECK

REVIEW

FILE No.

SCALEREV.

RE

VIS

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N D

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AD

DC

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RV

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15-20347

1520347N02

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JRD 02/05/15

ATN 02/05/15

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