NCD980602163_19810330_Warren County PCB Landfill_SERB C_Comments on Sverdrup & Parcel Proposal-OCR

.JAMES B. HUNT, .JR.
STATE OF NORTH CAROLINA
DEPARTMENT OF HUMAN RESOURCES · COVERNOR
Division of Health Services
SARAH T. MORROW, M.D., M.P.H.
SECRETARY
MEMORANDUM
TO:
P. 0. Box 2091 Raleigh 27602
March 30, 1981
Mr. David Kelly
Assistant Secretary
Public Safety
FROM: Mr. Bill Meyer, Environmental Engineer
Department of Human . Resources
Solid & Hazardous Waste Management Branch
( ,-/ .
SUBJECT: Comments on Sverdrup & Parcel Proposal For PCB Waste Disposal Site
Warren County
1-Page lA-3 Add Department of Human Resources to Sentence 1, 5.3
Define Contractor, Engineer and Owner.
2-Page lA-1 2. Coordination of Work. Add:
The State of N.C. will have a qualified engineer on site during
all construction activity to assist in coordination of work.
3-Page lA-4 Submittals During Construction Add to 7.1:
The engineer shall submit l copy of contractor submittals to the
State of N.C. for review.
Note: Required submittals should be outlined in contractor
specifications.
4-Page 2B-1 Earth Work
(a) There are no specifications for selection of fills and backfills
except all fill material shall be subject to the acceptance of the
engineer.
There should be specifications on select·ion and excavation of
liner materials; placement in stockpile areas, preparation of stock-
pile areas, moisture control and sampling for laboratory of field
testing. The specifications should include standards established for
clayey materials suitable for soil liner-s -on PCB landfills. (40 CFR
761.41 (b) ( l) i through v)
(b) Page 2B-2, 4.1 AAHSO T-180 Method Dor ASTM D 1557 Method D should
be evaluated for compaction standard. This would afford a safety
factor for engineering judgements on soil suitability for liner
construction.
(c) Page 2B-3 Specifications for stockpile areas (preparation methods
for ~tockpiling) How are selected excavated materials selected?
(d) Page 2B-3, 4.5.l The surficial soils on site are eroded and the
surface foot may be suitable for final grading. It is suggested that
the surface 611 or excavation to the minimum depth to exclude plant
roots and other organic material to be stockpiled for final grade.
It was noted during site evaluation that the highest soil clay content
was immediately below the soil root zone.
(e) Page 2B-3, 4.5.2 Detail specifications on materials, methods and
tests for selection excavation, stockpile and protection (ie. moisture
content) of clay liner materials.
(f) Page 2B-3, 4.8 Specify compaction test. The credibility of entire
project is based upon the clay liner and more specifically the per-
meability of the clay liner. It is essential that a combination of
field/lab tests to determine density, moisture and permeability be
implemented.
It is suggested that AASHO T 147-54 Method A or B; or ASTM D-2167,
1556 & 1557 be utilized on a 2000 ft2 basis in addition to the lab
compaction tests on 10,000 ft2 intervals per 6 inch.
*This point should be fully discussed and a decision made on the method
of testing a number of tests and lab selection as soon _as possible.
5-Page 2C-l, 2. 1. 1 Specify stockpile of materials on plans, (methods
and materials)
6-Page 2C-l, 2C-2, 2C-3 An evaluation should be made of the alternative
of installating a gravity leachate removal system(s) as to the proposed
system.
7-Page 2C-2, 2.3.1 Specifications for compacted bridging fill on top of
artifical liner and liner protection materials. Depth of liner protection
layer should be a minimum of 1 foot.
8-Page 2C-2, 2.4.1 Specify liner soils from 40 CFR 761.4l{b) (1) i thru v.
Consider modified proctor for compaction standard.
9-Specify method of liner construction, i.e. constructed flat, 3:1 slope,
etc. Evaluate alternatives for proposed construction on 3 to l slope,
i.e., excavate 1:1 construct 3:1, 4:1.
10-State testing for moisture/density, compaction in liner construction
section.
11-P. 2C-3, 2.6-Specify method and degree of compaction of PCB soil mixture.
12-2.6.2
Should be modified to include construction of ramp into exc~vation to
prevent damage to side wall from dumping and placing PCB waste. A N~s
ramp (long axis of landfill) to allow d~mping in the bottom excavation
should be considered. Ramp construction should be based on truck capability.
Ramp should be excavated for removal as the bottom 10-foot lift of waste is
placed insitu. A second ramp should be constructed for the upper 10-foot
lift. This assumes that the waste will be placed into the site in 2-10 foot
lifts (lifts should be compacted on 2-3 foot sublifts).
13-Sequence of construction on covering the landfill. _ Evaluate proposed
sequence : bridging layer -2 foot clay layer -PVC liner -protective
layer -1 foot topsoil; versus: bridging layer -PVC liner -l foot PVC
liner protection layer - 2 foot clay liner - 1 foot topsoil. They may offer
better protection for PVC liner. Evaluate 10 mil versus 30 mil PVC liner
for landfill cover.
14-Page 2C-4 2.7.7 Evaluate increasing depth of final cover to 3, 4, or 5 feet
utilizing excavated spil. Evaluate increasing final slope to 3-5% in east
to west direction to reduce contact time for infiltration.
15-Evaluate eliminating gas vent and utilizing upper leachate removal system
for gas venting (Predicted gas generation, diffusion pressure, etc.).
16-2F-3 PVC Liner -Specify distances of over lap and adhesives for all joints
of PVC liner.
17-Specifications (calculations) for sizing sediment basin (holding ~ond).
18-21-2, 3.1 Consider increasing topsoil depth (see comment 14) ..
19-21-2 Planting -If the site is completed in mid-summer a temporary vegetative
cover of a drought resistant grass (millet, milo, sudian, sudex) should be
considered, with permanent seeding to follow at optimum seeding season for
fescue and sericea.
20-Section 15A
Specify size of internal landfill sump, maximum anticipated or predicted
rainfall event, size and type of carbon for filtering PCB contaminated
water, rate of treatment capacility (what happens if 2 or 3 major rainfall
events occur) .
Should the septic tanks be plastered or coated with sealant to ensure
water proofing.
The design should consider a gravity system for leachate collection
(lower leachate and upper leachate removal pipes extended through side wall
of landfill) and be tied (separately) to the sand and carbon filter system(s).
Valves (external) would control leachate flow to the sand and carbon system(s).
ENGINEERING DRAWINGS
Sheet No. 2
Borrow area proposed has not been tested for soil engineering properties.
What type of borrow materials will be obtained from this area. Areas to the
N and S of the proposed landfill location has been evaluated for soil engineer-
ing properties.
Sheet No. 3
Are the concrete monuments identified as permanent bench marks; if so, where
are they located (specifically located)?
Sheet No. 4
Should include sections E-W & N-S to l~cate source and volumes of materials
to be excavated and stockpiled for various purposes, especially clay liner,
PVC liner protection, final covers, etc.
Sheet No. 5
Calculations for sizing holding pond possibly sections since dam sections are
included here.
Sheet No. 6
Should the final grading plan be modified to provide 3-5% grade along center-
line of landfill and establish several (2-4) control points (piped slope drains) ·
to reduce flow over 5:1 side slopes?
Sheet No. 7
Note in detail -should the tranks be plastered or further water-proofed,
siz~ type and volume of sand and carbon stated; sealing of pipe through side
walls (specs), at 125 gpm flow and the reduced volume for free board and sand
or carbon, there should be a control mechanism for liquid level to prevent
overflow. There should be a detail for containing the carbon below the inlet
pipe, as it will tend to float in the tank (e.g. removable screen).
Sheet No. 8
See comments concerning gravity leachate removal, sequence of top cover,
gas venting, top PVC liner thickness.
Evaluate all seal procedures, should the seal be l' or 2' and should the
seal extend up the sides of the PVC pipe.
Sheet No. 9
Cross section should include ramp section to allow placing PCB in bottom of
excavated areas.