February 18, 2019 Page 2
20190218 Nashua Phase Ill CQA Proposal.docx
Sanborn Head’s CQA Team also will monitor the following construction activities:
= Excavation of Phase III (on a limited basis only);
= Placement and compaction of soil fill in the Phase III area;
=" Modification of existing Detention Pond #6 and the associated site drainage
improvements;
2 Decommissioning of piezometers, monitoring wells, stormwater pipes, and leachate
collection pipes;
= Installation of leachate collection and forcemain/gravity main piping outside the limit of
waste;
= Installation of the Phase IJ] liner and leachate collection systems;
= Construction of the Sump Riser Building and associated components; and
= Installation of the perimeter road and supporting infrastructure.
The CQA Team will monitor the installation of the various components of the Phase III liner
and leachate collection systems. The components of the liner and leachate collection systems
include, listed from top to bottom:
a An 18-inch thick layer of drainage sand;
= A multi-linear drainage geocomposite or a geonet drainage geocomposite;
a A 60-mil thick textured high-density polyethylene (HDPE) geomembrane;
a A geosynthetic clay liner (GCL) (sump area);
a A 12-inch thick layer of drainage sand (base area only);
a A multi-linear drainage geocomposite or a geonet drainage geocomposite (the type of
geocomposite will be dependent on contractor pricing);
a A 60-mil thick textured HDPE geomembrane; and
a A 6-inch thick layer of Screened Till.
During earthwork construction, the CQA Team will: (i) monitor excavation activities and
review survey data documenting that the subgrade elevations are achieved; (ii) monitor the
placement of earth materials; and (iii) test the in-place moisture content and density of
compacted materials. Field moisture/density testing, as required, will be performed using a
nuclear density gauge in accordance with current ASTM standards.
The CQA Team will observe and document the construction of the new site drainage
components, the leachate management system modifications, and the Sump Riser Building.
Allowed variances from the construction documents will be noted and photographed.
Sanborn Head will review manufacturers’ data regarding the quality of resins used in the
production of the geomembranes and manufacturers’ certifications for the geosynthetic
components of the liner system against the Project specifications. Only geosynthetic
SANBORN i HEAD
