Westminster Sewer Improvements Project

Westminster, Colorado

OWNER

City of Westminster

GC

Brannan Construction Co.

ENGINEER

HDR Engineering, Inc.

TIME

2019

REVENUE

$1,150,000

D.CaseStudy Westminster 5 Edit 209302019
GRIFFIN DIFFERNCE

The highly variable soil conditions required a comprehensive dewatering design and specialized drilling methods to complete the installation. Griffin’s dewatering design experience and specialized drill rigs insured successful installation of the dewatering system.

Griffin installed and hydro-tested the treatment system and provided on-going site assistance to ensure seamless operation and compliance with the discharge permit. Regular monitoring and preventive maintenance were conducted during the entire project to ensure optimal system performance.

THE CHALLENGE

This project involved the construction and replacement of a new sanitary sewer line near Little Dry Creek. Soils ranged from river rock and cobbles to fine clays. The groundwater required treatment for total suspended solids (TSS) and various metals (iron, copper, manganese, lead and arsenic) to meet stringent State discharge requirements.

THE SOLUTION

Multiple drilling methods were required to install the wellpoint dewatering system in the varying conditions along Little Dry Creek. Griffin utilized Hollow Stem Auger and Air Rotary drill rigs to complete the installation based on the geology and adjusted the dewatering system design based on actual test pump data. The varying geology resulted in flow rates ranging from 20gpm to 200gpm. Griffin designed and installed a transfer pipeline system to convey water to a centralized treatment system. Griffin engineered a water treatment solution that incorporated oxidation, filtration, and several different types of media. The removal of the metals required chemicals for oxidation as well as acid and caustic feeds for pH adjustment, sand filters and bag filters. Griffin’s experienced field technicians operated the dewatering and treatment systems concurrently to maintain optimal system performance.

CALCULATOR

DEWATERING ADVISOR

Enter your excavation information to learn about options and considerations for selecting dewatering systems.

CASE STUDIES

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