2017-02-27_REVISION - M1987049 - Laserfiche WebLink

Home Browse Search

MEMORANDUM To: Joe Lamanna, File 0430.09 From: Timothy A. Crawford BBA water cbnsultants BISNoP-BROGDEN ASSOCIATES- INC. Subject: Ready Mixed Concrete Company — Spier Property Drainage System — As -Built Construction Summary Job: 0430.09 Date: February 10, 2017 This memorandum presents a summary of the as -built construction of the Spier Property drainage system located adjacent to the Ready Mixed Concrete Company (RMCC) Bromley Lake Pit site near Brighton, Colorado, as presented in attached Figure 1. The purpose of the installed drainage system is to Iower ground water levels on and near the Spier Property. The information in this summary memorandum is based only on information provided by the contractor. Bishop -Brogden Associates, Inc. (BBA) was not onsite during construction of the dewatering system. Drainage System Construction On December 27 — 29, 2016, Claystone Construction constructed the Spier Property drainage system for RMCC in accordance with specifications provided by BBA by first excavating approximately 6 -foot wide trenches for the collection and transmission portions of the drainage system. The collection trench was excavated to varying depth to allow the trench to intercept native gravel material below the water table. The transmission trench was excavated to allow for approximately 6 inches of gravel to be installed beneath the designed transmission pipe elevations. The trenches were backfilled to the approximate designed pipe elevations with Boral #9 gravel material before installing 8 -inch diameter, SDR35 PVC sewer pipe perforated to a slot size of 0.05 - inches (50 -slot) at the approximate designed elevations. After the installation of the pipe, the trenches were backfilled with the Boral #9 gravel material to a depth of 2 feet above the top of the pipe. The remainder of the trenches were backfilled with overburden and native materials. Geofabric material was installed as part of the drainage system to reduce the amount fine material transmitted by the system. The installed gravel in the transmission trench area was fully wrapped in the geofabric material. The installed gravel in the collection trench area had geofabric installed only on top. Two vertical 8 -inch pipe sections protected with 8 -inch steel caps at the surface that connect to the drainage system at "T" connectors were installed as cleanouts to facilitate periodic cleaning and maintenance. At the discharge point of the drain system where it discharges to the McCann Ditch, a discharge structure consisting of concrete and rip -rap material was installed to protect the McCann Ditch from erosion, as presented inset in Figure 1.