BALANCE HYDROLOGICS, Inc.
Memo
To: Lynell Garfield, Kerri Lanza (City of Reno), Toby Ebens (City of Sparks), and
Christian Kropf (Washoe County)
From: Brian Hastings
Date: September 17, 2014
Subject: 2014 Addendum to the 2013 Addenda and 2012 Truckee Meadows Storm Water Sampling & Analysis Plan (SAP)
Purpose
Recent instrumentation of 4 urban outfall sites identified in the 2013 SAP necessitated an addendum to describe the outfall site changes and equipment installed and how they will be operated or used to meet the goals and objectives of the 2013 Addenda to the SAP. Instrumentation includes automated samplers and area-velocity sensors for collection of multiple discrete samples based on measured runoff volume. In this addendum, we describe the site selection changes, instruments installed and planned operations during an event. A more detailed description of methods and procedures will be documented in a revised SAP, anticipated in 2015.
Outfall site changes were made between 2013 Addenda and 2014 (please use coding as posed in 2013 Addenda for each) to include: 1. Dickerson Road, Site 3 in the 2013 Addenda, changing to the Oxbow Bend Nature Park site. 2. Arlington North, Site 4 in the 2013 Addenda, (E-19), not feasible due to vault/backwater, depth, and access issues. 3. Fisherman’s Park 2 – after data and observations in January 29 storm, selected for automation and rigorous fabrication due to vandalism and theft of equipment. 4. Mary Wahl Ditch, selected for automation pending construction to enclose ditch.
Additional Equipment Installed
Automated samplers and area-velocity sensors were installed at the following urban outfall sites identified in the 2013 SAP:
1) Island Drive at Arlington (H-19)
2) Oxbow Nature Park (C-24)
3) Fisherman’s Park II (D-16)
4) Mary Wahl Ditch (Sparks SDOE-008936)[1]
Automated samplers include TeleDyne ISCO 6712 portable samplers which were already owned by the SWPCC but were not in use, as well as new purchases… isco samplers and av sensors. The samplers are integrated systems that are able to be programmed to collect water quality samples based on a pre-defined trigger. In this case, we are using runoff volume as measured using area-velocity sensors. This sampling strategy allows for collection of samples across a storm hydrograph and quantification of storm runoff volume. Samples can be composited for analysis or selected based on position of the hydrograph or visual characteristics to define peak pollutant concentrations. Together, accurate concentrations and runoff volumes provide for quantification of pollutant loading. Pollutant loads can then be used to compare across sites, identify areas where management should be targeted, and address existing or future Total Maximum Daily Loads (TMDLs). Sites equipped with automated samplers allow monitors to focus on other sites that require manual grab samples and measurements of runoff.
Automated Sampler Operations
Upon identifying a storm event, ISCO samplers will be programmed based on the anticipated rainfall (e.g., 0.5 inches). Immediately after cessation of rainfall-runoff, samples from the ISCO will be removed and composited to characterize 4 distinct hydrograph positions: 1) first flush, 2) rising hydrograph, 3) peak flow, 4) falling hydrograph. ISCO dataloggers will be downloaded for future analysis and use in computation of pollutant loading. Samples will be placed in a cooler, on ice, and transported to the laboratory within the minimum holding time designated for all constituents. Subsequently, ISCOs will be cleaned, re-tested, and prepared for the next event.
Once discrete limbs have been characterized for water quality in two representative storms per outfall, subsequent data collection may combine limbs into a composite sample per site, in order to save costs of analyses.
Protection Against Vandalism
Because the urban sites are visible to the general public and subject to vandalism, extra care has been taken to secure these instruments and their operations. Area-velocity sensors and intake valves have been secured to the culverts and protected using locking manhole covers or fabricated cages (See below). ISCO samplers have been secured in an enclosed, locked box with elements designed to thwart vandals.
Locking cage at the Fishermans Park II urban outfall protects in-stream sensors from vandalism but promotes through-flow and minimizes trash accumulation.
Add in picture of job box installed here as well?
Locking job box houses ISCO autosamplers and batteries with conduit lines running sampling tubes from culvert to secure box. Solar panels have been affixed to the box and protected from vandalism.
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213136 Addendum to 2013 SAP, Addendum 2014LG213136 Addendum to 2013 SAP, Addendum 2014
[1] Mary Wahl Ditch is currently under construction and equipment install is anticipated in October 2014.