{"id":9939,"date":"2024-09-18T20:05:17","date_gmt":"2024-09-18T20:05:17","guid":{"rendered":"https:\/\/versicolor.ca\/sandylakebedford\/?page_id=9939"},"modified":"2024-09-24T13:18:21","modified_gmt":"2024-09-24T13:18:21","slug":"aecom-2014","status":"publish","type":"page","link":"https:\/\/versicolor.ca\/sandylakebedford\/waters\/lakes\/limnol-profiles\/2024-limnological-profiles-return-to-historic-trends\/in-conclusion-the-precarious-state-of-sandy-lake\/aecom-2014\/","title":{"rendered":"About AECOM 2014"},"content":{"rendered":"

What is “AECOM 2014”?<\/strong><\/p>\n

The full title:<\/em>
\nHalifax Regional Municipality Sandy Lake Watershed Study Final Report<\/strong><\/em>
\nPrepared by AECOM Canada Ltd., submitted August 25, 2014. 64 pages + Appendices (66 pages).”This body of work represents our current understanding of the environmental conditions in the watershed with a focus on lake water quality. The application of a phosphorus load model (Lake Capacity Model) provides a numerical narrative of how development may impact water quality. We identify several methods that can be utilized to mitigate water quality impacts.” <\/em><\/p><\/blockquote>\n

The report is available<\/em> here<\/strong><\/em><\/a> (from the Sandy Lake Conservation Association; it is not,apparebtly, available on te HRM website,). Except for a few samples of lake water, the AECOM 2014 report was entirely a desktop study (as requested by HRM).<\/p>\n

Background to AECOM 2014
\n<\/strong><\/p>\n

The concept of a \u2018Sandy Lake-Sackville Regional Park\u2019 harks back to the 1970s<\/a>,\u00a0 \u00a0It would encompass lands surrounding Sandy and Marsh Lakes and the adjacent lands by the Sackville River (see map at right).\u00a0 \u00a0In our first\u00a0 (2006) Regional Plan, reference was made\u00a0 to\u00a0 \u201cJacks Lake Park\u201d as an \u201cAdditional Regional Park\u201d\u00a0 focussed on the east side of the lake.\u00a0 There was reference to an existing \u201cSandy Lake Regional Park\u201d \u2013 130 forested acres on the east side of Sandy Lake officially opened in 2004 as the \u201cSandy Lake Park\u201d \u2013\u00a0 but\u00a0 lands to the west of Sandy Lake were given an \u201cUrban Settlement\u201d designation, meaning they were identified as an area for future growth (housing) in HRM, not conservation & recreation. (For more details see \u201c2006 Regional Plan Note<\/a>\u201d at the bottom of\u00a0 this post).<\/p>\n

The Urban Settlement designation set in motion a requirement for a watershed study under Policy E-17 of the 2006 Regional Plan (see pp 44-52 in AECOM 2014<\/a> for details).<\/p>\n

Predicting impacts of development<\/strong><\/p>\n

The Study Objectives of \u00a0AECOM 2014 as given in Section 1.2 (p. 4):<\/p>\n\n\n\n
The primary, overarching objective of the Sandy Lake Watershed Study, as expressed in Regional Plan Policy E-17, is to:<\/p>\n

\u2026<\/em>determine the carrying capacity of the watersheds to meet the water quality objectives which shall be adopted following the completion of the studies<\/p><\/blockquote>\n

Carrying capacity is a measure of the watershed\u2019s ability to accommodate inputs from both man-made and naturally occurring pollutants without experiencing a significant decline in water quality and ecological function. In this study, different land development scenarios are evaluated to understand the potential water quality effects resulting from each scenario. The outcome of the study is to provide a number of guidelines and recommendations for the planning, design and implementation of new developments that will help to maintain existing water quality.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

AECOM 2014 used historic water quality info. and a few samples they collected in 2013\u00a0 to \u201cidentify water quality objectives\u00a0 for parameters that are affected by development\u201d and then applied a Lake Capacity Model \u201cto predict how future development may impact the phosphorus concentrations of the lakes\u201d.<\/p>\n

They set the WQOs (Water Quality Objectives) for Total P\u00a0 at 50% above the \u201ccurrent values\u201d\u00a0 for Total P (12 ug\/L\u00a0 for Sandy Lake, 10 ug\/L for Marsh Lake or 10.5 ug\/L if they used their modelled current value). The resultant WQOs were 18 ug\/L for Sandy Lake and 15 ug\/L for Marsh Lake (or 15.5 ug\/L if they used their modelled current value).<\/p>\n

The Lake Capacity Model predicted Total P levels of 13-16 ug\/L for Sandy Lake and 12 to 15 ug\/L for Marsh Lake under 3 scenarios (Planned Development; Planned Development + Removal of Uplands WWTF and Septic Systems near Sandy Lake;\u00a0 Adding Advanced Stormwater Management), i.e. the predicted levels with development fell within or not far above the WQOs. (In a subsequently modelled scenario<\/a> 2b (Revised Planned Development extended) the predicted values for Sandy Lake\u00a0 (18.1 ug\/L) and Marsh Lake (16.0) slightly exceeded the WQOs.)<\/p>\n

Separately<\/a> I have identified four major flaws in regard to the application of\u00a0 Lake Capacity Model\u00a0 by AECOM 2014. It’s difficult to understand why these were not flagged at the time. In documents submitted to HRM on Oct 30, 2013<\/a> and March 14, 2014<\/a>, Professional limnologist Shalom Mandeville raised perhaps the most fundamental issue, my #2 “Setting the Water Quality Objective (WQO)\u00a0 for Total P in Sandy Lake at 50% above the \u201ccurrent value\u201d rather than at the \u201cpredevelopment level\u201d is not justified<\/em><\/strong>”\u00a0 but evidently to no avail.<\/p>\n

Regardless of these issues,\u00a0 AECOM 2014 recognized that the The Lake Capacity Model provides only a first approximation to reality:<\/p>\n

The predictions from the phosphorus load model are consistent with observations of urbanization in other watersheds. However, the degree of influence of urbanization on water quality in Sandy Lake can only be approximated using the phosphorus load model because of limitations arising from assumptions and uncertainty in the application of the model. Therefore a robust water quality monitoring plan is proposed for the Sandy Lake watershed to provide a further assessment of current conditions and to evaluate the impacts of development on the water quality.<\/p><\/blockquote>\n

A\u00a0 water quality monitoring plan as recommended above \u00a0was not, however,\u00a0 initiated following the acceptance of the AECOM 2014 Report.<\/p>\n","protected":false},"excerpt":{"rendered":"

What is “AECOM 2014”? The full title: Halifax Regional Municipality Sandy Lake Watershed Study Final Report Prepared by AECOM Canada Ltd., submitted August 25, 2014. 64 pages + Appendices (66 pages).”This body of work represents our current understanding of the … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":9937,"menu_order":10,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-9939","page","type-page","status-publish","hentry"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/pages\/9939","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/comments?post=9939"}],"version-history":[{"count":10,"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/pages\/9939\/revisions"}],"predecessor-version":[{"id":10098,"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/pages\/9939\/revisions\/10098"}],"up":[{"embeddable":true,"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/pages\/9937"}],"wp:attachment":[{"href":"https:\/\/versicolor.ca\/sandylakebedford\/wp-json\/wp\/v2\/media?parent=9939"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}