Site Assessor’s Guide - IOWA · • Site Assessor’s WWT proposals in SCF must correspond with...

ONE-OFF HOUSING WITH ON-SITE WASTEWATER TREATMENT -INFORMATION TO SUPPORT PLANNING APPLICATIONS

Site Assessor’s Guide

Presentation to

IOWA Conference

21st October, 2015

Fergus O Connor EE,

Ruth Hennessy Ex Scientist

Michael Woulfe SEE

1

Presentation to

IOWA Conference

21st October, 2015 2

BACKGROUND

• Merger July 2014

• Staffing arrangements/resources changed

• Need for consistency of approach/practices countywide

• Environment/Planning - One-Off Housing with OSWWT at Planning Application Stage

Presentation to

IOWA Conference


ONE-OFF HOUSING WITH OSWWTINFORMATION TO SUPPORT PLANNING APPLICATIONS

• Current Issues with OSWWT at Planning Application Stage

• Need for Guidance

• Guidance Objectives

• Site Assessor’s Guide

• Is the Guide Working?

• Q&A

Presentation to

IOWA Conference


CURRENT ISSUES WITH OSWWT AT PA STAGE

• Rural county >50% one-off housing applications

• Too much staff time dealing with one-off applications

• Quality and nature of Planning Application supporting information received – Site Suitability Assessment, Wastewater Treatment Design, Application Supporting Information - improvement needed for good decisions

• Code of Practice limitations identified which need to be addressed

Presentation to

IOWA Conference


QUALITY OF PA INFORMATION RECEIVED

• Site Suitability Assessment– Some unsuitable sites selected

– SCF form incomplete

– Not using available desktop information

– Insufficient trial hole depths excavated

– Trial holes and P/T test holes not correctly sited

– Incorrect referencing of bedrock

– Incorrect separation distances

Presentation to

IOWA Conference



• Wastewater Treatment Design– Design proposals not clearly presented and thus not

easily understood

– Insufficient soil cover above percolation drains

– Percolation drains sometimes too deep

– Insufficient depth of ‘suitable’ soil below percolation drains

– Incorrect percolation area design

Presentation to

IOWA Conference



• Application Supporting Information– Not consistent with findings of SCR

– WWT proposals in SCF not corresponding with drawings

– Not all supporting information submitted with application

Presentation to

IOWA Conference


CODE OF PRACTICE LIMITATIONS

• Purpose of CoP – provide guidance on provision of WWT disposal systems for new single house with P.E. of less than or equal to 10

• Use by PA – site assessment methodology used to satisfy requirements of Planning and Development regulations

• could be developed/expanded further in some areas

Presentation to

IOWA Conference


CODE OF PRACTICE LIMITATIONS

• CoP doesn’t specifically deal with:

– percolation/polishing filter/ infiltration layout design i.e. generic layouts only in CoP (Section 11.4)

– impact of rock fragments/ stone content in determining the extent of ‘suitable soil’ i.e. when does rock content become excessive?

– the need to demonstrate that the WWTS proposals meet the planning/environment objective of “sustainable development”

– upgrade of/extension to existing dwellings– selection of WWTS type appropriate to site conditions i.e. consider

pressure dosing on site with very poor drainage

– specific examples of hydraulic calculations in WWTS design for different scenarios would help to choose correct system

– sewerage design specifics of the full sewage disposal system i.e.–doesn’t deal with

– design specifics of manholes, AJs/, distribution boxes etc - focus only on WWT unit and percolation area

Presentation to

IOWA Conference


NEED FOR GUIDANCE

• Conclusion - need for guidance to address issues with:

• Quality and nature of Planning Application supporting information received i.e.

• Site Suitability Assessment

• Wastewater Treatment Design

• Application Supporting Information

• Code of Practice limitations (at Planning Application stage)

Presentation to

IOWA Conference


GUIDANCE OBJECTIVES

“Prevention is better than

cure”

“it's easier to stop

something happening in the first place than to repair

the damage after it has

happened”.

Presentation to

IOWA Conference


GUIDANCE OBJECTIVES

• Immediate Objectives– mitigate potential negative impacts of new and legacy

OSWWTS at Planning Application stage– Positive planning decisions at appropriate locations– Streamline information collection and application

presentation to TCC– Streamline application processing by TCC– Reduce FI– Reduce refusals– Applications over the line first time– Develop guidance to address issues with SSA,

WWTS Design, Application Supporting Information and CoP limitations at planning stage

• Longer-term Objectives• mitigate potential negative impacts of new and legacy

OSWWTS at installation and maintenance stages?

Presentation to

IOWA Conference


SITE ASSESSOR’S GUIDE

• prepared by Environment in conjunction with Planning Section

• read in conjunction with CoP• assumes good knowledge of CoP by SA • addresses issues with SSA, WWTS Design,

Application Supporting Information and relevant CoPlimitations

• non-statutory, helpful tool, best practice• applicants expected to demonstrate guidance

followed• no reason why all information cannot be presented

with application first time round• Site Assessor’s Guide in place since July 2015

Presentation to

IOWA Conference


SITE ASSESSOR’S GUIDE

• Contents– Introduction

– Principles of On-Site Wastewater Treatment

– Roles and Responsibilities of SA and LA

– Existing House Upgrade/Extension Applications

– Site Selection and Site Characterisation

– Wastewater Treatment Design

– Application Supporting Information

– Appendix 1 – Checklist of Supporting Information

– Appendix 2 – Details of Supporting Information

Presentation to

IOWA Conference


ROLES AND RESPONSIBILITIES OF SA AND LA

• Role of Site Assessor/Agent– Ideally SSA carried out by “suitably qualified and

experienced Site Assessor” i.e. Site Suitability FETAC, hydrologist, geologist or other relevant qualifications/experience etc.(Suggest cannot insist on any/all of these

qualifications/experience as other/overlapping expertise could be excluded? CoP/Guide will filter out unsuitable submissions in any case. Advise (but don’t insist) on PI for Site Assessor.)

– Applicant and PA relying on SA expert judgement – Onus/responsibility on applicant/Site Assessor– Identify if site suitable for WWT– Decide where WWT to be located– Design appropriate WWT

Presentation to

IOWA Conference


ROLES AND RESPONSIBILITIES OF SA AND LA

• Role of Local Authority

– Evaluate the SSA, WWTS Design and Application Supporting Information

– Check that SA proposals adhere to fundamental environmental principles when evaluating SSA

Presentation to

IOWA Conference


EXISTING HOUSE UPGRADE/EXTENSION

• COP Section 6.6– “The CoP should be applied to all new development”

– “existing on-site domestic wastewater treatment systems may fail to meet the performance requirements as set out in this CoP”

– “Variances to the CoP requirements may be considered by the local authority when it is satisfied that the proposed upgrade will provide improved treatment and reduced environmental impact.”

• Further detailed guidance necessary to deal with this CoP limitation

Presentation to

IOWA Conference



• Where dwelling substantially upgraded and/or extended

• Applicant required to demonstrate adequacy or otherwise of existing WWT System

• Identify remedial measures if existing WWTS not adequate i.e. ‘improvement’ in line with the CoP

• Where upgrade to WWTS required

a) Compliance with full requirements of CoP desirable

b) where full compliance with CoP is not possible PA may consider a net improvement that will offer highest level of protection to human health and environment

c) designs must be proposed and justified

Presentation to

IOWA Conference



• Site Assessor’s report submitted to PA confirming

– Type of system that exists

– Capacity of tank vs. occupancy rating

– System can be (legally) accessed from public road i.e. In applicant’s ownership or way-leave available

– System can be maintained

– Clean roof/surface water not entering system

– No visible evidence of, or potential for, system causing risk to human health or environment i.e. no ponding, effluent break-out etc

Presentation to

IOWA Conference


SITE SELECTION AND SITE CHARACTERISATION

• Desktop Assessment– Awareness of previous/ adjacent site suitability

assessment results i.e. Informs likelihood of suitability/unsuitability of site

– Location of public and group water schemes and Groundwater Protection Zones - maps available and updated regularly

– Check Groundwater Protection Response with TCC if in doubt!

• Visual Assessment– Identify vulnerable receptors and ensure

separation distances are met on site

– Groundwater flow direction must reflect slope of site under proposed percolation area

Presentation to

IOWA Conference



• Trial Holes– ensure trial hole depth sufficient to reflect

recommendation that can be substantiated i.e. 3m deep trial hole for regionally important aquifers

– Location of trial hole (and P & T test holes) outside footprint of percolation area

– Depth of suitable soil below drain – 900mm (secondary treatment/package plant)/1200mm (septic tank system)

– Correct referencing of rock-layer with >20% fragments should not be treated as “suitable soil” for wastewater treatment purposes e.g. 50% fragments in a 0.9m deep layer => only 0.45m viable soil depth

– Excessive rock/stone content in underlying soil layers do not contribute to effective effluent treatment irrespective of T/P values

– Rock levels – potential for groundwater contamination when bedrock close to surface

– Soil profile log to bring all details together

Presentation to

IOWA Conference



• Site Characterisation Form– Incomplete/inconsistent information in SCF – could

lead to FI, supervised retesting or refusal

• Unsuitable Test Location/Site– if test location not suitable find another location on

the site or another site!

Presentation to

IOWA Conference



Presentation to

IOWA Conference

21st October, 2015

Location of P and T Test Holes

24


Presentation to

IOWA Conference

21st October, 2015

Tool for Estimating % of Soil Rock Fragments by Volume

50% rock fragments in layer

25

WASTEWATER TREATMENT DESIGN

• Design proposals clearly presented in plan and section drawings

– Understood by members of public at planning stage

– should be constructable in accordance with permission granted i.e. no guarantee that SA/Agent will be implementing recommendations

• Refer to Groundwater Protection Responses in CoP and comply with minimum requirements

• Make householder aware of operational and maintenance requirements associated with particular system being recommended

Presentation to

IOWA Conference



• Sufficient soil cover above percolation drains - 450mm (min) to 950mm (max). Desirable minimum cover 600mm

• Depth of suitable soil below percolation drain trenches - 900mm (secondary treatment/package plant)/1200mm (septic tank system)

• 300mm depth of stone fill under percolation drains

• Percolation area layout design:

– Percolation layouts – with sides measuring in 2:1 ratio; longer side aligned with contours of site (facilitate construction/reduction on groundwater impact)

– “with slope” type percolation areas – drains run aligned with contours of the site

– “cut and fill” type percolation areas – no restriction on orientation of percolation drains within ‘rectangle’

– Drains piped individually to distribution boxes

• Pumped/low pressure distribution systems – site specific design required, prepared by suitably qualified individual experienced in hydraulic design

Presentation to

IOWA Conference



Presentation to

IOWA Conference

21st October, 2015

Soil Cover above and Soil Depth below

Percolation Drains

28


Presentation to

IOWA Conference

21st October, 2015

Percolation Area Layouts

29

APPLICATION SUPPORTING INFORMATION• Notwithstanding SA/Agents’ experience, SA/Agent must assume

no knowledge by Planning Authority

• Need to demonstrate all aspects have been considered via supporting documentation

• All supporting information submitted with application in first instance

• Site specific vs. generic i.e. manufacturers details of WWTS insufficient on their own, need to show site specific layout and longitudinal, cross-sectional drawings etc.

• Supporting information must compliment and be consistent with findings/recommendations of SCR

• Site Assessor’s WWT proposals in SCF must correspond with Architect/Designer/Agent drawings

• Section 7 of Site Assessor’s Guide replaces Section 3.4 of SCF

Presentation to

IOWA Conference


APPENDIX 1 - CHECKLIST OF SUPPORTING INFORMATION

Presentation to

IOWA Conference


APPENDIX 2 - DETAILS OF SUPPORTING INFORMATIONSite Characterisation Report

• Signed by Site Assessor

• BS5930 descriptions to describe subsoil

(use % by volume descriptor to quantify amount of gravel/ stone fragments/ fractured rock – refer to Teagasc Soils to ascertain general soil type characteristics (Stones % total))

• Groundwater flow direction – local and regional (can be different!)

• T and P results included

Presentation to

IOWA Conference


DETAILS OF SUPPORTING INFORMATION

Maps

• Soil Map

• Subsoil Map

• Teagasc Soils website

• Aquifer Category Map

• Vulnerability Map

• Bedrock Map

• Wells Map

• 1:50,000 National Discovery Map

• Surface features map – relevant features within 250m radius of site

Presentation to

IOWA Conference



Photographs

• submitted with SCR

• In hardcopy

• In colour

• Date stamped

• Printed on A4 pages

• Minimum size 6”x4” (e.g.2 per A4)

• Clear and devoid of obscurities

• Use Digital Camera of high resolution and good

optical zoom - forget the smartphone!

Presentation to

IOWA Conference



Photographs

• Visual assessment

– Site relative to landscape

– Areas of poor drainage indicators

– Soil or rock outcrops

– Existing WWTS on-site

– Test pits/trial hole(s) spoil heap locations

Presentation to

IOWA Conference


DETAILS OF SUPPORTING INFORMATIONPhotographs

• Trial Holes

– No requirement for trial holes to remain open, therefore, reliance on photos will be paramount

– comprehensive set of photographs submitted to support trial hole assessment/evidence in SCF.

– trial hole + trial hole spoil heaps: photographs 6”x4” minimum size, printed on A4 page, maximum 2 per page, devoid of obscurities such as shadows, reflections etc.

Note: of all the photographs, Trial Hole ones are the most

critical. Blurry, unreferenced-to-scale, photos in this

regard may generate a further information request.

Presentation to

IOWA Conference



Photographs

• Trial Holes– Full profile of TH taken

– from correct/optimum location

– clear and devoid of obscurities/shadows/reflections etc

Presentation to

IOWA Conference

21st October, 2015

Unclear TH Photo Clear TH PhotoCorrect/Incorrect photo locations

37


Photographs

• Trial Holes– Levelling staff/tape – from distance and close up

(Best Method: 4” wide flexible tape i.e. see photo �)

– Mottling/water table/broken-rock/excessive rock fragments layers

– Trial hole and test pit spoil heaps

– Excessive rock fragments >20% by volume

Presentation to

IOWA Conference

21st October, 2015

Levelling staff from Distance Levelling staff close up Tape close up

38


Photographs

Critical:

• TH soil profile

• TH spoil Heap

• TH in context of site landscape (to prove TH has been dug on that particular site!)

Less Critical:

• Percolation P and T Tests– T/P test holes

– to identify locations (don’t forget to number and reference to a layout drawing!)

– to illustrate T/P test hole conditions (prior to filling with water)

Presentation to

IOWA Conference



Drawings

• Submitted with SCR

• Site Layout Plan 1:500 scale

– Trial hole and percolation test hole locations (referenced to photos: t1, t2, etc)

– Distances from all relevant features

– All springs and wells within 250m radius

– Contours and spot levels on and adjacent to the site

– etc

• Site Plans

– WWTS

– Surface water/SUDS drainage system

– Plan of percolation area/bed layout

Presentation to

IOWA Conference



Drawings

• Longitudinal Section and Cross-sections

– Through the dwelling, discharge drain, wastewater treatment system, boundary 1:100 scale minimum

– Drawings to show foul drainage system, invert level of percolation trench/polishing filter, original ground levels, depth of excavated trial holes, outline of trial hole superimposed on all cross-sections etc.

• Ancillary WWTS Details

– Plans and sections of manholes, distribution boxes etc.

• All drawings accompanying the SCR must have title block with site assessors name and contact details, company logo – this is confirmation that SCR and drawings represent proposed wwts for the site

• All elements of WWTS shown on all sections and on the plan

Presentation to

IOWA Conference



Presentation to

IOWA Conference

21st October, 2015

Site Layout, Longitudinal Section, Details

42


• Pumped Pressurised Distribution System Design– System design included with site suitability

assessment

– Design prepared by suitably qualified /experienced individual or consultant

– Hydraulic calculations submitted as part of WWTS proposals

• Certificate of Performance Results– Submitted as part of WWTS documentation Drawings

Presentation to

IOWA Conference


IS GUIDE WORKING?

• Early days - 3 months in use

• “work-in-progress” document

– Minor amendments identified already

– Position adopted re requirement to review existing wastewater treatment system for applications for existing house upgrade/extensions needs to be reviewed i.e

• At present Guide looks for review of existing WWTS “where dwelling substantially upgraded and/or extended”

• should there be concern about existing WWTS when application is for a porch extension? If we don’t are we abdicating on our responsibility to achieve a “sustainable” development?

• should concern be limited to applications where there is increase in occupancy , increase in effluent?

• working on a case by case basis at the moment.

Presentation to

IOWA Conference


IS GUIDE WORKING?

• 1st review after 6 months

• Some improvement already in information – particularly photographs

• Challenge in ensuring Guide is embedded

• Planning/Environment team overseeing implementation and measuring delivery of objectives

• Ongoing information sessions for Site Assessors and training of Planners needed

Presentation to

IOWA Conference


Presentation to

IOWA Conference

21st October, 2015

Presentation to Site 46

Site Assessor’s Guide - IOWA · • Site Assessor’s WWT proposals in SCF must correspond with...

Documents

Transcript of Site Assessor’s Guide - IOWA · • Site Assessor’s WWT proposals in SCF must correspond with...