TATTERSALL ~-' LANDER PTYLTD ~ 12th May 2017 OUR REF: 216199-L001004 - COU NelL YOUR REF: DA-291/2017 !', :u.COAST ... 16 MAY 1017 The General Manager MidCoast Council r.::or,DS PO Box 450 ----_...- FORSTER NSW 2428 Attention: Wayne Burgess - Project Manager-Development Assessment Dear Wayne, RE: LOT 100 IN DP 1047534 -182 MYALL WAY, TEA GARDENS DEVELOPMENT APPLICATION FOR EARTH MOUND With regard to DA 291/2017 and in response to your correspondence (dated 24 February 2017), please accept this letter and attached plans as a suitable response and also as an addendum to the previously submitted Statement of Environmental Effects. In addition to this correspondence, amended plans and an ecological report (by Wildthing Environmental Consultants) have also been prepared and are attached. As stated above, this correspondence is to be considered an addendum to the previously submitted Statement of Environmental effects and is therefore to be read in conjunction with the afore mentioned report. All issues raised by the Department of Primary Industries (Water) are addressed within this document and also within the attached amended plans and ecological report. Water Management Act 2000 The proposal includes works which fall under Section 91 Activity approvals of the Water Management Act 2000. The objective of the controlled activities provisions of the Water Management Act 2000 is to establish and preserve the integrity of riparian corridors. The following principles should be employed to meet this objective: Identify whether or not there is a watercourse present and determine its order in accordance with the Strahler System. Comment - It is acknowledged that a watercourse is present (Station Creek) and the watercourse at this location is a third order stream under the Strahler system. If a watercourse is present, define the RCNRZ on a map in accordance with Table 1. DEVELOPMENT CONSULTANTS IN ENGINEERING, SURVEYING, PLANNING & ENVIRONMENTAL Tattersall LanS r AEN ~ I 'h c,ly_ I" Pty Llllllted _ 2 Bourf,e Street RAYMOND TERRACE 232-1 All mail to PO Box 580 .~, ~.~G e 9' -19871"')0 Fax: Email: adl1l1ll(i COl1r.lu " \ Telephone: \(12) 1021-1987 1731 tallcllld t,>.,... .\,.~"", v"t. l li'md COIl1 au S:IClients1201612161 991Correspondencel2161 99-LOOl 004 Council Issues Earth Mound .docx TATTERSALL ~;- LAN 0E R PTY LTO Comment - The requirements for a third order stream are 30 metre width each side of the watercourse (60m plus channel width). This has been shown on the attached plans. Seek to maintain or rehabilitate a RCNRZ with fully structured native vegetation in accordance with Table 1. Comment - The previously submitted landscape plan shall assist in establishing native vegetation to assist in the rehabilitation of the site. It is acknowledged that this landscape plan only included trees and therefore it cannot be considered as fully structured; accordingly, an amended landscape plan has now been prepared and is attached. It is also acknowledged that the vegetation structure on top of the earthen mound shall be different to that located in the VRZ, however, given this proposal shall impact upon a small area of the VRZ, it is considered that the proposal shall not have a negative ecological impact overall, and the relatively minor incursion into the VRZ is able to be offset through the preservation of other areas of the VRZ. Seek to minimise disturbance and harm to the recommended RCNRZ. Comment - Whilst the proposed mound is to be located within the VRZ, the proposed landscaping shall ensure that appropriate vegetation results in there being no adverse ecological impacts. Minimise the number of creek crossings and provide perimeter road separating development from the RCNRZ. Comment - This proposal does not include any creek crossings nor does it involve any roads. The proposal does not include any development which may be separated from the RCNRZ via a perimeter road. Locates services and infrastructure outside of the RCNRZ. Within the RCNRZ provide multiple service easements and/or utilise road crossings where possible. Comment - The proposal does not include any services or infrastructure relevant to this principle. Treat storm water run-off before discharging into the RCNRZ. Comment - The proposal shall not result in any structures which would produce any stormwater run-off which would require treatment. Relevant cross sections and plan requirements requested by DPI Water have been included in the attached plans. Council has questioned the source of the fill required for the earthen mound. The quantity of fill required for the mound is 2400 cubic metres of fill. There is an approval for a dwelling and shed for the site and the required 2400 cubic metres of fill shall be available from the earthworks required for the dwelling and shed, therefore there is no requirement for any additional fill to be brought on to site and no requirement for an application for an extractive industry or considerations for a designated development are relevant. TATTERSALL ~\ ~T LANDER PTYLTD The earthen mound is to include fencing on top of it to assist in noise suppression. Details are contained on the attached plans. With regard to Councils concerns regarding the unauthorised works, our investigations have revealed that in all likelihood, there are apparent unauthorised works on the site and that these works were likely carried out by different parties. The two existing earth mounds shown on the design plans predate the LiDAR data run in December 2012, as can be seen on the overlay below. (LiDAR metadata also attached). These works existed on the property before it was purchased by the current owner, and are believed to be constructed by the RMS during highway upgrade works -2010 and this is identified and supported by Google images of the changes to the landscape during the Highway construction activities. Image 1 below identifies the relevant LiDAR diagram. It does appear that the more southern mound has been extended recently, by approximately 40m to the south west, along with the extension of the dam to the south of this mound. Neither appear on the Google image dated 10 January 2016, but do appear on the image dated 29 June 2016. (Our date of survey was 20 July 2016). It does not appear consent was obtained for these relatively minor works. Station Creek is a third order stream in this location, and while the dam was extended away from the creek line, it still would have involved works within the Riparian Zone (and would also appear to have included works within the waterway, filling over the western high bank). From the google images it would seem that approximately 10 trees were removed as a result of this work, 7 of which were within the riparian corridor. The recent construction would appear to have been a cut/fill operation - from our 'as built' survey data it has been calculated that approximately 2200cu.m was moved from the new dam/drain extension to create the mound extension. Image 2 below is a screen shot of the bulk earth works calculations. /" II I ": '0.1 (L Lf~ " TATTERSALL \ ~. LANDER PTYLTD ~~ Image 1 - LiDAR Image of 2012 information ,., ><.-. Image 2 - Screen shot of the bulk earthworks calculations. f- j, TATTERSALL ~.", , LANDER PTYLTD ~ Existing Storm water Pipes The existing pipes were surveyed as 3 x 1200mm dia., 3.3m long, U/S inverts approximately 7.5m AHD, D/S inverts approx. 7.45m AHD, equating to approximately 1.5% grade. The overflow level is approximately 9.Om AHD. The age of this culvert crossing is unclear - it is identified in the 2012 LiDAR data, and appears as a historical structure that has been onsite for a significant time. A simplified culvert calculation gives a capacity of approximately 7.9m3/s, but a significantly more detailed upstream catchment analysis (including upstream culverts under Myall Way and the Pacific Highway) would be required to give an accurate ARI analysis. Given it has been onsite for some time and does not provide permanent access to any dwelling or infrastructure that requires flood-free access, such an assessment of flow performance seems unwarranted. Preliminary flood routing models through the work area (screenshot is Image 3 below) have been undertaken. In summary, in the 100yr 2hr storm the current mound extension would have increased water levels at Myall Way by 0.03m. The proposed mound would increase this by a further 0.04m. The modelled water level is around 0.5m from topping the Myall Way, and there is no other upstream assets of infrastructure that would be affected. Both the Myall Way culverts and internal culverts on our site are permanently partially submerged and the water level is controlled by a spillway on the main dam that has been in place for many years and probably at least 30 years old. Further investigations are not considered relevant as to the age of the structures until Council has determined its position with respect to the details presented in this advice. Image 3 - Screen shot of Preliminary Flood Modelling of culvert operations r) ~ r'j, , I,.. c ~ TATTERSALL \ LANDER PTYLTD~,r With respect to the issue of the effectiveness of the mound structure the attached plans indicate a relevant long-section that provides clarity to the issue. Attached to this addendum is a Seven Part Test ecological report that has addressed the specifics of the request and its conclusion is that there will be no significant adverse impact on any viable populations of threatened species. Relevant copies (4x)of additional plans and reports are attached. We trust that the above is sufficient to enable processing of this Development Application, however, should you require any additional information or have any questions, please do not hesitate to contact either Bob Lander or myself at this office.