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HomeMy WebLinkAboutPublic CommentFrom: john belsherlaw.com Sent: Tuesday, February 21, 2023 11:54 AM To: Planning Commission Public Comments Cc: Paula Ramsum Subject: FW: Agenda item 2; Planning Commission meeting Feb 7, 2023 Attachments: Letter to Planning Commision 2 7 23.docx; Final Drainage Report 2018 updated 2021 excerpts re DMA8.pdf, Grading Plan for 18 inch culverts 7 21 21.pdf; Erosion contol plan.pdf; Civil Design Solutions opinion letter.pdf, Peabody letter for 2-14-23 meeting.pdf February 21, 2023 Atascadero Planning Commission Dear Commissioners: FEB 2 12023 `�P�Dv22—�c�v5l The Commission is referred to my letter of Feb 7, 2023 (attached). You will see our questions are not answered. Neither the City nor the letter from Carnesale's "own engineer" from Sacramento can explain why the runoff collected from Drainage Management Area 8 (DMA8) is not metered out per the project design but instead flows directly into the Ramsum collection area in her yard. Notably I am attaching an opinion from a local engineer which reiterates the concerns expressed two weeks ago, which concerns are as yet neither discussed or answered. See opinion of Robert Montoya of Civil Design Solutions. The essence of the problem is two -fold: First the project engineer from Sacramento apparently does not know what the developer has installed in the ground and what has been added by Improvement Plan page C-15. As mis-stated in the project's "own engineer" letter: "Our review of the proposed project drainage system and project grading plan showed that all drainage from the Ten850 project site is being collected by the new drainage system, detained onsite through the use of underground chambers, and is regulated for outflow from the site to insure the flow from the developed project does not exceed the existing drainage flow condition prior to the development of the project." See page 2 of the Peabody letter. We wish this were true. Unfortunately this is completely false. The drainage from DMA8 does not run uphill back into the storage area from which the metered storm water flows. The drainage from DMA8 goes directly at and to Paula Ramsum's property. Without any metering. We have shown you a photograph of the pipe through which this discharges into the project's 18" metering discharge culvert. The drain grate for this pipe is even on the Improvement Plans at page C-15 (attached). This unmetered drainage from DMA8 skews all the fancy calculations for metered outflow, rendering the projections invalid. The drain which Peabody ignored or missed serving DMA8 is plain as day on the current Improvement Plans at page C-15. This treatment for DMA8 is all contrary to the Final Drainage Report updated 2021, upon which all project decisions have been made. (See attached) Second, the project engineer does not address the new "solution" the City required by sheet C-15 of the Improvement Plans. That solution connects the two 18" pipes in Ms. Ramsum's backyard (she has not been approached about this yet, for the record). The problem is that there is nowhere for the water go which collects in the back yards of the residents on La Costa? The developer at 10850 has been steering water from winter rains to this collection area (when the fire department is not stopping them). The new Improvement Plan at page C-15 offers a grade level drain to accept this water (feeding into the top of the 18" culvert). But the water is currently collecting in the backyards at 12-24" below that level. That drain might also push water OUT onto the neighbors' yards, including Ramsum's yard and home. The grated box certainly won't accept the water from her back yard which is now collected at the bottom of the 18" culverts. The project engineer Peabody does not address either of these major, major problems. Neither does the City. Until this is solved, the City cannot and should not approve anything more (or less) on this property. And it should issue no certificates of occupancy. There are a few further comments about the developer's communication to the Commission worth noting: 1. Carnesale says in his undated letter (received by the City on Feb 16) and located in the Commission's agenda packet the following: "Neighbor Ramson[SIC] and her attorney claimed there was no record of a grading plan. There is a grading plan." This misdirection by Carnesale should be explored. What Ramsum and I said is that the "grading plan" from 2017 referred to in the negative declaration checklist does not appear to exist. City staff can't find it. We all recognize there is a "grading plan" as part of the current "Improvement Plans" which were first approved long after the 2017 negative declaration and updated as of 2021. In fact the Improvement Plans excerpts were attached by me in my Feb 7 communication and are attached again. See "Grading Plan for 18 inch culverts" attached to this email (and to my letter from February 7). The problem is that: A. The environmental document you are being told to accept was based on a "grading plan" from 2017. But it does not seem to exist. Instead we have a post 2017 grading plan which has been modified over time. The current grading plan within the Improvement Plans was NOT part of the 2017 negative declaration. So far, no one can tell us what the grading plan was in 2017. We now know there are big problems (coupled with unanswered questions) with the "grading plan" as it exists today, including: 1) Why is there now an inlet to the developer's 18" culvert a few feet from its egress point? This inlet apparently drains DMA8. The new drain and DMA8 is not accounted for in the "peer review" by the developer's "own" engineer, Ross Peabody. Your City staff has not addressed this. 2) The Improvements Plans are inconsistent with the Final Drainage Study (updated in 2021) which provided that drainage from DMA8 would somehow get uphill to the storage underneath the main parking lot. The Peabody regurgitation of calculations from the original drainage scheme does not take this into account. Your City staff has not addressed this. 2. The Improvement Plans contain a new connection for the 18" drainage pipes which dump off the 10850 site into an open collection sump in front of the 18" culvert on the Ramsum property. By the terms of the conditions of approval this is a condition to the final map. In fact, the developer may weasel out of this requirement, which has been in place since 2021. Its an offsite condition. The developer has made no effort to approach Ms. Ramsum on how it intends to trespass on her property and make this connection. The connection should be peer reviewed and the developer required to make the connection before any occupancy is allowed. After all the project is based on dumping drainage onto the Ramsum property. The project needs to take care of its own stuff. This connection solution must be a condition to any certificate of occupancy being granted for any building. 3. The peer review by the owner's engineer Peabody does not address concentration of flow beyond historical. What flowed off this site is now concentrated in a single 18" pipe directed at Ms. Ramsum's property. The math check by Peabody says the storage basin will work. This however assumes all the drainage installations are in place per plan. We know that drainage for DMA 8 appears to be unaccounted for in Peabody's calculations and to prove it there is a new inlet to the 18" developer culvert not on any plans, which will drain DMA8. The Commission needs answers for this issue as the project "planning" affects downstream neighbors. 4. Carnesale says there were well -know drainage issues in the neighborhood, specifically "quite a few drainage issues in that part of the City." This indicates the 2017 negative declaration was based on incomplete information and should be re -visited. More likely, Carnesale is misrepresenting the truth. Ms. Ramsum has been there since 2011, not 2020 as Carnesale states. Her only drainage issues were caused by Carnesale at 10850 EI Camino, by the flooding of 2021. If Carnesale is right then a new environmental document is needed to account z for his version of the drainage history for the neighborhood. In fact, a new environmental document is required owing to the flooding of Mr. Ramsum's property in 2021 by the re -concentration of runoff from the 10850 EI Camino project. The Planning Commission is in the trusted position of protecting the Atascadero property owners. It can ask important questions and demand complete answers. We hope you will consider this in your deliberations. John Belsher, Esq. Belsher Law, P.C. 3450 Broad Street, Suite 101 San Luis Obispo, CA 93401 From: john belsherlaw.com Sent: Tuesday, February 7, 2023 1:23 PM To: pc-comments@atascadero.orp Cc: Paula Ramsum Subject: Agenda item 2; Planning Commission meeting Feb 7, 2023 Attached find correspondence to be delivered to the Planning Commissioners and planning staff in advance of tonight's meeting. John Belsher, Esq. Belsher Law, P.C. 3450 Broad Street, Suite 101 San Luis Obispo, CA 93401 ATTENTION: This email originated from outside the City's network. Use caution when opening links and attachments. 3450 Broad Street, Suite 101 San Luis Obispo, CA 93401 805-316-5892 Planning Commission City of Atascadero 6500 Palma Avenue Atascadero, CA PC-comments@atascadero.org Re: Feb 7, 2023 Agenda Item 2 — 10850 EI Camino Real Tentative Tract Map Dear Commissioners: I represent the owner of property at 920 La Costa in Atascadero, Paula Ramsum. This property includes a custom rental house rented out by Ms. Ramsum for several years. The property has an 18" culvert which is designed to accept some run-off from the property at 10850 EI Camino Real. Prior to construction next door by 10850 LLC, there is no record of any flooding at my client's property. Although the 18" pipe on 920 La Costa connects directly to a City storm drain on La Costa, the City denies owning the 18" pipe. This issue is a subject of dispute and is under litigation. On January 27, 2021, stormwater from 10850 EI Camino overwhelmed the 18" culvert at 920 La Costa, causing extensive flooding of the house at 920 La Costa as well as a neighboring house. The construction site at 10850 was a mess, with grading going on that very day. Erosion control measures were unsuccessful and in fact clogged up the 18" culvert on Ms. Ramsum's property. Despite promises to help from both the City and the Developer, no help was forthcoming (aside from the much appreciated disaster response of the fire department). There is now a lawsuit filed against the City and the developer for damages to Ms. Ramsum from this incident. After two years,. my client has not yet been able to bring her tenants back into the property, suffering mounting losses. Atascadero Planning Commission January 7, 2023 Against this backdrop the City is now contemplating a tentative map to allow the developer to proceed with further development of the property at 10850 EI Camino. We appreciate that there is already an approved development. However, there are a few issues which the Planning Commission can and should take a close look at. I will list them here. 1. The project does not conform to the drainage documents approved by the City. A. The project was approved previously with reference to a "Grading plan" which was reported to be under review by Public Works. See 2017 project staff report, at page 8. There is no known record of this "grading plan". The 2017 approval is found at https://www.atascadero.org/files/CD/RECENT_ PROJECTS/Hartberg PC Staff Report.pdf B. After project approval in 2017, the City accepted a Drainage Report and Stormwater Control Plan, which was updated March 3, 2021. https:Hnetorg8050650.sharepoint.com/:b:/s/BeisherLaw/ETnFaXurPQhEinmSY[z 3391BweigsWJDYo2gfKKtYUdc_A?e=hQhzdo Attached is an excerpt from this report showing the area of concern. This report includes a mapping of the site into various drainage areas. The area next to Ms. Ramsum's site is designated DMA8. The water from this area is described as flowing through an unidentified "swale" back to the private street on the 10850 property. However, there is no such swale and it is actually uphill. Instead there is a drainage inlet placed in the 18" pipe belonging to 10850, which appears to be intended to siphon this water from DMA 8 directly into the 18" pipe of 10850. The result is that there is a large area of this site which is unaccounted for as to stormwater drainage and appears to add to the volume of water metered out to the 18" culvert on the property at 920 La Costa. C. The Improvement Plans approved by the City in 2021 include new provisions for connecting the two 18" pipes. See the attached excerpt, page C-15 from the updated Improvement Plans. This may be a good solution. However, it has not 2 Atascadero Planning Commission January 7, 2023 been discussed by anyone at the City or 10850, LLC with Ms. Ramsum or her representatives. In addition, the City has added numerous new conditions addressing the need for private easements. So far the developer has ignored all these needs and conditions, trespassing on Ms. Ramsum's property on numerous occasions, including today when a crew came onto Ms. Ramsum's property to "maintain" the culvert on her property. Previously the developer actually demolished and removed Ms. Ramsum's fence, both along her property line and for several feet into her property. Ms. Ramsum had to re -build portions of this fencing following the January 2021 flood event, at her cost. The developer provided a replacement property line fence in the form of a concrete block unfinished wall with fencing on top of it, as shown in photos submitted by Ms. Ramsum. D. Recent stormwater management by 10850, LLC has dumped water from the front of its property into the culvert on Ms. Ramsum's property. In her letter submitted to you today there are photos of 10850's new improvised drainage course running alongside EI Camino and then behind the houses at 900 and 910 La Costa, dumping into the 18" drain collection area on Ms. Ramsum's property. This is not on any plan we know of. On one occasion during a storm event in December 10, 2022, the Fire Department breached this impromptu ditch and diverted water to EI Camino, where it ended up back on La Costa but not at the entrance to the 18" pipe on Ms. Ramsum's property. This action saved certain flooding at 920 La Costa, where the drainage pipe was at full capacity. See photo with Ms. Ramsum's letter of today's date. E. Condition 28 of the proposed project approval requires the developer identify and secure easements for overflow routes. This does not appear to have a plan. Ms. Ramsum has not been approached. Given that flooding her house was the previous "overflow" route she would truly love to have this clarified. Deferring to some unspecified engineering at this point seems inadequate and irresponsible. 3 Atascadero Planning Commission January 7, 2023 2. The parking for the proposed project appears to be short of City requirements. In the 2017 approval there was a reduction of parking based on the proposed senior use. The senior use has been removed. Although density dropped somewhat in the current plan, there does not appear to be an explanation of the significant parking reduction afforded in 2017 and apparently carried through to 2023 as applied to the present new approval. 3. The environmental document should be reviewed. The present staff report refers to an environmental approval but the environmental document is nowhere to be found, even after inquiry to the City Community Development department. Instead the agenda report refers us to a one-page Negative Declaration from 2017, which is supposed to be the result of an environmental review. That document says it is releasing "a draft initial study and Mitigated Negative declaration". It then says "This document may be viewed by visiting the Community Development Department listed under the lead agency address, or accessed via the City's website." When we requested the document from the Community Development Department yesterday no one could find it. A search of the City's web site also came up empty. It is not included with the 2017 staff report for this project. Many City actions are represented with extensive environmental documents which are found on-line. Not so for this project. There is no trail of evidence to support the Negative Declaration. Normally this would include a checklist and supporting studies. There is a planning "checklist" in the 2017 staff report but it has only a few items relating to environmental issues. Normally this checklist is extensive and discloses many different issues of consideration. Referenced in the 2017 approval and its limited checklist are visual studies by staff, a grading plan with public works and other studies or evidence to back up the conclusions leading to mitigation and the Negative Declaration. These evidentiary bases for the Negative Declaration are not part of any public record online that could be located. The CEQA process should be reviewed in light of the concerns over stormwater management, visual concerns and parking, as well as other environmental issues the Commissioners may feel are relevant. At the very least, the City staff should produce the actual environmental document upon which the 2017 Negative Declaration was based. If the Commission determines the project has changed in any significant way (altered stormwater management) or new environmental E! Atascadero Planning Commission January 7, 2023 impacts are recognized (stormwater management), a new environmental document should be required. It is hoped the Commission will recognize that serious issues have arisen as a result of the construction of the current project. It is procedurally and ethically correct to re -assess the impacts of the project in light of these issues at this time. We hope the Planning Commission will get some solid answers to the concerns raised by this neighboring property owner. Cc: Paula Ramsum John Belsher 5 and STORMWATER CONTROL PLAN o Z �: ir� Imo, ■' • i I ilr, ..... VESTING TENTATIVE TRACT MAP #3099 Prepared for: Hartberg Properties, LLC Prepared by: Wallace Group January 31, 2018 Revised March 3, 2021 discharge into an 18 -Inch storm drain and discharge downstream within its historic pathway and ultimately into the Salinas River. DMA 'I and DMA 2 consist of the northernly rooftop area of the apartment building and the northerly parking lot areas and will discharge flows into an underground detention chamber, C1. Stormwater runoff from the southern rooftop and southern parking lot (DMA 3 and DMA 4) will discharge into C2. For large storms, flow from Cl and C2 will be conveyed to detention Chamber C3. DMA 5 and DMA 8 consist of the roadway (Keffury Lane) and the front portion of the proposed townhomes. Runoff from these two DMAs will be directed to Keffury Lane and conveyed to a curb Inlet connected to Chamber C3. DMA 7 and DMA 8 consist of the rear portions of the townhomes. This runoff will be conveyed through a rear yard drainage swalelopin to Keffury Lane. Runoff from DMAs 5 through 8 will discharge into detention chamber 3 wind will-- ultimately be discharged offsite. a.wuM�.xs[�asxrsmwa ®•�•• s:ar'anwroc s a y i i f vj Figure 4 — Drainage Management Area Delineation flows back to pre -development rates. The City of Atascadero Stormwater Control Plan Permit Documentation is included in Appendix B. The individual drainage basin peak flow rates are provided in Table 3 below: TABLE 3 DMA PEAK FLOW RATES Existing Storm Event Peak Flow 3.72 95TH 0.06 2 -YR 1.63 I O -YR 3.88 50 -YR 7.19 I 00 8.42 DMA1 0.245 0.12 0.23 0.41 0.66 0.75 DMA2 0.458 0.29 0.55 0.90 1.37 1.54 DMA3 0.246 0.12 0.24- 0.66 0.75_ DMA4 0.453 0.32 0.58 l -0..41 0,93 1,40 1.57 DMA5 0.622 0.31 0.62 1.07 1.69 1.93 DMA6 1.119 0.66 1.25 2.09 3.23 3.65 DMA7 0.273 0.10 0.22 0.41 0.68 0.78 DMA8 0.305 0.12 0.26 0.47 0.78 0.89 The routing schematic of storm flows through the bioretention basins and retention/detention chambers is shown in Figure 5 and outlined in Table 4 below. Figure 5 - Flow Routing Diagram oz -S t Slog o w NV'ld ONICIVIdO 1�tl211 :S3I-W3d02ld E)83SINVH ° �°a lf4lit �5( 'a s In�avv �umi wSg !£3 S@U d 6b* gW iw y�z ? 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LU O 1 y U) z Z Of j W O LL H �rrrtrl A wn �� W rn U poo �.LLJ 9 low y j °� U LLI w 0( ^ U) m Q G Q LJJ= O YMH r ■ U r- r f U) z Z Of j W O LL H $g5 Z W rn U poo �.LLJ 9 M LQL y j °� U LLI w 0( ^ U) m Q G Q LJJ= O YMH � U U $ pug "lit33g8 H $g5 ozR3m ° �3 YMH � w�z;�'a f ION1NOONOISON3 = _ S1N3W3AONdW1311S-NO 660£ lOHN1:S311N3dONd ON381NVH An q ��3AIR p** 7 Y � pa N a i I SiN3W3AOHdW131IS-NO C([C kkiA.[[li f�@E d lw iN M � E 3 x , 16}jjI})1 YF6�eQ � �eSagoc�g e� 1 c ° 880E 1OVU1:S311213dONd ON39V3S N a i I _a C([C N a -II11� 1r P'JIr :II ■r _a C([C kkiA.[[li f�@E d lw iN M � -II11� 1r P'JIr :II ■r _a d lw iN M � E 3 ori ��► vr' ! +Iron. 1 , 16}jjI})1 YF6�eQ � �eSagoc�g e� 1 BURRO BmUM �fff�71G_ Q CIVIL DESIGN TO: Mr John Belsher FROM: Civil Design Solutions RE: La Costa Draiange - Ramsun Property To Mr. Belsher: 18051621-3050 rob@ciyildesign-solutions.cem Based on our field inspection on January of 2023, and a review of the grading plans and associated drainage report it is our professional opinion that the current flooding situation at the above noted location is clearly caused by the adjacent development at 10850 El Camino Real and their inadequate outlet. There is an existing gap between the outlet pipe from the project and an existing 18" pipe that runs through the Ramsun Property. In large storm events the outlet pipe becomes full overflows and floods the existing house. This flooding will continue to occur until an adequate solution is determined. The City and the developers engineer have provided an updated plan that identifies a solution. However this solution is flawed and if implemented has the possibility to create additional flooding and additional damages to the adjacent homes. The following list outlines the issues with the developers engineers proposed solution. 1. The box that is being proposed on the Ramsun property does not allow for existing flow from the concrete gutter located on the Ramsun property and the neighboring properties to drain into it. This will basically block the existing flow from all the properties that drain to this location causing a worse flooding problem. 2. There is no adequate overland escape route should the pipes get clogged. Per standard civil engineering practices and City codes all drainage facilities must contain an adequate easement and all underground pipes must have a proper overflow should the underground pipes become non functioning or clogged. 3. The runoff from DMA 8 (rear yards of lots at 10850 EI Camino Real) as indicated in the project drainage report clearly does not go to their underground system on their site. The underground drainage collection system is uphill from the lowest point of drainage collection and conveyance. All of the runoff from the rear yards of DMA 8 and the back half of the roofs will flow directly to the Ramsun Property and not be collected in the underground collection system. 4. The proposed box located on 10850 El Camino Real does not include a way for the water from the adjacent swale to get into the box. The box indicated has an at grade inlet on the top and no provision for the water collected into the swale to get into the box. This will create a situation where the water from the swale diverts the box and flows onto the Ramsun property. Therefore it is our professional opinion that based on the existing condition and the proposed solution flooding will continue to occur on the Ramsun property causing damages to property. These damages are a direct a result of the construction of the project located at 10850 EI Camino Real improper inadequete design, not accounting for the runoff from all areas, not accounting for the possibility of clogging and not having a proper overflow. Robert J. Montoya Civil Design Solutions DATE 01/22/2023 CIVIL DESIGN SOLUTIONS r- 234 Atlantic City Ave Grover Beach, CA RCE #68101 PLS #7190 February 13, 2023 Ten850 LLC 701 Shadow Lane, #310 Las Vegas, NV. 89106 Mr, John Carnesale Regarding Ten850, LLC — Applicant Hearing on Tentative Map — February 21, 2023: Review of Drainage Design currently approved and being installed with the project improvements. Dear Mr. Carnesale: I have provided a review of the current drainage design for the project referenced and have conclusions based upon that review which are provided in this letter. Peabody Engineering is not the design engineer for the project nor have we been involved in the project drainage design or construction. We have reviewed the Final Drainage Report and Stormwater Control Plan for Hartberg Properties prepared by Wallace Group on January 31, 2018, and revised on July 31, 2018. We have also reviewed the approved Site improvement Plans for Hartberg Properties dated January 15, 2021 which design the site grading for the project and drainage system for the project. Both documents have been stamped and signed by Wallace Group as being complete and ready for construction. Both documents have been reviewed and approved by the City of Atascadero and are the basis for the construction of the project and the improvements ongoing. The drainage report provided a clear description of the existing drainage conditions. The existing site prior to construction drained to an existing 18" storm drain line with a flared end section to accept the drainage from the Ten850 site and into the public drain system in La Costa Court. This drain pipe system lies between 910 and 920 La Costa Court and is a public drain line owned and maintained by the City of Atascadero. This existing 18" storm drain pipe runs from the property boundary of Ten850, between the houses located at 920 La Costa Court and 910 La Costa Court, and to La Costa Court where the public drain line conveys the drainage further into the City of Atascadero rlr'inana eaie�nw 1 Fye i,v��i last V V $i Q items r,Xi�aJ tP � .11 � 1 Ll '7 iWilli %A I G since the time it was constructed with the suk VGv LQ %.,VW0 vt7 t1i i1 1 '-% 1"% .•..s EXISTING DRAINAGE PRIOR TO PROJECT DEVELOPMENT: The drainage condition and flow produced from the Ten850 project site prior to any construction has been evaluated in the drainage report. This analysis was completed using HydroCAD CIVIL ENGINEERING * SURVEYING * PROJECT MANAGEMENT * STRUCTURAL DESIGN Stormwater Modeling, which is an accepted modeling program for evaluating storm flows for 2 year through 100 year storm events. NOAA precipitation frequency estimates were used for the area to come up with the design storm events for modeling. NOAA precipitation history for storm events is one of the most widely used and accurate methods of modeling precipitation storm events and is considered an acceptable standard when producing stormwater modeling for various storm events. Through this analysis, Wallace Group found that existing flows from the Ten850 site into the 18" storm drain pipe prior to construction of this project were as designated below: PROPOSED DRAINAGE FROM PROJECT DEVELOPMENT: The project drainage was then evaluated and the drainage flows from each Drainage Management Area (DMA) were quantified in the drainage report. Each DMA has a certain amount of impervious surface (pavement, roof, street, driveways, etc.). This new impervious surface increases and concentrates the drainage within the project for each DMA. Such increase drainage flow was calculated for each DMA and a total drainage flow for each DMA was found. This increased flow represents the flow from the new project once the project is completely constructed. Our review of the proposed project drainage system and project grading plan showed that all drainage from the Ten850 project site is being collected by the new drainage system, detained onsite through the use of underground chambers, and is regulated for outflow from the site to insure the flow from the developed project does not exceed the existing drainage flow condition prior to the development of the project. To accomplish that, the underground chamber systems designed with the Site Improvement Plans have flow control manholes constructed to hold back storm water during the various storm events and reduce the flow to the existing drain system in all storms evaluated. Wallace Group found that the resultant outflow from the project site once development is completed would be reduced for the annual (95th Percentile) storm even, 10 year storm event, 50 year storm event, and 100 year storm event as determined below: CIVIL ENGINEERING * SURVEYING * PROJECT MANAGEMENT * STRUCTURAL DESIGN The flow into the 18" storm drain pipe from the project prior to the development is designated as "Existing", and the flows shown as "Detention C3" are the proposed flows from the project once the project development is completed. In ail storm event cases evaluated in the drainage report, the flow from the project into the 18" storm drain pipe running between 910 and 923 La Costa Court is reduced once the project construction is completed. Peabody Engineering has reviewed and checked the calculations provided in the drainage report and finds them to be accurate. This includes calculation of the existing storm event flows, calculation of the proposed storm event lows, and modeling of the detention onsite to reduce the outflows from the project once completed Sincerely, Ross Peabody CIVIL ENGINEERING * SURVEYING * PROJECT MANAGEMENT * STRUCTURAL DESIGN Planning Commission City of Atascadero 6500 Palma Ave. RE: 103850 LLC Tentative Track Map Feb. 7, 2023 Dear Commissioners - RF— I D FEB 7 2023 5Did- 0 C My name is Paula Ramsum, and 1 own a custom home at - ! La Costa" Court','which is adjacent to the Project at 10850 E1 Camino Real, I have invested in several homes in Atascaderoover the years, starting in 2010.1 have found Atascadero to be a nice area to invest in and my tenants have liked living here. This all changed the night of January 27, 2021, when my nightmare begaali,got a call from' my tenants late at night informing me the house they are living i6 -is flooded with mud`4nd water and the Eire Department had to unclog the small drain that runs across my property. Plater find'out the construction site had been instructed to divert ail water runoff fror»-this large 3.79 acres of newly graded unstable construction site to the small 18 inch drain at the back corner of my lot during construction. At this point, construction has taken years to build, still is not complete and now they want to build more. I was never informed of this plan to divert more water than this small drain cart handle.I was never informed that my home would be in danger. There was a well -advertised and predicted rain, event scheduled for January 27, 2021. mays before this rain event the construction crews 1.removed my fence at the back of my property that backs up to the 10850 site, without any notice or permission. This fence would have protected my house holding back the mud and water and giving the Fire department more time to protect our properties. There were other properties flooded that night as well. I've been informed the contractor was out there in the rain grading the lot during the day, which only made the soil even more unstable. Then in the middle of the heavy rain event, they went home and soon afterwardsmy Dome flooded. This was a preventable event, with proper drainage plans that actually v,. `,.-My house was severally damaged, which include all the flooring, walls, cabinets and more. My tenar+ta were displaced, 1 had to put them up in a hotel, and they eventually found ne-w housing. At first the i.7,eE,ner of the site accepters blame and assured me they would pay for all the damage and lost rents. After many delays they turned the claim over to their insurance company. Several months later the insurance company was ready to settle with me. Then Amanda, the main contact for the property owner and construction company, instructed the insurance adjuster not to issue the settlement. Amanda told the insurance adjuster that it was the City of Atascadero's fault the flood happened because the City instructed fabric to be placed over the drain pipe which caused the pipe to clog. Now i am stuck with no insurance settlement to repair my home, not knowing who caused this flood to happen. I filled a claim against the City of Atascadero, which was denied. I have had to borrow money to make the repairs and have lost rents for over 2 years now. You have some plans that may or may not work when the project is completed, which is a big issue. However there appears to be no real plan for during construction, which has been taking years, and now .. .T o. .. they want to build more. Since the original flood event, January 27, 2021, 1 have lived in fear that it would happen again, and sure enough it did on 12-10-22. However this time I was out there monitoring the drain in the pouring rain, as well as my neighbors. I have included a picture of the drain pipe at maximum, just before the l=ire Department arrived and saved our houses from damage. I have been living this nightmare for two years and something needs to be done to solve these major flaws in the project. These flaws need to be addressed and solved before allowing this contractor to continue. My neighbors and I have had to deal with the continuous noise, dust for we'.1..-over 2. years. Now we have intrusive block walls, and massive buildings that tower over our yards .> The original construction site property used to be below the grade ofimy, pri-perty, now it's 8 feet above my property, and I have to look at this massive block wall that was not sealed properly and is now a stained eyesore (see photos). On top of the block wail are massive two :tory attached buildings with high pitched roofs. The photos attached show the massive stained block wall, the open space above the wall will be blocked out with the massive second story that is to be built there. I also have a picture of my yard before construction, 5 foot fence looking out to open sky. Now we look at intrusive block wall and massive buildings. Another picture shows the drain that was installed by 10850 LLC looking through it from my side, with an inlet at the top of the developer's 18" outlet pipe discharging to my property. It shows an inlet on the top, but nowhere in the drainage plans show this. Where is this water coming from? it is not on the plan and not in the drainage calculations. Other pictures show a drainage canal that was built at the time the block wall was installed, which drains water from 10850 EI Camino behind 900 and 910 La Costa Court into the 18 inch pipe at the corner of my back yard. The construction site has dug a large trench along El Camino Real, which feeds water behind my neighbor's back yards to my property. This diverts water from the front of the flooded construction site to my property. After the flood on 12-10-22, water has overflowed onto El Camino turned the corner at La Costa and funneled into another City drain at the front of my home at 920 La Costa Court. When I brought this up to Lori Azeen, she told me this was blocked off and not being used, but as of today it is still there. Please either deny approval or table it until all the problems with this project can be solved to protect the neighboring properties. In the meantime we hope the City will control this out of control run-off situation as we still have months of potential storm action. Paula Ramsum s J .s ' § t " ff{fj -�t`y s _ ,f�E` .I.'a� r rv' ,'. rs1 i° t�•� r fir_ ,.ti s...' r "7,- 1 ,.s /, r as A • �i � Y ` 3' r i , s7 Iry �> �� � n r+ •f : ���. r �f`. . '".^.r £sjf tri ,n s•�> tf y...` r "+ #'8, r } r�� if{ rr "�.f �� �,�/ � � � Yr fi•Yr �r ¢, , -r ,J cif 4. rr' r r ' + r "f r•, r Tr e , i r t£ !{ rr. fit a r i i ✓, o J .v r f- f°° .ly Ys .• t .r3 i s�.r + s'jf 4f tY J.t I f.. �' . ' e •„� w f � .;, rts. ..!/ .• r. a At ;. rr. k-..°�`r y /i °i ��t" � �t sY. sr '?�+�Ey, e� ,� r "%e t r t •.. ,r �r l r{ • r If> �ri '�! A k ir�'r y ar" .. �` � }, far" t :r �•- Pf%! •.7rJ � Y :i � P , �f t; ` + y.. f'� '£/ ♦ y. k 4i J ; ^ 's, , A,P I q.s, Fi . rw 'r�r , s fe r ,,f`. of - ,rf _ . £,r r is '.ar�t1' 4t r .+'-� ; .Y f .SYS - " , ". I.s ,. ;`.<• '�.. M.J._ w ,•«,$ r .• ' - � M M _ , •. -�wa,• ...' �• �`+. _P r_ w y . RY �,�+ P' 6 w . , w y .. _.. -4" 2'STORY HO ..- W 7:39 sell w December 10, 2022 p, 9:12 PM TRENCH ALONG EL C MINO REAL 640 3450 Broad Street, Suite 101 San Luis Obispo, CA 93401 805-316-5892 Planning Commission FEB 7 2023 City of Atascadero (fiec`j- e r-JeaJ Iwo 6500 Palma Avenue Atascadero, CA PC-comments@atascadero.org Re: Feb 7, 2023 Agenda Item 2 — 10850 EI Camino Real Tentative Tract Map Dear Commissioners: I represent the owner of property at 920 La Costa in Atascadero, Paula Ramsum. This property includes a custom rental house rented out by Ms. Ramsum for several years. The property has an 18" culvert which is designed to accept some run-off from the property at 10850 EI Camino Real. Prior to construction next door by 10850 LLC, there is no record of any flooding at my client's property. Although the 18" pipe on 920 La Costa connects directly to a City storm drain on La Costa, the City denies owning the 18" pipe. This issue is a subject of dispute and is under litigation. On January 27, 2021, stormwater from 10850 EI Camino overwhelmed the 18" culvert at 920 La Costa, causing extensive flooding of the house at 920 La Costa as well as a neighboring house. The construction site at 10850 was a mess, with grading going on that very day. Erosion control measures were unsuccessful and in fact clogged up the 18" culvert on Ms. Ramsum's property. Despite promises to help from both the City and the Developer, no help was forthcoming (aside from the much appreciated disaster response of the fire department). There is now a lawsuit filed against the City and the developer for damages to Ms. Ramsum from this incident. After two years, my client has not yet been able to bring her tenants back into the property, suffering mounting losses. Atascadero Planning Commission January 7, 2023 Against this backdrop the City is now contemplating a tentative map to allow the developer to proceed with further development of the property at 10850 EI Camino. We appreciate that there is already an approved development. However, there are a few issues which the Planning Commission can and should take a close look at. I will list them here. 1. The project does not conform to the drainage documents approved by the City. A. The project was approved previously with reference to a "Grading plan" which was reported to be under review by Public Works. See 2017 project staff report, at page 8. There is no known record of this "grading plan". The 2017 approval is found at https://www.atascadero.org/files/CD/RECENT PROJECTS/HartbeLg PC Staff Report.pdf B. After project approval in 2017, the City accepted a Drainage Report and Stormwater Control Plan, which was updated March 3, 2021. htt s://netor 8050650.share oint.com/:b:/s/BelsherLaw/ETnFaXurPQhEinmSYlz 3391BweigsWJDYo2gfKKtYUdc A?e=hQhzdo Attached is an excerpt from this report showing the area of concern. This report includes a mapping of the site into various drainage areas. The area next to Ms. Ramsum's site is designated DMAB. The water from this area is described as flowing through an unidentified "swale" back to the private street on the 10850 property. However, there is no such swale and it is actually uphill. Instead there is a drainage inlet placed in the 18" pipe belonging to 10850, which appears to be intended to siphon this water from DMA 8 directly into the 18" pipe of 10850. The result is that there is a large area of this site which is unaccounted for as to stormwater drainage and appears to add to the volume of water metered out to the 18" culvert on the property at 920 La Costa. C. The Improvement Plans approved by the City in 2021 include new provisions for connecting the two 18" pipes. See the attached excerpt, page C-15 from the updated Improvement Plans. This may be a good solution. However, it has not 2 Atascadero Planning Commission January 7, 2023 been discussed by anyone at the City or 10850, LLC with Ms. Ramsum or her representatives. In addition, the City has added numerous new conditions addressing the need for private easements. So far the developer has ignored all these needs and conditions, trespassing on Ms. Ramsum's property on numerous occasions, including today when a crew came onto Ms. Ramsum's property to "maintain" the culvert on her property. Previously the developer actually demolished and removed Ms. Ramsum's fence, both along her property line and for several feet into her property. Ms. Ramsum had to re -build portions of this fencing following the January 2021 flood event, at her cost. The developer provided a replacement property line fence in the form of a concrete block unfinished wall with fencing on top of it, as shown in photos submitted by Ms. Ramsum. D. Recent stormwater management by 10850, LLC has dumped water from the front of its property into the culvert on Ms. Ramsum's property. In her letter submitted to you today there are photos of 10850's new improvised drainage course running alongside EI Camino and then behind the houses at 900 and 910 La Costa, dumping into the 18" drain collection area on Ms. Ramsum's property. This is not on any plan we know of. On one occasion during a storm event in December 10, 2022, the Fire Department breached this impromptu ditch and diverted water to EI Camino, where it ended up back on La Costa but not at the entrance to the 18" pipe on Ms. Ramsum's property. This action saved certain flooding at 920 La Costa, where the drainage pipe was at full capacity. See photo with Ms. Ramsum's letter of today's date. E. Condition 28 of the proposed project approval requires the developer identify and secure easements for overflow routes. This does not appear to have a plan. Ms. Ramsum has not been approached. Given that flooding her house was the previous "overflow" route she would truly love to have this clarified. Deferring to some unspecified engineering at this point seems inadequate and irresponsible. 3 Atascadero Planning Commission January 7, 2023 2. The parking for the proposed project appears to be short of City requirements. In the 2017 approval there was a reduction of parking based on the proposed senior use. The senior use has been removed. Although density dropped somewhat in the current plan, there does not appear to be an explanation of the significant parking reduction afforded in 2017 and apparently carried through to 2023 as applied to the present new approval. 3. The environmental document should be reviewed. The present staff report refers to an environmental approval but the environmental document is nowhere to be found, even after inquiry to the City Community Development department. Instead the agenda report refers us to a one-page Negative Declaration from 2017, which is supposed to be the result of an environmental review. That document says it is releasing "a draft initial study and Mitigated Negative declaration". It then says "This document may be viewed by visiting the Community Development Department listed under the lead agency address, or accessed via the City's website." When we requested the document from the Community Development Department yesterday no one could find it. A search of the City's web site also came up empty. It is not included with the 2017 staff report for this project. Many City actions are represented with extensive environmental documents which are found on-line. Not so for this project. There is no trail of evidence to support the Negative Declaration. Normally this would include a checklist and supporting studies. There is a planning "checklist" in the 2017 staff report but it has only a few items relating to environmental issues. Normally this checklist is extensive and discloses many different issues of consideration. Referenced in the 2017 approval and its limited checklist are visual studies by staff, a grading plan with public works and other studies or evidence to back up the conclusions leading to mitigation and the Negative Declaration. These evidentiary bases for the Negative Declaration are not part of any public record online that could be located. The CEQA process should be reviewed in light of the concerns over stormwater management, visual concerns and parking, as well as other environmental issues the Commissioners may feel are relevant. At the very least, the City staff should produce the actual environmental document upon which the 2017 Negative Declaration was based. If the Commission determines the project has changed in any significant way (altered stormwater management) or new environmental 4 Atascadero Planning Commission January 7, 2023 impacts are recognized (stormwater management), a new environmental document should be required. It is hoped the Commission will recognize that serious issues have arisen as a result of the construction of the current project. It is procedurally and ethically correct to re -assess the impacts of the project in light of these issues at this time. We hope the Planning Commission will get some solid answers to the concerns raised by this neighboring property owner. Cc: Paula Ramsum John Belsher 5 Im-EM" *kI;j -IOC~ 2 Prepared for: Hartberg Properties, LLC Prepared by: Wallace Group WALLACE GROUP .January 31, 2018 Revised March 3, 2021 discharge into an 18 -inch storm drain and discharge downstream within its historic pathway and ultimately into the Salinas River. DMA 1 and DMA 2 consist of the northernly rooftop area of the apartment building and the northerly parking lot areas and will discharge flows into an underground detention chamber, C1. Stormwater runoff from the southern rooftop and southern parking lot (DMA 3 and DMA 4) will discharge into C2. For large storms, flow from C1 and C2 will be conveyed to detention Chamber C3. DMA 5 and DMA 6 consist of the roadway (Keffury Lane) and the front portion of the proposed townhomes. Runoff from these two DMAs will be directed to Keffury Lane and conveyed to a curb inlet connected to Chamber C3. DMA 7 and DMA 8 consist of the rear portions of the townho es. This runoff will be conveyed through a rear yard drainage swale lopin to Keffury Lane. Runoff from DMAs 5 through 8 will discharge into detention C'hamber 3 and will ,. ultimately be discharged offsite. 5 fO' S� uol flows back to pre -development rates. The City of Atascadero Stormwater Control Pian Permit Documentation is included in Appendix P. The individual drainage basin peak flow rates are provided in Table 3 below: TABLE 3 DMA PEAK FLOW RATES Basin Existing Storm Event Pak Flow •- 3.72 95TH 0.06 2 -YR 1.63 1 0 -YR 3.88 i 7.19 f0 8.42 DMA1 0.245 0.12 0.23 0.41 0.66 0.75 DMA2 0.458 0.29 0.55 0.90 1.37 1.54 DMA3 0.246 0.12 0.24 j 0.41 0.66 0.75 DMA4 0.453 0.32 0.58 1 0.93 1.40 1.57 DMA5 0.622 0.31 0.62 1.07 1.69 1.93 DMA6 1.119 0.66 1.25 2.09 3.23 3.65 DMA7 0.273 0.10 0.22 0.41 0.68 0.78 DMA8 0.305 0.12 0.26 0.47 0.78 0.89 The routing schematic of storm flows through the bioretention basins and retention/detention chambers is shown in Figure 5 and outlined in Table 4 below. Figure b- Flow Routing Diagram pYY\A q H I ��' vJ OZ -9L S1O1 NV -1d JNIOVi19 ci w ° 660£ 1OV8i :S311213dO21d ON391NVH o <Q oW ,., € g�S � 8 � 6'� bG u % �w �— O mi:: Q'wSL+ "4 °$ P;w �6 5 ao a IS s �e 83a W w a ov 8 a w y Yuii U 2uj i6 o aY3paZ °s < : fx W® x - ,^ 133HS 31111 d w S1N3W3AONdIN1311S-NO Q 31V0 unlln 660£ 1OV211:S311213dOad 9N381NVH to ° � VI N Q W LU 0 R p 3 sig W 3g o E a s RRaa� r�'�q�a3 MH a � � -----'050 � 0000. w xr -a0Hmaay € w 5 F a g� ;sz. zo �A o� 2 i 5 5 5 a 3 5 5 5 5 Q 1IVA Q CL ■ E Q 96 WCL 0)U 000 w �Y UJ ffial--w O i co _ w ■ a Q Q a s RRaa� r�'�q�a3 MH a � � -----'050 � 0000. w xr -a0Hmaay € w 5 F a g� ;sz. zo �A o� 2 i 5 5 5 a 3 5 5 5 5 Q Q CL w w LL Q 96 WCL 0)U 000 w �Y UJ ffial--w O co Q Q U = O U U a s RRaa� r�'�q�a3 MH a � � -----'050 � 0000. w xr -a0Hmaay € w 5 F a g� ;sz. zo �A o� 2 i 5 5 5 a 3 5 5 5 5 IONINOO NOISON3 i S1N3W3AONdW13AS-NO a 660£ 1OV'd1 :S3LL'd3dO'dd 9N39iUVH s a o a o R z g eb a Y a till gg®®e dg�E� z `6ppa � V � 0 0 0 0 a M y 0 If w 0 ��;-{ ♦wow m..e an�m E S.LN3W3AONdW131IS-NO HIS z =M'w SlIV130 G \ t pp =p 660£ 1OHN1;S311b3dONd E)dBSV3S [ o M y 0 If w 0 ��;-{ ♦wow m..e an�m ,rirsr�ucc - E 'i HIS = s 6C( =M'w G \ t pp =p v. 2 Q mm N F 0 a h ,rirsr�ucc - E 'i = s 6C( d y f I Q a h sal r -non _ gd i u p iag � a = Y�Si E i Q ,rirsr�ucc - l rp I Q a h sal r -non _ Ten850, LLC 701 Shadow Lane, Suite 150 Las Vegas, NV 89106 Kelly Gleason, Planning Department City of Atascadero 6500 Palma Avenue Atascadero CA 93422 Re: Ten850, LLC —Applicant Hearing on Tentative Ma — February 21. 2023 Dear Kelly: EIS FEB 16 2023 I wanted to put on record some things that came up during the Planning Commission hearing on February 7, 2023. We are going back in front of the Commission on February 21, 2023, so I hoped this information could be provided to the Commission prior to our next hearing. The item for approval by the Commission on February 21, 2023, is approval of a new tentative map, which takes 48 "for rent" units, and instead proposes 43 "for sale" units. The amount of parking has been increased from 60 spaces to 83 spaces, as the previously -approved map was for senior housing which generally requires less parking. The parking for the modified project meets all City requirements, and will be on-site. The Ten850 project will not contribute to parking issues on El Camino.. Drainage and Engineering: Ross Peabody is our engineer, and he explains in the attached letter that the drainage plan was updated in 2022, and meets all current City and state requirements. There were statements made that the engineering was out of date, and that it has not been revised to address current code requirements. That is not true. Engineer Peabody explains that in his letter. The neighbor who spoke at the hearing, Paula Ramsum, alleged that there was no history of drainage issues prior to construction beginning at 10850 El Camino. However, the owner only purchased her property in 2020, and the flooding occurred in January of 2021. In fact, historically there were quite a few drainage issues in that part of the City. In the City -approved drainage plans for the Ten850 project — and this is also addressed in Engineer Peabody's letter — the site elevation was raised by eight feet, in order to insure any run-off drains away from the neighbor's subdivision and towards the retention basin on the Ten850 property. During construction, Ten850 installed a block wall on the property line, and the old fence (which was on the Ten850 property, not on the neighbor's property) was removed. There is a new drainage pipe that starts at the property line, adjacent to the new wall, and collects surface water, moving it to the south, away from the neighbor's property and into the retention basin. Drainage from the neighbor's subdivision is directed to the east through a collection drain on the neighbor's side of the, wall, and that drain directs water through the neighbor's subdivision, through an underground pipe, across El Camino to a drainage pond. The Ten850 project installed a swale to help the neighbor's subdivision with their drainage, Both City and state inspectors are on the Ten850 project site on a regular basis, inspecting the existing drainage and flood control construction, and enforcing the conditions in those plans. The City can confirm those inspections have taken place. The 2021 Flooding Incident: The flooding incident that the neighbor and her attorney spoke of during the February 7th Commission hearing was a freak occurrence, due to the drainage improvements being under construction. Two homes were affected — 910 La Costa and 920 La Costa; 910 La Costa was more heavily damaged. The complaining neighbor owns 920 La Costa. The neighbor categorically told this Commission that the developer of the Ten850 project provided no help, which is absolutely not true. We must assume she was exaggerating the circumstances due to her lawsuit, currently pending against both the City and the developer. In fact, immediately after the flooding damage occurred, the neighbor's tenants were moved into a hotel, and Sery-Pro was sent in to box up belongings and use their equipment to dry out the house. Ten850, LLC, contacted its insurance company. Simultaneously, Ten850 LLC has spent more than $36,000.00 to help the complaining neighbor. The neighbor's tenants were relocated, and $8,416.86 in hotel expenses were paid. The neighbor was reimbursed $6,900.00 in lost rental income. Sery-Pro was paid $3,141.86, and $8,696.50 was paid in legal fees to gain the insurance company's cooperation. Neighbor Ramsum claimed $80,000.00 in damages to the 920 La Costa house, when the developer had estimates at 25% that, and she refused to mediate or enter into formal discussions before filing suit. The neighbor's last communication with the developer was in January of 2022. By August of 2021, neighbor Ramsum had filed suit against the developer and the City. If she had cooperated with us, she could have been back in her house in March of 2021, like her neighbor at 910 La Costa. Ten850 LLC repaired the damage to 910 La Costa and had that owner back in his house, all repairs completed, within a few months. The owners of 910 La Costa received alternate housing through the end of March 2021, and while they were out, the 910 La Costa home was restored, drywall replaced and re -painted, the floors replaced, and the countertops replaced. The owner of 910 La Costa noted that his deck — and most owners' decks in that subdivision — were built raised due to the regular drainage problems. Future drainage issues in that neighboring subdivision should be solved, in part, by the drainage plans that will be implemented for the Ten850 project. By the way, neighbor Ramsum's attorney claimed there was three feet of water in the 920 La Costa house, but there was no more than three inches, according to Sery-Pro. It's important to note that the recent atmospheric river rains in the area have not produced any additional flooding to the surrounding properties, including 910 La Costa and 920 La Costa. On a similar note, 910 La Costa is lower than 920 La Costa as it relates to the drainage. Grading: Neighbor Ramson and her attorney claimed there was no record of a grading plan. There is a grading plan. The approved Site Improvement Plans include sheets C-10 through C- 16 which are the final grading plans for all the lots, streets, and open space areas for the project. By approving the Site Improvement Plans, the City has approved the grading for the site which is the grading permit approval that was referenced by one of the Commissioners during the meeting. CEOA Compliance: The neighbor's attorney, John Belsher, claimed that the environmental review from 2017 was done without any engineering in hand, but there is no possible way to challenge the CEQA work done at that time. The project in front of the Commission at the February 215' hearing is only to reduce the number of units from 48 to 43, and allow for sale of those units. This change has no potential environmental impacts that are more or different than the project approved in 2017. Attorney Belsher said he spent an afternoon at the City and was unable to locate the 2017 Negative Declaration; that is no reason to open up environmental review on such a simple modification. Conclusion: The developer has been in the City of Atascadero for 25 years, as owners of the 140 apartment units across El Camino. After 25 years, there have been no significant complaints from the tenants or the neighbors for that complex. After 25 years, the developer has no desire to cause issues with the neighbors, and it would appear that only one neighbor is disgruntled and unhappy with the situation. We hope this information is helpful. We will be available to answer any questions at the February 28�h hearing. Thank you. Sincerely, John Camesale February 13, 2023 Ten850 LLC 701 Shadow Lane, #310 Las Vegas, NV. 89106 Mr. John Carnesale Regarding Ten850, LLC —Applicant Hearing on Tentative Map — February 21, 2023: Review of Drainage Design currently approved and being installed with the project improvements. Dear Mr. Carnesale: I have provided a review of the current drainage design for the project referenced and have conclusions based upon that review which are provided in this letter. Peabody Engineering is not the design engineer for the project nor have we been involved in the project drainage design or construction. We have reviewed the Final Drainage Report and Stormwater Control Plan for Hartberg Properties prepared by Wallace Group on January 31, 2018, and revised on July 31, 2018. We have also reviewed the approved Site Improvement Plans for Hartberg Properties dated January 15, 2021 which design the site grading for the project and drainage system for the project. Both documents have been stamped and signed by Wallace Group as being complete and ready for construction. Both documents have been reviewed and approved by the City of Atascadero and are the basis for the construction of the project and the improvements ongoing. The drainage report provided a clear description of the existing drainage conditions. The existing site prior to construction drained to an existing 18" storm drain line with a flared end section to accept the drainage from the Ten850 site and into the public drain system in La Costa Court. This drain pipe system lies between 910 and 920 La Costa Court and is a public drain line owned and maintained by the City of Atascadero. This existing 18" storm drain pipe runs from the property boundary of Ten850, between the houses located at 920 La Costa Court and 910 La Costa Court, and to La Costa Court where the public drain line conveys the drainage further into the City of Atascadero drainage system. This existing 18" storm drain line has drained this property at Ten850 since the time it was constructed with the subdivision to the south encompassing 910 & 920 La Costa Court. EXISTING DRAINAGE PRIOR TO PROJECT DEVELOPMENT: The drainage condition and flow produced from the Ten850 project site prior to any construction has been evaluated in the drainage report. This analysis was completed using HydroCAD CIVIL ENGINEERING * SURVEYING * PROJECT MANAGEMENT * STRUCTURAL DESIGN ftabod engm Stormwater Modeling, which is an accepted modeling program for evaluating storm flows for 2 year through 100 year storm events. NOAA precipitation frequency estimates were used for the area to come up with the design storm events for modeling. NOAA precipitation history for storm events is one of the most widely used and accurate methods of modeling precipitation storm events and is considered an acceptable standard when producing stormwater modeling for various storm events. Through this analysis, Wallace Group found that existing flows from the Ten850 site into the 18" storm drain pipe prior to construction of this project were as designated below: PROPOSED DRAINAGE FROM PROJECT DEVELOPMENT: The project drainage was then evaluated and the drainage flows from each Drainage Management Area (DMA) were quantified in the drainage report. Each DMA has a certain amount of impervious surface (pavement, roof, street, driveways, etc.). This new impervious surface increases and concentrates the drainage within the project for each DMA. Such increase drainage flow was calculated for each DMA and a total drainage flow for each DMA was found. This increased flow represents the flow from the new project once the project is completely constructed. Our review of the proposed project drainage system and project grading plan showed that all drainage from the Ten850 project site is being collected by the new drainage system, detained onsite through the use of underground chambers, and is regulated for outflow from the site to insure the flow from the developed project does not exceed the existing drainage flow condition prior to the development of the project. To accomplish that, the underground chamber systems designed with the Site Improvement Plans have flow control manholes constructed to hold back storm water during the various storm events and reduce the flow to the existing drain system in all storms evaluated. Wallace Group found that the resultant outflow from the project site once development is completed would be reduced for the annual (95th Percentile) storm even, 10 year storm event, 50 year storm event, and 100 year storm event as determined below: CIVIL ENGINEERING * SURVEYING * PROJECT MANAGEMENT * STRUCTURAL DESIGN . I u The flow into the 18" storm drain pipe from the project prior to the development is designated as "Existing", and the flows shown as "Detention CY are the proposed flows from the project once the project development is completed. In all storm event cases evaluated in the drainage report, the flow from the project into the 18" storm drain pipe running between 910 and 920 La Costa Court is reduced once the project construction is completed. Peabody Engineering has reviewed and checked the calculations provided in the drainage report and finds them to be accurate. This includes calculation of the existing storm event flows, calculation of the proposed storm event flows, and modeling of the detention onsite to reduce the outflows from the project once completed. Sincerely, �n �� Ross Peabody CIVIL ENGINEERING * SURVEYING * PROJECT MANAGEMENT * STRUCTURAL DESIGN