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Agenda Item - 2007-01-10 ``t{O LAKE Os k,ECO ,� CommunityDevelopmentDepartment De artment Planning Division Memorandum OR[GON TO: Infill Task Force FROM: Denny Egner DATE: January 5,2007 SUBJECT: Sloped Lot Information The Task Force has discussed sloped lot information on numerous occasions. This memorandum consolidates some of the materials from previous memos and meeting notes in preparation for our work session on sloped lot issues. The materials include: • Task Force Recommendations—July 5, 2006 • Memo and Draft Code - May 31, 2006 • Handout - December 14, 2006 • Meeting Notes—Subcommittee 1 and Task Force At the meeting on January 10, I hope to bring a few site plans for sloped lot development and we can test the concepts on actual sites. At the last meeting, task force members asked for some photo examples of sloped lot development. I have not yet attempted to reconcile any issues that might result from combining the December 14 concepts with the May 31 draft code. The materials follow. Page 1 01/25/2007 1 • Task Force Recommendations —July 5, 2006 (Note these recommendations were never finalized) 12. Sloped Lots Issues: Provide greater flexibility on steeply sloped lots. Recommendations: ■ Increase height up to 45 feet on steeply sloped lots. ■ Apply special design standards to homes greater than 35 feet. ■ Define "steep slope" as an average slope of 20% or more, measured between the front lot line and the most distant point of the building. ■ Measure building height on sloped lots from the middle of the lot. ■ Require that no exterior wall plane on sloped lots exceed 35'in height. ■ For lots sloping downhill from the street at more than 12%, set measurement point for front setback plane height at either 3'below the curb line or the average grade of the front property corners. ■ Allow 18'minimum setback on steeply sloped lots. ■ Do not require support structures to be enclosed. ■ Base front setback plane on the average slope of the land on steeply sloped lots. Page 2 01/25/2007 Memo and Draft Code - May 31, 2006 Sloped Lots 1. Except as noted below, apply the proposed sloped lot standards recommended by the Planning Commission(Exhibit F-2). The recommendations allow building height to be up to 45 feet on steeply sloped lots. Additional setbacks and landscaping are required when height exceeds 35 feet. 2. Adjust the standards so that support structures do not need to be enclosed. A more open, less imposing design can be provided if the base does not need to be enclosed. 3. Define "steep slope"as an average slope of 20%or more. Measure the average slope between the front lot line and the most distant point of the building. This would measure the slope in the area that slope is a problem for a building rather than measuring it across the full length of a property where slope can vary greatly. 4. Front Setback Plane—On steeply sloped properties (a slope of 20% or more), rather than require a 6:12 front setback plane,the slope of the front setback plane should be established based on the average slope of the land. The proposal provides greater flexibility for application of the front setback plane on sloped lots. 5. Front Setback Plane—On lots sloping downhill (away from the street) at more than 12%, the point at which the front set back plane height is measured should be set at either of the following locations: 1) Three feet below the elevation of the curb line(measured at the midpoint of the house frontage); or 2) At the average grade of the front two property corners. This provides flexibility for down slope lots. Page 3 01/25/2007 Point at which Height of the Front Setback Plan is Measured Slope Option 1 — 3 ft. below Option 2 - average curb at midpoint of house grade at property 6. Setbacks on Sloped Lots—Allow an 18 foot minimum setback (from the right-of- way) on lots with an average slope of 20% or more. The proposal allows less site disturbance on a sloped lot. Exhibit F-2 Proposed Code Amendments for Development on Sloped Lots (Subcommittee #1 amendments are shown in the track changes mode) A. Definitions Section 50.02 Definitions Amend Section 50.02 Definitions to include the following: Slope. Slone is measured by the following eauation S=E/D, where S is the slope, E is the vertical elevation change from the highest point to the lowest point, and D is the horizontal distance from the highest point to the lowest point [cross reference sloped lotl. B. Amendments to Height Requirements Section 50.06.055 Height of Structures (R-0, R-2, R-3, and R-5 zones) Add the following section: Page 4 01/25/2007 6. Exceptions to Maximum Building Height on Sloped Lots. The maximum building height on sloped lots may be increased one foot for every 3% of slope over 25%.provided: a. Maximum building height does not exceed 45 feet. and b. For every one-foot increase in height above 35 feet. a corresponding two-foot increase in the yard setback shall be provided. This increased setback shall be applied only to the portion of the structure exceeding 35 feet in height. The setback increase shall be in the down slope direction and may affect the rear yard, side yard. or both the rear and side yards depending on the direction of the slope. No increase to the front Yard setback is reauired. Section 50.07.030 Height of Primary Structures (R-6 Zone) Add the following section: 3. Exceptions to Maximum Building Height on Sloped Lots The maximum building height on sloped lots may be increased one foot for every 3% of slope over 25%. Provided: a. Maximum building height does not exceed 45 feet. and b. For every one-foot increase in height above 35 feet. a corresponding two-foot increase in the yard setback shall be provided. This increased setback shall be applied only to the portion of the structure exceeding 35 feet in height. The setback increase shall be in the down slope direction and may affect the rear yard, side yard. or both the rear and side yards depending on the direction of the slope. No increase to the front yard setback is required. Section 50.08.035 Height of Structures(R-7.5,R-10, and R-15 Zone) Add the following section: 3. Exceptions to Maximum Building Height on Sloped Lots The maximum building height on sloped lots may be increased one foot for every 3% of slope over 25%. provided: a. Maximum building height does not exceed 45 feet. and b. For every one-foot increase in height above 35 feet. a corresponding two-foot increase in the Yard setback shall be provided. This increased setback shall be applied only to the vortion of the structure exceeding 35 feet in height. The setback increase shall be in the down slone direction and may affect the rear yard. side yard. or both the rear and side yards depending on the direction of the slope. No increase to the front yard setback is required. Page 5 01/25/2007 D. Appearance Standards Section 50.06.060 -Dwelling Design—R-5 Zone Add the following sections: 1. Front Setback Plane a. Except as set forth in LOC 50.06.060(n(c), the The front profile of a structure shall fit behind a plane that starts at the front yard setback line and extends upward, to 20 feet in height,then slopes toward the rear of the lot at a minimum slope of 6:12, up to the maximum allowed height at the peak highest point of the roof, as illustrated in Appendix 50.07-C. c. Front Setback Plane on Sloped Lots. i. Down slone (Lots sloping downhill away from the street). The front setback plane shall fully apply on lots that slope down from the street or right-of-way. On lots where the average slope is 12% or greater as measured between the front lot line and the front of the house, the front setback plane shall be measured at either of the following locations: 1) Three feet below the curb line at the midpoint of the house frontage: or 2) At the average grade of the front two property corners. ii. Upslone. On sloped lots that rise up in elevation from the street or right- of-way and -where the average lot slope is 20% or more as measured from the front lot line to the most distant point of the dwelling, the front setback plane shall be determined as follows: the front profile of a structure shall fit behind a plane that starts at the front yard setback line and extends upward, to 24 feet in height.then slopes toward the rear of the lot at a slope eeaual to the average lot slope for a horizontal distance of ten feet. at which noint the structure may rise to the maximum allowed height of 35 feet. as illustrated in Appendix 50.07-D. 3. Maximum Rear Wall Plane. When the height of a structure exceeds 35 feet in the R-5 Zone,the rear elevation of the structure must be divided into smaller areas or planes to minimize the appearance of bulk to properties abutting the site on which the structure is located. When the rear elevation of a structure is more than 500 square feet in area, the elevation must be divided into distinct planes of 500 square feet or less. For the purpose of this standard, areas of wall planes that are entirely separated from other wall planes are those that result in a change in plane such as a recessed or projecting section of the structure, that projects or recedes at least two feet from the adjacent plane, for a length of at least six feet. Windows and doorways are exempt from the 500 square foot limitation. I 4. Support Structures—Finished Appearance. Page 6 01/25/2007 When supporting structures are exposed,the underside of the dwelling shall have a finished appearance. Mechanical and utility systems shall be screened or enclosed within the building. When the height of a structure exceeds 35 feet in the R 5 Zone. supporting structures shall be enclosed. The enclosure shall be sidt:rr:ith ►m.teri l ►hat i lire resistant . iir wMll p LAYS Q viT ric. 5. Landscape Screening of Wall Planes on Steeply Sloped Lots. When the height of a structure exceeds 35 feet in the R-5 Zone. landscape screening shall be provided along the down slope facade or facades of the structure. Landscape screening shall meet the standards of LOC 50.47.015. No screening is reauired in front of building entrances or where the property line of the down slope facade abuts public or private open space. At a minimum, the following plant materials shall be provided: a. A minimum of one tree shall be required for each 12 feet of buildine length alone the down slope facade or facades. b. Trees shall be of a species that reaches a minimum height of 18 feet at maturity. c. Trees shall be planted within 20 feet of the wall or walls that they are intended to screen. 6. Special Setbacks for Sloped Lots. Where the average lot slope is 20%or more as measured from the front lot line to the most distant point of the dwelline.the minimum required front yard setback shall be 18 feet. Section 50.07.040 -Dwelling Design Add the following sections: 3. Front Setback Plane a. Except as set forth in LOC 50.07.040 (31(c).the The front profile of a structure shall fit behind a plane that starts at the front yard setback line and extends upward, to 20 feet in height,then slopes toward the rear of the lot at a minimum slope of 6:12, up to the maximum allowed height at the peak highest point of the roof, as illustrated in Appendix 50.07-C. c. Front Setback Plane on Sloped Lots. i. Down slope(Lots sloping downhill away from the street). The front setback plane shall fully apply on lots that slope down from the street or right-of-way. On lots where the average slope is 12%or greater as Page 7 01/25/2007 ■ measured between the front lot line and the front of the house. the front setback plane shall be measured at either of the following locations: 1) Three feet below the curb line at the midpoint of the house frontage: or 2) At the average grade of the front two property corners. ii. Upslope. On sloped lots that rise up in elevation from the street or riaht- of-way and where the average lot slope is 20%or more as measured from the front lot line to the most distant point of the dwelling. -the front setback plane shall be determined as follows: the front profile of a structure shall fit behind a plane that starts at the front yard setback line and extends upward. to 24 feet in height, then slopes toward the rear of the lot at a slope eaual to the averaae lot slope of 6:12 for a horizontal distance of ten feet. at which point the structure may rise to the maximum allowed height of 35 feet. as illustrated in Appendix 50.07-D. 5. Maximum Rear Wall Plane. When the height of a structure exceeds 35 feet. the rear elevation of the structure must be divided into smaller areas or planes to minimize the appearance of bulk to properties abutting the site on which the structure is located. When the rear elevation of a structure is more than 500 square feet in area. the elevation must be divided into distinct planes of 500 sauare feet or less. For the purpose of this standard, areas of wall planes that are entirely separated from other wall planes are those that result in a change in plane such as a recessed or projecting section of the structure, that projects or recedes at least two feet from the adjacent plane, for a length of at least six feet. Windows and doorways are exempt from the 500 square foot limitation. 6. Support Structures—Finished Appearance. When supporting structures are exposed. the underside of the dwelling shall have a finished appearance. Mechanical and utility systems shall be screened or enclosed within the building. The closure shall be sided viich turitcriaf th�xati is-{rne-resistant. -sty' tturee enclosures shall be considered part of the exterior mall elevation for purposes of addressing wall plane standards. 7. Landscape Screening of Wall Planes on Steeply Sloped Lots. When the height of a structure exceeds 35 feet, landscape screening shall be provided along the down slope facade or facades of the structure. Landscape screening shall meet the standards of LOC 50.47.015. No screening is required in front of building entrances or where the property line of the down slope facade abuts public or private open space. At a minimum, the following plant materials shall be provided: Page 8 01/25/2007 a. A minimum of one tree shall be required for each 12 feet of building length along the down slope facade or facades. b. Trees shall be of a species that reaches a minimum height of 18 feet at maturity. c. Trees shall be planted within 20 feet of the wall or walls that they are intended to screen. 6. Special Setbacks for Sloped Lots.. Where the average lot slope is 20% or more as measured from the front lot line to the most distant point of the dwelling. the minimum required front yard setback shall be 18 feet. Section 50.08.045 - Dwelling Design Add the following sections: 1. Front Setback Plane a. Except as set forth in LOC 50.08.045 (1)(c).the The front profile of a structure shall fit behind a plane that starts at the front yard setback line and extends upward, to 20 feet in height,then slopes toward the rear of the lot at a minimum slope of 6:12, up to the maximum allowed height at the peak highest point of the roof, as illustrated in Appendix 50.07-C. c. Front Setback Plane on Sloped Lots. i. Down slone(Lots sloping downhill away from the street). The front setback plane shall fully apply on lots that slope down from the street or right-of-way. On lots where the average slope is 12% or greater as measured between the front lot line and the front of the house, the front setback plane shall be measured at either of the following locations: 1) Three feet below the curb line at the midpoint of the house frontage: or 2) At the average grade of the front two property corners. ii. Upslope. On sloped lots that rise up in elevation from the street or right- of-way and where the average lot slope is 20%or more as measured from the front lot line to the most distant point of the dwelling,the front setback plane shall be determined as follows: the front profile of a structure shalt fit behind a plane that starts at the front yard setback line and extends upward, to 24 feet in height. then slopes toward the rear of the lot at a slope equal to the average lot slope of 6:12 for a horizontal distance of ten feet. at which point the structure may rise to the maximum allowed height of 35 feet. as illustrated in Appendix 50.07-D. 3. Maximum Rear Wall Plane. When the height of a structure exceeds 35 feet. the rear elevation of the structure must be divided into smaller areas or planes to minimize the appearance of bulk to properties Page 9 01/25/2007 abutting the site on which the structure is located. When the rear elevation of a structure is more than 750 sauare feet in area, the elevation must be divided into distinct planes of 750 sauare feet or less. For the purpose of this standard. areas of wall planes that are entirely separated from other wall planes are those that result in a change in plane such as a recessed or projecting section of the structure, that projects or recedes at least two feet from the adjacent plane. for a length of at least six feet. Windows and doorways are exempt from the 750 square foot limitation. 4. Support Structures—Finished Appearance. When supporting structures are exposed. the underside of the dwelling shall have a finished appearance. Mechanical and utility systems shall be screened or enclosed within the building. The enclosure shall be sided with material that is fire resistant. Support structure enclosures shall be considered part of the exterior wall elevation far uurnacaQ if addre&iri.r,e wall Wane-standards, 5. Landscape Screening of Wall Planes on Steeply Sloped Lots. When the height of a structure exceeds 35 feet, landscape screening shall be provided along the down slope facade or facades of the structure. Landscape screening shall meet the standards of LOC 50.47.015. No screening is required in front of building entrances or where the property line of the down slone facade abuts public or private open space. At a minimum, the following plant materials shall be provided: a. A minimum of one tree shall be required for each 12 feet of building length along the down slope facade or facades. b. Trees shall be of a species that reaches a minimum height of 18 feet at maturity. c. Trees shall be planted within 20 feet of the wall or walls that they are intended to screen. 6. Special Setbacks for Sloped Lots. Where the average lot slope is 20% or more as measured from the front lot line to the most distant point of the dwelling, the minimum required front yard setback shall be 18 feet. Page 10 01/25/2007 Appendix 50.7-D Front Setback Plane Sloped Lots—Unslone Direction A Averaue Lot Slope Minimum 6:12 Pane B e�baG�tc` Pto .\ri� Qe 35 2 I A I � � I J I 2E' a I o a 2 Sloped Lot a ROW 14A i 10' Side View Legend -I Permitted Building Envelope A Front Yard Setback B Maximum Building Height 01/25/2007 Handout - December 14, 2006 Sloped Lot—Height Measurements/Application of Side Yard Setback Planes Problem: Sloping lots may have problems complying with side yard setback plane requirements. Lots that are sloping but don't meet the City's definition of sloped lot(10 feet of elevation change across the building envelope)may also face problems. Solutions: Option 1: For lots/houses that aren't currently classified as sloped lots, measure height at the midpoint of the house along the side of the house. Option 2: Consider a sliding scale for heights related to the elevation change across the footprint: R-6 and R-7.5 Zones Fall across 0 1' 2' 3' 4' 5' 6' 7' 8' 9' 10' lot—in feet Height 28' 28' 29' 30' 30' 31' 32' 32' 33' 34' 35' Side Yard Setback Plane Examples: The following pages include conceptual illustrations of side yard setback planes under different lot slope scenarios. Example 3 includes an option to increase the slope of the side yard setback plane when slopes are very steep. Page 12 01/25/2007 w Example 1 Side Yard Setback Plane on Sloped Lots Approximately 22% Slope Current - - ___ _ building New building envelope- Side ` s, envelope yard setback plane 12:12 slope - -----_ _ at 12' above property line T ,/,4::' -- 12:12 -- -- ITI 10 7.5' 35' f-- ► >1iH . _2: 7.5' _ 60' > Section from side yard to side yard Page 13 01/25/2007 Page 14 01/25/2007 Example 2 Side Yard Setback Plane on Sloped Lots Approximately 16% Slope Current building New building envelope - Side envelope yard setback plane 12:12 slope at 12' above property line 1?:12 ♦ 10' ss 28' 7 5' 60' Section from side yard to side yard Page 15 01/25/2007 Example 3 Side Yard Setback Plane on Sloped Lots Approximately 44% Slope ter` ,, , , 24:12 - 200% slope— option for side yard setback plane 12:12 - 100% -:, slope I, • 7:\r:___ 7.5' ,...,,,i,.....,...—j--: ,, ,, T— , >10' _ i • I f 60' Y Section from side yard to side yard L Option for an increase to the slope of the side yard setback plane. Page 16 01/25/2007 Meeting Notes Subcommittee 1 - Meeting Notes — January 19, 2006 Work Session—Sloped Lots Dennis Egner said the Planning Department had drafted sloped lot standards but decided to shelve them when Measure 37 passed. Dennis gave a PowerPoint presentation highlighting various aspects of the proposed standards, including measurement clarifications, new height limits indexed to slope,and appearance and screening standards for structures over 35 feet. Brad Beals suggested that strict appearance standards should only apply to building segments visible from the street or from neighboring properties. Ralph Tahran expressed concern that those appearance standards could make structures seem more imposing. Dennis Egner explained that the goal was to push the bulk of these houses away from the street. Sheila Ostly noted that sloped lots were increasingly considered buildable because so few vacant flat lots were left. Dennis Hartman asked how many sloped lots were in Lake Oswego, and Stephan Lashbrook said there were hundreds. Stephan also said that reviewing development applications for these lots was complex and consumed a lot of staff time. Dennis Hartman said standards should be as straightforward as possible, and Ted Argo added that complying with complex rules significantly increases design and construction costs. Ted said he thought the proposed sloped lot standards made sense overall, but he made several suggestions. He said minimum slope vs. maximum slope should be addressed explicitly in the Code. He recommended front setback plane— upslope standards should be tested. Finally, Ted expressed concern that landscape standards could require more trees than would be viable. Patt Thomas asked about safety and seismic risk on sloped lots. Stephan Lashbrook said that many geological and soil qualities factored into risk, not just slope. Brad Beals noted that the homes currently threatened with mudslides in Oregon City were cheaply-built. Subcommittee 1 - Summary Memo - February 2, 2006 Sloped Lots—It was emphasized the front set back plane is a problem for sloped lots. Proposed changes include: Front Setback Plane -Rather than require a 6:12 front setback plane,the front setback plane slope should correspond to the average slope of the site. Front Setback Plane—Lots sloping downhill (away from the street) at more than 12% should set the point at which the front set back plane height is measured at one of the following locations: 1) Three feet below the elevation of the curb line; or 2) At the average grade of the front two property corners. Page 17 01/25/2007 Setbacks on Sloped Lots—Allow an 18 foot minimum setback (from the sidewalk) on lots with an average slope of greater than 20-25%. Subcommittee 1 - Meeting Notes - February 2, 2006 III. Work Session— Sloped Lots Denny Egner then discussed the proposed slope lots standards that he, Ted Argo, and Ralph Tahran had crafted. One component would tie the front setback plane of a sloped lot to its average slope, since the 6:12 standard severely limited buildable space on some lots. Another component would allow 18-foot front setbacks for steeply sloped lots. Ted Argo explained that driveways could not climb too steeply, so deeper setbacks made some lots unbuildable. Ted added that houses on sloped lots should be no more imposing from the street than two-story houses on flat lots. The group discussed various methods and starting points from which to measure front setback plane. Patt Thomas suggested a method drawing a line from the midpoint of the lot frontage to the midpoint of the back side of the lot. Denny Egner agreed to discuss this question further with staff. Dennis Hartman emphasized the need for easy-to-understand standards, especially since neighborhood associations would play a role. Brad Beals said an infill handbook with graphics was essential. Subcommittee 1 - Meeting Notes - February 16, 2006 Work Session —Sloped Lots The group continued to discuss the recommendations summarized in Denny Egner's memo: 1. Except as noted below, apply the proposed sloped lot standards recommended by the Planning Commission. There were no comments on this item. 2. Adjust the standards so that support structures do not need to be enclosed. The group did not reach consensus on this issue. Several members expressed concerns about tall, unsightly support structures, but most were unsure whether enclosing them would be better or worse. Sheila Ostly noted that the placement of mechanicals could be an issue. Others noted that maximum plane area standards would require frequent wall offsets in enclosed support structures. 3. Define "steep slope"as an average slope greater than 20%. Measure average slope between the front lot line and the most distant point of the building. Page 18 01/25/2007 Ralph Tahran said designers could manipulate building outlines to meet the sloped lot definition and obtain greater height. Patt Thomas asked if slope averaging could provide greater height potential with less slope than the current standard. Denny Egner said that was possible. Sheila Ostly asked about flag lots and Ted Argo responded that measurement on flag lots should not include the pole. 4. Front Setback Plane—On steeply sloped properties (a slope greater than 20%), rather than require a 6:12 front setback plane, the front setback plane should be established based on the average slope of the land. Patt Thomas suggesting changing"greater than 20%"to "20%or more." Denny Egner said he would ask the Current Planning Department to review this item. 5. Front Setback Plane— On lots sloping downhill(away from the street)at more than 12%, the point at which the front set back plane height is measured should be set at one of the following locations: 1) Three feet below the elevation of the curb line; or 2)At the average grade of the front two property corners. Sheila Ostly asked what the rationale was for the 12% standard and Ted Argo explained that driveway incline was the constraint. 6. Setbacks on Sloped Lots—Allow an 18 foot minimum setback (from the right- of-way) on lots with an average slope of greater than 20%. Task Force - Meeting Notes — April 6, 2006 V. Work Session—Sloped Lots Denny Egner explained that current sloped lot standards encourage multi-level houses and some homeowners had complained about limited space on the main floor. He explained how the proposed revisions attempted to address this concern. Adrianne Brockman said the proposal's impact on downslope neighbors was alarming. Patt Thomas suggested the proposal would lead to smaller houses. Denny said Subcommittee 1 thought supporting beams under sloped lot houses should be open rather than enclosed and the ground landscaped to the extent possible. Marylou Colver agreed that big,blank walls on enclosed structures were undesirable. Ted Argo thought the proposed options for height measurement locations could be abused and recommended careful wording to avoid this. Brad Beals mentioned problems when side slopes were combined with back slopes. Sherry Finnigan asked about houses that front downhill streets,and Ted Argo responded that front setback planes would step down the hill. Ralph Tahran noted that the maximum street grade in Lake Oswego was 20%. Jim Bolland suggested increased side yard setback areas on sloped lots. Patt Thomas added that the proposed side yard setback plane would apply. Dennis Hartman Page 19 01/25/2007 questioned whether the City was obligated to accommodate conventional houses on sloped lots. Denny explained how the current front setback plane was especially restrictive on upslope lots and presented a proposal to tie the front setback plane to lot slope. Ted Argo added that there were limits to how steep driveways could be. Dennis Hartman suggested a smaller group of experts consider these issues and then present findings to the full Task Force. Patt Thomas said sketches would be helpful. Jim Bolland added it would also be helpful to see examples from other cities. Marylou Colver asked that the question of design review for large houses be put on the agenda for a future meeting. Task Force - Meeting Notes — December 14, 2006 (draft) IV. Work Session Sloped Lot Issues—Stephan Lashbrook said the Task Force may want to consider simplifying height standards and adopting a default height standard that would allow all applicants to build at least a 1 'A story house regardless of the location and slope. Ted suggested the following methodology to measure height for the front setback plane on sloped lots: Measure from the average of the front two property corners and subtracting two feet. He said the same type of methodology should be applied to side yard setback planes. The Task Force discussed characteristics of sloped lots and side to side relationships. Doug Cushing asked how the Glenmorrie house with the sloped side yards (on the tour) would fare under the proposals. Testing was proposed. Ted suggested that new trees will mitigate most large walls. Brad suggested looking at examples of sloped lots to see what works and what doesn't. Denny agreed to collect images of sloped lot properties for a work session. 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