Today we will look at the form शाद्वले mLs from श्रीमद्भागवतम् 10.13.7.

तथेति पाययित्वार्भा वत्सानारुध्य शाद्वले ।
मुक्त्वा शिक्यानि बुभुजुः समं भगवता मुदा ॥ १०.१३.७ ॥

श्रीधर-स्वामि-टीका –
आरुध्य संरुध्य । शाद्वले हरिततृणे देशे ॥ ७ ॥

Gita Press Translation – Saying “Amen!”, the (cowherd) boys made the calves drink water, set them to feed on the green grass, opened their bags and lunched with the Lord in (great) delight. (7)

शादाः सन्त्यस्मिन्निति = शाद्वलः (देशः) – A place abounding in green grass.
In the verse, the विवक्षा is सप्तमी-एकवचनम् । Hence the form is शाद्वले।

(1) शाद जस् + ड्वलच् । By 4-2-88 नडशादाड्ड्वलच् – To denote any of the four senses* prescribed by the rules 4-2-67 through 4-2-70, the तद्धितः affix ‘ड्वलच्’ may be optionally applied following a syntactically related सुबन्तं पदम् (a पदम् ending in a सुँप् affix) in which the सन्धिः operations have been performed, provided the base is either ‘नड’ or ‘शाद‘।
Note: *Even though the affix ‘ड्वलच्’ prescribed by this rule could denote any of the four senses prescribed by the rules 4-2-67 through 4-2-70, in practice it is only used to denote the sense prescribed by the rule 4-2-67 तदस्मिन्नस्तीति देशे तन्नाम्नि।

(2) शाद जस् + वल । अनुबन्ध-लोपः by 1-3-3 हलन्त्यम्, 1-3-7 चुटू, 1-3-9 तस्य लोपः ।
Note: ‘शाद जस् + वल’ gets the designation प्रातिपदिकम्‌ by 1-2-46 कृत्तद्धितसमासाश्च। This allows 2-4-71 सुपो धातुप्रातिपदिकयोः to apply in the next step.

(3) शाद + वल । By 2-4-71 सुपो धातुप्रातिपदिकयोः – A सुँप् affix takes a लुक् elision when it is a part of a धातुः or a प्रातिपदिकम्।

(4) शाद् + वल । By 6-4-143 टेः – When the अङ्गम् has the भ-सञ्ज्ञा, then its टि portion (ref: 1-1-64 अचोऽन्त्यादि टि) takes लोप: when followed by an affix that has the letter ‘ड्’ as an indicatory letter. Note: The अङ्गम् does not have the भ-सञ्ज्ञा here. But still टि-लोप: is done because otherwise no purpose would be served by having the letter ‘ड्’ as a इत् in the affix ‘ड्वलच्’। डित्वसामर्थ्यादभस्यापि टेर्लोपः।

= शाद्वल । Note: Since ‘शाद्वल’ qualifies the masculine noun ‘देश’, the प्रातिपदिकम् ‘शाद्वल’ declines like राम-शब्दः।

Similarly,
नडाः सन्त्यस्मिन्निति = नड्वलः (देशः) – A place abounding in reeds.